Download - w Stein Good 53p
-
8/6/2019 w Stein Good 53p
1/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
Australia and Europe
Partnerships for Sustainable Energy R&D
Solar Thermal Developments in Australia
Wesley Stein
Sponsored by The Australian Academy ofTechnological Sciences and Engineering (ATSE) and
CSIRO, Australia's National R&D organisation.
30 June 2002
-
8/6/2019 w Stein Good 53p
2/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
DriversDriversDriversDrivers
Renewable and sustainable energyincentives
Solar is pure green
Abundance of solar energy resource
Compatibility with both existing and
advanced energy technologies Distributed or large scale centralised
New investment opportunity
-
8/6/2019 w Stein Good 53p
3/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
Aust ra l ia s Mandat oryAust ra l ia s Mandat oryAust ra l ia s Mandat oryAust ra l ia s Mandat ory
Renew able Energy TargetRenew able Energy TargetRenew able Energy TargetRenew able Energy Target
9500GWh/yr of renewable energyrequired by 2010
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 2020
Year
GWh
-
8/6/2019 w Stein Good 53p
4/53ENERGYENERGYENERGYENERGY TECHNOLOGY
Aust ra l ia s Mandat oryAust ra l ia s Mandat oryAust ra l ia s Mandat oryAust ra l ia s Mandat ory
Renew able Energy TargetRenew able Energy TargetRenew able Energy TargetRenew able Energy Target
9500GWh/yr of renewable energyrequired by 2010
Liability on electricity retailers
Certificate trading system
$40/MWh penalty for non-compliance
-
8/6/2019 w Stein Good 53p
5/53
1100
1400
1950
1700
1950
1700
1400
1100
2200
2200
1950 1950
1950
1950
1950
17001700
170019502200
2200
2200
2200
Solar Global Radiation > 2200 kWh/ma very good qualified
Qualification for Solar Electricity Generation
Solar Global Radiation > 1950 kWh/ma good qualified
Global Solar Radiation
-
8/6/2019 w Stein Good 53p
6/53
-
8/6/2019 w Stein Good 53p
7/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
Solar t herm al t ec hnologiesSolar t herm al t ec hnologiesSolar t herm al t ec hnologiesSolar t herm al t ec hnologies
Solar hot water Solar tower
Solar ponds
Solar-assisted chilling
Solar steam/ Rankine cycle
Solar dish - Stirling or Brayton cycle Central Receivers
Solar reforming or dissociation
-
8/6/2019 w Stein Good 53p
8/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
Solar t herm al /b iom assSolar t herm al /b iom assSolar t herm al /b iom assSolar t herm al /b iom ass
hybr idshybr idshybr idshybr ids
Bioenergy and solar thermal both utilisethe same thermodynamic cycles
Each fuel offers advantages to the other
Solar unlimited, biomass low cost(sometimes)
No exotic material breakthroughsrequired
Transitional
-
8/6/2019 w Stein Good 53p
9/53
-
8/6/2019 w Stein Good 53p
10/53
Solar Tower ProjectSolar Tower Project
-
8/6/2019 w Stein Good 53p
11/53
-
8/6/2019 w Stein Good 53p
12/53
-
8/6/2019 w Stein Good 53p
13/53
-
8/6/2019 w Stein Good 53p
14/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
-
8/6/2019 w Stein Good 53p
15/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
ENERGY LOSSES UNDER TYPICAL OPERATION
at 475degC, 900W/m2
0
50
100
150
200
250
300
350
400
Insolation
Interceptedbyrec
Stea
mproduced@
rec
D
eliveredatLRJ
DeliveredatEngine
Gros
sengineoutput
Ne
tengineoutput
kW
0%
20%
40%
60%
80%
100%
120%
Percentage
Energy, kW
Percentage
-
8/6/2019 w Stein Good 53p
16/53
0
50
100
150
200
250
300
350
0 100 200 300 400
Solar direct radiation into dish aperture, kW
Thermalp
oweroutpu
t,kWth
Measured data,
480
o
C
Model data for improved dish
SOLAR COLLECTOR PERFORMANCE DATA
Wesley Stein, March 2000
-
8/6/2019 w Stein Good 53p
17/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
The Dish and Col lec t or The Dish and Col lec t or The Dish and Col lec t or The Dish and Col lec t or
-
8/6/2019 w Stein Good 53p
18/53
-
8/6/2019 w Stein Good 53p
19/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
-
8/6/2019 w Stein Good 53p
20/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
Mul t iMu l t iMu l t iMu l t i ----t ow er so lar ar rayt ow er so la r a rrayt ow er so la r a rrayt ow er so la r a rray
(Univers i t y of Sydney)(Univers i t y of Sydney)(Univers i t y of Sydney)(Univers i t y of Sydney)
ReceiverInsolationReceiver
Reflector orientation patterns set up to allow avoidance of blocking ofreflected radiation under close packing. This diagram applies schematically tothe MTSA along two axes. Courtesy of Philippe Schramek and David Mills.
