SINTEF Energy Research Emerging technologies for decarbonization of natural gas Dr. ing. Ola Maurstad
Mar 31, 2015
SINTEF Energy Research
Emerging technologies for decarbonization of natural gas
Dr. ing. Ola Maurstad
SINTEF Energy Research
Outline of the presentation
Emerging technologies Natural gas based power cycles with CO2 capture
Hydrogen production from natural gas
Two energy chain calculations Gas to electricity Gas to hydrogen/transport
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Decarbonization of natural gas: CO2 capture and storage (CCS)
CO2 is a natural product of combustion of fossil fuels
CCS is a strategy for reduction of greenhouse gas emissions
CO2 is captured at its source (power or hydrogen plant)
Several storage options are being investigated depleted oil and gas reservoars geological structures etc
Enhanced oil recovery (EOR) where CO2 is used as pressure support This could give the CO2 a sales value => would help market
introduction of CCS technologies
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The Sleipner project in the North sea (Norway) is the world’s first commercial-scale CO2 capture and storage project (started 1996)
1 million tonnes are stored yearly in the Utsira formation 800 m below the sea bed
Statoil: Storage capacity for all CO2 emissions from European power stations for 600 years
The project triggered by the Norwegian offshore CO2 tax
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Natural gas fired power plants with CO2 capture
Several concepts have been proposed Two concepts based on commercially available
technology Post-combustion exhaust gas cleaning (amine absorption) Pre-combustion removal of CO2
No plants have been built Could be built in 3-6 years from time of decision Cost of electricity increases with ~ 100 %
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Power plant Conventional
CO2
capture
Coal
Oil
Natural gas
CO2 storage
1
Gasification Reforming
Water-shift
CO2
capture Power plant Hydrogen-rich fuel2
Air separation Power plant Oxy-fuel combustion
Waterremoval
3
Exhaust, 0.3-0.5% CO2
Exhaust, 0.1-0.5% CO2
OHOH 222 22
COH 2 22 COH
OHCOOCH 2224 2
2O
1: Post-combustion principle2: Pre-combustion principle3: Oxy-fuel principle
Principles of power plants with CO2 capture
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65
SOFC+CO 2
capture
Eff
icie
ncy
pote
ntia
l in
cl. C
O2 c
ompr
essi
on (
2%-p
oint
s)
Year1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Time until commercial plant in operationgiven massive efforts from t=0
43
45
47
49
51
53
55
57
59
61
63
Combined Cycle
Post-combustion amin-absorption
Pre-combustion, NG reforming
Chemical Looping Combustion
AZEP
Oxy-fuel Combined Cycle
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Example: Oxyfuel power cycle
FuelPressurized oxygen
To storageWater
Water separator
HRSG
Compressor
Turbine
Heat
Recycle
Steam cycle
Combustor
83% CO2
15% H2O
1.8 % O2
96% CO2
2% H2O
2.1 % O2
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Natural gas reforming (NGR)
Cheapest production method for large scale hydrogen production
NGR is a commercially available technology Gas separation systems are also commercially available However, no NGR with CO2 capture and storage exist
Cost estimate for hydrogen production: Without CO2 capture: 5.6 USD/GJ
With CO2 capture: 7 USD/GJ
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Simplified process description, steam methane reforming (SMR)
Reforming reaction (endothermic) :
CmHn + mH2O = (m+½ n)H2 + mCO
Water gas shift reaction (slightly exothermic):
CO + H2O = H2 + CO2
ReformingWater gas
shiftAdsorption
process
Natural gas
SteamCO ,H2 22 CO ,H
2CO
2H
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Hydrogen liquefaction
Why liquefy hydrogen? LH2 is suitable for transport to
filling stations because of the high energy density: 2.36 kWh (LHV) per liter
Petrol: 9.1 kWh (LHV) per liter Mature technology but
improvements expected Theoretical minimum work
required to liquefy 1 kg of hydrogen: 14.2 MJ
Best large plants in the US require 36 MJ/kg H2
Linde cycle
