egyptian german high level joint committee for renewable...

Egyptian German High Level Joint Committee for

Renewable Energy, Energy Efficiency and Environmental

Protection

Electric Utility and Consumer Protection Regulatory

Agency

Boosting Capacity of Electric Generation through the use of

Turbo-Expanders in Natural Gas Network

Prepared by

In collaboration with

Dr. Mohamed Salah Elsobki (jr.)

Professor Electric Power Engineering

Director Energy Research Center

Faculty of Engineering – Cairo University

November 2013

Egyptian German High Level Joint Committee for Renewable

Energy, Energy Efficiency and Environmental Protection

Electric Utility and Consumer Protection Regulatory Agency

Boosting Capacity of Electric Generation through the use of

Turbo-Expanders in Natural Gas Network

Prepared by

6 Dokki St. 12th Floor, Giza 12311 Tel.: (+2010) 164 81 84 – (+202) 376 015 95 – 374 956 86 / 96

Fax: (+202) 333 605 99

Email: [email protected]

Website: www.environics.org

In collaboration with

Dr. Mohamed Salah Elsobki (jr.)

Professor Electric Power Engineering

Director Energy Research Center

Faculty of Engineering – Cairo University

November 2013

mailto:[email protected]

http://www.environics.org/

Boosting Capacity of Electric Generation through the use of Turbo-Expanders in Natural Gas Network iii

Environics in collaboration with Mohamed Salah Elsobki (jr) November 2013

Executive Summary

The Egyptian energy sector is becoming more reliant on natural gas as a prime source of

energy. The use of natural gas has increased by 6.5% in the year 2010/2011 compared with the

year before. It reached 29,210 million cubic meters the last year in the electricity sector1. A

range of 55%2 to 60%

3 of the domestic natural gas production is utilized by electricity sector.

More than 80% of electric generation power plants have been converted to use natural gas.

This tendency toward using natural gas is attributed to its availability, its higher combustion

efficiency and positive environmental impact as compared to other fossil fuels. As a result of

the increasing demand for natural gas, the Egyptian Government seeks more efficient options

for power generation in addition to renewable energy sources.

Nowadays, the energy crisis has pushed for the need to recover the energy which is normally

wasted in industrial processes. Gas pressure reducing process in power stations is one of these

processes in which the energy is wasted due to the presence of pressure reduction valves.

Natural gas is transported in pipelines at high pressures. To distribute the gas locally to

locations along the pipeline, the pressure must be reduced before the gas enters the local

distribution system. Most pressure reduction stations use throttling valves for this purpose

which is an energy wasting process.

In order to reduce the wasted energy, the pressure drop can be achieved by passing the gas

through a turbo-expander which generates electrical power. Based on the inlet and outlet

properties of natural gas flow and its flow rate, the amount of electricity which can be

produced from natural gas pressure reduction could be calculated when using a turbo-expander.

The study shows the increase of generation capacities and energy production through the use of

turbo-expanders in natural gas networks and assesses the potential of extracting electric

generation capacities from wasted energy in the natural gas pressure reduction stations of

electricity power plants. An estimated overall additional capacity at about 91MW, with

individual capacity ranging between 70 kW and 5.78 MW, could be generated through the use

of turbo-expanders in the existing natural gas networks. In addition, different issues are

addressed such as sizing of the turbo-expander as well as temperature constraints related to the

natural gas.

Turbo-expander generates an additional 800 GWh without affecting the natural gas

consumption by power plants. The total natural gas avoided per year is estimated to reach 130

ktoe compared to 21,663 ktoe consumed by the existing power plants. This will lead to 45 tons

savings of CO2 emissions which represents about 0.6% of the total CO2 emissions from the

existing power plants. Although turbo-expander installations involve high capital cost, they

also give high annual natural gas savings. This explains the short payback period which in case

of using unsubsidized natural gas prices ranges between 2 and 5 years.

1 Ministry of Electricity and Energy, “Annual Report 2011/2012”

2 “The Development of the Natural Gas Industry in Egypt and the World Presentation”, presented at the World

Energy Council Meeting (WEC), Cairo, Egypt, June 28th

, 2012 3 New and Renewable Energy Authority (NREA), “Annual Report 2010/2011”

Boosting Capacity of Electric Generation through the use of Turbo-Expanders in Natural Gas Network iv


Table of Contents Executive Summary .................................................................................................................... iii

Table of Contents ........................................................................................................................ iv

List of Figure............................................................................................................................... vi

List of Tables ............................................................................................................................. vii

List of Abbreviations ................................................................................................................ viii

1 Natural Gas Networks Scene in Egypt .................................................................................... 1

1.1 Introduction ................................................................................................................... 1

1.2 Development of Natural Gas Usage .............................................................................. 1

1.3 Development of Natural Gas Local Consumption ........................................................ 2

1.3.1 Natural Gas Local Consumption by Sector ........................................................... 2

1.4 Future Natural Gas Demand .......................................................................................... 5

1.4.1 Prospects of Natural Gas Demand to 2030 according to OME Estimates ............. 5

1.4.2 Prospects of Natural Gas Demand till 2030 according to Nexant’s Estimates ...... 6

1.5 Egyptian Natural Gas Supply Chain ............................................................................. 8

1.6 Natural Gas Network Development ............................................................................ 10

1.7 Pressure Levels in Natural Gas Network .................................................................... 13

1.8 Natural Gas Transportation and Distribution Grid ...................................................... 13

1.8.1 Pressure Reduction Stations (PRS) Operation ..................................................... 14

2 Turbo-Expander Mechanism ................................................................................................. 16

2.1 Power Generation through Natural Gas Pressure Reduction ...................................... 17

2.2 Temperature Constraints ............................................................................................. 18

3 Potential of Energy Recovery from the Gas Network in Egypt ............................................ 19

3.1 Identification of Possible Stations for the Installation of Turbo-Expanders ............... 20

4 Possible Electric Capacity Output from the Identified Possible Turbo-Expander Installations

25

4.1 Evaluating the Potential of Electricity Generation from Natural Gas Pressure

Reduction Stations................................................................................................................. 27

4.2 Technical Assessment of Generation Potential from PRS .......................................... 28

4.2.1 The Possible Electric Capacity Output ................................................................ 28

4.2.2 Environmental Impact and Natural Gas Avoided ................................................ 30

Boosting Capacity of Electric Generation through the use of Turbo-Expanders in Natural Gas Network v


5 Economic Assessment for the Application ........................................................................... 34

5.1 Factors Affecting the Project Economics ................................................................... 34

5.1.1 Capital Costs ........................................................................................................ 34

5.1.2 Operating Costs .................................................................................................... 34

5.1.3 Revenue from Power Sales .................................................................................. 34

5.1.4 Pressure Ratio ...................................................................................................... 34

5.1.5 Flow Rate ............................................................................................................. 35

5.2 System Cost Calculation ............................................................................................. 35

5.3 Potential Profit Margin ................................................................................................ 41

6 Assessment of Operating the Proposed Units in Parallel with the Existing Electricity

Systems ...................................................................................................................................... 45

7 The Current Institutional Setup and Relevant National Legislations .................................... 48

7.1 Description of the Electricity Market Structure .......................................................... 48

8 Expected Roles for the Different Stakeholders including Owners of the NG Networks and

Pressure Reduction Stations ....................................................................................................... 50

Annex A. Important Definition and Basic Concept of some Thermodynamics Properties ......... 1

Annex B. Evaluating the Potential of Electricity Generation from Industrial and Residential

Sector ........................................................................................................................................... 1

Annex C. Request Letters sent to EGAS and GASCO ................................................................ 1

Annex D. Units Conversion Tables ............................................................................................. 1

Annex E. Natural Gas Measurements and Conversions .............................................................. 1

Annex F. Characteristics of some Gas Pressure Regulating and Metering Station in Egypt and

other Countries ............................................................................................................................. 3

Boosting Capacity of Electric Generation through the use of Turbo-Expanders in Natural Gas Network vi


List of Figure Figure ‎1-1 Natural Gas Total Demand Development (1990/1991-2010/2011) ......................................... 2

Figure ‎1-2 Natural Gas Consumption by Sector (2010-2011) ................................................................... 4

Figure ‎1-3 Natural Gas Consumption by Industrial Subsectors (2010-2011) ............................................ 4

Figure ‎1-4 Natural Gas Demand Development by Sector during the Period (2009/2010-2030) ............... 6

Figure ‎1-5 Natural Gas Demand Development in Egypt till 2029/2030.................................................... 7

Figure ‎1-6 Simplified Schematic Diagram for the Natural Gas Chain ...................................................... 9

Figure ‎1-7 Natural Gas Network in Egypt .............................................................................................. 11

Figure ‎1-8 Schematic Diagram for Pressure Levels in the Gas Network of Egypt ................................ 13

Figure ‎1-9 Schematic Diagram for Natural Gas City Distribution Network .......................................... 14

Figure ‎2-1 Different Pressure Reduction Processes ................................................................................. 16

Figure ‎2-2 Schematic Diagram of a Turbo-Expander Driving a Compressor ......................................... 17

Figure ‎2-3 Power Generation through Natural Gas Pressure Reduction ................................................ 18

Figure ‎2-4 Schematic Diagram for a Turbo-expander Installed Parallel to the Existing ........................ 19

Figure ‎3-1 The Recommended Pressure Reduction Levels for Turbo-Expander Installation ................. 20

Figure ‎4-1 Variation of Turbo-expander Efficiency with Gas Flow Rate ............................................... 26

Figure ‎4-2 Potential Power Generation versus Flow and Pressure Ratio ................................................ 28

Figure ‎6-1 A Generator Being Paralleled with A Running Power System .............................................. 46

Figure ‎6-2 Parallel Operation - Synchronizing Generators ..................................................................... 46

Figure ‎6-3 Parallel Connection Control System ..................................................................................... 47

Figure ‎7-1 Current Electricity Market in Egypt ....................................................................................... 48

Figure ‎7-2 Phase Two towards Market Structure ........................................ Error! Bookmark not defined.

Figure ‎7-3 Phase Three towards Market Structure ...................................... Error! Bookmark not defined.

Boosting Capacity of Electric Generation through the use of Turbo-Expanders in Natural Gas Network vii


List of Tables Table ‎1-1 Development of Electricity Demand ........................................................................................ 1

Table ‎1-2 Natural Gas Consumption by Sector (2010/2011) ..................................................................... 4

Table ‎1-3 Natural Gas Demand in Egypt in 2029/2030 ............................................................................. 7

Table ‎1-4 Natural Gas Demand Development in Egypt (2008/2009-2029/2030) ..................................... 8

Table ‎1-5 Recent Domestic Natural Gas Pipelines Characteristics ........................................................ 12

Table ‎1-6 Recently Added Natural Gas Pipelines ................................................................................... 12

Table ‎3-1 Fuel Type and Estimated NG Consumption of Generation Power Plants .............................. 21

Table ‎4-1 Examples of Power from Gas Pressure Reduction .................................................................. 27

Table ‎4-2 Expected Electricity Generation at Power Plants by Turbo-Expander .................................... 29

Table ‎4-3 The Annual Natural Gas Avoided Cost ................................................................................... 31

Table ‎5-1 Total Capital Costs and Payback Period for Turbo-Expander Installations ............................ 36

Table ‎5-2 Turbo-Expander Annualized Total Cost .................................................................................. 38

Table ‎5-3 The Average Cost of Energy at Electricity Production Companies ........................................ 41

Table ‎5-4 Capital Cost of Turbo-Expander versus the Annual Profit ...................................................... 43

Table ‎7-1 Recent Effectively Prevailing Legislations in Egypt ................... Error! Bookmark not defined.

Table ‎7-2 Electricity Market Limitations .................................................... Error! Bookmark not defined.

Boosting Capacity of Electric Generation through the use of Turbo-Expanders in Natural Gas Network viii


List of Abbreviations

BBOE billion barrels of oil equivalent

BCF/Y billion cubic meters per year

bcm billion cubic meters

BOOT Build Own Operate and Transfer

CNG Compressed Natural Gas

EEA Egyptian Electricity Authority

EEHC Egyptian Electricity Holding Company

EETC Egyptian Electric Transmission

EEUCPRA Egyptian Electric Utility and Consumer Protection Regulatory Agency

EGAS Egyptian Natural Gas Holding Company

EGP Egyptian pound

EGPC Egyptian General Petroleum Corporation

EHV Extra High Voltage

GASCO Egyptian Natural Gas Company

GoE Government of Egypt

hp Horsepower

HV High Voltage

IBE Investment Bank of Egypt

IPP Independent Power Producers

ISP Independent Service Providers

ktoe kilo ton oil equivalent

kWh kilo Watt hours

LCOE Levelized Cost of Energy

LNG Liquefied Natural Gas

LPG Liquefied Petroleum Gas

Mio Million

MMSCF/D million standard cubic feet per day

MoEE Ministry of Electricity and Energy

MoP Ministry of Petroleum

MW Mega Watt

NG Natural Gas

NGG Natural Gas Grid

NGL Natural Gas Liquid

NREA New and Renewable Energy Authority

OME Observatoire Mediterraneen de l'Energie

PPA Power Purchase Agreements

Boosting Capacity of Electric Generation through the use of Turbo-Expanders in Natural Gas Network ix


PR Pressure Reduction Ratio

PRS Pressure Reduction Stations

PRVs Pressure Reducing Valves

T.Exp. Turbo-Expander

TCF trillion cubic feet

toe ton oil equivalent

WEC World Energy Council

Boosting Capacity of Electric Generation through the use of Turbo-Expanders in Natural Gas Network 1


1 Natural Gas Networks Scene in Egypt

1.1 Introduction

The energy system in Egypt relies mainly on depleted oil and natural gas resources to satisfy

energy needs for social and economic development. In 2010/2011, total primary energy

production reached 89.756 million ton oil equivalent (Mtoe) of which natural gas represented

about 59.1% compared to 37.5% for oil, 3% for hydropower and only 0.4% for other

renewable sources4.

The last few decades have witnessed a tremendous increase in energy demand with an average

annual growth rate of about 4% for petroleum products, more than 10.4% for natural gas and

about 7% for electricity, a situation which lead to a remarkable increase in petroleum energy

subsidy that reached about 114 billion EGP during the year 2011/20125. Unless immediate and

effective measures are taken to curb the energy demand, the energy situation in Egypt will

worsen, adversely affecting social and economic development plans. Table ‎1-1 shows the

development of electricity over the last five years up to the year 2012.

Table ‎1-1 Development of Electricity Demand 6

2007/2008 2008/2009 2009/2010 2010/2011 2011/2012

Peak Load (MW) 19,738 21,330 22,750 23,470 25,705

Fuel Consumption

(ktoe) 23,562 24,895 26,772 27,430 29,728

Fuel Consumption Rate

(gm o.e/kWh gen) 218.9 217.6 215.6 208.1 209

Natural gas to Total

Fuel Ratio (%) 79.3 78 77.7 80.4 84.3

1.2 Development of Natural Gas Usage

The total demand for natural gas increased from 8.5 billion cubic meters (bcm) in 1990/1991 to

61.7 bcm in 2010/2011 with an average annual growth rate of about 10.4% during that period,

as shown in Figure ‎1-1. Local consumption of natural gas reached 46.9 bcm in 2010/2011 with

an average annual growth rate of about 8.7% during that period.

