20 presentation chps cogen_tech_env_benefits 57pp.pdf

EC-ASEAN COGEN Programme Phase IIIClean Efficient Biomass, Coal, Gas Cogeneration

Cogeneration Technologies and Its Environmental Benefits

Cogeneration Technologies and Its Environmental Benefits

Seminar on “COGEN 3: A Business Facilitator”

30 August 2002Singapore

22 August 2002Cebu, Philippines20 August 2002Bangkok, Thailand

2-3 September 2002Kuala Lumpur, Malaysia

28-29 August 2002Ho Chi Minh, Vietnam

20-21 August 2002Manila, Philippines

30-31 August 2002Hanoi, Vietnam

26-27 August 2002Jakarta, Indonesia22-23 August 2002Phnom Penh, Cambodia


Outline

1. Cogeneration

2. Steam Turbine Cogeneration

3. Gas Turbine Cogeneration

4. Combined Cycle Cogeneration

5. Gas Engine Cogeneration

6. Steam Engine Cogeneration

7. Cogeneration Case Studies

8. Environmental Benefits of Cogeneration


Cogeneration or Combined Heat and Power (CHP)

• Sequential generation of two different forms of useful energy using a single primary energy source

• Most usual:

– electrical (or mechanical)

– thermal: heating or cooling


Benefits of Cogeneration

• Lower primary energy consumption

• Reduced energy bills

• No transmission and distribution losses

• Less burden on national government for power generation

• Less environmental pollution


Conventional Power Generation vsCogeneration

Conventional system

Cogeneration system


Efficiency Comparison between Cogeneration and Separate Production of Electricity and Heat

(Numbers below arrows represent units of energy in typical values)Source: The European Educational Tool on Cogeneration, 2nd ed., December 2001

Power Plant

Boiler

Cogeneration System

Fuel

Fuel

100

100

Electricity36

Heat80

55

Fuel

100

Separate Production of Electricity and Heat

Cogeneration Electricity

Heat

Total efficiency: η = 36 + 80 = 0.58 200

Total efficiency: η = 30 + 55 = 0.85 100

30


Typical Cogeneration Performance Parameters

78 – 8126 – 31 10 – 20 MWLarger Gas Turbines

74 – 81 24 – 31 800 – 10,000 kWSmaller Gas Turbines

Up to 80*17 – 34 10 – 100 MW Steam Turbines

76 – 86 26 – 36 500 – 3,000 kWLarger Reciprocating Gas Engines

74 – 82 20 – 32 10 – 500 kWSmaller Reciprocating Gas Engines

Overall Cogeneration

Electrical Conversion

Nominal Range (Electrical)

Prime Mover in Cogeneration Package

Efficiencies %

NOTE: Adapted from Cogeneration Handbook California Energy Commission, 1982* taken from Cogeneration Guide Cogen Europe


Characteristics of an Ideal Cogeneration Facility

• Reliable power requirement

• Utilisation of higher thermal energy (kWth) than electricity (kWe)

• Quite stable load patterns of thermal energy and electricity

• Long operating hours

• High price of grid electricity or inaccessibility to grid


Typical Cogeneration Applications

• Industrial cogeneration

wood and agro-industries, food processing, pharmaceutical, pulp and paper, oil refinery, textile industry, steel industry, cement industry, glass industry, ceramic industry

• Residential/commercial/institutional cogeneration

hospitals, schools & universities, hotels, houses & apartments, stores & supermarkets, office buildings


Steam Turbine Cogeneration



Principle


• Boiler∗ Fixed grate boiler∗ Inclined grate boiler∗ Travelling grate boiler∗ Vibrating grate boiler∗ Fluidised bed boiler∗ Circulated fluidised bed boiler

• TurbineBack pressure turbineExtraction condensing turbine

• Generator• Condenser • Feed water pump

Steam Turbine CogenerationMain Elements


Appropriate for sites where

• Electrical base load is over 250 kWe

• High pressure process steam is required

• Cheap, low-premium fuel is available

• High grade process waste heat is available

• Existing boiler plant is in need of replacement

Steam Turbine CogenerationApplication


Section Through of a Steam Turbine of Higher Output


• Biomass, solid waste

• Coal

• Natural gas

• Petroleum

• Others: basically every fuel that can be burnt in a boiler


Possible Fuels


• Versatility of fuel• Well-established technology• Flexibility in the size of plants

Disadvantages

• Low electrical plant efficiency• Low part load performance• High operating cost


Advantages


Gas Turbine Cogeneration



Basics

• Fuel is burnt in a pressurised combustion chamber using combustion air supplied by a compressor

• Conversion of mechanical energy (turbine) into electrical energy with the help of the generator.

• Utilisation of gases escaping from the turbine for heat supply.



