Hydrogen from nuclear energy and the potential impact on climate change

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Hydrogen from nuclear energyand the potential
impact on climate change

• Alistair I. Miller
• Romney B. Duffey
• International Energy Workshop
• International Institute for Applied Systems
  Analysis
• Laxenburg, Austria2003 June 24-26

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Basis and Overview

• The need for a reduction of GHG emissions to
  about 40 of current levels to stabilize the GHG
  level
• That level depends on many things
• It could be as low as 450 ppm CO2 though 550 ppm
  is considered more likely
• Without vigorous international action, there will
  be no leveling at all
• Hydrogen by electrolysis from nuclear energy
• Is available technology and creates little CO2
• Can be much more affordable than is often assumed
• Provides hydrogen where it is needed and avoids
  the need to develop a huge infrastructure ahead
  of extensive demand

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Hydrogen and the Environment

• Vehicles use 25 of all energy and the proportion
  is rising
• Electricity generation is a comparable 25 and
  much from coal
• Both are major contributors to the CO2 waste
  problem
• Electricity must go off-carbon transport needs
  hydrogen fuel
• But conversion will be a huge job and its vital
  that we do it properly and start as soon as
  possible
• Sufficient applications technologies are
  available
• Make H2 locally by electrolysis quite affordably
• Store mostly as 70 MPa gas LH2 where appropriate
• Preference is to use fuel cells but we could use
  ICEs initially
• Level the electricity load by making hydrogen
  off-peak

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A Felicitous Partnership

• Beyond about a 50 base-load, electricity is
  usually produced by burning fossil fuels,
  especially coal, because this approach is
  relatively capital-lean
• Displacing coal-fired with nuclear raises a big
  question What to do with the off-peak
  electricity?
• MAKE HYDROGEN by electrolysis
• Important to keep the capital cost of the
  electrolysis low
• Important that the electricity by low-cost
• With those two addressed, an attractive, flexible
  solution
• No need to wait
• Electricity at 3 US/kW.h from reactors such as
  AECLs ACRÒ will be available in a few years
• Fuel cells would be desirable (and may well be
  available) but could use ICEs in short term and
  still gain significant efficiency of conversion

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The Best Face of Hydrogen

• Effective electric storage batteries would be
  even nicer but
• Too heavy, too costly and inefficient so
• Fuel cells
• A factor of 3 gain in efficiency over typical
  ICEs
• Perhaps start with ICEs burning H2 - 20
  efficiency gain
• Make H2 locally
• Avoid the intrinsically high cost of hydrogen
  distribution and the huge cost and inconvenience
  of any new, large-scale distribution network
  piggy-back distribution onto existing electric
  grids
• Store as high-pressure (70 MPa) gas

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How not to make the H2?

• Avoid SMRs (Steam Methane Reformers)
• Even if the CO2 by-product can be sequestered
• (unthinkable with on-board reforming)
• distribution costs will be ruinous
• SMRs do not scale-down well
• Avoid high-cost electrolysers
• Both electricity and equipment need to be cheap
• Electricity will be cheaper if it can be
  diverted to premium markets
• Higher-cost electrolysers cost more than the
  electricity they save
• Avoid taking reactors off electricity?
• Electricity is a very flexible, premium product
• compared to very high-temperature heat

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Alberta Pool Electricity Price (US/MW.h)
2002 Hourly Actuals
29.3
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Details of 2002 Alberta Electricity Prices

• Average value was 29.3 US/MW.h (compare ACR at
  30)
• Only 35.5 of power cost gt 30 US/MW.h
• The other 64.5 had an average value of 14.6
  US/MW.h
• At below 60 US/MW.h
• Average cost was 22.4 US/MW.h
• Using that, electrolysis would have been on-line
  for 95 of time
• The other 5 sold for an average of 157.8
  US/MW.h
• Interestingly, the fuel cell can produce 1 kW.h
  from each 3 kW.h of input
• Scope for re-selling electricity

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Electrolytic Hydrogen

• Focus on low-cost electrolysis
• 300 US/kW
• Penalty on electricity use (total equivalent to
  2.1 volts)
• Storage
• Use tube-trailers (a conservative costing)
• 800 000 US/tonne H2
• Store at least 12-hours of average demand
• Optimize
• Cheaper power
• Less time on-line
• More electrolysis cells
• More storage

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Optimum

• Lowest cost of 2000 US/tonne H2
• 60 US/MW.h cut-off
• 125 electrolysis installation
• 15 hours storage

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Can do somewhat better

• 2000 US/tonne is with a rigid scheme
• The electricity price is known one week in
  advance
• So, if the storage level is low, can occasionally
  accept higher power costs
• And install less electrolysis and only 12-h
  storage
• Simple scheme with a normal ceiling 60 US/MW.h
  and an upper ceiling of 325 US/MW.h when storage
  levels are less than one hours production
• 1965 US/tonne H2
• This still relatively rigid
• One should be able to do a little better

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Home-Produced Hydrogen

• Average Canadian car covers 21 000 km/a
• With a fuel cell, would need about 160 kg of H2
• Based on 2.1 volts 9.1 MW.h/a
• Assume retail off-peak power at 37 /MW.h
  (including 20 /MW.h of distribution costs)
  available 75 of time in Alberta in 2002
• Electricity cost is 337 US/a (and needs 14.2 h/d
  for average demand)
• Home-refueller electrolysis unit at 2000 US (for
  1.7 kW unit), 6 financing over 10 years 272
  US/a
• Total of 610 US/a
• Gasoline at 45 /L (which includes taxes)
• Annual 836 US/a for a typical 11.3 L/100 km car
  (20.8 mpg)

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And if one reversed the power flow?

• The figures are very approximate but
• In terms of fuel costs, H2 is competitive
• Interesting possibility of reversing the current
• Not efficient (0.7 x 0.5) but pays if selling
  price for electricity is x3 of the buying price.
  
• In Alberta in 2002, paid an average of 240
  US/MW.h for top 2.5 of time
• Fuel cell can deliver 15.4 MW.h/a
• Even 1 of time at that price, could earn 37
  US/a
• Collectively, an interesting no-cost generating
  reserve for the grid

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Points on the SMR alternative

• SMR H2 is cheap for large units with local,
  industrial markets
• These markets usually demand high reliability
• A typical industrial SMR (250 tonne/d) could fuel
  600 000 cars
• CO2 sequestration, where available, is a bearable
  extra
• But would be very difficult for the 30 produced
  as flue gas
• Natural gas at 5 /GJ is bearable
• Problem is with scale SMRs scale with about a
  0.66 power
• Reducing size by factor of 1000, raises unit cost
  by a factor of 10
• Or, alternatively, with huge distribution costs
• Electrolysis scales perfectly and can be
  installed incrementally to match demand

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Estimated Costs of Hydrogen
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Additional Issues for Thermochemical H2

• Intrinsically centralized
• So will have distribution costs
• Cannot switch to selling electricity instead of
  H2
• For large-scale industrial use, will need a
  secure supply through a back-up source
• One approach applicable to any reactor-based H2
  supply is to have a hybrid supply where one
  usually depends for 50 of the H2 on an SMR
• By oversizing the SMRs base capacity by a factor
  of 2, it can then double its output very rapidly

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SCWR (or VHTR) for H2 ( O2) electricity heat?
or
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SCWR (or VHTR) electricity heat
Reaching 850 C is no longer crucial
And make H2 and O2 electrolytically when and
where needed
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