Total exports to the international gas market accounted for about 14.8 bcm with a share of

about 24% of the total natural gas demand during 2010/2011 compared to a consumption of

46.9 bcm for the local market with a share of 76%.7

4 “Energy in Egypt Presentation 2010/2011”, presented at the World Energy Council (WEC) Meeting, Cairo,

Egypt, June 28th

, 2012. 5 “The Development of the Natural Gas Industry in Egypt and the World Presentation”, presented at the WEC

Meeting, Cairo, Egypt, June 28th

, 2012 6 EEHC, “Annual Reports”

7 Source:

“The Development of the Natural Gas Industry in Egypt and the World Presentation”, presented at the WEC


, 2012

EGAS



Figure ‎1-1 Natural Gas Total Demand Development (1990/1991-2010/2011)8

1.3 Development of Natural Gas Local Consumption

As shown in Figure ‎1-1, local consumption of natural gas increased from 8.5 bcm in

1990/1991 to reach 46.9 bcm in 2010/2011 with an average annual growth rate of about 8.7%

during that period.

1.3.1 Natural Gas Local Consumption by Sector

As shown in

8 Source:

• “The Development of the Natural Gas Industry in Egypt and the World Presentation”, presented at the WEC

Meeting, Cairo, Egypt, June 28th, 2012

• EGAS



Table ‎1-2, Figure ‎1-2 and Figure ‎1-3, total local consumption of natural gas reached about

1,657 BCF/Y (about 4,533 MMSCF/Day) in the year 2010/2011. The Electricity sector is the

main natural gas consumer with a share of about 56% of total natural gas consumption during

that year (2010/2011) compared to 30% for industry, 12 % for the petroleum sector, 2% for

transport and 1% for residential & commercial sectors. 9

Fertilizer production is the major natural gas consuming10

industrial subsector with a share of

about 38% of the total industrial natural gas consumption during the year (2010/2011).It is

followed by cement 22% then iron & steel 11% while other industrial subsectors such as

refractories, textile, food, etc. represent 29% as shown in Figure ‎1-3.

9 EGAS: “Annual Report 2010/2011”.

10 Not only as energy source but also as raw material



Table ‎1-2 Natural Gas Consumption by Sector (2010/2011)11

Sector MMSCF/D BCF/Y %

Electricity 2,517 919 56%

Fertilizer 507 185 11%

Iron & Steel 151 55 3%

Cement 290 106 6%

Other 397 145 9%

Petroleum 526 192 12%

Residential 101 37 2%

Transport 44 18 1%

Total 4,533 1,657 100%

Figure ‎1-2 Natural Gas Consumption by Sector (2010-2011

Figure ‎1-3 Natural Gas Consumption by Industrial Subsectors (2010-2011)

11

EGAS: “Annual Report 2010/2011”.

Electricity56%

Fertilizer11%Iron & Steel

3%

Cement6%

Others9%

Petroleum12%

Residential2%

Transport1%

Total = 4533 MMSCF/D = 1657 BCF/Year

Fertilizer38%

Iron & Steel11%

Cement22%

Others29%

Total = 1345 MMSCF/D = 491 BCF/Year



1.4 Future Natural Gas Demand

Several studies for estimating natural gas demand in the coming years have been made by

EGAS in cooperation with some international firms such as Observatoire Mediterraneen de

l’Energie (OME) and Nexant; the following section presents the most important outputs of

each.

1.4.1 Prospects of Natural Gas Demand to 2030 according to OME Estimates

During the period (2009-2010), the OME in cooperation with the Egyptian Energy Holding

Company EGAS prepared the Mediterranean Energy Perspectives for the year 2010 with the

main focus on the Egyptian energy sector. One of the main issues that have been assessed by

that publication is the possible future evolution of natural gas consumption during the period

(2008-2030). In building up the demand forecast for the different energy commodities in

Egypt, including natural gas during the period (2008-2030), four scenarios have been

considered; these are:

1. The Conservative or business as usual Scenario: considers past trends, policies in force in

addition to ongoing projects. However, it takes a more cautious approach regarding the

implementation of policy measures and planned projects. At the same time this scenario

considers no implementation of large scale demand efficiency programs and no major

efforts for energy conservation.

2. The Proactive Scenario which considered a progressive energy efficiency program and a

more diversified energy supply mix which include the nuclear option in addition to higher

share of renewable energy.

3. Two High Economic Growth Scenarios based on the economic growth projections of the

Egyptian Ministry of Economic Development. While the High Economic Growth Scenario

(HEG) presents the impact of a more sustained economic growth; the High Economic

Growth Diversification Scenario (HEG Div) presents a future with a significantly

diversified electricity generation mix (Coal 12.5% , oil and gas 52.5% of which 20% of

oil and 80% of gas, nuclear 12.5%, and renewable 22.5%).

According to the results obtained by the utilization of a tailored model for Egypt which

developed by OME, and as shown from Figure ‎1-4:

Natural gas demand is expected to increase from about 44 Billion Cubic Meters (BCM) in

2009/2010 to about 90 to 120 BCM in 2030 according to the different scenarios.

The electricity and industrial sector are expected to have a share of more than 80% of total

natural gas demand in all scenarios during the forecast period (2009/2010-2030).



Figure ‎1-4 Natural Gas Demand Development by Sector during the Period (2009/2010-2030)12

1.4.2 Prospects of Natural Gas Demand till 2030 according to Nexant’s Estimates

Natural gas demand in Egypt is estimated through a study entitled “Egypt Energy Strategy till

2030” prepared in 2009-2010 by Nexant Corporation in cooperation with EGAS and other

concerned entities in Egypt.

According to that study and as shown in Figure ‎1-5, Table ‎1-3 and Error! Reference source

not found. 13

:

Total domestic and export demand for natural gas is expected to grow by an average

3.6-3.5% till 2030 to reach about 13.9-14.7 MMSCF/D in 2030 according to EGAS and

Nexant estimates, respectively.

The highest natural gas demand growth rates are expected to occur in the industrial

sector, in particular the petrochemical industry.

Both EGAS and Nexant forecasts estimate that the power sector will be the largest gas

consuming sector, contributing to 53% of the total gas demand by 2030. It is expected

to be followed by exports and the industrial sector, which will make up to 15% and

25%, respectively in 2030.

12

Source: Mediterranean Energy Perspectives- Egypt, OME, 2010. 13

Egypt Energy Strategy to 2030, “Final Report, Section 5”, Nexant, February 2009



Figure ‎1-5 Natural Gas Demand Development in Egypt till 2029/2030

Table ‎1-3 Natural Gas Demand in Egypt in 2029/2030

EGAS Forecast Nexant Forecast

Average Annual

Growth, percent

Gas Demand

(MMSCFD)

Average Annual

Growth, percent

Gas Demand

(MMSCFD)

2009 to

2019

2009 to

2030 2029/30

2009 to

2019

2009 to

2030 2029/30

Power 4.7 3.8 4,923 5.3 5.2 7,795

Fertilizers 5.6 4.2 1,172 4.2 2.7 1,033

Petrochemicals 42.2 18.9 493 45.8 20.8 584

Steel 14.2 7.1 675 11.9 6.7 657

Cement 8.4 5.5 1,320 3.8 2.7 588

Other Industries 16.1 10.2 2,863 6.0 4.9 679

Petroleum &

Gas Derivatives 7.4 6.1 728 10.4 4.0 680

Residential &

Commercial 9.5 7.7 433 10.6 6.0 284

CNG 10.1 10.0 285 10.1 7.6 174

Exports -2.4 4.1 1,005 -2.0 0.6 2,205

Total Demand 6.1 3.6 13,896 4.8 3.5 14,679



Table ‎1-4 Natural Gas Demand Development in Egypt (2008/2009-2029/2030)

Demand

Side

Transport

R&C, LI

Industries

Power Exports Other

Industries

EI

Industries

Total

Demand

2008/9 368 2,704 2,440 1,054 506 7,072

2009/10 417 2,906 2,640 1,141 552 7,656

2010/11 474 2,938 2,660 1,252 630 7,953

2011/12 516 3,163 2,830 1,366 738 8,612

2012/13 562 3,351 3,025 1,600 817 9,356

2013/14 611 3,595 3,080 1,858 863 10,007

2014/15 660 3,783 3,080 1,909 890 10,321

2015/16 685 3,984 3,080 1,970 917 10,637

2016/17 712 4,036 3,055 2,014 946 10,763

2017/18 739 4,268 3,055 2,057 975 11,094

2018/19 767 4,535 3,055 2,103 1,005 11,465

2019/20 796 4,789 3,055 2,143 1,024 11,807

2020/21 825 5,046 3,055 2,191 1,043 12,160

2021/22 856 5,149 3,055 2,235 1,063 12,359

2022/23 888 5,480 2,910 2,283 1,083 12,643

2023/24 920 5,630 2,645 2,301 1,104 12,600

2024/25 954 5,987 2,645 2,334 1,125 13,044

2025/26 988 6,166 2,645 2,321 1,146 13,266

2026/27 1,024 6,592 2,415 2,311 1,168 13,510

2027/28 1,061 6,842 2,415 2,304 1,191 13,813

2028/29 1,099 7,309 2,205 2,297 1,217 14,125

2029/30 1,138 7,795 2,205 2,297 1,245 14,679

Where,

LI Industry: Low Energy Intensity Industry,

EI Industries: Energy Intensive Industries e.g. cement, Iron& steel, Fertilizers, etc.

It is worth mentioning that due to the decision made by the Ministry of Petroleum (MoP) in

2011 to stop gas exports through the eastern gas pipeline and through the Arab gas pipeline due

to continued attacks to it, the previous mentioned estimates (Exports) are expected to be

decreased.

1.5 Egyptian Natural Gas Supply Chain

Normally, natural gas is produced from gas wells at high pressure that could be at an average

level of about 60-70 bars. Such is the case of most natural gas wells in Egypt. Starting from

the gas producing wells till the gas consuming centers passing through transmission and

distribution systems and networks; natural gas is subject to several treatment processes to



extract valuable derivatives such as condensates for refineries, ethane and propane for

petrochemical industries and LPG for residential & commercial sectors.

In addition, undesirable components that could be harmful to the environment, consumer’s

health and equipment such as mercury and carbon dioxide (CO2) are also removed through

treatment and processing facilities. This leaves gas that is mainly composed of methane (CH4)

to be pumped through the network pipelines to the domestic consumers. Figure ‎1-6 shows a

simplified schematic diagram for the natural gas chain.

Figure ‎1-6 Simplified Schematic Diagram for the Natural Gas Chain14

Where,

C2/C3: Mixture of ethane and propane,

GTL: Gas to Liquids,

LNG: Liquefied Natural Gas,

LPG: Liquefied Petroleum Gas and,

NGL: Natural Gas Liquefaction

14

Source: EGAS [Online], Available at: http://www.egas.com.eg/Egyptian_Natural_Gas/Introduction.aspx

http://www.egas.com.eg/Egyptian_Natural_Gas/Introduction.aspx



Meanwhile, as natural gas is utilized by different consumers at low pressures 7, 4 and 2 bars.

The high pressure of natural gas produced at the well-head (normally at 60-70 bars as

mentioned above) is reduced through throttling or Pressure Reducing Valves (PRVs) that result

in large amounts of energy loss. This valuable potential energy can be either a source for

power generation, or an energy saving measure for process industries consuming large

volumes of natural gas.

1.6 Natural Gas Network Development

In order to keep up with the growth of natural gas demand by different economic sectors and to

implement the petroleum sector’s policy of replacing liquid petroleum products by natural gas,

for the MoP developed the natural gas infrastructure including the National Gas Grid (NGG) to

serve as a link from the upstream fields and gas processing facilities to end-users.

Accordingly, NGG has expanded from only about 40 km in 1975 to reach a length of around

18 thousand km15

with a capacity of 180 MMSCM/Day by June 2011 covering most of the

inhabited area in the country. By June 2011, the gas grid supplied natural gas to about 4.37

million clients in the residential and commercial sectors, 1800 clients in the industrial sector in

addition to about 185 thousand vehicles.16

The development of NGG started in 1975 with a 40 km, 12-inch pipeline with capacity of

0.085 MMSCM/Day from the Abu Madi gas field to Talkha area in the middle of the Delta

region to feed a power generation plant, a fertilizer factory and a textile factory.17

Later, an

offshore collection network was installed and started operation in the Gulf of Suez to recover

associated gas from the oil fields. Today, natural gas is transmitted and distributed through the

NGG, which extends from Matrouh in the northwest and the Western Desert to Sinai in the

east with high densities in the Nile Delta and Suez areas. Figure ‎1-7 shows the natural gas

network in Egypt and its development during the period (1980-2010) and Table ‎1-5 shows

several projects that were recently added to expand the NGG and to supply natural gas for the

first time to other cities and governorates.

15



, 2012 16

EGAS: “Annual Report 2009/2010”. 17

General information presented in several papers & reports.



Figure ‎1-7 Natural Gas Network in Egypt 18

18



, 2012



Table ‎1-5 Recent Domestic Natural Gas Pipelines Characteristics 19

Length

(km)

Diameter

(inches)

Capacity

(MCM/Day)

Operation

Date

Taba - Sharm El Sheikh Pipeline 208 20 6 2007

Shukir - Hurghada Gas Pipeline 127 24 4 2007

Upper Egypt Gas Pipelibe: 930 30-36 -- 2009

Phase 1: Dahshour - El Kurimat 90 36 20 2007

Phase 2: El Kurimat - Beni Suef 28 30 10 2007

Phase 3: Beni Suef to Abu-Qorqas 150 32 5 2008

Phase 4: El Minia (Abu-Qorqas) to

Assiut 150 32 3 2009

Phase 5: Assiut - Gerga 122 32 1 2009

Phase 6: Gerga - Qena - Aswan 390 30 1 2009

El Tina - Abu Sultan Pipeline 62 32 18 2007

Abu Hommos - El Nubaria Gas Pipeline 65 42 50 2009

Port Fouad - El Tina Gas Pipeline 42 42 40 2009

Trans - Sinai Gas Pipeline / Phase 1 55 36 -- 2010

Abu Sultan - El Sokhna Gas Pipeline 105 32 13 2010

Trans - Sinai Gas Pipeline / Phase 2 77 36 -- 2010

Sinai - Military Pipeline 16 16 -- 2010

Suez Canal Crossing 5 30 -- 2010

Inter Sinai Loop from Al Tina to Drish 155 36 -- 2010

In addition to the natural gas pipelines mentioned above that already exist and are in operation,

three other pipelines are recently added as shown in Table ‎1-6.

Table ‎1-6 Recently Added Natural Gas Pipelines 20

Name Length

(km)

Diameter

(inch)

Capacity

(MMCM/Day)

Belbis-10th

of Ramadan 36 24 3.4

Abu Madi - Gemsa 14 24 3.4

Abu Sultan – El Shabab 35 24

The distribution of natural gas in Egypt is regulated by the MoP, mostly through the state

owned company EGAS which supervises 15 distribution companies working now in this

activity; 5 are state-owned and 10 are from the private sector. Each company is responsible for

the design, construction and operation of the distribution network in some specified concession

areas, starting from the off-take at the national gas grid, operated by GASCO, until the end

users. Distribution companies quote a tariff level on gas sales in return to pipeline operation

19

Source: GASCO, length and the diameter of the pipelines are available online at:

http://www.egas.com.eg/Egyptian_Natural_Gas/Establishing_gas.aspx 20

Source: EGAS, “Annual Report 2010/2011”

http://www.egas.com.eg/Egyptian_Natural_Gas/Establishing_gas.aspx



and maintenance. However, some large industrial consumers and power plants take natural gas

directly from the transmission grid of GASCO.

