Emerging technologies for decarbonization of natural gas

1. Emerging technologies for decarbonization of natural gas Dr. ing. Ola Maurstad

2. 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

3. 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

4. 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

5. 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 %

6. Principles of power plants with CO2 capture 1: Post-combustion principle 2: Pre-combustion principle 3: Oxy-fuel principle

7. 65 63 61 Combined Cycle 59 57 55 SOFC+CO2 capture Efficiency potential incl. CO2 compression (2%-points) 53 Chemical Looping Combustion Post-combustion amin-absorption 51 AZEP 49 Pre-combustion, NG reforming 47 Oxy-fuel Combined Cycle 45 43 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Time until commercial plant in operation given massive efforts from t=0 Year

8. Example: Oxyfuel power cycle Pressurized oxygen Fuel Combustor Turbine Compressor Water separator Recycle HRSG To storage Heat Water Steam cycle 96% CO2 2% H2O 2.1 % O2 83% CO2 15% H2O 1.8 % O2

9. 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

10. 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

11. Hydrogen liquefaction Linde cycle • 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

12. 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 20,4K: 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) Ortho-Para conversion

13. Modified 2002 Toyota Prius: Hydrogen combustion engine + electric motor

14. The energy chains – Two examples • Gas fired power plant with CO2 capture • Energy product: 1 kWh electricity delivered to the grid • 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

16. 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

17. 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)

18. Results: Power generation

19. Results: Hydrogen production(natural gas to liquid hydrogen)

20. Results: Hydrogen production(natural gas to transport product)

21. 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)

22. Thank you for your attention!