hydrogen technology for vehicles: potential and challenges
TRANSCRIPT
Univ. of Maryland Energy Research Center
College Park, MD
Hydrogen Technology for Vehicles:
Potential and ChallengesMarch 25, 2011
Greg Jackson
Dept. of Mechanical Engineering
University of Maryland, College Park, MD, USA
Virginia Clean Cities Fleet Innovation: Driver
Feedback, Electric, and Hydrogen
Univ. of Maryland Energy Research Center
College Park, MD
Acknowledgements
• Thanks to the following for providing slide material
– Peter Sunderland from Univ. of Maryland
– Catherine Grégoire Padró from Los Alamos National Laboratory
– Sunita Satyapal from DOE Hydrogen and Fuel Cell Program
– Pat Hearn from Ballard Power Systems
– John Turner from National Renewable Energy Laboratory
– Santosh Limaye – now with Vesta Ceramics, LLC
– Robert Kee from Colorado School of Mines
Univ. of Maryland Energy Research Center
College Park, MD
1 Exajoule = 2.77*1011 kWh
Potential for
distributed power
with combined
cooling and heating
with SOFC’s and
PEMFC’s
Potential for H2 derived
from non-petroleum
sources for PEMFC
powered vehicles
from Lawrence Livermore Natl. Laboratory
http://eed.llnl.gov/flow (June 2004)
Potential for central
power SOFC’s with
carbon capture
Where we are today: Identifying the Opportunities
Univ. of Maryland Energy Research Center
College Park, MD
Suggested Global Warming Abatement Strategies
for Transportation Power Needs• Reducing the dependence of transportation on oil
– Make fuels from CO2 captured from the environment
– Making fuels from biomass (preferably not food sources)
• Adaptation of fuel cell and H2-powered vehicles
– Challenge of cost and resources
• Pt loading of catalysts
– Challenge of changing fuel infrastructure for H2 delivery and storage
• Implementation of electric vehicles
– Limitations of batteries, the consumers, and the automotive market
– Environmental questions
• Improving efficiency of conventional vehicles
– Hybrid electric vehicle technology
– Increased use of diesel engines
• How far does this take us in addressing the problem
Univ. of Maryland Energy Research Center
College Park, MD
Why and Why not Hydrogen for Transportation?• Hydrogen like electricity is an energy carrier not an energy supply
– Unlike electricity, it can be stored though not easily.
• Energy densities are too low and storage requires high pressures or low
temperatures.
• Fuel Cells: a historical driver for H2
– Low temperature fuel cells have needed pure H2 (<100 ppm CO) for higher power
density (approach 1 kW/liter of fuel cell, longer life (> 5000 hrs.)
• Proton Exchange Membrane (PEM) fuel cells for transportation will dictate the
needs for H2 infrastructure (leaders – Ballard, GM, Honda, UTC)
• Hydrogen is clean and can be produced from several sources
– Fossil fuels with easier CO2 sequestration
– Solar power with electrolysis or high-temperature thermolysis
– Nuclear power, wind power, and hydroelectric with high temperature electrolysis
• Competitors – synfuels, biofuels, and battery-powered vehicles
• Current Usages of Hydrogen > 50 million tons/yr & growing
– As a fuel refining agent
– Ammonia production
Univ. of Maryland Energy Research Center
College Park, MD
Fueling Our Transportation Sector toward
Sustainability: Why not H2 Fuel Cells?
from Sandy Thomas using Argonne National Laboratory GREET 1.8a
-
0.5
1.0
1.5
2.0
2.5
3.0
2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
Greenhouse Gas Pollution (Light duty vehicles only)
(Billion/ tonnes CO2-equivalent/year)
1990 LDV GHG
Level
GHG Goal: 60% below
1990 Pollution
GHG Goal: 80% below 1990
Pollution
FCV Scenario
Ethanol PHEV
Scenario
Gasoline PHEV
Scenario
PHEVs
Base Case:
Gasoline HEV
Scenario
100% Gasoline
ICEVs
Univ. of Maryland Energy Research Center
College Park, MD
Fuel Cells and H2 in Transportation News
• DOE (Sec’y Chu) has proposed cuts
in EERE Fuel Cell program from
$179 M in FY10 to $100M in FY12
– Strongly questioned by car manufacturers
• California continuing with Fuel Cell
Partnership program
– 26 H2 fueling stations in CA
– Goal is commercial vehicles in 2017
• Japan Hydrogen Highway for fuel
cell vehicles with stations in 11
cities. METI in Japan still moving
toward commercialization in 2015 of
fuel cell vehicles.
