A. Shakouri 9/18/2008
University of California Santa CruzElectrical Engineering Department
Energy Storage and Hydrogen Economy
Ali Shakouri
EE80J-180J; 21 May 2009
Edited by Mona Zebarjadi for EE80j, Summer 2009
A. Shakouri 9/18/2008
Electricity Usage Pattern
A. Shakouri 9/18/2008
Energy Usage in a typical household
Electricity Usage ~15 kWh/day (54 MJ/day) power ~ 625W
Storage:
• Water: 78,717 liter (a cube whose side measures at 4.3 m) at 100 meter (70% conversion efficiency)
• Flywheel: 2138kg, 4m radius, 600rpm (80% conversion efficiency)
• Compressed Air: 3600 liter (0.03 MJ/liter, 50% conversion efficiency)
Hot Water Usage ~25-35MJ
150-200 liter water heated from 15C up to 55C
• Burn 4-5kg of wood in 50% efficient wood stove.
A. Shakouri 9/18/2008
Energy Storage Options
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Compressed air energy storage • Air is compressed and stored under
ground– Huntorf, Germany 1978, hold pressures up to
100bar (2kWh/m3)– Alabama (1991) 70bar energy density
0.54kWh/m3
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Battery
• Primary batteries– Zinc-Carbon– Alkaline
• Secondary (rechargeable) batteries– Lead-Acid– Nickel-Cadmium– Vanadium
A. Shakouri 9/18/2008Battery Characteristics
• Battery capacity: Amount of charge that it holds (amp-hours) I x t
• Discharge rate: number of hours over which the battery discharges
• A battery rated at 100 A·h will deliver 5 A over a 20 hour period at room temperature. However, if it is instead discharged at 50 A, it will run out of charge before the 2 hours theoretically.
. Practically, when discharging at low rate, the battery's energy is delivered more efficiently than at higher discharge rates
A. Shakouri 9/18/2008
Discharge Characteristics
A. Shakouri 9/18/2008Battery Characteristics
Cycle life• State of charge (SOC): percentage of
storage capacity still available in the battery
• Battery cycle: cycle of discharge and recharge from a given SOC down to a lower state of charge and back to the original state of charge
A. Shakouri 9/18/2008Battery Characteristics
Figure 1: Cycle life of nickel-metal-hydride batteries under different operating conditions. (Zhang, 1998)NiMH performs best at DC and analog loads and has lower cycle life with digital a load.
Figure 2: Cycle life of lithium-ion at varying discharge levels. (Choi et al., 2002)Like a mechanical device, the wear-and-tear of a battery increases with higher loads
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Lead Acid Battery
www.daviddarling.info
A. Shakouri 9/18/2008Battery Discharging
Pb PbO2H2SO4
Pb+PbO2+2H2SO4 → 2 PbSO4 + 2 H2O
A. Shakouri 9/18/2008Battery Charging
Pb+PbO2+2H2SO4 ← 2 PbSO4 + 2 H2O
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Vanadium flow Battery • Advantages:
– Rechargeable– it can offer almost unlimited capacity simply by
using larger and larger storage tanks,– it can be left completely discharged for long periods
with no ill effects,– it can be recharged simply by replacing the
electrolyte if no power source is available to charge it, and if the electrolytes are accidentally mixed the battery suffers no permanent damage.
• Disadvantages – a relatively poor energy-to-volume ratio, 87 liter
1kWh (compare to 1liter gasoline which has 9.3kWh)
– the system complexity in comparison with standard storage batteries
– Shortage of vanadium supply
A. Shakouri 9/18/2008
Fuel Cells
H2 + O2 ® H2O + electrical energy
What are Fuel Cells?2H2+ O2
2H2O + electricalpower + heat
www.hpower.com
membrane conducts protons from anode to cathodeProtonExchangeMembrane (PEM)Membrane conducts protons from anode to
cathodeproton exchange membrane(PEM)
What are Fuel Cells?2H2+ O2
2H2O + electricalpower + heat
www.hpower.com
membrane conducts protons from anode to cathodeProtonExchangeMembrane (PEM)
What are Fuel Cells?2H2+ O2
2H2O + electricalpower + heat
www.hpower.com
membrane conducts protons from anode to cathodeProtonExchangeMembrane (PEM)
What are Fuel Cells?2H2+ O2
2H2O + electricalpower + heat
www.hpower.comProtonExchangeMembrane (PEM)Membrane conducts protons from anode to cathodeproton exchange membrane (PEM)
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Specific Energy (Wh/kg)
Spe
cific
Pow
er (
W/k
g)
Combustion Engine
Energy Storage Options
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June 24, 2004DOE Nano SummitWashington, D.C.
