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Los AlamosNational Laboratory
LA-UR-06-7180
Nuclear-Power AmmoniaNuclear-Power AmmoniaProductionProduction
William L. Kubic, Jr.
Process Engineering, Modeling,and Analysis Group
Los Alamos National Laboratory
Los Alamos, New Mexico
October 9, 2006
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Why Nuclear-Powered AmmoniaProduction?
• Many in the nuclear community are interested in nuclear-powered hydrogen production
– Interest primarily motivated by talk of a hydrogen economy
– Focusing on a hydrogen economy makes commercializationdependent on the economics of hydrogen-powered cars
• It would be better to focus on current markets forhydrogen
– If nuclear-powered is not economical source of hydrogen forcurrent users, it will not be an economical source oftransportation fuel
• Ammonia production is the logical place to begincommercializing nuclear-powered hydrogen production
– Ammonia is the largest consumer of hydrogen in the world
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Topics for Discussion
• Large centralized nuclear-powered ammoniaproduction (2000 tonne / day plants)
• Ammonia production powered by small nuclearreactors (IAEA defines small as <300 MWe)
• Transportable nuclear-powered hydrogenproduction (if time permits)
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Major Process Decisions
• Which process should be used to produce hydrogen?– Water electrolysis (existing technology)
– Steam electrolysis (developmental)
– Thermochemical cycles (developmental)
– Hybrid cycles (developmental)
• Which process should be used to produce nitrogen?– Cryogen air separation (existing technology)
– Pressure-swing absorption (existing technology)
– Burning hydrogen to remove oxygen (existing technology)
• What type of nuclear power system should be used?– Pressurized water reactor (PWR) (existing technology)
– Boiling water reactor (BWR) (existing technology)
– High temperature gas cooled reactor (HTGR) (developmental)
– Other high temperature reactors (developmental)
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Electrolytic Hydrogen Production
• Water electrolysis
– Commercial technology
– Produces pure hydrogen
– Could be operated using existing nuclear reactors
• Steam electrolysis
– Both Idaho National Laboratory (INL) and the Japanesehave developed processes
– Produces a hydrogen-steam mixture and pure oxygen
– Efficiencies of 40 - 50% are possible when powered by anhigh-temperature gas-cooled reactor (HTGR)
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Hydrogen Production UsingThermochemical Cycles
2 H2O + SO2 + I2 !
H2SO4 + 2 HI (125°C)
2HI ! H2 + I2
(400°C)
H2SO4 ! H2O +
SO2 + 1/2 O2 (850°C)
HIH2SO4
I2SO2 H2O2
H2O
HeatHeat
Water Feed HydrogenProduct
H2O
The Iodine Sulfate Cycle
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Thermochemical and Hybrid Cycles
• Theoretical efficiencies of 50% - 65% have been reportedin the literature
– Literature efficiency estimates often neglect the energyconsumed by the separation processes
– Integrated process studies in the literature indicateefficiencies of 40% - 45% are more realistic
• Requires very high temperatures
– HTGR and molten salt reactors are the only types of nucelarreactors that can supply the required temperatures
• Capital cost of a iodine-sulfate process is about 8 timesthat of a seam electrolysis process
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Choice for Hydrogen Production
• Steam electrolysis is the primary choice for hydrogenproduction
– The efficiency is greater than water electrolysis
– The efficiency is comparable to the practical efficiencies ofthermochemical processes if powered by an HTGR
– Steam electrolysis can be powered by a pressurized waterreactor (PWR) or a boiling water reactor (BWR)
– Capital costs are significantly lower than thermochemicalprocesses
• Water electrolysis evaluated as a possible option
– Less efficient than steam electrolysis
– Capital cost are lower than steam electrolysis
– Proven technology
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Nitrogen Production
• Commercial ammonia production requires large volumesof high-purity nitrogen
• Removing oxygen, carbon dioxide, and water are theprimary concern
– Water should be <150 ppm
– Oxygen and oxygen containing compounds must be <10ppm
– Argon does not need to be removed
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Nitrogen Plant SelectionBased on Purity and Capacity
Figure reproduced from Kirk-Othmer Encyclopedia of Chemical Technology
Pressure SwingAdsorption (PSA)
Membrane
Cryogenic
DeliveredBulk Liquid
Delivered Bulk Liquid + Purification
Nitrogen Flow Rate (m3 / h)
Nit
rog
en
Pu
rity
(v
ol.