– H2 stations run on reformed natural gas
• Many successful fuel cell bus demo
programs outside of U.S.
ISE Ultra-E™ 500 Bus
35kW battery pack
75 or 150 kW Ballard HD6
Siemens ELFA™ Motors
Honda FCX
Clarity
GM Equinox
Univ. of Maryland Energy Research Center
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Fuel Cells and H2 in Auxiliary Power News
• DOE has identified early markets for fuel cells which
are either commercially viable or almost so
– Hybrid forklifts for warehouse applications in combination with
local H2 generation
– Back-up power for cell phones and other applications
– Stationary power for critical supplies
• Military fuel cell applications have led to many recent
increases in DOD fuel cell applied R&D
– Underwater unmanned vehicles (UUVs)
– Portable gensets operating on portable fuels
• Other applications may also be viable and fundable
through other means
– CHP or CCHP for both residential and commercial applications
– Building power in regions with high electric costs (> 10¢/kWh)
Hybrid PEM Fuel Cell /
Battery Fork Lift
Univ. of Maryland Energy Research Center
College Park, MD
A DOE H2 Program Perspective on Alternative
Vehicles (Satyapal 2011)
Univ. of Maryland Energy Research Center
College Park, MD
Components of Fuel Cell Vehicles
• Fuel cell vehicles
are electric vehicles
but with the
potential for much
further range than
battery-powered
vehicles.
• 430 mi range on 156
liter H2 storage tank
at 70 MPa (Toyota in
California 2009)
• 53-59% efficient
based on H2 for
typical drive cycle
(DOE EERE)
Univ. of Maryland Energy Research Center
College Park, MD
Proton Exchange Membrane Fuel Cell Architecture
• Acidic polymer electrolytes
(25-100 µm thick) conduct
H+ (or H3O+) ions from
anode to cathode
– Nafion electrolytes require
hydration and thus low-
temperature operation.
• Carbon paper provide
porous media for gas
transport to active catalyst
layer for electrochemistry
• Precious metal catalyst for
H2 oxidation at anode and
O2 reduction to H2O at
cathode Image from
http://www.ballard.com/About_Ballard/Resources/How_Fuel_Cells_Work.htm
Univ. of Maryland Energy Research Center
College Park, MD
Comparison of Fuel Cell Stack Technology
• Proton Exchange Membrane Fuel Cells
– Operation at low temperatures < 120ºC
– Expensive precious metal catalysts
– Fuel limited to relatively pure H2 with inert
diluents for high power density applications
– H2O management critical for most designs
• PEMFC applications – vehicles,
forklifts, small gensets, portable power
Delphi, 3.4 kW SOFC system efficiency ≈ 38%
operating on nat. gas (FC Sem. 2007)
• Solid Oxide Fuel Cells
– Operation at high temperatures > 600ºC
– Energy intensive fabrication processes
– Potential for direct fueling – coal gas, NG,
ethanol, biogas
– Readily integrated with gas turbines for
high efficiency hybrid plants
• SOFC applications – small central
power, distributed power, APU’s
Ballard Power System stack (liquid cooled
producing ~ 8 kW at ≈ 55% stack efficiency)
Univ. of Maryland Energy Research Center
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Eo, Nernst
Crossovers and shorts Eo, experiment
Total Cell Resistances
Membrane ionicContact
resistances
Cables
Cathode Overpotential
Anode Overpotential
Mass Transport
Diffusivity under landings
(2D/3D)
Diffusivity through GDL (1D)
Catalyst Diffusivity
O2 depletion at outlet
Current Density (A/cm2)
Cell
Voltage (V)
Understanding Voltage (Polarization) Losses
in PEM Fuel Cells
Fast Transient Polarization
• Voltage losses results in heat released in fuel cell which can be used to heat
reactants, provide hot water, or other heating application.