1.7 Pressure Levels in Natural Gas Network

The gas networks are working at different potential (pressure) levels. The pressure level of 70

bars is used to connect the production centers with the main distribution stations, at which the

pressure is reduced to 42 bars. Large consumers such as power, fertilizers, cement and

metallurgical plants as well as industrial districts are supplied at that pressure. Pressure is

further reduced in these distribution stations to 7 bars for distribution to the medium size

industrial and residential districts. Inside the facilities, gas is distributed at 4 bars till the

consuming equipment at which the pressure is reduced to the equipment operating pressure.

The working pressure of normal combustion system is around 20 mbar. Figure ‎1-8 shows

schematic diagram for the predominant pressure levels in the gas network of Egypt.

Figure ‎1-8 Schematic Diagram for Pressure Levels in the Gas Network of Egypt 21

1.8 Natural Gas Transportation and Distribution Grid

As mentioned before, natural gas is transported from the main producing fields to major

consuming centers and cities through the main gas pipelines at pressures ranging between 70

and 30 bars which is reduced to 7 and 4 bars through the Pressure Reducing Station. In

addition, an odorant is added to gas utilized by residential and commercial consumers for

safety reasons. Natural gas distribution grid to cities is composed of the following components:

Main distribution pipelines made of steel or polyethylene in which gas pressure ranges

between 7-2 bars.

21

“Power Generation using Recovered Energy from Natural Gas Networks”, 17th

International Conference on

Electricity Distribution, Barcelona, May 12-15th

2003



Gas valves and regulators that reduce gas pressure of the high pressure distributions

pipelines to 2-0.1 bars for medium pressure distributions pipelines and to 0.1 for the

main low pressure distributions pipelines.

Main medium pressure distributions pipelines through which natural gas is transported

at a pressure of 2-0.1 bars.

Main low pressure distribution pipelines through which natural gas is transported at a

pressure of 0.1 bars.

Both the medium and low pressure gas distribution pipelines are made of polyethylene. Figure

‎1-9 is a schematic diagram for city natural gas distribution network.

Figure ‎1-9 Schematic Diagram for Natural Gas City Distribution Network 22

1.8.1 Pressure Reduction Stations (PRS) Operation 22

As mentioned before, natural gas is usually transmitted at high pressure. To satisfy the

distribution network needs or the end users, the pressure is then gradually reduced to low-

pressure ranges. Traditionally this has been done through PRVs at PRS. The PRS include

seven main stages: inlet, filtration, heating, reduction, measuring, odorizing and outlet.

22

“Environmental and Social Impact Assessment Framework for Greater Cairo Natural Gas Connections Project”,

September 2007



1.8.1.1 Inlet stage:

It is essential that the inlet parts of the PRS are completely isolated from the cathodic system

applied to the feeding steel pipes. This could be done by installing an isolating joint with

protection. In case of emergencies, the PRS could be shut off by locally or remotely controlling

the main station valve included in the inlet stage.

1.8.1.2 Filtration stage

Filtration is required to remove dust, rust, solid contaminants and liquid traces. Two filters and

two separators are installed in parallel; each filter-separator operates with the full capacity of

the PRS. While operating one line, the other one is kept on standby. Filter-separator lines are

equipped with safety devices such as differential pressure gauges, relief valves, liquid

indicators, etc.

1.8.1.3 Heating stage

Because of the relatively high difference between inlet and outlet pressure, icing could occur

around outlet pipes. This may cause blockings that reduce or stop the gas flow. To avoid this, a

heater is installed to keep the temperature of the outlet pipes over 7°C. Each PRS is equipped

with two heaters in parallel to allow for a standby heater in emergencies.

1.8.1.4 Reduction stage

Two parallel reduction lines are included in each PRS allowing for a standby line. To maintain

safe operation conditions, the lines are equipped with safety gauges, indicators and

transmitters. According to the Institution of Gas Engineers and Managers (IGEM) standards, a

reduction unit should be installed in a well-ventilated-closed area or, alternatively, in an open

protected area.

1.8.1.5 Measuring stage

After adjusting the outlet pressure, gas flow and cumulative consumption are then measured, to

monitor NG consumption from the PRS and to adjust the dosing of the odorant as indicated

below. Measuring devices should be sensitive to low gas flow, which normally occurs during

the first stages after connecting a small portion of targeted clients.

1.8.1.6 Odorizing stage

The aim of the odorant stage is to enable the detection of gas leaks in residential units, at low

concentration, before gas concentration becomes hazardous. The normally used odorant is

formed from Tertiobutylmercaptin (80%) and Methylehylsulphide (20%). The normal dosing

rate of the odorant is 12-24 mg/cm3. The system will consist of a stainless steel storage tank,

receives the odorant from 200-liter drums, injection pumps and associated safety devices.

Operation of the odorant unit is controlled automatically and could be switched to manual

operation.

1.8.1.7 Outlet stage

The outlet stage includes the outlet valve gauge, temperature indicators, pressure and

temperature transmitters and non-return valves. The outlet pipes are also, as inlet pipes,

isolated from cathodic protection by an isolating joint.



2 Turbo-Expander Mechanism The gas pressure is reduced at the reduction station using throttling valves. The throttling

process is a constant enthalpy process23

-at an almost constant temperature. This process is

thermodynamically irreversible.

Expansion through the turbo-expander is ideally an isentropic process, as work is extracted

from the expanding high pressure gas, as opposed to throttling gas through a regulator which is

ideally an isenthalpic process, as a large amount of latent energy of high pressure gas is wasted

during the pressure reduction process24

. In an isenthalpic throttling, there is a temperature

decrease in the gas due to the Joule-Thompson effect, but there is no change in the enthalpy of

the gas as it is reduced in pressure. In an isentropic expansion, the enthalpy of the gas also

decreases as the gas is expanded as shown in Error! Reference source not found.. This

change in enthalpy releases energy that is converted to power. The extraction of energy from

the gas results in a greater temperature reduction for an isentropic expansion compared to an

isenthalpic throttling over the same pressure ratio. The low pressure outlet gas from the turbine

is at a very low temperature, −150 °C or less depending upon the operating pressure and gas

properties. Partial liquefaction of the expanded gas is not uncommon. For natural gas pipeline

applications where certain minimum temperatures must be maintained to prevent condensation

or hydrate formation, the greater temperature drop of an isentropic power expansion can be a

critical consideration.

Figure ‎2-1 Different Pressure Reduction Processes24

A turbo-expander is essentially a compressor in reverse. Instead of shaft power being used to

compress gas to a higher pressure, shaft power is produced by expanding gas to a lower

pressure. Expanders are commonly used in air separation, LNG and hydrocarbon processing

applications where steady pressure ratios and flows, and high load factors are common.

23

Further information regarding isentropic process, Joule-Thompson effect and other thermodynamics definitions

are provided in ‎Annex A. 24

“Steam Distribution System Desk Book” by James F. McCauley, Fairmont Press, Inc., 2000

http://en.wikipedia.org/wiki/Temperature



As shown in Figure ‎2-2, a turbo-expander, also referred to as an expansion turbine, is a

centrifugal or axial flow turbine through which a high pressure gas is expanded to produce

work that is often used to drive a compressor. 25,26,27

Figure ‎2-2 Schematic Diagram of a Turbo-Expander Driving a Compressor28

Turbo-expanders are very widely used as sources of refrigeration in industrial processes such

as the extraction of ethane and natural gas liquids (NGLs) from natural gas, the liquefaction of

gases (such as oxygen, nitrogen, helium, argon and krypton) and other low-temperature

processes. Turbo expanders which are in operation range in size from about 750 W to about 7.5

MW or 1 hp to about 10,000 hp25

.

2.1 Power Generation through Natural Gas Pressure Reduction

Power generation through natural gas pressure reduction is a closed loop operation as shown in

Figure ‎2-3. It is worth to mention that power generation through natural gas pressure does not

require any additional fuel burning and therefore does not require any additional natural gas for

the electricity production. When pre-heating is necessary; (as explained in section 2.2 below),

only a small portion of main gas is consumed as a fuel gas for preheating. All the natural gas

going into the expansion engine or turbine comes out as low pressure gas to the end user or the

gas network. Both expansion engines and turbo expanders can easily operate under the

following nominal parameters29

:

a) Inlet Pressure Range: from 100 psig to over 1000 psig.

b) Pressure regulation ratio: 2:1 to 16:1 or even higher.

c) Annual Availability: between 355 to 360 days.

d) Estimated Operating Life: minimum 30 years with regular servicing and

maintenance.

25

“Turbo-Expanders and Process Applications”, Heinz P. Bloch and Claire Soares, Gulf Professional Publishing.,

Jun 15, 2001 26

“Industrial Gas Handbook: Gas Separation and Purification.” Frank G. Kerry, 2007 27

“Cryogenics Engineering” (Second Edition ed.), Thomas Flynn, 2004 28

Turbo-expander, Wikipedia 29

“Power Generation Opportunities in Bangladesh from Gas Pressure Reduction Stations”, 3rd

International

Conference on Electrical & Computer Engineering ICECE 2004, 28-30 December 2004, Dhaka, Bangladesh

http://en.wikipedia.org/wiki/Turbine

http://en.wikipedia.org/wiki/Pressure

http://en.wikipedia.org/wiki/Refrigeration

http://en.wikipedia.org/wiki/Ethane

http://en.wikipedia.org/wiki/Natural_gas_processing

http://en.wikipedia.org/wiki/Natural_gas

http://en.wikipedia.org/wiki/Gases

http://en.wikipedia.org/wiki/Oxygen

http://en.wikipedia.org/wiki/Nitrogen

http://en.wikipedia.org/wiki/Helium

http://en.wikipedia.org/wiki/Argon

http://en.wikipedia.org/wiki/Krypton

http://en.wikipedia.org/wiki/Watt



Figure ‎2-3 Power Generation through Natural Gas Pressure Reduction 30

2.2 Temperature Constraints

The expansion process produces a temperature decrease which can cause cooling of the gas

and condensation of the gas composition. When the turbo-expander is used, the temperature

drop is much greater; as the gas is doing work in the expansion. This means the gas need to be

preheated before it enters the turbo-expander to temperature higher than when using throttling

valves.

If the supplied gas is at the ambient temperature the exhaust gas temperature will be at a lower

temperature depending on the expansion pressure ratio, type of the gas and expansion

efficiency. In cases when the turbo-expander is not being used for condensation and

consequently it is not required to have low downstream temperature, suitable upstream gas

preheating is used. This is preferably achieved by recovering the waste heat from any available

heat source in the PRS or the industrial plant to which gas is fed (through e.g. Heat exchanger).

If this is not possible, a dedicated gas pre-heater is used. Gas preheating boosts the power of

the Turbo-expander due to the increase in the enthalpy of the upstream gas. Figure ‎2-4 shows a

schematic diagram for a pressure reducing station, which uses a parallel turbo-expander for

pressure reduction with gas pre-heater.

30


International




Figure ‎2-4 Schematic Diagram for a Turbo-expander Installed Parallel to the Existing 31

3 Potential of Energy Recovery from the Gas Network in Egypt Turbo-expanders can be installed in parallel with PRVs in order to reduce the gas pressure for

downstream consumptions and to recover waste energy. Moreover, the power extracted by

turbo-expanders can drive electrical generators, compressors and other loads. In short, in a gas

transmission and distribution network, it is possible to recover substantial amounts of energy to

produce electricity. 32,33 and 34

The category of reducing stations which include the input/output: 70/42, 42/7 and 42/13 are the

most attractive sites to install Turbo-expander units35

. These stations enjoy steady, high

pressure ratio as well as high flow rate. Furthermore most of them are supplying large

industrial companies as well as power plants and accordingly they are close to the electricity

grid. On the other hand, down-stream reduction stations are not attractive, as they are highly

dispersed and consequently supplying limited number of equipment. Accordingly they suffer

from low diversity factor, which makes the gas flow less steady. Also they have limited flow

rates as well as low pressure ratios. All these factors limit the potential recovered power per

site as well as reduce the unit loading ratio. Accordingly these micro units will have higher

31




2003 32

“Lecture Notes on Thermodynamics”, Joseph M., Power Department of Aerospace and Mechanical

Engineering,University of Notre Dame, Notre Dame, Indiana 46556-5637 USA, October 2012. 33

“Use of Expansion Tubines in Natural Gas Pressure Reduction Stations”, Pozivil J., Acta Montanistica

Slovakia,2004 34

“Power Generation from Pressure Reduction in the Natural Gas Supply Chain in Bangladesh”, Rahman M.M,

Transaction of the Mech. Eng. Div., The Institution of Engineers, December 2010 35

“Exergy Analysis of Helium Liquefaction Systems Based on Modified Claude Cycle with Two-Expanders”,

Thomas R. J., Ghosh P., Kanchan Chowdhuryk, June 2011



cost and less financial attractiveness. The identified pressure reduction levels which Turbo

expanders are recommended to be installed are shown in Figure ‎3-1.

Figure ‎3-1 The Recommended Pressure Reduction Levels for Turbo-Expander Installation36

3.1 Identification of Possible Stations for the Installation of Turbo-

Expanders

Table ‎3-1 shows estimated NG consumption of generation power plant. Knowing this flow rate

is essential to forecast the electric output of the turbo-expander system.

36




2003



Table ‎3-1 Fuel Type and Estimated NG Consumption of Generation Power Plants 37

Company Station

Installed

Capacity

(MW)

Annual Gross

Generation

(GWh)

Specific Fuel

Consumption

(gm/kWh gen.)

Fuel

Type

Average Fuel

Consumption

(ktoe/yr)

Average NG

Consumption

(m3/sec)

Cairo

Shoubra El-

Kheima (St) 1,260 5,473 243.147

N.G-

H.F.O 1,331 35.17

Cairo West

(St) 350 682 334.514

N.G-

H.F.O 228 6.02

Cairo West

Ext. (St) 1,360 7,181 214.689

N.G-

H.F.O 1,541 40.72

Tebbin (St) 700 4,276 198.251 N.G-

H.F.O 848 22.41

Cairo South

I (CC) 450 2,681 231.063

N.G-

H.F.O 619 16.36

Cairo South

II (CC) 165 719 261.261 N.G 188 6.62

Cairo North

(CC) 1,500 10,432 160.743

N.G-

L.F.O 1,677 44.31

Wadi Hof

(G) 100 127 383.618

N.G-

L.F.O 49 1.29

6 October

(G) 450 628 235.620

N.G-

L.F.O 148 3.91

Sub Total 6,335 32,199

East

Delta

Ataka (St) 900 4,260 255.730 N.G-

H.F.O 1,089 28.78

Abu Sultan

(St) 600 3,674 260.040

N.G-

H.F.O 955 25.24

Shabab (G) 100 106 364.456 N.G-

L.F.O 39 1.03

37

EEHC, "Annual Report 2011/2012”



Company Station

Installed

Capacity

(MW)

Annual Gross

Generation

(GWh)

Specific Fuel

Consumption

(gm/kWh gen.)