%)
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Pressure Swing Adsorption Will Be usedfor Nitrogen Production
• Pressure swing adsorption (PSA) and cryogenic airseparation are appropriate processes for producing largevolumes of nitrogen
• PSA produces lower purity nitrogen than cryogenic airseparation
– Removes carbon dioxide, but …
– The nitrogen product contains 0.1 - 2% oxygen
• Nitrogen with ppm levels of oxygen can be obtained fromPSA by reacting the oxygen with hydrogen
• The energy required for PSA plus the hydrogen forremoving the residual oxygen is much less thancryogenic air separation
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Choice of Nuclear Power System
• A HTGR with a Brayton cycle is the primary choice forthe nuclear power system
– An HTGR has the highest operating temperatures whichfavors high cycle efficiencies
– Brayton cycle is better suited for a HTGR than a Rankinecycle
• A GE Advanced Boiling Water Reactor (ABWR) with aRankine cycle also evaluated as a possible option
– Less efficient than an HTGR
– An example of proven technology
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Baseline Process Design:Steam Electrolysis Flowsheet
Raw WaterFeed
Hot Heliumfrom Reactor
Return toReactor
O2 (g)
H2O (g),H2
ElectrolyticCell
Steam RecycleCompressor
WaterTreatment
Plant
H2O (g)
From NH3
Reactor
O2 (g)
Superheater
Wate
rS
ep
ara
tor
H2O (L)
H2O (g),H2
To NH3
Reactor
C.W
SteamGenerator
Wet Hydrogen toDeOxo Reactor
Condenser
Electrolytic Cell• 80% efficient based on
free energy• 50% per pass
conversion
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Baseline Process Design:Pressure Swing Adsorption Flowsheet
H2O (L)
AfterCooler
Wa
ter
Se
para
tor
Air
C.WAirCompressor
Filter
Air
Re
ce
ive
r
N2, O
2, A
r,CO
2, H
2O
Nit
rog
en
Su
rge
Tan
k
N2, A
r, O
2
De-OxoReactor
Wet HydrogenFrom Electrolysis
H2, N2,Ar, O2,H2O (g)
Dri
er
Receiv
er
Dri
er
Su
rge
Tan
k
H2O
(g)
DryReactant
Gas
Adsorber Beds
Drier BedsAbsorber bedsremove CO2
De-oxo reactorreduces O2 to 5ppm
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Baseline Process Design:Ammonia Process Flowsheet
RecycleCompressor
H2, N2, Ar,H2O, O2
H2, N2,NH3, Ar,H2O, O2
C.W
Am
monia
Synth
esi
sReacto
rDryReactant
Gas
De
-Oxo
Re
ac
tor
C.W
LiquidNH3
Fla
sh
Dru
m
Deg
asin
gD
rum
LiquidAmmoniaProduct
PurgeGas
Reactant GasCompressor
PrimaryCondenserIntermediate
Condenser
RefrigeratedCondenser
Superheater
Multiple intercoolersused for compressor
Ammonia Reactor• 200 atm• 20 % NH3 in exit
Use NH3 refrigeration
Dissolved argonprevents excessiveaccumulation
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Baseline Process Design:Fully Integrate Brayton Cycle
Primary Loop Working Fluid: HeliumPrimary Loop Pressure: ~70 atm
Secondary Loop Working Fluid: HeliumSecondary Loop High Pressure: ~70 atm Secondary Loop Low Pressure: ~20 atm
HTGR
IntermediateHeat Exchanger
Primary LoopCompressor
Secondary LoopCompressor
InterstageCooler
CoolerRecuperater
Driver forSecondaryLoopCompressor
Driver for PrimaryLoop Compressor
ProcessHeat
Drivers forOther ProcessCompressors
Driver forNH3 PlantCompressor
Driver forDC ElectricGenerator
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Energy Consumption for HTGR-PoweredAmmonia Process with Steam Electrolysis
NuclearReactor
Electricity84%
Compressors10%
Process Heat6%
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Performance and Costs of LargeNuclear-Powered Ammonia Plants
20016800.23Water
ElectrolysisABWR
19615400.29Steam
ElectrolysisABWR with heat
integration
18715900.37Water
ElectrolysisHTGR
18915700.41Steam
ElectrolysisHTGR with no
heat integration
17214400.48Steam
ElectrolysisHTGR with heat
integration
ProductionCost
($/tonne)
CapitalInvestment
(million $)
Efficiency(MJ fuel* /
MJT)
HydrogenProcess
Reactor Type
* Fuel value based on higher heating value
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Cost Breakdown for HTGR-PoweredSteam-Electrolysis Plant
Capital Costs Operating Costs