-
8/6/2019 w Stein Good 53p
21/53
CARNOT CYCLE EFFICIENCY AND SOLAR CONCENTRATION RATIO
0%
10%
20%
30%
40%
50%
60%
70%
80%
0 200 400 600 800 1000 1200
Temperature, deg C
Carnotcy
cleefficiency
10
100
1000
10000
Solarconcentrationratio,
Aa/A
r
1
-
8/6/2019 w Stein Good 53p
22/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
Gas Turbine
Steam Turbine
Condenser
Solar Field
SolarSteamGenerator
Fuel
Heat RecoverySteam Generator
Stack
-
8/6/2019 w Stein Good 53p
23/53
0
100
200
300
400
500
600
0% 20% 40% 60% 80% 100%
% heat transferred
Temperatur
e,oC
Single pressure
Dual pressure
Infinite ressure sta es eva oration external to HRB
Flue gas profile
-
8/6/2019 w Stein Good 53p
24/53
20%
22%
24%
26%
28%
30%
32%
34%
36%
0% 20% 40% 60% 80% 100%
% of peak solar steam input
Intern
alandoverall
steam
cycleefficienc
y
73%
74%
75%
76%
77%
78%
79%
80%
81%
82%
HRBefficiency
Internal steam cycle efficiency* Overall steam cycle efficiency*
HRB efficiency
Solar topping/ solar evaporation performance with
increasing solar input
Wesley Stein, March 2000
-
8/6/2019 w Stein Good 53p
25/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
-
8/6/2019 w Stein Good 53p
26/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
Process heat
OrganicRankine cycle
Chiller
Reverse cycleair conditioning
Electricity
CO/TRI-GENERATION FORDISTRIBUTED ENERGY APPLICATIONS
Solar gas or Solar HTF
preheated air
-
8/6/2019 w Stein Good 53p
27/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
ThermochemicalThermochemical EnergyEnergy
-
8/6/2019 w Stein Good 53p
28/53
ThermochemicalThermochemical EnergyEnergy
StorageStorage
NH3 + 66.8kJ/mol 1/2N2 + 3/2H2
H2 / N2gas
liquid
NH3
Heat Exchangers
Power Generation(Steam Cycle)
Ammonia Synthesis(Exothermic Reactor)
Ammonia Dissociation(Endothermic Reactor)
Separation and Storage
Tow ards Sust a inab leTow ards Sust a inab leTow ards Sust a inab leTow ards Sust a inab le
-
8/6/2019 w Stein Good 53p
29/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
Tow ards Sust a inab leTow ards Sust a inab leTow ards Sust a inab leTow ards Sust a inab le
EnergyEnergyEnergyEnergy CSIRO so la rCSIRO solarCSIRO solarCSIRO solar
re formingre formingre formingre forming
Aim: demonstrate a solar thermal fossil energy hybrid concept for high
efficiency / low CO2 powergeneration and appropriate forAustralian conditions
-
8/6/2019 w Stein Good 53p
30/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
Projec t Dr iversPro jec t Dr iversPro jec t Dr iversPro jec t Dr ivers
Deregulation of electricity and gas supply industries
Move towards smaller-scale power generation based on gas
By 2010 an additional 9,500 GWh pa to be sourced from newrenewable energy
Introduction of renewable energy accreditation schemes by which
electricity generated from renewable sources attracts a premium Legislation requiring distributors to sell electricity with reduced
Greenhouse gas emissions