from Pat Hearn, Ballard Power Systems
Univ. of Maryland Energy Research Center
College Park, MD
PEMFCs in the News• Plug Power developed Gensys system for small-scale CHP: high-temperature
(160-180 ºC) PBI-based PEMFC system running on natural gas reformate at
ηelec = 30% and ηCHP = 85%
– Inadequate costs and durability ($10000/kWe at currently 2000 hrs durability)
• Ballard Power Systems with others developing Ballard’s FC-Gen 1300 for
back-up power in Asian markets (India)
– up to 3 kWe powered by natural gas or LPG, ηelec > 30%
http://www.plugpower.com/userfiles/file/GenSysHT-03-09.pdfPapageorgopoulos (DOE) 2010
Univ. of Maryland Energy Research Center
College Park, MD
Feasibility of SOFC Hydrocarbon-Fueled Auxiliary
Power Unit for Large Trucks
from Scheffer , Delphi, Fuel Cell Seminar 2007
Univ. of Maryland Energy Research Center
College Park, MD
Making H2 for Fuel Cells: Possible Pathways
Hydrogen
SourcesLiquid Fuels
Hydrogen
Separation
NaturalGas
BiomassWater
Electrolysis
Partial Oxidation
Autothermal Reforming
Steam Reforming
Fuel Decomposition
Hydrogen
PurificationMembrane Technology
PSATechnology
Electrochemical Separation
Preferential Oxidation
Hydrogen
DistributionPipeline
Distributed Generation
On-Demand Generation
Electrolysis
Fuel
TreatmentSulfur
Removal
Truck Delivery LH2
Fuel Refinement
Hydrogen
StorageCompressed
ContainerCryogenic
LiquidMetal
HydrideChemically
Bound
Cryogenics
Carbon Nanotubes
from Santosh Limaye (2005),
consultant for Oak Ridge Natl. Lab
95% of H2 produced today,
efficiency between 70-80%
95% of H2 derived from NG
Univ. of Maryland Energy Research Center
College Park, MD
Solar Energy
Heat
Hydrogen
Thermolysis
Mechanical Energy
Electricity
Electrolysis
Biomass
Conversion
Photolysis
Sustainable Paths to Hydrogenfrom John Turner, NREL 2006
Univ. of Maryland Energy Research Center
College Park, MD
Fuel Cells for Cars: Well to Wheel Issues
Fuel Cell
Fuel
Supply
Fuel
Processor
Hydrogen
Clean-UpCombustor
Hydrogen
StorageAir
Oxygen
Enrichment
Waste
CO, CO2, H2, N2, H2O
ΔH<5 ppm CO
Exhaust
Exhaust
Exhaust
Other Thermal & Water Management Systems not shown
from Santosh Limaye (2005),
consultant for Oak Ridge Natl. Lab
• GREET Model from Argonne Natl. Lab
for Well-to-Wheel analysis
Univ. of Maryland Energy Research Center
College Park, MD
87 kg Total Wt
166 L (5.9 ft3)
Composite Cylinders
@ 700 bar
390 kg Total Wt 340
L (12 ft3)
Commercial Gas
Cylinders @ 180 bar
50 kg Total Wt
46 L ( 1.6 ft3)
Diesel Fuel + Reformer
Diesel Fuel
Storage of 4.0kg of Hydrogen = 60kw-hrs (electric )
Storing H2 for Portable and Distributed Power
Univ. of Maryland Energy Research Center
College Park, MD
Catalytic Fuel Reforming of Natural Gas to Make H2
• Endothermic Steam Reforming (SR)–Gives highest concentration of H2 out (up to 70% H2)
CH4 + H2O + 20.6 kJ/gmol → CO + 3H2
Heat must be added indirectly, usually by burning fuel.