Principle


Suitable if

• Power demand is continuous and over 1 MWe

• Natural gas is available (though not a limiting factor)

• There is high demand for medium/high pressure steam or hot water, particularly at temperature higher than 140 °C


Application


Section Through of a Gas Turbine of Higher Output


• Gas

• Petroleum

– Kerosene

– Light oil

– Diesel oil

• Gasification of coal


Possible Fuels


• High reliability• Wide fuel range capability• Relatively low investment cost per kW

electrical output• Low emission

Disadvantages• Poor efficiency at low loading (but can

operate continuously at low loads)• High maintenance cost• High fuel cost

Gas Turbine – Cogeneration

Advantages


Combined Cycle Cogeneration


Combined Steam-and-Gas Cycle Cogeneration

Principle



Possible Fuels

• Gas

• Petroleum

• Fuels obtained through gasification of biomass or coal


• High electrical efficiency

Disadvantages

• Only suitable for high electrical output

• High operating cost


Advantages


Gas Engine Cogeneration


Gas Engine CogenerationBasics


Suitable for sites where

• Power or processes are cyclical or not continuous

• Low pressure steam or medium or low temperature hot water are required

• Low heat to power demand ratio


Application


1. Compression-ignition (diesel) engines [100 kWe to 20 MWe]

2. Spark-ignition engines [3 kWe to 10 MWe]


Main types


• Biogas

• Natural gas

• Gas oil

• Heavy fuel oil


Possible Fuels


• High power efficiency over a wide load range

• Relatively low investment cost per kWeelectrical output

• Multi-fuel capability• Low exhaust emission

Disadvantages

• High levels of low frequency noise

• High maintenance cost


Advantages


Steam Engine Cogeneration


Steam Engine CogenerationBasics



• Steam throughput rates up to 40 tph

• Power outputs up to 1,500 kW

• Intake pressures from 6 to 60 bars

• Steam temperatures from saturated steam to 450 °C

• Back pressures up to 25 bars


Steam Engine CogenerationPossible Fuels

• Coal

• Petroleum

• Biomass, garbage

• Others: basically every fuel is possible

Efficiency

• Electrical efficiency : 6 – 20%

• Overall efficiency : 80 – 90 %


• Long service life• Very good part-load performance• Mature technology

Disadvantages

• Low electrical plant efficiency

• Requires much maintenance work

• Noise intensive


Advantages


Cogeneration Case Studies


2.5 MW Cogeneration Plant

Cost : 3.60 M € (1997)

Steam boiler : • Reciprocating inclined grate type• Capacity: 17 tph, 35 bar, 420 oC

Customer : Chia Meng Co., Ltd., Thailand

Cogeneration Case Study (I)

A Rice Husk Fired Plant in Thailand

Turbine : 2.5 MW gross


• Uses • 6 x 35 MW gas turbine generators• 2 x 152 MW steam turbine generators• 2 x Circulating Fluidised Bed Boilers• 4 x Heat Recovery Units

• Primary fuels: • Natural gas • Indonesian bituminous coal

• Back-up fuel:

• Diesel oil

Cogeneration Case Study (II)

Hybrid Cogeneration Plant in Thailand


Cost: approx. 600 M €

Product

• 514 MW electricity

• 200 tph steam (medium pressure)

• 150 m3/h demineralised water

Cogeneration Case Study (II)

Hybrid Cogeneration Plant in Thailand


Environmental Benefits of Cogeneration


• Increased energy efficiency leads to less

emissions

• Less contribution to acid rain phenomenon

• Significant reduction in greenhouse gas

emissions

• Elimination of unwanted solid wastes



Source: Joule Thermie, 1997



CO2, CH4 and N2O Direct Greenhouse Gas Effect

NOX and SOX Acid rain

CO Public health

Particulates Public health

CO, NOX and NMVOC Indirect Greenhouse Gas Effect

Emissions Associated with Cogeneration


Clean Development Mechanism (CDM) and Cogeneration

Clean Development Mechanism (CDM) and Cogeneration

CDM can be defined as

a mechanism under which developed countries can implement GHG mitigation projects in developing countries and acquire Certified Emission Reductions to meet a part of their commitments.


How does CDM work for Cogeneration?How does CDM work for Cogeneration?

If you are developing/implementing any project, such as cogeneration, which results in the global mitigation of Greenhouse Gas effect(caused by CO2, CH4 and N2O emission) then you could get a certificate for your emission mitigation (Certified Emission Reduction –CER).1 Unit = 1 ton of CO2 equivalent mitigation


This CER can be sold in the international market.

Current market price: 2 - 4 US$ / ton of CO2

equivalent

Expected to increase depending on the demand and supply

(continued)

How does CDM work for cogeneration?How does CDM work for cogeneration?


For more information on CDM…For more information on CDM…

• http://unfccc.int/cdm/ebhome.html

• http://www.undp.org/seed/eap/Climate_Change/CDM.html

• http://www.unido.org/knitt/

• http://unfccc.int/cdm/

• http://www.unctad.org/ghg/Projects/projects.htm

• http://www.ieta.org/

• http://www.itut.de/cdm/pages/aboutCDM_cycle.html

20 presentation chps cogen_tech_env_benefits 57pp.pdf

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