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 gt would
  help market introduction of CCS technologies

4

• The Sleipner project in the North sea (Norway) is
  the worlds 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
(No Transcript)
8
Example Oxyfuel power cycle
Pressurized oxygen
Fuel
Combustor
Turbine
Compressor
Water separator
Recycle
HRSG
To storage
Heat
Water
Steam cycle
83 CO2 15 H2O 1.8 O2
96 CO2 2 H2O 2.1 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
(m½ 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
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 paragt In 24 h
  18 of the liquid will evoparate even in a
  perfect insulated tank (spontaneous, exothermic
  reaction from ortho to para)

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

15
(No Transcript)
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/le
  tter/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
  capturegt Markets for CCS technologies will not
  be developed without government policies
  (economic incentives)

22
Thank you for your attention!