Presented by: Mildred Dresselhaus
Massachusetts Institute of [email protected]
617-253-6864
Basic Research Needs for the Hydrogen Economy
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“Tonight I'm proposing $1.2 billion in research funding
so that America can lead the world in developing
clean, hydrogen-powered automobiles… With a new
national commitment, our scientists and engineers will
overcome obstacles to taking these cars from
laboratory to showroom, so that the first car driven by
a child born today could be powered by hydrogen, and
pollution-free.”
President Bush, State-of the-Union Address,
January 28, 2003
Hydrogen: A National Initiative in 2003
M. S. Dresselhaus, MIT
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The Hydrogen Economy
solarwindhydro
fossil fuelreforming
nuclear/solar thermochemical
cyclesH2
gas orhydridestorage
automotivefuel cells
stationaryelectricity/heat
generation
consumerelectronics
H2O
production storage use in fuel cells
Bio- and bioinspired
9M tons/yr
150 M tons/yr(light cars and trucks in 2040) 9.70 MJ/L
(2015 FreedomCAR Target)
4.4 MJ/L (Gas, 10,000 psi) 8.4 MJ/L (Liquid H2)
$3000/kW
$30/kW(Internal Combustion Engine)
H2
M. S. Dresselhaus, MIT
A. Shakouri 9/18/2008
Hydrogen issues 1 –H2 is not dense even liquid H2 is 10 times less dense than gasoline
H2 vs Gasoline– 3 x more energy per gram (or per lb) – 3 x less energy per gallon (or per liter)
2- H2 liquid is dangerous to store; expands by a factor of a thousand if warmed
3-There is virtually no hydrogen gas in the environment
3.1.If we use methane to create H2, we also create Co2
3.2.A Hydrogen production plant would get its power from somewhere else.
Hydrogen is not a source of energy. It is only a means for transporting energy.
4-Hydrogen production (electrolysis) 70% efficient, Best efficiency from a fuel cell 60%>>Overall 70x60~ 40%
5-It is not yet competitive with the fossil fuel economy in cost, performance, or reliability
- The most optimistic estimates put the hydrogen economy decades away
A. Shakouri 9/18/2008
Hydrogen Production Panel
Current status: • Steam-reforming of oil and natural gas produces 9M tons H2/yr• We will need 150M tons/yr for transportation• Requires CO2 sequestration.
Alternative sources and technologies: Coal:
• Cheap, lower H2 yield/C, more contaminants• Research and Development needed for process development,
gas separations, catalysis, impurity removal.Solar:
• Widely distributed carbon-neutral; low energy density.• Photovoltaic/electrolysis current standard – 15% efficient• Requires 0.3% of land area to serve transportation.
Nuclear: Abundant; carbon-neutral; long development cycle.
Panel Chairs: Tom Mallouk (Penn State), Laurie Mets (U of Chicago)
M. S. Dresselhaus, MIT
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Current Technology for automotive applications • Tanks for gaseous or liquid hydrogen storage. • Progress demonstrated in solid state storage materials.System Requirements• Compact, light-weight, affordable storage. • No current storage system or material meets all targets.