Need for Greenhouse gas mitigation strategies to go beyondmore efficient fossil energy technologies and fuel substitution
-
8/6/2019 w Stein Good 53p
31/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
Projec t Dr iversPro jec t Dr iversPro jec t Dr iversProjec t Dr ivers (c ont .)(cont . )(cont . )(cont . )
No exotic material breakthroughs required
Thermal and chemical processes well understood
Simple integration with existing thermodynamic cycles and energyprocesses
Coincidence of high levels of solar and gas
Storage of solar energy in chemical form
-
8/6/2019 w Stein Good 53p
32/53
O t i l M d /O t i l M d /O t i l M d /O t i l M d /
-
8/6/2019 w Stein Good 53p
33/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
Operat ional Modes /Operat ional Modes /Operat ional Modes /Operat ional Modes /
Produc t s 1Produc t s 1Produc t s 1Produc t s 1 Green syngas for electricity generation
Production of synthesis gas as precursorfor gas-to-liquids production (potential
bottled sunshine)
Closed loop heat generation
(methanation) (zero GHG emission)
-
8/6/2019 w Stein Good 53p
34/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
The Conc eptThe Conc eptThe Conc eptThe Conc ept
FossilFuel (CH4)
Water
water
CO/H2/CO2 H2/CO2 H2 - fuel
CO2 to disposal /sequestration
Fuel cells Gas turbines Cogeneration etc
CH4 + H2O(llll) + 250 KJ CO + 3H2
CO + H2O(llll) H2 + CO2 + 3 KJ
SolarThermal
Fuel
Reforming
Solar Thermal
Water GasShift
Conversion
CO2Recovery
AdvancedPower
Generation~
O t i l M d /O t i l M d /O t i l M d /O t i l M d /
-
8/6/2019 w Stein Good 53p
35/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
Operat ional Modes /Operat ional Modes /Operat ional Modes /Operat ional Modes /
Produc t s 2Produc t s 2Produc t s 2Produc t s 2 Hydrogen production with CO2
capture/sequestration Fuel cell electricity generation from
hydrogen
Hydrogen for refining of heavier crude
oils
-
8/6/2019 w Stein Good 53p
36/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
The Conc eptThe Conc eptThe Conc eptThe Conc ept
FossilFuel (CH4)
Water
water
CO/H2/CO2 H2/CO2 H2 - fuel
CO2 to disposal /sequestration
Fuel cells Gas turbines Cogeneration etc
CH4 + H2O(llll) + 250 KJ CO + 3H2
CO + H2O(llll) H2 + CO2 + 3 KJ
SolarThermal
Fuel
Reforming
Solar Thermal
Water GasShift
Conversion
CO2Recovery
AdvancedPower
Generation~
The CSIRO Dem onst rat ionThe CSIRO Dem onst rat ionThe CSIRO Dem onst rat ionThe CSIRO Dem onst rat ion
-
8/6/2019 w Stein Good 53p
37/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
The CSIRO Dem onst rat ionThe CSIRO Dem onst rat ionThe CSIRO Dem onst rat ionThe CSIRO Dem onst rat ion
Fac i l i t yFac i l i t yFac i l i t yFac i l i t y A 107m2 twin axis tracking solar dish
Catalytic gas reforming reactors Receiver and flux modifier at focal point
Absorption-based H2/CO2 separation units A 10 kWe polymer electrolyte membrane fuel cell
(unavailable)
Complete integrated operation has been
successfully demonstrated - H2 has CO levels low