Fuel

Type

Average Fuel

Consumption

(ktoe/yr)

Average NG

Consumption

(m3/sec)

Port Said

(G) 73 62 366.382

N.G-

L.F.O 23 0.61

EL-Arish

(St) 66 367 257.900

N.G-

H.F.O 94 2.48

Oyoun

Mousa (St) 640 5,188 214.400

N.G-

H.F.O 1,112 29.38

Damietta

(CC) 1,200 7,522 193.100

N.G-

H.F.O 1,453 38.40

New Gas

Damietta

(G)

500 2,989 256.300 N.G-

L.F.O 766 20.24

New Gas

Shabab (G) 1,000 6,013 275.183

N.G-

L.F.O 1,655 43.73

Sharm El-

Sheikh (G) 178 43 400.1 L.F.O 17 -

Hurghada

(G) 143 44 439.5 L.F.O 19 -

Sub Total 5,400 30,268

Middle

Delta

Talkha (CC) 290 1,698 236.800 N.G-

L.F.O 402 10.62

Talkha

steam 210

(St)

420 2,197 243.700 N.G-

H.F.O 535 14.14

Talkha 750

(CC) 750 3,462 165.872

N.G-

L.F.O 575 15.19

Nubaria

1,2,3 (CC) 2,250 11,169 163.931

N.G-

L.F.O 1,831 48.38

Mahmoudia

(CC) 316 2,052 235.200

N.G-

L.F.O 483 12.76



Company Station

Installed

Capacity

(MW)

Annual Gross

Generation

(GWh)

Specific Fuel

Consumption

(gm/kWh gen.)

Fuel

Type

Average Fuel

Consumption

(ktoe/yr)

Average NG

Consumption

(m3/sec)

El-Atf (CC) 750 5,652 160.825 N.G-

L.F.O 909 24.02

Sub Total 4,776 26,230

West

Delta

Kafr El-

Dawar (St) 440 2,116 276.500

N.G-

H.F.O 585 15.46

Damanhour

Ext. 300

(St)

300 539 251.700 N.G-

H.F.O 136 3.59

Damanhour

(St) 195 1,050 293.010

N.G-

H.F.O 308 8.14

Damanhour

(CC) 156.5 1,049 215.282

N.G-

L.F.O 226 5.97

Abu Kir (St) 911 5,179 247.000 N.G-

H.F.O 1,279 33.80

El-Seiuf (G) 200 214 390.442 N.G-

L.F.O 83 2.19

Karmouz

(G) 23.1 6 407.607 L.F.O 3 -

Sidi Krir

(St) 640 4,004 211.678

N.G-

H.F.O 848 22.41

Sidi Krir

(CC) 750 5,461 158.913

N.G-

H.F.O 868 22.94

Matroh (St) 60 366 289.631 N.G-

H.F.O 106 2.80

Sub Total 3,675.6 19,984

Upper

Egypt

Kuriemat

(St) 1,254 7,602 211.820

N.G-

H.F.O 1,625 42.94

Kuriemat 1

(CC) 750 5,072 156.000

N.G-

L.F.O 791 20.90



Company Station

Installed

Capacity

(MW)

Annual Gross

Generation

(GWh)

Specific Fuel

Consumption

(gm/kWh gen.)

Fuel

Type

Average Fuel

Consumption

(ktoe/yr)

Average NG

Consumption

(m3/sec)

Kuriemat 2

(CC) 750 4,435 173.800

N.G-

H.F.O 771 20.37

Walidia (St) 624 3166 234.63 H.F.O 743 -

Assiut (St) 90 406 305.76 H.F.O 124 -

Sub Total 3,468 20,681

BOOT

Sidi Krir 3,4

(St) 682.5 4,614

205.7

N.G-

H.F.O 915 24.18

Suez Gulf

North (St) 682.5 3,994

N.G-

H.F.O 847 22.38

Port Said

East (St) 682.5 4,247

N.G-

H.F.O 883 23.33

Sub Total 2,047.5 12,855

Total 25,702 142,217

NG consumption by the Egyptian power plants reached 22,458 ktoe in 2011/2012 representing 75.5% of their total fuel

consumption38

. Cairo South II power plant depend mainly on N.G while Sharm El-Sheikh, Hurghada, Karmouz, Walidia and Assiut

support electricity without N.G. Hence, those 5 plants are excluded.

38

EEHC, “Annual Report 2011/2012”

Boosting Capacity of Electric Generation through the use of Turbo-Expanders in Natural Gas Network


4 Possible Electric Capacity Output from the Identified Possible

Turbo-Expander Installations

Various applications have been made worldwide to harness the energy loss during natural gas

pressure reduction through conventional throttling valves and experimental work to examine

the most important factors that determine the level of power to be produced through the

utilization of turbo expanders instead of throttling valves.

It is obvious that both the gas flow rate and the pressure reduction ratio (PR) (the ratio of inlet

high pressure over outlet low pressure) are the most important parameters.

The parameters required to size the turbo-expander are39

:

1. Gas Composition

2. Flow Rate

3. Pressure Ratio

4. Inlet Temperature

A twofold optimal formulation is introduced to account for the proposed locations of Turbo-

expanders and their capacities40

. The first stage of the optimal formulation is the determination

process of the best locations for the installation of turbo-expenders in the gas distribution

network. The selection process is executed through a combinatorial optimization process,

where pressure ratio “Rp” across the reduction station is maximum, the flow rate “G” is

maximum, the variation in the flow rate “ΔG” is minimum and interconnection requirements

with the electricity grid are minimum.

The second stage of the optimal formulation is to determine the optimum rating of the turbo-

expander and the corresponding operational conditions. The target is to reach the maximum

possible electric energy “E”, as well as minimum fuel consumption for preheating, with a

target upper limit of the cost per kWh generated. This is expressed as41

:

(Equation ‎4-1)

Where,

P: Rated Electric output of the turbo-expander system

As: Availability of the turbo-expander system

The rated electric power “P” is expressed in terms of the rated flow capacity “GR” of the turbo-

expander, the specific heat “CP” of the gas, the density of the gas at normal conditions “ρNG”,

the inlet temperature “Tin” to the turbo-expander, the pressure ratio “RP”, the overall efficiency

of the turbo-expander system “ηS”, and gas specific heat ratio “k”. Gas specific heat is

considered as a function in temperature. The electric power “P” is expressed as:

(Equation ‎4-2)

39

“Fundamental of Turbo-Expanders (Basic theory and Design)”, presented by: Mr. James Simms, Simms

Machinery International, INC, California, March 23th

, 2009 40

“Exergy Based Analysis on Different Expander Arrangements in Helium Liquefiers”, Thomas R. J., Ghosh P.,

Kanchan Chowdhuryk, November 2011 41




2003



The availability “AS” of the Turbo-expander system is normally a manufacturer based value

and is around 92%42

.

The pressure ratio “RP” is expressed in terms of the upstream and downstream pressure levels

“Pu” and “Pd” at the gas reduction station and is expressed as:

The overall efficiency of the turbo-expender system “ηS” represents all the sub systems

efficiencies including the turbo-expander efficiency “ηT”, the transmission efficiency “ηTran”

(gearbox) and the generator efficiency “ηG”, and is expressed as:

(Equation ‎4-3)

Both the Turbo-expander efficiency “ηT” and the generator efficiency “ηG” are functions in the

load factor. Figure ‎4-1 shows the dependence of the expander efficiency on the load factor

(design flow percent).

Figure ‎4-1 Variation of Turbo-expander Efficiency with Gas Flow Rate

The design flow of a turbo-expander is the flow rate at which the maximum efficiency is

observed. As the flow rate increases or decreases from the design flow, the efficiency will

decrease.

The turbo-expander inlet temperature “Tin” is related to the downstream temperature “Td” of

the gas reduction station as:

The downstream temperature “Td” is limited by the possible liquid condensation, if the

downstream temperature went below the dew point “Tdp” of the heavy constituents of the gas.

42

“Rotoflow Turbo-Expander for Hydrocarbon Applications”, GE Power System-Gas and Oil, 2002



Condensation increases the erosion of expander blades as well as reduces its efficiency. Since

the concentration of the heavy constituents can vary, then a safety margin “ΔTs” should be

considered.

Therefore inlet gas preheating is needed to control the downstream temperature and the main

point is that the outlet temperature should always be greater that the dew point of natural gas

composition (butane) at outlet pressure. Additional heating of the inlet gas will lead to an

increase in the turbine output yet this will take place on the expense of the system efficiency.

Finally, the turbo-expander outlet temperature “To” is function in the turbo-expander inlet

temperature “Tin”. The isentropic (ideal case)43

outlet temperature of turbo-expander “To isen” is

expressed as:

The actual outlet temperature of turbo-expander “To act” is related to the isentropic outlet

temperature as following:

4.1 Evaluating the Potential of Electricity Generation from Natural Gas

Pressure Reduction Stations

Table ‎4-1 illustrates the impact of gas flow rates and pressure reduction ratios on the level of

power generation according to an experiential work done in a natural gas PRS in Bangladesh to

examine that correlation.

Table ‎4-1 Examples of Power from Gas Pressure Reduction44

NG Flow

(Standard m3/hr)

Incoming Gas

Pressure (bar g)

Outlet Gas

Pressure (bar g)

Pressure

Reduction

Ratio

Power

Generated

(kW)

10,000 60 2 30:1 700

45,000 37 15 2.45:1 1500

6,500 55 9 6.1:1 750

9,000 40 7 5.6:1 470

16,000 18 6 3:1 850

5,500 50 3 16.7:1 570

43

“Lecture Notes on Thermodynamics”, Joseph M., Power Department of Aerospace and Mechanical Engineering

University of Notre Dame, Notre Dame, Indiana 46556-5637 USA, October 2012. 44

Sources:

“Gas Expansion Power Plants with Modular System Gas Expanders” a publication of Spilling Energy System.


International




Furthermore, in order to evaluate the potential of power generation for any natural gas PRS at

different pressure reduction ratio, the following figure can be utilized. As an example, if a gas

expansion station has a pressure ratio of 4.0 and a gas flow rate of 15 million standard cubic

feet per day (MMSCF/day) then the potential power generation capability from this gas

expansion station is 500 kW.

Figure ‎4-2 Potential Power Generation versus Flow and Pressure Ratio45

4.2 Technical Assessment of Generation Potential from PRS

4.2.1 The Possible Electric Capacity Output

The previous figure is a suitable method to estimate the expected electricity generation at

power plants using turbo-expanders (T.Exp.). However, calculations were conducted based on

the following equations. The results are shown in Table ‎4-2.

(Equation ‎4-1) and

(Equation ‎4-2)

45

Sources:

PiP™ Power Generation & Pressure into Power™ Energy Reclamation; Dresser Inc.,


International




Table ‎4-2 Expected Electricity Generation at Power Plants by Turbo-Expander

Company No. Station T.Exp. Capacity

(MW)

T.Exp. Annual

Electricity

Generated (GWh)

Cairo

1 Shoubra El-Kheima (St) 4.21 36.84

2 Cairo West (St) 0.72 6.31

3 Cairo West Ext. (St) 4.87 42.65

4 Tebbin (St) 2.68 23.47

5 Cairo South I (CC) 1.96 17.13

6 Cairo South II (CC) 0.79 6.94

7 Cairo North (CC) 5.30 46.41

8 Wadi Hof (G) 0.15 1.36

9 6 October (G) 0.47 4.10

Sub Total 21.14 185.21

East

Delta

10 Ataka (St) 3.44 30.14

11 Abu Sultan (St) 3.02 26.43

12 Shabab (G) 0.12 1.08

13 Port Said (G) 0.07 0.64

14 EL-Arish (St) 0.30 2.60

15 Oyoun Mousa (St) 3.51 30.78

16 Damietta (CC) 4.59 40.21

17 New Gas Damietta (G) 2.42 21.20

18 New Gas Shabab (G) 5.23 45.80

Sub Total 22.7 198.88

Middle

Delta

19 Talkha (CC) 1.27 11.13

20 Talkha steam 210 (St) 1.69 14.81

21 Talkha 750 (CC) 1.82 15.91

22 Nubaria 1,2,3 (CC) 5.78 50.68

23 Mahmoudia (CC) 1.53 13.37

24 El-Atf (CC) 2.87 25.16

Sub Total 14.96 131.06

West

Delta

25 Kafr El-Dawar (St) 1.85 16.19

26 Damanhour Ext. 300 (St) 0.43 3.76

27 Damanhour (St) 0.97 8.52

28 Damanhour (CC) 0.71 6.25

29 Abu Kir (St) 4.04 35.40

30 El-Seiuf (G) 0.26 2.30

31 Sidi Krir (St) 2.68 23.47

32 Sidi Krir (CC) 2.74 24.02

33 Matroh (St) 0.33 2.93

Sub Total 14.02 122.84



Company No. Station T.Exp. Capacity

(MW)

T.Exp. Annual

Electricity

Generated (GWh)

Upper

Egypt

34 Kuriemat (St) 5.13 44.97

35 Kuriemat 1 (CC) 2.50 21.89

36 Kuriemat 2 (CC) 2.44 21.34

Sub Total 10.07 88.20

BOOT

37 Sidi Krir 3,4 (St) 2.89 25.32

38 Suez Gulf North (St) 2.68 23.44

39 Port Said East (St) 2.79 24.44

Sub Total 8.36 73.20

Total 91.26 MW 799.39 GWh

An estimated overall additional capacity at about 91 MW, with individual capacity ranging

between 70 kW and 5.78 MW, could be generated through the use of turbo-expanders in the

existing PRS at the electricity production companies. The total electricity produced in one year

is approximately 800 GWh.

Evaluating the potential of electricity generation from industrial sector is also provided in

Error! Reference source not found..

4.2.2 Environmental Impact and Natural Gas Avoided

The turbo-expander additional electricity is generated without affecting the natural gas

consumption by power plants. Hence, the amount of natural gas avoided could be computed

using the following equation:

The table below illustrates the annual natural gas avoided. This is calculated using the specific

consumption of each plant (Table ‎3-1), based on 75.5%46

share of their total fuel consumption.

This practically means that the output of the plant will be reduced in an amount equal to power

generated by the turbo-expander. This might not be the case in periods of the day of high

demand on electricity, and N.G avoided will be smaller than the mentioned in the table below.

Avoided N.G will result in carbon dioxide release avoidance assumed to be 2.6147

ton CO2 to

ton NG.

