A1258150556TiDvy

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Greenhouse Gases Mitigation and
UtilisationKingston, ON, 11th July 2007
Carbon-neutral Flying for Conventional Aircraft
using Jet-fuel Re-synthesised from Sequestrated
CO2
K. Winch, R. Mann and P.N.SharrattUniversity of
Manchester, UKSchool of Chemical Engineering and
Analytical Sciencer.mann_at_manchester.ac.uk
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Outline

• Motivation
• Problem issues
• Convenient source of CO2
• Transforming CO2 to liquid fuels
• Re-synthesis energy penalty
• Wind energy as UK power source
• Economics
• Conclusions

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Motivation
There is terrific growth in flying There are
believed to be no technical options for avoiding
the release of CO2 into the atmosphere Aviation
presents the biggest challenge to avoiding
dangerous climate change
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Motivation
People like flying! Flying is a huge global
business There are powerful vested interests
which resist the green lobbys call for less
flying
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Motivation

• Flying is a huge growth business

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Problem issues
New designs of aircraft now entering service have
an anticipated 50 year life The engines and fuel
tanks are designed for jet-fuel They will thus
burn jet-fuel until 2058
The Airbus Super Jumbo
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Problem Issues
New aircraft are designed to be technically
superior in terms of fuel economy However, these
advances in reducing CO2 emissions will be
swamped by growth in passenger miles and
numbers To meet the projected post-Kyoto
agreement of 50 reductions by 2050 requires
something radical
The Boeing 787 Dreamliner
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Problem issues

• If all other sources of CO2 are reduced to meet
  the 450ppm target by 2050, then aviation becomes
  bigger than all of these combined (Bows et al,
  2006)

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Convenient source of CO2
Coal fired power stations dominate current CO2
emissions By operating with oxy-fuelling using
pure O2, a pure CO2 stream is obtained With no
separation problems, this is a valuable chemical
resource Furnace draughting modified to give
similar combustion behaviour Thermal efficiency
improved by avoiding N2 emissions
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Conventional Coal Combustion
Air Feed
Component MT/year
O2 16.5
N2 54.3
Drax Power Station
Flue Gas
Component MT/year
CO2 20.0
N2 54.3
Coal Feed
Component MT/year
CH 0.72O0.09 9.44

• Nitrogen serves no purpose
• Dilution makes the separation difficult

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Oxy-Coal Combustion
Water Feed
Hydrogen By-Product
Component MT/year
H2O 18.6
Component MT/year
H2 2.08
Flue Gas
Drax Power Station
Electrolysis
Component MT/year
CO2 20.0
Electrolysis Qin 10.9 GW
Coal Feed
CO2 Recycle
Component MT/year
CH 0.72O0.09 9.44
Component MT/year
CO2 54.9

• Nitrogen dilution problem eliminated
• CO2 stream is gt 99 pure
• CO2 now a useful chemical resource

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Transforming CO2 to liquid fuels

• Hydrogenation of CO2 in three steps
• Reverse water gas shift
• CO2 H2 CO H2O
• Fischer-Tropsch hydrocarbon synthesis
• CO 2H2 CH2 H2O
• Hydrocracking of heavy ends back to liquid fuels
• R1CH2---CH2R2 H2 R1CH3 R2CH3

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Transforming CO2 to liquid fuels
Anderson-Flory-Schulz Kinetics (Sie et al., 1991)
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Transforming CO2 to liquid fuels

• Carbon number/fuel ranges

Fraction Carbon Number of hydrocarbon
Fuel Gas 1 2
LPG 3 4
Naphtha 5 9
Kerosene 8 16
Gas Oil 11 21
Wax gt 22
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Transforming CO2 to liquid fuels

• Hydrocarbon distributions

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CO2 to kerosene (jet-fuel)

• Stage 1 water electrolysis combines perfectly
  with oxy-fuelling

Drax Power Station
CO2 H2O
Coal
60 ºC
CO2 H2 H2O
O2
25 ºC
36.6 ºC
Water Electrolysis
H2O
25 ºC
15.2 GW
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CO2 to kerosene (jet-fuel)

• Stage 2 - Reverse water gas shift

0.56 GW
CO H2 H2O
CO2 H2 H2O
rWGS Reactor
250 ºC
36.6 ºC
250 ºC
0.45 GW
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CO2 to kerosene (jet-fuel)