enough for PEM fuel cell operation
-
8/6/2019 w Stein Good 53p
38/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
The Dish and Col lec t or The Dish and Col lec t or The Dish and Col lec t or The Dish and Col lec t or
-
8/6/2019 w Stein Good 53p
39/53
CSIRO MARK 2 SOLAR REFORMERWATER
PRODUCT
GAS
NATURAL GAS / CO2
SOLAR ENERGY
PREDICTED THERMAL PERFORMANCE OF CSIRO MARK II SOLAR REFORMER WITH 900W/M2 DIRECT SOLAR ENERGY
-
8/6/2019 w Stein Good 53p
40/53
112 MIRROR PANELS
48 ACTIVE MIRRORS
43.2kW (900W/m2) INCIDENT ON MIRROR SURFACE AREA
40.6kW REFLECTED FROM 48 ACTIVE MIRRORS
94% DISH REFLECTIVITY
8.6kW LOST BY ABSORPTION
OR RERADIATION
32.0kW USED
FOR REFORMING
SS20T
DISH
FEED
NATURAL GAS
(95.7kW HHV)
PRODUCT GAS
(120.2kW HHV)
11.9 kW RECOVERED IN PRODUCT GAS
THROUGH WATER PREHEATING
FEED
WATER
7.5kW LOST TO STEAMAND SENSIBLE HEAT IN PRODUCT GAS
PREDICTED THERMAL PERFORMANCE OF CSIRO MARK II SOLAR REFORMER WITH 900W/M2 DIRECT SOLAR ENERGY
Methane conversion @ 850C, 1MPa and steam-to-methane molar ratio of 2.5 = 87.1%
Solar-to-chemical energy conversion (HHV)= 60.3%
Increase in chemical energy of feed natural gas (HHV) = 25.6%
Fut ure Plans & Out look forFut ure Plans & Out look forFut ure Plans & Out look forFut ure Plans & Out look for
-
8/6/2019 w Stein Good 53p
41/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
Fut ure Plans & Out look for Fut ure Plans & Out look for Fut ure Plans & Out look for Fut ure Plans & Out look for
CSIRO so la r re fo rm ingCSIRO so la r re fo rm ingCSIRO so la r re fo rm ingCSIRO so la r re fo rm ing Commercial prospects being evaluated
Demonstration facility establishing proof ofconcept being pursued
Appropriate solar concentrator is required
Industrial partners being sought to move intoa commercial implementation phase
-
8/6/2019 w Stein Good 53p
42/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
0
200
400
600
800
1,000
1,200
1,400
3 5 7 9 11 13 15 17 19
Equivalent gas price, $/GJ
Total
installedcostofsolararray
,$/m2(aperture)
6000MJ/m2, 0% O&M
4000MJ/m2, 3% O&M
5000MJ/m2, 3% O&M
6000MJ/m2, 3% O&M
4000MJ/m2, 0% O&M
Estimated costs for
Tennant Creek
25 yr life, 7% discount rate
Gas boiler avge efficiency = 83%
0%/yr gas price escalation
5000MJ/m2, 0% O&M
Greenhouse gas em issions
-
8/6/2019 w Stein Good 53p
43/53
12 21 15 18 1684
442
980
0
200
400
600
800
1000
SEGS
Parab
olicTrough
Dish/S
tirling
PHOE
BUSP
owerTower
SolarT
ower
WindT
urbine
Photov
oltaics
Combine
dCycle
CoalPl
ant(Au
stralia)
G
reenhouseGa
semissionsin
CO2equivale
nts
[g/kWhel]
Source: Weinrebe, G.: Greenhouse Gas Mitigation with Solar Thermal Power Plants, Proceedings of the PowerGen Europe 1999 Conference, Frankfurt, Germany, June 1-3
In te rna t iona lIn te rna t iona lIn te rna t iona lIn te rna t iona l
-
8/6/2019 w Stein Good 53p
44/53
Oppor tun i t iesOppor tun i t iesOppor tun i t iesOppor tun i t ies
ABENGOA
Solel
KfWFICHTNER
EEA/NREA
KJCSMA
World BankBECHTEL
ONE NEPCO
