SINTEF Energy Research Emerging technologies for decarbonization of natural gas Dr. ing. Ola...

SINTEF Energy Research

Emerging technologies for decarbonization of natural gas

Dr. ing. Ola Maurstad


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


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


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


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 %


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


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


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


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


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


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


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)


Modified 2002 Toyota Prius: Hydrogen combustion engine + electric motor


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


Naturalgas

Powerplant

Hydrogenproduction

Naturalgas

Hydrogenliquefaction

Atmosphere

CO2 Storage reservoir

Electricalgrid

Hydrogenfilling

station

Hydrogencar

CO2

CO2


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


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)


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

)


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


gra

m

H2 liquefaction

H2 production


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


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


gra

m

H2 liquefaction

H2 production


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)


Thank you for your attention!

SINTEF Energy Research Emerging technologies for decarbonization of natural gas Dr. ing. Ola...

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