46

EEHC, “Annual Report 2011/2012” 47 EEHC: “Annual Report 2010/2011”



To determine the annual N.G avoided cost as shown Table ‎4-3, two sets of N.G prices are

used. The subsidized price of N.G for the electricity sector is 0.06$ per m3.48

As for the

unsubsidized N.G prices, N.G is sold in the spot market for 10.75$ per MMBtu.49

Table ‎4-3 The Annual Natural Gas Avoided Cost

Company No. Station

Annual NG Avoided Annual

CO2

Avoided

(ton Co2) ktoe m

3 Subsidized

NG ($)

Unsubsidized

NG ($)

Cairo

1

Shoubra El-

Kheima

(St)

6.72 7,463,805 447,828 2,863,523 2,315

2 Cairo West

(St) 1.58 1,758,986 105,539 674,843 546

3 Cairo West

Ext. (St) 6.87 7,630,021 457,801 2,927,292 2,367

4 Tebbin (St) 3.49 3,877,257 232,635 1,487,527 1,203

5 Cairo South

I (CC) 2.97 3,298,636 197,918 1,265,537 1,023

6 Cairo South

II (CC) 1.81 2,013,832 120,830 772,616 625

7 Cairo North

(CC) 5.60 6,216,965 373,018 2,385,167 1,929

8 Wadi Hof

(G) 0.39 433,519 26,011 166,322 134

9 6 October

(G) 0.72 804,243 48,255 308,551 249

East

Delta

10 Ataka (St) 5.78 6,422,777 385,367 2,464,128 1,992

11 Abu Sultan

(St) 5.15 5,727,391 343,643 2,197,340 1,777

12 Shabab (G) 0.30 327,811 19,669 125,766 102

13 Port Said

(G) 0.17 194,346 11,661 74,562 60

14 EL-Arish

(St) 0.50 559,104 33,546 214,503 173

15 Oyoun

Mousa (St) 4.95 5,498,483 329,909 2,109,518 1,706

16 Damietta

(CC) 5.82 6,470,848 388,251 2,482,570 2,007

48

The Egyptian Cabinet decree No. 1257 of the year 2012, regarding the sale price per cubic meter of the local

natural gas supplied to all the electricity producing companies. The subsidized price of N.G is 44 PT per m3.

49 Based on private communication



Company No. Station


CO2

Avoided

(ton Co2) ktoe m

3 Subsidized

NG ($)

Unsubsidized

NG ($)

17

New Gas

Damietta

(G)

4.08 4,527,836 271,670 1,737,125 1,405

18 New Gas

Shabab (G) 9.45 10,503,472 630,208 4,029,705 3,258

Middle

Delta

19 Talkha

(CC) 1.98 2,195,437 131,726 842,290 681

20

Talkha

steam 210

(St)

2.71 3,006,925 180,416 1,153,620 933

21 Talkha 750

(CC) 1.98 2,199,653 131,979 843,907 682

22 Nubaria

1,2,3 (CC) 6.23 6,922,496 415,350 2,655,847 2,147

23 Mahmoudia

(CC) 2.36 2,619,979 157,199 1,005,167 813

24 El-Atf (CC) 3.03 3,371,559 202,294 1,293,514 1,046

West

Delta

25 Kafr El-

Dawar (St) 3.36 3,730,476 223,829 1,431,214 1,157

26

Damanhour

Ext. 300

(St)

0.71 789,470 47,368 302,884 245

27 Damanhour

(St) 1.87 2,081,356 124,881 798,522 646

28 Damanhour

(CC) 1.01 1,122,095 67,326 430,497 348

29 Abu Kir

(St) 6.56 7,285,860 437,152 2,795,253 2,260

30 El-Seiuf

(G) 0.67 747,391 44,843 286,740 232

31 Sidi Krir

(St) 3.73 4,139,853 248,391 1,588,273 1,284

32 Sidi Krir

(CC) 2.86 3,181,211 190,873 1,220,486 987

33 Matroh (St) 0.64 708,050 42,483 271,647 220

Upper 34 Kuriemat

(St) 7.14 7,938,412 476,305 3,045,608 2,463



Company No. Station


CO2

Avoided

(ton Co2) ktoe m

3 Subsidized

NG ($)

Unsubsidized

NG ($)

Egypt 35 Kuriemat 1

(CC) 2.56 2,845,866 170,752 1,091,829 883

36 Kuriemat 2

(CC) 2.78 3,090,420 185,425 1,185,653 959

BOOT

37 Sidi Krir

3,4 (St) 3.77 4,184,841 251,090 1,605,533 1,298

38 Suez Gulf

North (St) 3.73 4,142,628 248,558 1,589,338 1,285

39 Port Said

East (St) 3.81 4,233,986 254,039 1,624,388 1,313

Total 129.85 144,267,295 8,656,038 55,348,802 44,753

The 130 ktoe avoided are a result of using the turbo-expander to generate the additional 799

GWh without increasing the natural gas consumption by power plants. The total natural gas

avoided per year is estimated to reach 130 ktoe, representing about 0.6% of the 21,663 ktoe

consumed by the existing power plants. This will lead to 45 tons annual savings of CO2

emissions which represents again about 0.6% of the total CO2 emissions from the existing

power plants.



5 Economic Assessment for the Application

High-efficiency expanders made even smaller units economically attractive. Turbo-expanders

offer great promise from an energy efficiency perspective in that they have the potential to

provide power at very high efficiency (low heat rates). This heat rate can be further reduced if

the heating can be provided by a source of waste heat from another process or application.

5.1 Factors Affecting the Project Economics 50

The most important factors affecting project economics are the high capital cost of the systems

themselves, and the recoverable value of the electricity generated. Other key variables include

the gas flow rate and pressure drop, which together determine the power generation potential,

and the hourly, daily and seasonal variability in flow.

5.1.1 Capital Costs

The total costs for a turbo expander system include the equipment costs for the expander,

gearbox, generator, pre-heaters, utility interconnect and controls, and pipeline connection, as

well as the overall engineering and installation costs. According to a study conducted in Iran

the costs ranges from 600$ to 2,300$/kW. The lowest cost per kW was on the largest system

indicating that some economies of scale exist.51

5.1.2 Operating Costs

Turbo-expander installations generating electricity will have significantly higher operating

costs than regulator stations. The highest cost will be in the fuel required for pre- or post-

heating of the gas. However, this study assumed the inlet gas is pre-heated using power plant

waste heat recovery system (e.g. heat exchanger). Along with this are maintenance costs for

the turbo expander equipment itself. The annual non-fuel operating and maintenance (O&M)

costs were estimated at two percent of capital costs52

.

5.1.3 Revenue from Power Sales

The total revenue depends on the sales price and the amount of power generated. The amount

of power is a function of the flow rate and pressure ratio at the location, and the efficiency of

the expander/ gearbox/ generator system in converting pressure drop to electricity. Daily and

seasonal variations in flow and pressure will affect power output and will most likely impact

the value of the power to the ultimate purchaser.

5.1.4 Pressure Ratio

Higher pressure ratios (ratio of inlet pressure to outlet pressure) result in higher power

production. While normal pipeline operating pressures are well below maximum turbo-

expander pressure ratios, there is also a minimum pressure ratio (approximately 1.3:1) that

must be maintained below which the turbo-expander will not function.

50

“Waste energy Recovery Opportunities for Interstate Natural Gas Pipelines”, prepared by: Bruce A. Hed,am

Energy and Environmental Analysis, INC., An ICF International Company,February 2008 51

“Energy Regeneration in Natural Gas Pressure Reduction Stations by Use of Gas Turbo-Expander; Evaluation

of Available Potential in Iran”, Ardalj, E.K and Heybatial, E. 2009 52

“Application of Turbo-expanders for Pressure Letdown Energy Recovery”, Engineering Technical Note,

Operating and Engineering Services Group, American Gas Association, 1987



5.1.5 Flow Rate

Power output is also a function of flow rate. Variability in flow rate is an important

consideration in project economics, and gas flow rates, particularly at stations, will vary over a

wide range due to seasonal, daily and hourly demand fluctuations. Turbo-expanders can

generally operate between 50 and 140 percent of design flow, although exact capabilities will

vary from manufacturer to manufacturer. This can make optimum sizing for an installation

difficult to estimate. If the system is too large, there may be significant periods of the year

where flow and pressure are below the minimum requirements and the system will remain idle.

If the system is sized too small and capital cost economies are lost and there may be extended

periods where a significant portion of the flow will need to bypass the turbo expander.

5.2 System Cost Calculation

In order to evaluate the turbo-expander economics, the different range of capital cost per kilo

Watt generated should be taken into consideration. To be conservative, the capital costs per

kW is assumed to be 2,300 $/kW inclusive the cost of finance.

Assuming 25 years as lifetime and considering that no additional cost required for pre-heating

the gas, e.g. inlet gas is pre-heated using power plant waste heat recovery system.

The payback period is determined by calculating the total capital cost of turbo-expander

system divided by the annual natural gas avoided. This is expressed as:

The table below estimates the total capital costs, the annual O&M, the annual N.G avoided

cost53

as well as the payback period for unsubsidized natural gas.

53

The unsubsidized N.G price in the spot market is 10.75$ per MMBtu, based on private communication.



Table ‎5-1 Total Capital Costs and Payback Period for Turbo-Expander Installations

Company Station Capital

Costs ($)

Annual

O&M

Costs ($)

Annual

NG

Avoided

Cost ($)

Payback

period

(years)

Cairo

Shoubra El-Kheima (St) 9,671,947 7,738 2,863,523 3

Cairo West (St) 1,656,802 1,325 674,843 2

Cairo West Ext. (St) 11,197,950 8,958 2,927,292 4

Tebbin (St) 6,162,142 4,930 1,487,527 4

Cairo South I (CC) 4,498,073 3,598 1,265,537 4

Cairo South II (CC) 1,821,514 1,457 772,616 2

Cairo North (CC) 12,186,218 9,749 2,385,167 5

Wadi Hof (G) 356,067 285 166,322 2

6 October (G) 1,075,468 860 308,551 3

East

Delta

Ataka (St) 7,913,412 6,331 2,464,128 3

Abu Sultan (St) 6,939,677 5,552 2,197,340 3

Shabab (G) 283,400 227 125,766 2

Port Said (G) 167,134 134 74,562 2

EL-Arish (St) 683,068 546 214,503 3

Oyoun Mousa (St) 8,080,545 6,464 2,109,518 4

Damietta (CC) 10,558,482 8,447 2,482,570 4

New Gas Damietta (G) 5,566,275 4,453 1,737,125 3

New Gas Shabab (G) 12,026,351 9,621 4,029,705 3

Middle

Delta

Talkha (CC) 2,921,204 2,337 842,290 3

Talkha steam 210 (St) 3,887,672 3,110 1,153,620 3

Talkha 750 (CC) 4,178,339 3,343 843,907 5

Nubaria 1,2,3 (CC) 13,305,286 10,644 2,655,847 5

Mahmoudia (CC) 3,509,805 2,808 1,005,167 3

El-Atf (CC) 6,605,410 5,284 1,293,514 5

West

Delta

Kafr El-Dawar (St) 4,251,006 3,401 1,431,214 3

Damanhour Ext. 300

(St) 988,268 791 302,884 3

Damanhour (St) 2,238,137 1,791 798,522 3

Damanhour (CC) 1,642,269 1,314 430,497 4

Abu Kir (St) 9,294,080 7,435 2,795,253 3



Company Station Capital

Costs ($)

Annual

O&M

Costs ($)

Annual

NG

Avoided

Cost ($)

Payback

period

(years)

El-Seiuf (G) 603,134 483 286,740 2

Sidi Krir (St) 6,162,142 4,930 1,588,273 4

Sidi Krir (CC) 6,307,476 5,046 1,220,486 5

Matroh (St) 770,268 616 271,647 3

Upper

Egypt

Kuriemat (St) 11,808,351 9,447 3,045,608 4

Kuriemat 1 (CC) 5,747,942 4,598 1,091,829 5

Kuriemat 2 (CC) 5,602,608 4,482 1,185,653 5

BOOT

Sidi Krir 3,4 (St) 6,649,010 5,319 1,605,533 4

Suez Gulf North (St) 6,154,876 4,924 1,589,338 4

Port Said East (St) 6,416,476 5,133 1,624,388 4

Although turbo-expander installations involve high capital cost, the high annual N.G savings

cost explains the short payback period using unsubsidized N.G cost. The payback periods

depend on the N.G prices. Therefore, utilizing subsidized price results in long payback period.

As the turbo-expander power generated increases, the total capital costs increase as well which

explains the long payback period e.g. 5 years. The N.G avoided cost varies according to the

specific consumption of each plant. The inefficient plants involve high natural gas specific

consumption which explains the short payback period e.g. 2 years.



The annualized cost of turbo-expander system is adopted using the following equation as the

sum of the system expenses which include capital costs over a lifetime associated with the

annual operating and maintenance costs. Table ‎5-2 demonstrates the total annual cost of turbo-

expander system.

Table ‎5-2 Turbo-Expander Annualized Total Cost

Company No. Station

T.Exp. Annual

Electricity

Generated

(GWh)

T.Exp. Total

Annualized

Cost ($)

Cairo

1 Shoubra El-Kheima (St) 36.84 394,615

2 Cairo West (St) 6.31 67,598

3 Cairo West Ext. (St) 42.65 456,876

4 Tebbin (St) 23.47 251,415

5 Cairo South I (CC) 17.13 183,521

6 Cairo South II (CC) 6.94 74,318

7 Cairo North (CC) 46.41 497,198

8 Wadi Hof (G) 1.36 14,528

9 6 October (G) 4.10 43,879

East

Delta

10 Ataka (St) 30.14 322,867

11 Abu Sultan (St) 26.43 283,139

12 Shabab (G) 1.08 11,563

13 Port Said (G) 0.64 6,819

14 EL-Arish (St) 2.60 27,869

15 Oyoun Mousa (St) 30.78 329,686

16 Damietta (CC) 40.21 430,786

17 New Gas Damietta (G) 21.20 227,104

18 New Gas Shabab (G) 45.80 490,675

Middle

Delta

19 Talkha (CC) 11.13 119,185

20 Talkha steam 210 (St) 14.81 158,617

21 Talkha 750 (CC) 15.91 170,476

22 Nubaria 1,2,3 (CC) 50.68 542,856

23 Mahmoudia (CC) 13.37 143,200

24 El-Atf (CC) 25.16 269,501



Company No. Station

T.Exp. Annual

Electricity

Generated

(GWh)

T.Exp. Total

Annualized

Cost ($)

West

Delta

25 Kafr El-Dawar (St) 16.19 173,441

26 Damanhour Ext. 300 (St) 3.76 40,321

27 Damanhour (St) 8.52 91,316

28 Damanhour (CC) 6.25 67,005

29 Abu Kir (St) 35.40 379,198

30 El-Seiuf (G) 2.30 24,608

31 Sidi Krir (St) 23.47 251,415

32 Sidi Krir (CC) 24.02 257,345

33 Matroh (St) 2.93 31,427

Upper

Egypt

34 Kuriemat (St) 44.97 481,781

35 Kuriemat 1 (CC) 21.89 234,516

36 Kuriemat 2 (CC) 21.34 228,586

BOOT

37 Sidi Krir 3,4 (St) 25.32 271,280

38 Suez Gulf North (St) 23.44 251,119

39 Port Said East (St) 24.44 261,792



After determining the total annual cost of turbo-expander, the annual generation cost of unit

electricity can be characterized as 7.4 PT/kWh54

and expressed as:

The calculation of the electric output generated is based on the assumptions that:

1. The inlet temperature was assumed constant as 80°C,

If the inlet temperature changes by 10 degrees Celsius reduction, then the capacity will

fall by 2.8% and vice versa.