LOCATIONLOCATION TYPETYPE solar MWsolar MWAus traliaAus tralia CLFRCLFR FresnelFresnel 1313CreteCrete SEGSSEGS TroughTrough 5252EgyptEgypt ISCCSISCCS TroughTrough 30-8030-80IndiaIndia ISCCSISCCS TroughTrough 3535
IranIran ISCCS/SEGSISCCS/SEGS TroughTrough 30-8030-80JordanJordan PHOEBUSPHOEBUS TowerTower 3030MexicoMexico ISCCSISCCS TroughTrough 30-8030-80MoroccoMorocco ISCCS/SEGSISCCS/SEGS TroughTrough 30-8030-80SpainSpain SEGS, SP10SEGS, SP10 Trough,TowerTrough,Tower 10-5010-50
USAUSA SEGSSEGS TroughTrough 354354
BOEING DukeSolar
GamesaGhersa
AGOESTIAEuropean Solar Thermal Power
Industry Association
Slide courtesy of:
-
8/6/2019 w Stein Good 53p
45/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
Where t o f rom here?Where t o f rom here?Where t o f rom here?Where t o f rom here?
A number of technology types opening up many
different opportunities. Major hurdle at present is capital cost of the
collector / concentrator.
Apart from mirrors, manufacturing and civilworks similar to wind turbines so could followsame cost reduction curve.
Opportunity to link the best technologies ofEurope and Australia to produce flexible solarthermal driven packages that can becustomised for specific applications.
-
8/6/2019 w Stein Good 53p
46/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
Required st epsRequired st epsRequired st epsRequired st eps
Demonstration plants at pre-commercial level
are critical. Problem-free operation is possiblymore crucial to technology confidence than costat this time.
Such plants should be installed in hybridconfigurations (with reliable back-up fuel suchas gas) and in parallel so that seamlessoperation can be demonstrated
They should operate in a commercialenvironment (whether or not they are producingcommercially-competitive energy) so that realexperience is gained and investors see realsolutions emerging
-
8/6/2019 w Stein Good 53p
47/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
Col laborat ive opport un i t iesCol laborat ive opport un i t iesCol laborat ive opport un i t iesCol laborat ive opport un i t ies
Alliance with European partners soughtfor various aspects
Collaboration could be:Technical R&D
ModellingProduct development
Product demonstration and testing
C l l b i i iC l l b i i iC l l b i i iC l l b i i i
-
8/6/2019 w Stein Good 53p
48/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
Col laborat ive opport un i t iesCol laborat ive opport un i t iesCol laborat ive opport un i t iesCol laborat ive opport un i t ies
Some immediate areas of interest: Solar/gas hybrid Brayton cycle
Solar thermal supplementation of distributedgeneration plants, especially cogen and trigen
Solar steam Rankine cycle integration
Solar reformed methane
Solar biomass hybrids Work also required on associated equipment,
for example: Small heat engines utilising medium temperature
steam Organic Rankine Cycles
Absorption cycle chilling
-
8/6/2019 w Stein Good 53p
49/53
ENERGYENERGYENERGYENERGY TECHNOLOGY