Hydrogen Storage PanelPanel Chairs: Kathy Taylor (GM, Retired) and Puru Jena (Virginia Commonwealth U)
IDEAL SOLID STATE STORAGE MATERIAL• High gravimetric and volumetric density• Fast kinetics• Favorable thermodynamics• Reversible and recyclable• Safe, material integrity• Cost effective• Minimal lattice expansion• Absence of embrittlement
M. S. Dresselhaus, MIT
A. Shakouri 9/18/2008
Metal Hydrides and Complex HydridesDegradation, thermophysical properties, effects of surfaces, processing, dopants, and catalysts in improving kinetics, nanostructured composites
Nanoscale/Novel MaterialsFinite size, shape, and curvature effects on electronic states, thermodynamics, and bonding, heterogeneous compositions and structures, catalyzed dissociation and interior storage phase
Theory and ModelingModel systems for benchmarking against calculations at all length scales, integrating disparate time & length scales, first principles methods applicable to condensed phases
Priority Research Areas in Hydrogen Storage
NaAlH4 X-ray view NaAlD4 neutron viewNaAlH4 X-ray view NaAlD4 neutron view
H D C O Al Si Fe
X ray cross section
Neutron cross section
H D C O Al Si Fe
X ray cross section
Neutron cross section
NaBH4 + 2 H2O 4 H2 + NaBO2
Cup-Stacked Carbon Nanofiber
H Adsorption in Nanotube Array
Neutron Imaging of Hydrogen
M. S. Dresselhaus, MIT
A. Shakouri 9/18/2008
Types of Fuel Cells
Solid Oxide FC(SOFC) 100 kWSiemens- Westinghouse
Proton Exchange Membrane (PEM) 50 kW, Ballard
Molten Carbonate FC(MCFC) 250 kWFuelCell Energy,
Alkaline Fuel Cell(AFC), Space Shuttle12 kWUnited Technologies
Low-Temp
High Temp
Phosphoric Acid FC(PAFC), 250 kWUnited Technologies
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Fuel Cell Vehicle Learning Demonstration Project Underway; 3 Years into 5 Year Demo
• Objectives– Validate H2 FC Vehicles and Infrastructure in Parallel
– Identify Current Status and Evolution of the Technology
Photo: NRELHydrogen refueling station, Chino, CA
Keith WipkeNational Renewable Energy Laboratory
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Vehicle Status: All of First Generation Vehicles Deployed, 2nd Generation Initial Introduction in Fall 2007
On-Board Hydrogen Storage Methods
-
10
20
30
40
50
60
70
80
90
2005Q2 2005Q3 2005Q4 2006Q1 2006Q2 2006Q3 2006Q4 2007Q1 2007Q2
# o
f V
eh
icle
s (
All
Te
am
s)
Liquid H2
10,000 psi tanks
5,000 psi tanks
Created Aug-28-2007 9:29PM
77
Keith WipkeNational Renewable Energy Laboratory
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Fuel Cells and Novel Fuel Cell Materials Panel
Current status: Limits to performance are materials, which
have not changed much in 15 years.
Panel Chairs: Frank DiSalvo (Cornell), Tom Zawodzinski (Case Western Reserve)
Challenges: Membranes Operation in lower humidity, more strength, durability and higher ionic conductivity. Cathodes Materials with lower overpotential and resistance to impurities. Low temperature operation needs cheaper (non- Pt) materials. Tolerance to impurities: S, hydrocarbons, Cl. Anodes Tolerance to impurities: CO, S, Cl. Cheaper (non or low Pt) catalysts.Reformers Need low temperature and inexpensive reformer catalysts.
2H2 + O2 2H2O + electrical power + heat
M. S. Dresselhaus, MIT
A. Shakouri 9/18/2008
Messages
http://www.sc.doe.gov/bes/hydrogen.pdf
Enormous gap between present state-of-the-art capabilities and requirements that will allow hydrogen to be competitive with today’s
energy technologies production: 9M tons 150M tons (vehicles)
storage: 4.4 MJ/L (10K psi gas) 9.70 MJ/L fuel cells: $3000/kW $30/kW (gasoline engine)
Enormous R&D efforts will be required Simple improvements of today’s technologies
will not meet requirements Technical barriers can be overcome only with high
risk/high payoff basic research
Research is highly interdisciplinary, requiring chemistry, materials science, physics, biology, engineering, nanoscience, computational science
Basic and applied research should couple seamlessly
M. S. Dresselhaus, MIT
A. Shakouri 9/18/2008
Some Useful References
Basic Research Needs for the Hydrogen Economy (DOE/BES) http://www.sc.doe.gov/bes/hydrogen.pdf
Basic Research Needs to Assure a Secure Energy Future (DOE/BES) http://www.sc.doe.gov/bes/besac/Basic_Research_Needs_To_Assure_A_Secure_Energy_Future_FEB2003.pdf
Powering the Future - Materials Science for the Energy Platforms of the 21st Century: The Case of Hydrogen (MIT lecture notes) http://web.mit.edu/mrschapter/www/IAP/iap_2004.html
Hydrogen Programs (DOE/EERE) http://www.eere.energy.gov/hydrogenandfuelcells/
National Hydrogen Energy Roadmap (DOE/EERE) http://www.eere.energy.gov/hydrogenandfuelcells/pdfs/national_h2_roadmap.pdf
FreedomCAR Plan (DOE/EERE) http://www.eere.energy.gov/vehiclesandfuels/
Fuel Cell Overview (Smithsonian Institution) http://fuelcells.si.edu/basics.htm
The Hydrogen Economy: Opportunities, Costs, Barriers, and R&D Needs (National Research Council Report, 2004) http://www.nap.edu/books/0309091632/html/
M. S. Dresselhaus, MIT