2. Base load power plants running full time (8760 hours) and the availability of turbo-

expander was assumed equal to 100%,

If any of the capacity or time changes by 10% reduction, then the cost will rise by 10%

while if this reduction change goes to 20% then the cost changes or increases to 25%

3. Overall efficiency was assumed equal to 72%,

As expressed in (Equation 4-3) and assuming 83%, 92% and 95% are the turbo-

expander efficiency, the transmission efficiency and the generator efficiency

respectively.55

54

1 $=6.9 EGP, Source: http://www.eip.gov.eg/Services/CurrencyConvertor.aspx , October12th

2013 55

Based on “Power Generation using Recovered Energy from Natural Gas Networks”, 17th

International

Conference on Electricity Distribution, Barcelona, May 12-15th

2003 and accessibility to the detailed model

http://www.eip.gov.eg/Services/CurrencyConvertor.aspx



5.3 Potential Profit Margin

The cost per kWh of the turbo-expander system is limited by the upper value shown in Table

‎5-3 which shows the average cost of energy from production stations. Thus, the system will be

feasible, if the turbo-expander generation cost of electricity is less than the values below.

Table ‎5-3 The Average Cost of Energy at Electricity Production Companies

Company No. Station

Cost of Service at that Station (2011/2012)

(PT/kWh)

With Subsidized

Price of N.G 56

With Unsubsidized

Price of N.G

Cairo

1 Shoubra El-Kheima (St) 13.52 29.20

2 Cairo West (St) 24.72 53.40

3 Cairo West Ext. (St) 24.72 53.40

4 Tebbin (St) 23.85 51.52

5 Cairo South I (CC) 14.25 30.78

6 Cairo South II (CC) 14.25 30.78

7 Cairo North (CC) 11.95 25.81

8 Wadi Hof (G) 23.16 50.03

9 6 October (G) 46.71 100.89

East Delta

10 Ataka (St) 14.91 32.21

11 Abu Sultan (St) 13.00 28.08

12 Shabab (G) 32.47 70.14

13 Port Said (G) 30.66 66.23

14 EL-Arish (St) 45.53 98.34

15 Oyoun Mousa (St) 14.14 30.54

16 Damietta (CC) 13.17 28.45

17 New Gas Damietta (G) 14.02 30.28

18 New Gas Shabab (G) 17.81 38.47

Middle

Delta

19 Talkha (CC) 9.52 20.56

20 Talkha steam 210 (St) 18.09 39.07

21 Talkha 750 (CC) 15.82 34.17

22 Nubaria 1,2,3 (CC) 18.07 39.03

23 Mahmoudia (CC) 14.26 30.80

24 El-Atf (CC) 17.78 38.40

56

“The Cost of Electricity Production, Transmission and Distribution Report, 2011/2012”, Egyptian Electric

Utility and Consumer Protection Regulatory Agency (EgyptERA)



Company No. Station

Cost of Service at that Station (2011/2012)

(PT/kWh)

With Subsidized

Price of N.G 56

With Unsubsidized

Price of N.G

West

Delta

25 Kafr El-Dawar (St) 11.99 25.90

26 Damanhour Ext. 300

(St) 25.70 55.51

27 Damanhour (St) 25.70 55.51

28 Damanhour (CC) 25.75 55.62

29 Abu Kir (St) 14.55 31.43

30 El-Seiuf (G) 51.02 110.20

31 Sidi Krir (St) 18.53 40.02

32 Sidi Krir (CC) 18.45 39.85

33 Matroh (St) 33.41 72.17

Upper

Egypt

34 Kuriemat (St) 13.20 28.51

35 Kuriemat 1 (CC) 14.22 30.72

36 Kuriemat 2 (CC) 14.22 30.72

BOOT

37 Sidi Krir 3,4 (St) 16.76 36.20

38 Suez Gulf North (St) 16.57 35.79

39 Port Said East (St) 16.36 35.34

Fuel cost represents 29% of the total cost of generated energy at the thermal companies

compared to 71% for operating costs, depreciation and return on assets.57

This percent involves

the subsidized fuel price. On the other hand, determining the unsubsidized price of fuel

improves the economic feasibility of the system. This necessitates significant opportunity costs

account at least 5 times58

of subsidized fuel price. Thus, the unsubsidized fuel cost could reach

145% of the total cost of generated energy at the thermal companies achieving 216% as a total

cost of generated energy at the thermal companies. Hence, the cost of service utilizing

unsubsidized fuel price at the electricity production companies can be considered as 216% of

the prices mentioned in Cost of Service Report57

.

57

“The Cost of Electricity Production, Transmission and Distribution Report, 2011/2012”, Egyptian Electric

Utility and Consumer Protection Regulatory Agency (EgyptERA) 58

Educated Assumption



Sale prices to an electric utility can be considered up to 99% of the average cost of electricity

from power plants in accordance with the subsidized fuel price. Assuming 90% of the average

cost of electricity and subtract turbo-expander generation cost (7.4 PT/kWh) from this value

results in varies widely profit.

As mentioned before, the cost of service utilizing unsubsidized fuel price at the electricity

production companies is considered as 216% of the average cost of electricity from power

plants. Subtracting turbo-expander generation cost (7.4 PT/kWh) from this value results in the

annual profit in the unsubsidized case.

Table ‎5-4 Capital Cost of Turbo-Expander versus the Annual Profit

Company Station

Capital

Cost

(Mio

EGP)

Subsidized Unsubsidized

Annual

Profit

(Thousand

EGP)

Payback

period

(years)

Annual

Profit

(Thousand

EGP)

Payback

period

(years)

Cairo

Shoubra El-Kheima

(St) 67 1,756 38 8,032 8

Cairo West (St) 11 937 12 2,902 4

Cairo West Ext. (St) 77 6,333 12 19,617 4

Tebbin (St) 43 3,301 13 10,354 4

Cairo South I (CC) 31 929 33 4,005 8

Cairo South II (CC) 13 376 33 1,622 8

Cairo North (CC) 84 1,557 54 8,546 10

Wadi Hof (G) 2 182 13 578 4

6 October (G) 7 1,419 5 3,830 2

East Delta

Ataka (St) 55 1,814 30 7,476 7

Abu Sultan (St) 48 1,137 42 5,466 9

Shabab (G) 2 236 8 677 3

Port Said (G) 1 129 9 374 3

EL-Arish (St) 5 874 5 2,366 2

Oyoun Mousa (St) 56 1,639 34 7,122 8

Damietta (CC) 73 1,791 41 8,464 9

New Gas Damietta

(G) 38 1,106 35 4,851 8

New Gas Shabab

(G) 83 3,952 21 14,231 6

Middle

Delta

Talkha (CC) 20 130 155 1,465 14

Talkha steam 210 27 1,315 20 4,690 6



Company Station

Capital

Cost

(Mio

EGP)

Subsidized Unsubsidized

Annual

Profit

(Thousand

EGP)

Payback

period

(years)

Annual

Profit

(Thousand

EGP)

Payback

period

(years)

(St)

Talkha 750 (CC) 29 1,088 27 4,260 7

Nubaria 1,2,3 (CC) 92 4,491 20 16,029 6

Mahmoudia (CC) 24 726 33 3,128 8

El-Atf (CC) 46 2,164 21 7,800 6

West

Delta

Kafr El-Dawar (St) 29 549 53 2,995 10

Damanhour Ext. 300

(St) 7 592 12 1,811 4

Damanhour (St) 15 1,341 12 4,101 4

Damanhour (CC) 11 987 11 3,016 4

Abu Kir (St) 64 2,016 32 8,506 8

El-Seiuf (G) 4 885 5 2,362 2

Sidi Krir (St) 43 2,177 20 7,657 6

Sidi Krir (CC) 44 2,211 20 7,796 6

Matroh (St) 5 665 8 1,900 3

Upper

Egypt

Kuriemat (St) 82 2,015 40 9,495 9

Kuriemat 1 (CC) 40 1,182 34 5,104 8

Kuriemat 2 (CC) 39 1,152 34 4,975 8

BOOT

Sidi Krir 3,4 (St) 46 1,946 24 7,294 6

Suez Gulf North (St) 43 1,761 24 6,655 6

Port Said East (St) 44 1,790 25 6,828 6



6 Assessment of Operating the Proposed Units in Parallel with

the Existing Electricity Systems

When the turbo-expander is installed parallel to the throttling valve in a PRS, the pressure

reduction is only achieved by the turbo-expander. The throttling valve is only used during the

maintenance of the expander. The use of the turbo-expander shows more reliability and it does

not affect the performance of the pressure reduction station under different operating

conditions. The turbo-expander is used to drive an electric generator which either is

interconnected with the electricity grid or can be synchronized with the power plant existing

generator. The additional generator (drive by turbo-expander) will be connected to operate in

parallel with each other and supply power to the same load.

Synchronization is the process of connecting a generator to anther generator or to power grid.

This process is carried out in order to parallel a generator onto a live bus-bar, either with

multiple generator sets as the only supply, or to the utility. Three major advantages for

operating synchronous generators in parallel are:

1. The reliability of the power system increases when many generators are operating in

parallel, because the failure of any one of them does not cause a total power loss to the

loads.

2. When many generators operate in parallel, one or more of them can be taken out when

failures occur in power plants or for preventive maintenance.

3. If one generator is used, it cannot operate near full load (because the loads are

changing), then it will be inefficient. When several machines are operating in parallel, it

is possible to operate only a fraction of them. The ones that are operating will be more

efficient because they are near full load.

Generally, four essential paralleling conditions must be met to ensure perfect synchronization:

1. Their terminal voltage must be the same (Voltage magnitude of the two generators shall

be nearly equal within tolerance ),

The stator line voltage must be equal to the line voltage of the power grid. This is

achieved by controlling the rotor current (excitation).

2. Their frequencies must be the same (frequency of the two voltage sources shall be

equal within tolerance ),

The synchronous generator must be driven by the prime mover at a speed such that the

stator frequency is equal to the bus-bas frequency.

3. Their phase sequence must be the same (phase angle of the two generators shall be

equal within tolerance),

The phase sequence of the synchronous generator must be the same as the phase

sequence of the bus-bas.

4. No phase shift,

The phase angle of the synchronous generator must be equal to the phase angle of the

bus-bas.



If only one of the conditions is not satisfied or this synchronizing process is not done correctly,

a power system disturbance will result and the generators, which are connected in parallel, can

be damaged. Synchronizing a generator to the power system must be done carefully to prevent

damage to the generators and disturbances to the power system.

Figure ‎6-1 illustrates a synchronous generator (GEN 1) supplying power to a load with another

generator (GEN 2) that is about to be paralleled with (GEN 1) by closing the switch (S1).

Figure ‎6-1 A Generator Being Paralleled with A Running Power System

The figure below shows the real operation of two synchronizing generators ready for load

sharing. Synchronizing equipment is required to monitor the bus frequency and the incoming

generator frequency, to ensure that the generators are in synchronism. When the synchronizing

equipment indicates that the incoming generator (GEN 1) is in phase with the bus-bar

frequency, the circuit breaker can be safely closed.

The incoming generator should always be slightly faster than the loaded generator. This

ensures that the incoming generator always takes a small proportion of load when the breaker

is closed. This will prevent reverse power protection tripping.

Figure ‎6-2 Parallel Operation - Synchronizing Generators 59

59

“Parallel Operation of A.C Generators Presentation”, Cummins Generator Technologies STAMFORD®



Figure ‎6-3 shows the parallel operating connection adopts the PLC (programmable logic

controller) as a logic control device to control the generators and parallel connection of

switches of the generator circuit breaker. It is capable of actualizing the power distribution to

multiple sets and the synchronous parallel connection inspection. It combines the functions of

load distribution, synchronous control, set control into one, having complete functions of sets

control, monitoring and protection.

Figure ‎6-3 Parallel Connection Control System 60

60

“Parallel Generators and Synchronization, Generator Power System Design”, AKSA Power Generation



7 The Current Institutional Setup and Relevant National

Legislations

7.1 Description of the Electricity Market Structure

The Ministry of Electricity and Energy (MoEE) is responsible for looking after the current

electricity market, through its:

Heading the board of directors of the electric regulatory agency by the Minster of

Electricity and Energy.

Semi/direct involvement in managing all the state owned utilities.

The current electricity market in Egypt is mainly composed of:

State owned utilities:

o Seven generation entities:

five thermal generation companies (covering around 81% of the generation)

one hydropower (covering around 8% of the generation) and,

one wind (covering around 1% of the generation)

o One transmission company and

o Nine distribution companies

Three Build Own Operate and Transfer (BOOT) projects (covering around 10% of the

generation).

A limited number of small isolated and/or semi connected Independent Service Providers

(ISP) (currently at the end of 2013; the number is 15 generation utilities and 24

distribution utilities); these ISP cover less than 0.5% of the electricity market so far, their

share is growing.

Figure ‎7-1 shows the current structure of the electricity market in Egypt which started in 2001.

The state utilities as well as the three BOOT projects currently operates under a single buyer

model, while the private sector ones operate under a competitive conditions.

Figure ‎7-1 Current Electricity Market in Egypt



The arrows in figure 7.1 represent the flow of electricity (solid ones reflects actual agreements

while the doted ones reflects possible agreements which are not there). ISP are either

generating electricity and selling at the medium and low voltage levels, or buying bulk electric

energy and distributing that. It is also possible for ISP to sell electricity directly to any type of

customers at any voltage level, but this is not exercised at the Ultra High Voltage (UHV) and

High Voltage (HV) levels, mainly due to price competition with government owned utilities.



8 Expected Roles for the Different Stakeholders including

Owners of the NG Networks and Pressure Reduction Stations In view of the current prevailing legislations that are governing the electricity market in Egypt

as well as both the investment and technical requirements needed the following would be

consider. The turbo expander location will be within the gas pressure reduction station; that

implies that its operation would be conducted by the staff of the PRS. On the other hand the

ownership of the turbo expander can be assumed by one of the following:

a) The owner of the PRS

b) An investor

c) The generation utility

In cases a) or b) the generated electricity would be sold to the generation utility at prices less

than its cost of production as indicated in section 5 of this study. In the third case c) the

generated electricity will be part of the overall generated electricity from the power station, but

at a less cost than the one being generated form the power station.



Annexes

Boosting Capacity of Electric Generation through the use of Turbo-Expanders in Natural Gas Network A-1


Annex A. Important Definition and Basic Concept of some Thermodynamics

Properties

This appendix is based on the following references:

1. DOE Fundamentals Handbook Thermodynamics, Heat Transfer and Fluid Flow , Elie

Tawil, P.E., LEED AP, U.S. Department of Energy, Washington

2. “Steam Distribution System Desk Book” by James F. McCauley, Fairmont Press, Inc.,

2000

3. “Fundamentals of Engineering Thermodynamics”, 7th

Edition.

1) Enthalpy

Enthalpy “H” is defined as:

Where “U” is the internal energy (KJ) of the system being studied, “P” is the pressure of the

system (N/m2), and “V” is the volume (m

3) of the system. Specific enthalpy “h” is the enthalpy

per unit mass (kJ/Kg).

Enthalpy is a property of a substance, like pressure, temperature, and volume, but it cannot be

measured directly. Normally, the enthalpy of a substance is given with respect to some

reference value. For example, the specific enthalpy of water or steam is given using the

reference that the specific enthalpy of water is zero at 0.01°C and normal atmospheric pressure.

The fact that the absolute value of specific enthalpy is unknown is not a problem, however,

because it is the change in specific enthalpy (∆h) and not the absolute value that is important in

practical problems.

2) Entropy

Entropy “S” is a property of a substance, as are pressure, temperature, volume, and enthalpy.