THANK YOUTHANK YOUTHANK YOUTHANK YOU
M k 2 S l C i R i P di d P f (N di h l ) i h R f @ 8 0C & 000kP
-
8/6/2019 w Stein Good 53p
50/53
Mark 2 Solar Cavity Receiver Predicted Performance (No dish louvers) with Reformer @ 850C & 1000kPa,
LT WGS @215C, Solar Energy @43kW (900W/m2), Gas Engine Efficiency = 40% & Fuell Cell Efficiency = 60%
0.0
10.0
20.0
30.0
40.0
1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50
Water-to-Methane Molar Ratio
OverallSolar-To
-ElectricalEnergy
Convers
ion(LHV),%
0.0
15.0
30.0
45.0
60.0
S
olar-To-ChemicalEn
ergyconversion(LH
V),
%
Overall Conversion
with Heat Recovery @300C,
LT WGS@215C & Fuel Cell Unit
Overall Conversionwith Heat Recovery@200C
& Gas Engine
CO2/CH4
ratio
= 0
= 1.0
= 0.5
Chemical energy
conversion (LHV)
reforming only
Chemical energy
conversion (LHV)
with LT WGS
M k 2 S l C it R i P di t d P f (N di h l ) ith R f @ 850C & 1000kP
-
8/6/2019 w Stein Good 53p
51/53
Mark 2 Solar Cavity Receiver Predicted Performance (No dish louvers) with Reformer @ 850C & 1000kPa,
LT WGS @215C, Solar Energy @43kW (900W/m2), Gas Engine Efficiency = 40% & Fuell Cell Efficiency = 60%
0.0
10.0
20.0
30.0
40.0
1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50
Water-to-Methane Molar Ratio
Ov
erallSolar-To-Electr
icalEnergyConvers
ion,
%
10.0
35.0
60.0
85.0
110.0
Feednaturalgas(LHV),kW
Conversion with Heat Recovery @300C,
LT WGS@215C & Fuel Cell Unit
Conversionwith Heat Recovery@200C
& Gas Engine
CO2/CH4
ratio
= 0
= 1.0
= 0.5
Feed natural gas (LHV)
reforming only
Feed natural gas (LHV)
with LT WGS
M k 2 S l C it R i P di t d P f (N di h l ) ith R f @ 850C & 1000kP
-
8/6/2019 w Stein Good 53p
52/53
Mark 2 Solar Cavity Receiver Predicted Performance (No dish louvers) with Reformer @ 850C & 1000kPa,
LT WGS @215C and Solar Energy @43kW (900W/m2)
10.0
20.0
30.0
1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50
Water-to-Methane Molar Ratio
Increaseinchemicalenergy(LHV),kW
20.0
40.0
60.0
80.0
100.0
120.0
Feednaturalgas(LHV),kW
Feed natural gas (LHV)reforming only
CO2/CH4
ratio
= 0
= 1.0
= 0.5
Increase in Chemical Energy (LHV)
with Heat Recovery @300C,
LT WGS@215C & Fuel Cell Unit
Increase in Chemical Energy (LHV)
with Heat Recovery@200C
& Gas Engine
Feed natural gas (LHV)
with LT WGS
PREDICTED THERMAL PERFORMANCE OF CSIRO MARK II SOLAR REFORMER WITH 900W/M2 DIRECT SOLAR ENERGY
-
8/6/2019 w Stein Good 53p
53/53
112 MIRROR PANELS
48 ACTIVE MIRRORS
43.2kW (900W/m2) INCIDENT ON MIRROR SURFACE AREA
40.6kW REFLECTED FROM 48 ACTIVE MIRRORS
94% DISH REFLECTIVITY
8.6kW LOST BY ABSORPTION
OR RERADIATION
32.0kW USED
FOR REFORMING
SS20T
DISH
FEED
NATURAL GAS
(86.4kW LHV)
PRODUCT GAS
(105.6kW LHV)
11.9 kW RECOVERED IN PRODUCT GAS
THROUGH WATER PREHEATING
FEED
WATER
7.5kW LOST TO STEAM
AND SENSIBLE HEAT IN PRODUCT GAS
Methane conversion @ 850C, 1MPa and steam-to-methane molar ratio of 2.5 = 87.1%
Solar-to-chemical energy conversion (LHV) = 47.4%
Increase in chemical energy of feed natural gas (LHV) = 22.3%