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Ortho-Para conversion
The two forms of dihydrogen: diatomic molecule
Equilibrium composition depending on temperature Room temperature: “normal hydrogen” (25 % para, 75 % ortho) Liquid hydrogen temperature: nearly 100 % para
Necessity to convert from ortho to para in the cycle Heat released by conversion at 20,4 K: Qconv = 525 J/g
Latent heat: Qvap = 450 J/g
Without conversion from ortho to para=> In 24 h 18 % of the liquid will evoparate even in a perfect insulated tank (spontaneous, exothermic reaction from ortho to para)
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Modified 2002 Toyota Prius: Hydrogen combustion engine + electric motor
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The energy chains – Two examples
1. Gas fired power plant with CO2 capture Energy product: 1 kWh electricity delivered to the grid
2. Large scale hydrogen production from natural gas with CO2 capture – liquefaction of H2 for transport to filling stations Energy product: 1 kWh liquid hydrogen (LHV) Energy product: 1 km of car transport
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Naturalgas
Powerplant
Hydrogenproduction
Naturalgas
Hydrogenliquefaction
Atmosphere
CO2 Storage reservoir
Electricalgrid
Hydrogenfilling
station
Hydrogencar
CO2
CO2
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Assumptions used for the energy chain analyses Power plant with CO2 capture:
50 % (LHV) efficiency, 85 % capture of formed CO2
Power plant without CO2 capture: 58 % (LHV) efficiency
Hydrogen production with CO2 capture: 73 % (LHV) efficiency, 85 % capture of formed CO2
Hydrogen production without CO2 capture: 76 % (LHV) efficiency
Hydrogen liquefaction 36 MJ electricity required per kg of liquid H2
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Hydrogen filling station Insignificant electricity consumption compared with the liquefaction
process
Hydrogen car Storage tank with H2 in liquid form Hydrogen consumption of 14.2* gram/ km (corresponds to a petrol
consumption of 0.52 litres per 10 km)* Energy Conversion Devices claims their modified Toyota Prius can drive 44 miles per kg
hydrogen (http://www.hfcletter.com/letter/December03/features.html)
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Results: Power generationNatural gas consumption per
kWh electricity produced
0.00
0.50
1.00
1.50
2.00
2.50
With CO2 capture Without capture
kWh
(LHV
)
CO2 emissions per kWh electricity produced
0.00
50.00
100.00
150.00
200.00
250.00
300.00
350.00
400.00
With CO2 capture Without capture
kWh
(LHV
)
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Results: Hydrogen production(natural gas to liquid hydrogen)
Natural gas consumption per kWh liquid H2 (LHV)
0.00
0.50
1.00
1.50
2.00
2.50
With capture Withoutcapture
kWh
(L
HV
)
H2 liquefaction
H2 production
CO2 emissions per kWh liquid H2 (LHV)
0.0
50.0
100.0
150.0
200.0
250.0
300.0
350.0
400.0
With capture Withoutcapture
gra
m
H2 liquefaction
H2 production
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Results: Hydrogen production(natural gas to transport product)
Natural gas consumption per km
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
With capture Withoutcapture
kWh
(L
HV
)
H2 liquefaction
H2 production
CO2 emissions per km
0.0
20.0
40.0
60.0
80.0
100.0
120.0
140.0
160.0
180.0
200.0
With capture Withoutcapture
gra
m
H2 liquefaction
H2 production
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Conclusions
CO2 Capture and storage (CCS) technologies can reduce the emissions of CO2 by 80-100 % per unit electricity or H2
In general, the capture and storage processes impose an energy penalty on efficiency of around 2-10 %-points
Estimate of the added costs today (technologies closest to commercialization): - Cost of electricity: ~ 100 % increase - Cost of hydrogen: ~ 30 % increase
The costs will always be higher with CO2 capture=> Markets for CCS technologies will not be developed without government policies (economic incentives)
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Thank you for your attention!