Because entropy is a property, changes in it can be determined by knowing the initial and final

conditions of a substance. Entropy quantifies the energy of a substance that is no longer

available to perform useful work. Because entropy tells so much about the usefulness of an

amount of heat transferred in performing work. Entropy is sometimes referred to as a measure

of the inability to do work for a given heat transferred. Entropy is represented by the letter S

and can be defined as “ΔS” in the following relationships:

Where:

∆S: The change in entropy of a system during some process (KJ/°K)

∆Q: The amount of heat transferred to or from the system during the process (KJ)

Tabs: The absolute temperature at which the heat was transferred (°K) ∆s: The change in specific entropy of a system during some process (KJ/Kg °K)

∆q: The amount of heat transferred to or from the system during the process (KJ/Kg)



Like enthalpy, entropy cannot be measured directly. Also, like enthalpy, the entropy of a

substance is given with respect to some reference value. For example, the specific entropy of

water or steam is given using the reference that the specific entropy of water is zero at 32 °F

(zero °K). The fact that the absolute value of specific entropy is unknown is not a problem

because it is the change in specific entropy “∆s” and not the absolute value that is important in

practical problems.

3) Reversible Process

A reversible process for a system is defined as a process that, once having taken place, can be

reversed, and in so doing leaves no change in either the system or surroundings. In other words

the system and surroundings are returned to their original condition before the process took

place.

In reality, there are no truly reversible processes; however, for analysis purposes, one uses

reversible to make the analysis simpler, and to determine maximum theoretical efficiencies.

Therefore, the reversible process is an appropriate starting point on which to base engineering

study and calculation. Although the reversible process can be approximated, it can never be

matched by real processes.

4) Irreversible Process

An irreversible process is a process that cannot return both the system and the surroundings to

their original conditions. That is, the system and the surroundings would not return to their

original conditions if the process was reversed. For example, an automobile engine does not

give back the fuel it took to drive up a hill as it coasts back down the hill.

There are many factors that make a process irreversible. Four of the most common causes of

irreversibility are friction, unrestrained expansion of a fluid, heat transfer through a finite

temperature difference, and mixing of two different substances.

Finally, a process is called irreversible if the system and all parts of its surroundings cannot be

exactly restored to their respective initial states after the process has occurred. A process is

reversible if both the system and surroundings can be returned to their initial states.

5) Adiabatic Process

An adiabatic process is one in which there is no heat transfer into or out of the system. The

system can be considered to be perfectly insulated (q=zero).

6) Isentropic Process

An isentropic process is one in which the entropy of the fluid remains constant. This will be

true if the process the system goes through is reversible and adiabatic. An isentropic process

can also be called a constant entropy process.

In an isentropic or constant entropy expansion, work is extracted during the expansion,

removing energy from the gas and resulting in a lower temperature of the expanded gas. The

figure below shows states having the same value of specific entropy.

Figure A-1 T–s and h–s Diagrams



Where:

T: Temperature

P: Pressure

k: Gas specific heat ratio

7) Isenthalpic Process

An isenthalpic process or isoenthalpic process is a process that proceeds without any change in

enthalpy “∆h” or specific enthalpy “h”

Significant changes in pressure and temperature can occur to the fluid and yet the process will

be isenthalpic expansion if there is no transfer of heat to or from the surroundings, no work

done on or by the surroundings, and no change in the kinetic energy of the fluid.

The throttling process is a good example of an isenthalpic process. Consider the lifting of a

relief valve or safety valve on a pressure vessel. The specific enthalpy of the fluid inside the

pressure vessel is the same as the specific enthalpy of the fluid as it escapes from the valve.

With knowledge of the specific enthalpy of the fluid, and the pressure outside the pressure

vessel, it is possible to determine the temperature and speed of the escaping fluid.

8) Throttling Process

A throttling process is defined as a process in which there is no change in enthalpy from state

one to state two, h1 = h2; no work is done, W = 0; and the process is adiabatic, Q = 0.

To better understand the theory of the ideal throttling process let’s compare what we can

observe with the above theoretical assumptions.

http://www.answers.com/topic/enthalpy



The theory that hin = hout was confirmed. Remember h = u + Pv (v = specific volume), so if

pressure decreases then specific volume must increase if enthalpy is to remain constant

(assuming “u” is constant). Because mass flow is constant, the change in specific volume is

observed as an increase in gas velocity, and this is verified by our observations. The change in

velocity can be neglected as it is usually observed to be small.

The theory also states W = 0, clearly no work has been done by the throttling process. Finally,

the theory states that an ideal throttling process is adiabatic. This cannot clearly be proven by

observation since a real throttling process is not ideal and will have some heat transfer.

The purpose of throttling a gas is to reduce it from higher pressure to a lower pressure to

produce a substance in a more usable form. In theory this can be done at 100 percent

efficiency. However, the throttling process is extremely inefficient. In most cases so much so

that in reality when attempting to throttle the flow of a substance often times the process

approaches isentropic. See below.

Figure ‎8-2 Pressure Reducing Processes

What usually happens is that with the expansion of the gas from a higher pressure to a lower

pressure there is a cooling effect causing a change in “Q”. However, useful work is not

performed since the throttle in itself cannot convert heat energy to mechanical energy.

Therefore, a more profitable means of reducing the pressure of a gas is to expand it through a

turbine or other type of engine. By doing so, the lower pressure is attained while producing

mechanical work.



Consider Error! Reference source not found. and Error! Reference source not found., a

reducing valve and a turbine, respectively. In the reducing valve, Error! Reference source not

found., there is a large quantity of rejected heat while reducing the pressure from P1 to P2. In

the turbine, Error! Reference source not found., where the machine can be thoroughly

insulated, the rejected heat is negligible. Also the gas can be expanded isentropically from P1

to P2 and produce useful mechanical work in the rotating shaft of the turbine at the same time.

Figure ‎8-3 Throttle on Pressure Reducing Valve

Figure A-4 Turbine used as a Pressure Reducing Machine

Figure ‎8-5 Expansion of a Gas



Error! Reference source not found. shows the expansion process of the gas. Line1-2 or 1-2s represents an

isentropic expansion and line 1-2’ or 1-2’act represents an irreversible adiabatic expansion.

Actual work is expressed as

Where,

: Turbo-expender efficiency

Mass flow rate

Isentropic work is expressed as

9) Joule-Thomson Effect The Joule-Thomson effect is defined as the cooling that occurs when a highly compressed gas

is allowed to expand in such a way that no external work is done. This cooling is inversely

proportional to the square of the absolute temperature.

The Joule-Thomson describes the temperature change of a gas or liquid when it is forced

through a valve. No heat is exchanged with the environment.

Boosting Capacity of Electric Generation through the use of Turbo-Expanders in Natural Gas Network B-1


Annex B. Evaluating the Potential of Electricity Generation from Industrial

and Residential Sector

Based on published data and information on61

:

Natural gas consumption by different economic sectors e.g. electricity, industrial gas main

consumers such as fertilizer, cement, iron & steel, petroleum, residential in addition to

transport.

Characteristic data and information of some PRSs in Egypt and some other countries that

include natural gas flow rate, pressure of inlet and outlet gas as presented in Error!

Reference source not found..

Error! Reference source not found. illustrate the level of electricity that could be produced

from turbo expanders at different natural gas flow rates and pressure reduction ratios as

presented before.

PRS’ natural gas flow, inlet and outlet pressure at different consumers.

The level of electricity to be generated from turbo expanders at different locations of PRSs has

been estimated. The following section presents the detailed assumptions, calculations and

results of estimating electricity generation using turbo expanders at different natural gas

consumers based on the previous mentioned data and information.

As previously mentioned, for estimating the potential of electricity generation from natural gas

pressure reduction in the national grid using the turbo expanders instead of conventional

throttling valves the following assumptions have been considered:

Natural gas consumption by different economic sectors for the year 2010/2011.

Average pressure of natural gas at different points or locations of the whole gas

chain is as shown in Error! Reference source not found. and Figure ‎1-9 given before.

Table ‎8-1 Assumed Inlet and Outlet Pressures at PRS for Different Natural Gas Consumers

Location/ Sector P

(bars) Pi Po PR

Producing wells 100

Treatment & conditioning facilities 70

High pressure gas transmission lines 70

Medium pressure gas transmission lines 40

Low pressure gas transmission lines 20

PRS at HP industrial plants (cement, fertilizer and iron &

steel). 70 20 3.5

PRS at MP industrial plants (refractory, textile, food, etc.). 40 8 5

PRS at LP industrial plants 20 4 5

61

Letters were sent to the Chairmen of both the Egyptian Natural Gas Holding company EGAS and the Egyptian

Natural Gas company GASCO on February 27, 2013. A copy of the letter is presented in ‎‎0. In addition, a meeting

with some of GASCO staff responsible for natural gas network activities was done on early March 2013.

However, the team responsible for performing the study did not receive the data requested.



PRS at residential & commercial sectors 20 4 5

Where, P: pressure; Pi: inlet pressure; Po: outlet pressure; PR: pressure reduction ratio; HP:

high pressure; MP: Medium Pressure; LP: Low Pressure.

Industrial Plants Only main energy intensive industrial facilities; mainly cement, fertilizer and iron & steel have

been considered for estimating the potential of electricity generation as a result of natural gas

pressure reduction. Accordingly, total electricity potential is estimated at about 25 MW based

on natural gas flow rates and pressure levels at inlet and outlets points of the Pressure

Reduction Stations (PRS) at those plants.

Cement Plants

As shown in Error! Reference source not found., total capacity generation potential from

different cement plants as a result of utilizing turbo expanders is estimated at 8.7 MW based on

natural gas flow rates and pressure levels at inlet and outlets points of PRS at those plants.

Table ‎8-2 Total Expected Capacity Generation at Different Cement Plants Using Turbo-Expander

Sector Total

(MMCF/D) Pi Po PD PR

Estimated Capacity

Gen. (MW)

Torrah 25 70 20 50 3.5 0.80

Helwan 31 70 20 50 3.5 0.90

Alexandria 12 70 20 50 3.5 0.35

Kawmia 26 70 20 50 3.5 0.80

Suez 33 70 20 50 3.5 0.90

Assuit 32 70 20 50 3.5 0.90

America 29 70 20 50 3.5 0.90

Beni Sueif 10 70 20 50 3.5 0.35

Misr Beni Suief 11 70 20 50 3.5 0.35

Masria 54 70 20 50 3.5 1.50

Kena 11 70 20 50 3.5 0.35

Sinai (gray cement) 11 70 20 50 3.5 0.35

Sinai (white cement) 4 70 20 50 3.5 0.20

Menya (white cement) 2 70 20 50 3.5 062

Total 290 8.65

Fertilizer Plants

As shown in Error! Reference source not found., total electricity generation potential from

different fertilizer plants as a result of utilizing turbo expanders is estimated at 13 MW based

on natural gas flow rates and pressure levels at inlet and outlets points of the PRS at those

plants.

62

Very low flow rate



Table ‎8-3 Total Expected Capacity Generation at Different Fertilizer Plants

Sector Total


Estimated Capacity

Generation (MW)

Talkha (Delta) 80 70 20 50 3.5 2.40

Abu Qir 135 70 20 50 3.5 4.20

Suez 25 70 20 50 3.5 0.70

Alexandria 50 70 20 50 3.5 1.50

Masria (1& 2

plants) 90 70 20 50 3.5 2.70

Helwan 45 70 20 50 3.5 1.35

Total 425 13.02

Iron & Steel Plants

Only iron & steel plants with significant natural gas flow as shown in Error! Reference source

not found. have been considered in estimating the potential of electricity as a result of natural

gas pressure reduction. Accordingly; total capacity generation potential from iron & steel

plants as a result of utilizing turbo expanders is estimated at 3.8 MW based on natural gas flow

rates and pressure levels at inlet and outlets points of the PRS at those plants.

Table B-4 Total Expected Capacity Generation at Different Iron & Steel Plants

Sector Total


Estimated Capacity Generation

(MW)

EZZ

(Dekhila) 71 70 20 50 3.5 2.20

Beshaai 24 70 20 50 3.5 0.75

Attal 7 70 20 50 3.5 0.25

Kotta 11 70 20 50 3.5 0.30

Dawlia 9 70 20 50 3.5 0.30

Total 151 3.80

Other Natural Gas PRS

Based on the published data on some natural gas pressure reduction stations as shown from

Error! Reference source not found., the potential for electricity generation is estimated at about

24 MW.

Table ‎8-5 Estimated electricity production from some PRS

PRS Name Total


Estimated Power Generation

(MW)

Natgas 1 85 70 5 66 16 6.50



Natgas 2 85 55 5 51 12 6.00

Egypt Gas 170 70 40 30 2 3.50

TransGas 34 70 5 65 14 2.40

Nubaria Gas 271 70 27 43 3 5.15

Total 644 65 20 45 3 23.55

Boosting Capacity of Electric Generation through the use of Turbo-Expanders in Natural Gas Network C-1


Annex C. Request Letters sent to EGAS and GASCO

Boosting Capacity of Electric Generation through the use of Turbo-Expanders in Natural Gas Network D-1