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Depreciation is the Largest Component ofOperating Costs for a Nuclear-Powered
Ammonia Plant
HTGR-Powered Plant Steam Reforming Plant
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Lessons for Study of Large Nuclear-Powered Ammonia Plants
• Efficiency is not the most important factor affecting theeconomic viability of a nuclear-powered ammonia plant
– Efficiency varied by a factor of 2 for cases studied
– Capital investment and operating costs only varied by 16%
• None of the options considered in this study was clearlysuperior to the others
– Accuracy of the estimates is ±30%
– Capital costs of steam electrolysis and water electrolysisdiffer by <10%
– Capital costs of an HTGR and a ABWR differ by <10%
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The US Department of Energy!s GlobalNuclear Energy Partnership (GNEP)
• The goal of GNEP is to expand the worldwide use ofeconomical, environmentally responsible nuclear energyto meeting growing electricity demand while virtuallyeliminating the risk of nuclear material misuse
• An important element of the GNEP program is grid-appropriate reactors
– Small, proliferation-resistant reactors suitable fordeveloping countries
– Built in standardized modules that generate 50 - 300 MWe
– Feature fully passive safety systems
– Simple to operate
– Highly secure
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The International Reactor - Safe andSecure (IRIS) is an Example of a Grid-
Appropriate Reactor
IRIS is a Westinghouse-designed PWR thatgenerates up to 335 MWe
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Other Modular Reactor Designs
--100 -300PWRTechocatome
FranceNP-300
700-195Pebble Bed
Reactor
Chinergy
ChinaHTGR-PM
85047.0300HTGRJAERIJapan
GTHTR
--50 -300PWRJAERI
JapanMRX
-30.3100PWRSouth KoreaSMART
-27.027PWRCNEA & INVAP
ArgentinaCAREM
-31.5110PWRRussiaVBER-150
--285HTGRGeneral Atomics
USAGT - MHTR
--50 & 200BWRGE
USAMSBWR
32833.550 - 335PWRWestinghouse
USAIRIS
Temperature(°C)
Efficiency (%)Power(MWe)
TypeManufacturer
CountryReactor
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Performance and Costs ofNuclear-Powered Ammonia Plants
2100
2100
1080
1120
Production(tonne NH3/day)
17214400.48HTGR
19615400.29ABWR
2277000.42GTHTR
2015800.29IRIS
ProductionCost
($/tonne)
CapitalInvestment
(million $)
Efficiency(MJ fuel* / MJT)
ReactorType
* Fuel value based on higher heating value
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Alternatives to be Considered
• Nuclear options
– Large HTGR with steam electrolysis
– ABWR with steam electrolysis
– IRIS with steam electrolysis
– GTHTR with steam electrolysis
• Non-nuclear options
– Steam reforming natural gas with and without carbonssequestration and a natural gas price of $7.25 / MMBTU
– Partial oxidation of coal with and without carbonssequestration and a coal price of $35 / short ton
– Wind-powered plant based on water electrolysis
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Comparison of Alternatives
172144048.32100HTGR
196154029.42100ABWR
20158028.71120IRIS
21887042.72100Coal
22770041.51080GTHTR
291100039.52100Coal
w/sequestration
3214000-2100Wind
33136079.02100Natural Gas
340---June 2006 Price
35642076.42100Natural gas w/
Sequestration
165---Historic Average
ProductionCost
($/tonne)
CapitalInvestment
(million $)
Efficiency
(MJ fuel* / MJT)
Production(tonne NH3/day)
Process
* Fuel value based on higher heating value
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Observations
• Nuclear-powered ammonia production has the lowestoperating costs
– 10 - 20% less than partial oxidation of coal
– 40 - 50% less than steam reforming methane
• Nuclear-powered ammonia production has the highestcapital costs
– 65 - 75% more than partial oxidation of coal
– 400 - 430% more than steam reforming methane
• Efficiency is not a good indicator of operating costs orcapital costs
– Efficiency of ABWR plant 60% less than HTGR plant
– Capital investment for ABWR plant only 7% greater
