A. Shakouri 9/18/2008 University of California Santa Cruz Electrical Engineering Department Energy Storage and Hydrogen Economy Ali Shakouri EE80J-180J;

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


Electricity Usage Pattern


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.


Energy Storage Options


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


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


Discharge 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


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


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


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


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)



www.hpower.com

membrane conducts protons from anode to cathodeProtonExchangeMembrane (PEM)



www.hpower.com

membrane conducts protons from anode to cathodeProtonExchangeMembrane (PEM)



www.hpower.comProtonExchangeMembrane (PEM)Membrane conducts protons from anode to cathodeproton exchange membrane (PEM)


Specific Energy (Wh/kg)

Spe

cific

Pow

er (

W/k

g)

Combustion Engine

Energy Storage Options


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


“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


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



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


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)



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



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



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


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


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


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



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



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/


Documents

A. Shakouri 9/18/2008 University of California Santa Cruz Electrical Engineering Department Energy Storage and Hydrogen Economy Ali Shakouri EE80J-180J;