Annex D. Units Conversion Tables

1) Decimal Multiples and Sub-Multiples

Name Symbol Equivalent Name Symbol Equivalent

Tera

Giga

Mega

kilo

hector

deca

T

G

M

k

h

-

1012

109

106

103

102

10

deci

centi

milli

micro

nano

pico

d

c

m

µ

n

p

10-1

10-2

10-3

10-6

10-9

10-12

2) Length Units

Millimeters Centimeters Meters Kilometers Inches Feet Yards Miles

mm cm m km in ft yd mi

1 0.1 0.001 0.000001 0.03937 0.003281 0.001094 6.21e-07

10 1 0.01 0.00001 0.393701 0.032808 0.010936 0.000006

1000 100 1 0.001 39.37008 3.28084 1.093613 0.000621

1000000 100000 1000 1 39370.08 3280.84 1093.613 0.621371

25.4 2.54 0.0254 0.000025 1 0.083333 0.027778 0.000016

304.8 30.48 0.3048 0.000305 12 1 0.333333 0.000189

914.4 91.44 0.9144 0.000914 36 3 1 0.000568

1609344 160934.4 1609.344 1.609344 63360 5280 1760 1

3) Area Units

Millimeter

square

Centimeter

square

Meter

square

Inch

square

Foot

square

Yard

square

mm2

cm2

m2

in2

ft2

yd2

1 0.01 0.000001 0.00155 0.000011 0.000001

100 1 0.0001 0.155 0.001076 0.00012

1000000 10000 1 1550.003 10.76391 1.19599

645.16 6.4516 0.000645 1 0.006944 0.000772

92903 929.0304 0.092903 144 1 0.111111

836127 8361.274 0.836127 1296 9 1

4) Volume Units

Centimeter

cube

Meter

cube Liter

Inch

cube

Foot

cube

US

gallons

Imperial

gallons

US

barrel

(oil)

cm3

m3

ltr in3

ft3

US gal Imp. gal US brl

1 0.000001 0.001 0.061024 0.000035 0.000264 0.00022 0.000006

1000000 1 1000 61024 35 264 220 6.29



1000 0.001 1 61 0.035 0.264201 0.22 0.00629

16.4 0.000016 0.016387 1 0.000579 0.004329 0.003605 0.000103

28317 0.028317 28.31685 1728 1 7.481333 6.229712 0.178127

3785 0.003785 3.79 231 0.13 1 0.832701 0.02381

4545 0.004545 4.55 277 0.16 1.20 1 0.028593

158970 0.15897 159 9701 6 42 35 1

5) Mass Units

Grams Kilograms Metric

tonnes Short ton Long ton Pounds Ounces

g kg tonne shton Lton lb oz

1 0.001 0.000001 0.000001 9.84e-07 0.002205 0.035273

1000 1 0.001 0.001102 0.000984 2.204586 35.27337

1000000 1000 1 1.102293 0.984252 2204.586 35273.37

907200 907.2 0.9072 1 0.892913 2000 32000

1016000 1016 1.016 1.119929 1 2239.859 35837.74

453.6 0.4536 0.000454 0.0005 0.000446 1 16

28 0.02835 0.000028 0.000031 0.000028 0.0625 1

6) Density Units

Gram/milliliter Kilogram/meter

cube Pound/foot cube Pound/inch cube

g/ml kg/m3

lb/ft3

lb/in3

1 1000 62.42197 0.036127

0.001 1 0.062422 0.000036

0.01602 16.02 1 0.000579

27.68 27680 1727.84 1

7) Volumetric Liquid Flow Units

Liter/second Liter/minute Meter

cube/hour

Foot

cube/minute

Foot

cube/hour

US

gallons/minute

US

barrels

(oil)/day

L/sec L/min m3/hr ft

3/min ft

3/hr gal/min US brl/d

1 60 3.6 2.119093 127.1197 15.85037 543.4783

0.016666 1 0.06 0.035317 2.118577 0.264162 9.057609

0.277778 16.6667 1 0.588637 35.31102 4.40288 150.9661

0.4719 28.31513 1.69884 1 60 7.479791 256.4674

0.007867 0.472015 0.02832 0.01667 1 0.124689 4.275326

0.06309 3.785551 0.227124 0.133694 8.019983 1 34.28804

0.00184 0.110404 0.006624 0.003899 0.2339 0.029165 1



8) Volumetric Gas Flow Units

Normal meter cube/hour Standard cubic feet/hour Standard cubic feet/minute

Nm3/hr scfh scfm

1 35.31073 0.588582

0.02832 1 0.016669

1.699 59.99294 1

9) Mass Flow Units

Kilogram/hour Pound/hour Kilogram/second Ton/hour

kg/h lb/hour kg/s t/h

1 2.204586 0.000278 0.001

0.4536 1 0.000126 0.000454

3600 7936.508 1 3.6

1000 2204.586 0.277778 1

10) High Pressure Units

Bar Pound/square

inch Kilopascal Megapascal

Kilogram

force/

centimeter

square

Millimeter

of

mercury

Atmospheres

bar psi kPa MPa kgf/cm2 mm Hg atm

1 14.50326 100 0.1 1.01968 750.0188 0.987167

0.06895 1 6.895 0.006895 0.070307 51.71379 0.068065

0.01 0.1450 1 0.001 0.01020 7.5002 0.00987

10 145.03 1000 1 10.197 7500.2 9.8717

0.9807 14.22335 98.07 0.09807 1 735.5434 0.968115

0.001333 0.019337 0.13333 0.000133 0.00136 1 0.001316

1.013 14.69181 101.3 0.1013 1.032936 759.769 1

11) Low Pressure Units

Meter of

Water

Foot of

water

Centimeter

of

mercury

Inches of

mercury

Inches of

water Pascal

mH2O ftH2O cmHg inHg inH2O Pa

1 3.280696 7.356339 2.896043 39.36572 9806

0.304813 1 2.242311 0.882753 11.9992 2989

0.135937 0.445969 1 0.39368 5.351265 1333

0.345299 1.13282 2.540135 1 13.59293 3386

0.025403 0.083339 0.186872 0.073568 1 249.1

0.000102 0.000335 0.00075 0.000295 0.004014 1



12) Speed Units

Meter/second Meter/minute Kilometer/hour Foot/second Foot/minute Miles/hour

m/s m/min km/h ft/s ft/min mi/h

1 59.988 3.599712 3.28084 196.8504 2.237136

0.01667 1 0.060007 0.054692 3.281496 0.037293

0.2778 16.66467 1 0.911417 54.68504 0.621477

0.3048 18.28434 1.097192 1 60 0.681879

0.00508 0.304739 0.018287 0.016667 1 0.011365

0.447 26.81464 1.609071 1.466535 87.99213 1

13) Dynamic Viscosity Units

Centipoise Poise Pound/foot·second

cp poise lb/(ft·s)

1 0.01 0.000672

100 1 0.067197

1488.16 14.8816 1

14) Temperature Conversion Formulae

Degree Celsius (°C)

Degree Fahrenheit (°F)

Kelvin (K)

15) Power Units

Giga Joule Mega Watt

hour

Giga Watt

Kalori

Million units,

temperature

British

Tons of oil

equivalent

GJ MWh GW Kalori Mio BTU toe

41.87 11.63 10 39.69 1

1.05 0.29 0.25 1 0.025

4.19 1.16 1 3.97 0.1

3.6 1 0.86 3.41 0.086

1 0.28 0.24 0.95 0.034

Boosting Capacity of Electric Generation through the use of Turbo-Expanders in Natural Gas Network E-1


Annex E. Natural Gas Measurements and Conversions

995 tons of oil equivalent = Tons of crude oil

1,111 tons of oil equivalent = Tons of natural gas

1.125 tons of oil equivalent = Ton liquid propane gas (LPG)

972 tons of oil equivalent = Tons of fuel oil

1,086 tons of oil equivalent = Tons of kerosene

1,103 tons of oil equivalent = Tons of gasoline

1,066 tons of oil equivalent = Tons diesel

7.3 barrels of oil = Tons of crude oil

0.67 tons of oil equivalent = Tons of coal

5000 cubic feet of natural gas = Barrels of natural gas

1330 m3

= Tons of natural gas

35,315 cubic feet = Cubic meters of natural gas

1 cubic foot natural gas (NG) – wet = 1,109 Btu

1 cubic foot – dry = 1,027 Btu

1 cubic foot – dry = 1,087 kilojoules

1 cubic foot – compressed = 960 Btu

1 pound = 20,551 Btu

1 gallon – liquid = 90,800 Btu – HHV

1 gallon – liquid = 87,600 Btu – LHV

1 million cubic feet = 1,027 million Btu

1 metric ton liquefied natural gas

(LNG)

= 48,700 cubic feet of natural gas

1 billion cubic meters NG = 35.3 billion cubic feet NG

1 billion cubic meters NG = 0.90 million metric tons oil equivalent

1 billion cubic meters NG = 0.73 million metric tons LNG

1 billion cubic meters NG = 36 trillion BTUs

1 billion cubic meters NG = 6.29 million barrels of oil equivalent

1 billion cubic feet NG = 0.028 billion cubic meters NG

1 billion cubic feet NG = 0.026 million metric tons oil equivalent

1 billion cubic feet NG = 0.021 million metric LNG

1 billion cubic feet NG = 1.03 trillion BTUs

Boosting Capacity of Electric Generation through the use of Turbo-Expanders in Natural Gas Network E-2


1 billion cubic feet NG = 0.18 million barrels oil equivalent

1 million metric tons LNG = 1.38 billion cubic meters NG

1 million metric tons LNG = 48.7 billion cubic feet NG

1 million metric tons LNG = 1.23 million metric tons oil equivalent

1 million metric tons LNG = 52 trillion BTUs

1 million metric tons LNG = 8.68 million barrels oil equivalent

1 million metric tons oil equivalent = 1.111 billion cubic meters NG

1 million metric tons oil equivalent = 39.2 billion cubic feet NG

1 million metric tons oil equivalent = 0.805 million tons LNG

1 million metric tons oil equivalent = 40.4 trillion BTUs

1 million metric tons oil equivalent = 7.33 million barrels oil equivalent

1 million barrels oil equivalent = 0.16 billion cubic meters NG

1 million barrels oil equivalent = 5.61 billion cubic feet NG

1 million barrels oil equivalent = 0.14 million tons oil equivalent

1 million barrels oil equivalent = 0.12 million metric tons of LNG

1 million barrels oil equivalent = 5.8 trillion BTUs

1 trillion BTUs = 0.028 billion cubic meters NG

1 trillion BTUs = 0.98 billion cubic feet NG

1 trillion BTUs = 0.025 million metric tons oil equivalent

1 trillion BTUs = 0.2 million metric tons LNG

1 trillion BTUs = 0.17 million barrels oil equivalent1 short ton

= 53,682.56 cubic feet

1 long ton = 60,124.467 cubic feet

1 cubic foot = 0.028317 cubic meters

1 cubic meter – dry = 36,409 BTU

1 cubic meter – dry = 38.140 Mega Joules

1 cubic meter = 35.314 cubic feet



Annex F. Characteristics of some Gas Pressure Regulating and Metering

Station in Egypt and other Countries

National Gas Company “NATGAS“, Egypt:

Gas Pressure Regulating and Metering Station

(City Gate) Capacity/Flow: 100.000 m³/h Natural Gas

Inlet Pressure: 70 barg

Outlet Pressure: 4,5 barg

Heating Facility: 3.200 kW

Commissioning: 2000

National Gas Company “NATGAS”, Egypt:


(City Gate)

Capacity/Flow: 100.000 m³/h



Heating Facility: 2.580 kW

Commissioning: 2003

Egypt Gas, Cairo/Egypt:

Gas Pressure Reduction/Fuel Gas Supply Station:



Outlet Pressure: 40 barg

Commissioning: 2003

Transgas, Cairo/Egypt:

Gas Pressure Regulating and Metering Station:




Heating Facility: 990 kW

Commissioning: 2004

Egypt, Nubaria Gas Company, Cairo /2004-2005 Gas Pressure Reducing & Metering Station – 2 lines

100%

Flow: 320.000 Nm³/h

Inlet pressure: 32-70 bar(g)

Outlet pressure: 27 bar(g)

Sub contract via Actaris

Design by: B. Wiede

Executed by: Egypt Gas, Cairo

City of Nubaria

Nile Delta/

Power Plant

Germany, SHELL /2010

Gas Pressure Reducing & Metering Station – 2 lines

100%

Flow: 50.000 Nm³/h


Outlet pressure: 27-46 bar(g)

Executed by: GEVA, Germany

Godorf, Germany/

Power Plant

Bakhrabad Gas Systems Ltd., Bangladesh

Gas Pressure Regulating and Metering Station:




Commissioning: 2002

HKM Hüttenwerke Krupp Mannesmann, Germany

Gas Pressure Reducing and Metering System

Capacity/Flow Rate: 103.000 m³/h



Commissioning: 2003

VA TECH Combined Cycle, Austria

Turnkey Gas Fuel System, Turkey:




Commissioning: 2004

Wintershall AG, Germany



Inlet Pressure Class: ANSI 600, 100 bar

Inlet Pressure: 84 bar

Outlet Pressure: 30 bar



Commissioning: 2004

Wintershall AG, Germany





Outlet Pressure: 21 bar/4 bar/1,5 bar

Commissioning: 2004

WINGAS GmbH, Germany





Outlet Pressure: 40 bar

Commissioning: 2004

Transgaz S. A., Medias/Romania





Commissioning: 2004

Pratiwi Putri Sulung, Indonesia

Offtake Station




Commissioning: 2004

Bayer Industry Services, Germany





Commissioning: 2005

Algeria, Sonelgaz Production d’Èlectricite /1986

1x HP Reducing & Metering Station

Flow: 165.000 Nm³/h

Inlet pressure: 40 bar(g)


1x LP Reducing & Metering Station

Flow: 165.000 Nm³/h



Sub contract via Technopromexport

Design by: B. Wiede

Executed by: Rombach Germany

Jijel, Algeria/

Power Plant

Greece

PUBLIC POWER

CORPORATION S.A. /

1966-1997 Gas Pressure Reducing Station - 2 lines 100%

with heater and silencer

Flow: 60.000 Nm³/h


Outlet pressure: 1,5 bar(g)


Executed by: whb Germany

Greece, Athens/

Power Plant

Iran

IPDC (Iran Power

Development Company) /

1997-1998


50%

with silencer

Flow: 225.000 Nm³/h





Esfahan TPS, Unit 8

4x200 MW/

Power Plant



Iran IPDC (Iran Power Development Company) /

1997-1998


50%

with silencer Flow: 207.000 Nm³/h





Ramin TPS, Unit 5-6

2x315 MW/

Power Plant

Uzbekistan, State Electricity Board /2000-2002


100%

with silencer Flow: 2x225.000 Nm³/h



Sub contract via Siemens


Talimardjan TPE

1x 800 MW/

Power Plant

Libya Sirte Oil Company / 2002 Gas Pressure Reducing & Metering Station – 4 lines

50%

with scrubber, filter, heater

Flow: 4x3.729 Nm³/h



Sub contract via MAN

Design by: B. Wiede

Executed by: Rombach Germany

Wachkan Compression

Facilities/

Process Gas

Iraq Gerneral Company for Electrical Projects /

2002-2004 Gas Pressure Reducing & Metering Station – 2 lines

100%

with filter, heater and silencer

Flow: 2x110.000 Nm³/h,




Design by: B. Wiede

Executed by: GEVA Germany

Youssifiyah TPS,

2x210 MW/

Power Plant

Iraq Gerneral Company for Electrical Projects /

2002-2004 Gas Pressure Reducing Station – 2 lines 100%

with silencer

Flow: 2x55.000 Nm³/h




Youssifiyah TPS,

5x210 MW/

Power plant

Iran Mobin Petrochemical Co. / 2004-2005

1x HP Metering Station

Flow: 220.000 Nm³/h

Pressure: 50 bar(g)

1x HP Metering Station

Flow: 101.000 Nm³/h

Pressure: 50 bar(g)

6x Gas Pressure Reducing & Metering Station

Flow: 1.500 to 50.000 Nm³/h


Outlet pressure: 4 to 11 bar(g)

Sub contract via Actaris

Design by: B. Wiede

Executed by: GEVA, Germany

Assaluyeh,

Persian Gulf Region/

Process Gas

Germany Krupp – Mannesmann 2005


100%

Flow: 35.000 Nm³/h

Inlet pressure 40-60 bar(g)

Outlet pressure 10 bar(g)


Aachen, Germany/

Power Plant

Germany STEAG / BASF / 2005


100%

Flow: 20.000 Nm³/h




Ludwigshafen,

Germany/ Power Plant Belgium,

ELECTRABEL/2006

Germany E.ON Ruhrgas / 2007





100%

Flow: 50.000 Nm³/h




Brüssel, Belgium/

Heating Plant

100% Flow: 40.000 Nm³/h




Wülfrath,

Germany/

Process Gas

Germany, E.ON Ruhrgas /2008 Gas Pressure Reducing & Metering Station – 2 lines

100%

Flow: 114.000 Nm³/h




Nette Eisenbeck,

Germany/

Power Plant

Germany, Hagen Kabel / 2008


100% Flow: 50.000 Nm³/h


Outet pressure: 27-46 bar(g)


Hagen, Germany/

Heating Plant

Croatia, HEP-PROIZVODNJA/ 2010-2012


100%

Flow: 59.900 Nm³/h




Design by: B. Wiede


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