– Production costs for ABWR plant only 14% greater
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Before Tax Return on Investment Assumingan Ammonia Price of $340 / tonne
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$500/tonne
Ammonia Price Needed to Earn a 20% ROIBefore Taxes
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Observations
• At $340 / tonne, an ammonia plant is not an attractiveinvestment
• An IRIS-powered plant may be the best method ofproducing ammonia without carbon dioxide emissions
– Highest rate of return at current ammonia prices
– Price to earn 20% ROI is comparable to natural gas withcarbon sequestration
– ROI is not sensitive to fluctuations in natural gas andammonia prices
– Does not required exotic technologies
• Capital investment, not efficiency, is the most importantfactor governing the economics of nuclear-poweredammonia production
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Summary and Conclusions
• The main advantages of nuclear-powered ammoniaproduction are
– Uses readily available raw materials (air and water)
– Low, stable operating costs
– No carbon dioxide production
• High capital costs are the major disadvantage of nuclear-powered ammonia production
• Smaller, standardized modular reactors could reducecapital costs
– Reduce construct cost and time
– Reduce licensing cost and time
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Ammonia is a Possible Petroleum-FreeMilitary Fuel
• Advantages
– Readily available world-wide
– Can be produced from a variety of raw materials
– Can be used in a variety of power systems(diesel, turbines, fuel cells)
– Could be produced in or near the theater ofoperations from air and water
• Disadvantages
– More difficult to handle and transport thanhydrocarbon fuels
– Not a good fuel for aircraft
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Some Considerations When ProducingAmmonia in the Theater of Operation
• Would like to maximize production, so yield is a moreimportant consideration than capital cost
• Would like to maximize flexibility
– Obtain power from local electrical grid if available
– Use transportable nuclear reactor if local power unreliable
• Need a transportable ammonia plant and reactor
• Would like to simplify set-up and operations
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Configuration for a TransportableNuclear-Powered Ammonia Plant
• The proposed ammonia plant is electric powered anduses steam electrolysis to produce hydrogen
– Can be powered by a nuclearreactor or the local electricalgrid
– Simplifies the interface between the reactor and ammoniaplant
– Steam electrolysis plant consumes ~20% less power than awater electrolysis plant
• The ammonia plant will be powered by a small 10-MWtgas-cooled reactor
– A pebble-bed reactor is the most likely choice
– Power generated a a Brayton cycle or Stirling cycle
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Efficiencies of a Small Ammonia PlantPowered by a 10 MWt Reactor
0.2811328PWR
0.3915850Pebble Bed
0.4216950Pebble Bed
Efficiency
(MJfuel / MJt)
ProductionRate
(tonne/day)
Reactor OutletTemperature
(°C)Reactor Type
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Skid Mounted Sections of a SmallAmmonia Plant Commercially Available
• Commercially availableequipment
– Electric-powered boilers
– PSA nitrogen plants
– Ammonia refrigeration
– Compressor
• Other equipment expectedto be small
– Electrolyzers
– Ammonia reactors
Small PSA nitrogen plant
Likely scale of electrolyzers
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The TRISO Fuel Particles Used in a PebbleBed Reactor Are the Primary Barriers to
the Release of Radioactive Materials
Will withstand a loss-of-coolantaccident without melting
Will withstand air ingresswithout burning
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A Proposed Pebble Bed Reactor Design
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Reactor Shielding Provided byan Earthen Barrier
Nuclear Reactor Ammonia Plant