• Stage 3 Fischer-Tropsch synthesis of liquid
  fuels

C1 C4
Fuel Gases
30 ºC
H2O
30 ºC
-2.38 GW
-1.59 GW
CO H2 H2O
FTS Reactor
250 ºC
230 ºC
30 ºC
gt C5
30 ºC
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CO2 to kerosene (jet-fuel)

• Stage 4 hydrocracking of heavier ends back to
  liquid fuels

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CO2 to kerosene (jet-fuel)FT products
Carbon Number of hydrocarbon in product by mole in product by mass
lt C10 37.0 8.61
C10 - C20 27.2 19.7
gt C20 35.9 71.7
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CO2 to kerosene (jet-fuel)hydrocracked products

• Liquid fuel product distribution after
  hydrocracking

Hydrocarbon Fraction in product by mole in product by mass
Fuel Gases 5.61 1.62
Naphtha 33.0 24.6
Kerosene 44.8 49.2
Gas Oil 16.6 24.6
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Re-synthesis energy penalty
82.3
94.9
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Energy balances
Process Input , GW Output , GW
Water Electrolysis 15.2
Reverse Water Gas Shift 1.01
Fischer-Tropsch Synthesis -3.97
Hydrocracking 0.64 -0.43
Total 16.9 -4.40
Electrolysis is dominant energy
requirement. Scope for energy integration. Energ
y re-synthesis penalty to be reduced to 40.
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UK Costs of renewable electricity
Generation Method Cost of Generation 2005, p/kWh Cost of Generation 2020, p/kWh
Natural Gas 3.0 2.15 0.15
Coal 3.0 3.25 0.25
Onshore Wind 3.2 2.0 0.5
Offshore Wind 5.5 2.5 0.5
Offshore wind massively plentiful Politically
and socially acceptable Cheapest option as
technology develops
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Wind energy as UK power source
Offshore out-of-sight acceptable. This is a 5MW
EApower turbine in N Sea. Next generation will be
20MW each.
Onshore wind controversial due to landscape
intrusion
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Price of re-synthesised jet-fuel
Fuel Onshore Wind Power Onshore Wind Power Offshore Wind Power Offshore Wind Power
Fuel current price, p/l 2020 Price, p/l Current price, p/l 2020 Price, p/l
Naphtha 46 33 84 41
Jet Fuel 50 36 90 44
Gas Oil 52 37 98 46
Average 49 35 89 44
Advances in offshore wind and process technology
will make it competitive.
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Price of re-synthesised jet-fuel
UK p per litre Canadian c per litre
Current commodity price 24 52

Existing re-syn estimate 2007 offshore 90 191
Electrolysis efficiency 90 86 182
Energy integration (50) 77 163
Electricity price 5.1 p/kWh 2007 offshore 77 163
Electricity price 2.8 p/kWh 2007 onshore 42 90
Electricity price 2.5 p/kWh 2020 offshore 38 80
Electricity price 2.0 p/kWh 2020 onshore 30 64

Electricity price 1.0 p/kWh 2007 offpeak 15 32
According to Die Tageszeitung on 15/01/07 the
price for one MWh fell to zero due to high winds
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Carbon Neutral Flying
oxyfuelled combustion
catalytic hydrogenation
carbon-neutral hydrocarbon
renewable electricity
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Conclusions

• Closed-cycle oxy-fuelling of conventional coal
  fired power plants conveniently provides CO2 at
  gt99 purity.
• Jet-fuel can be re-synthesised from this
  sequestrated CO2 by reaction with H2 sourced from
  water electrolysis.
• This re-syn fuel is of a higher quality than
  conventional jet fuel and fully compatible with
  current aircraft designs.
• Offshore wind energy provides a renewable energy
  source
• At current costs, such re-syn jet-fuel at 90p per
  litre is not competitive with that conventionally
  sourced at 24 pence per litre.
• However, by 2020, due to falling wind energy
  prices the price of the re-syn fuel will drop to
  36 p per litre.
• The price of conventional fuel is certain to rise
  due to carbon taxes.
• Re-syn jet fuel produced renewably from CO2
  provides net carbon-neutral flying.