CH4 + 2*O2 → CO2 + 2*H2O + 80.2 kJ/mgol
Water-gas shift drives further H2 production
CO + H2O ↔ CO2 + H2 + 4.1 kJ/mgol
• Thermally Neutral Auto-thermal Reforming (ATR)CH4 + ½O2 + ½H2O → CO2 + 2½H2 +19.8 kJ/gmol
CO + H2O ↔ CO2 + H2 + 4.1 kJ/gmol
• Exothermic Partial Oxidation (POx)
– Gives lower concentration of H2 out due to N2 dilution from air
CH4 + O2 = CO + 2H2 + 31.9 kJ/gmol
All Heats of reaction at 300 K
Univ. of Maryland Energy Research Center
College Park, MD
DOE Projected Near and Long Term H2 Dispensed
Costs (Satyapal 2011)
Univ. of Maryland Energy Research Center
College Park, MD
Challenge of H2 Storage and Distribution• Renewable pure H2 production from a variety of sources now requires means
of storing H2 on vehicles or at power sites.
• Current-day technology requires H2 storage as gas in high-pressure
composite tanks with pressures at 350 to 700 bar.
– Safety concerns with high pressures and significant costs for tank
– Range of high-end fuel cell vehicles approaching best IC engine cars.
– Local compression to fill tanks
• Shipping is only easily done in pipelines and such infrastructure is not
economical.
• Local compression to fill tanks can be done quickly but with a substantial
pump-to-car inefficiency.
• Possibility of shipping around renewable or nuclear electricity to do
electrolysis (need to develop higher efficiency, high-T electrolysis).
• Costs for natural gas steam reforming supply in 100 largest metropolitan
areas and along every interstate range from $12B up to $100B+
– Not long-term solution but transition technology to renewable sources for H2.
• Value of H2 does not need to be in energy efficiency, but in security and
greenhouse gas reductions
Univ. of Maryland Energy Research Center
College Park, MD
DOE Hydrogen Storage Targetsfrom Catherine Grégoire Padró of Los Alamos National Laboratory
Univ. of Maryland Energy Research Center
College Park, MD
H2 Safety Considerations
• Steel embrittlement.
• For vehicles, gas storage pressures range from 5,000 to 10,000 psi
• Highest volumetric leak propensity of any fuel.
• Permeation leaks.
• Smallest ignition energy of any fuel in air (28 J).
• Lowest autoignition temperature of any fuel in heated air jet (640 °C).
• Wide flammability limits in air (4 – 75% by volume).
• Highest laminar burning velocity of any fuel which can transition to
detonations in very crowded spaces.
• Smallest quenching distance of any fuel premixed with air (0.51 mm).
• Highest heat of combustion (120 kJ/g).
• Dimmest flames of any fuel in air.
Univ. of Maryland Energy Research Center
College Park, MD
H2 Safety Considerations
• Status of H2 vehicles and fueling stations in U.S.
• Selected U.S. H2 vehicle demonstration programs.
• SAE J2578 – Recommended Practice for General Fuel Cell Vehicle
Safety.
‒ Required H2 below 25% of the lean flammability limit in air
‒ Maximum release in accident or system failure is 7370 standard liters
of H2
• SAE J2579 – Technical Information Report for Fuel Systems in Fuel
Cells and Other H2 Vehicles.
• SAE J2601 – Technical Information Report for Fueling Protocols for
Light Duty Gaseous H2 Surface Vehicles.
• Other U.S. standards – NFPA 2, “H2 Technologies Code” NFPA
Univ. of Maryland Energy Research Center
College Park, MD
Closing Thoughts: Perspective on Fuel Cells
• Fuel cell stack costs have dropped dramatically in the past decade but
– Stacks costs remain high for SOFC’s (~$175/kW) and for PEMFC’s (~$60/kW)
but have fallen enough that high balance of plant and/or fuel processor costs
may not be prohibitive for some key markets including
• Distribute power with CHP, back-up power
• Truck APU’s
• Urban bus fleets
• Materials handling.
• Materials advances in areas like high-temp PEMFCs (150 to 200 °C) and
lower-temperature SOFCs (500 to 650 °C) are needed for these promising
technologies to provide adequate durability and cost effectiveness to
perhaps open up broader markets.
• Some available fuels (such as ethanol) may be very favorable for fuel cell
power plants
• Government need not be the only source of funding for these nearer term
markets.
• Government is still needed to drive the infrastructure and long-term
investment needed for H2 vehicles and H2 production from renewable energy.