Hydrogen Fuel Cells

Hydrogen (H2) is a fuelnot an energy source.

It is the most abundant element but must be removed from larger

molecules like water or petroleum.

ProductionHydrogen can be produced from• Fossil Fuels (currently 90% of 42 mtons/yr)• Water

ProductionFossil Fuels

• Coal– converted to mixture of hydrogen (50%),

methane (35%), and carbon monoxide (8%)• Steam Reforming Methane (SRM)

– Most efficient, widely used, and cheapest• Partial Oxidation

– Range of feed stocks, 75% SRM• Directly cracking Methane or other

hydrocarbons

ProductionFossil Fuels

The downside:

All of these methods release CO2

ProductionWater: Electrolysis

• Electricity + H2O → H2 + O + H2O (steam)

• Large-scale units using alkaline electrolyte can run at 70–75% efficiency (EE - H2 )

• Smaller systems with polymer electrolytes reach 80–85% efficiency (EE - H2 )

• Steam electrolyzers in development may be able to reach 90% efficiency (EE - H2 )

ProductionWater: Electrolysis

• When using electricity generated from thermal power stations the overall efficiency of converting fossil fuel to hydrogen via electrolysis would, typically, be only about 30%. (Rand, Dell, 2005)

• CO2 is released at the power plant

ProductionWater: Direct Methods

• Thermochemical– Could utilize waste heat from a nuclear plant– Could be achieved with solar mirrors

• Photoelectrolysis – sunlight to H2

– presently only 1–2% efficiency– new technique reporting 4.5% efficiency

• Biophotolysis – algae to H2

ProductionReview

Congressional Research Service

Hydrogen StorageThe Challenge: store large amounts of hydrogen at ambient temperature and pressure.

-compressed gas tanks

-cryogenic liquid hydrogen tanks

-metal hydrides

-chemical reactions (e.g. hydrolysis)

-nanomaterials

One solution: a three-dimensional lattice of tiny hollow cubes, each capable of storing eight hydrogen molecules insideJeff Long, UC-Berkeley

Hydrogen Storage

J.T.S. Irvine / Journal of Power Sources 136 (2004) 203–207

UsesWays to release the energy

• Catalytic Combustion– High control, low temperatures possible– Heating, cooking

• Direct Steam Generation– Burn it with pure oxygen to form pure steam– Peak load generation

• Internal Combustion Engine– More efficient (20%) less powerful (15%) than

gasoline ICE– Can be used in gas turbines and jets

• Fuel Cells

UsesFuel Cell

Inputs:HydrogenOxygen

Outputs:ElectricityWaterHeat

UsesTypes of Fuel Cells

• Alkaline fuel cells (AFC)• Polymer Electrolyte Membrane (PEMFC)• Phosphoric Acid fuel cells (PAFC)• Direct Methanol fuel cells (DMFC) • Molten Carbonate fuel cells (MCFC)• Solid Oxide fuel cells (SOFC)

Overall reaction is the same

H2 + ½ O2 → H2O

Low temperature fuel cellsAFC, PEMFC, PAFC, DMFC

High temperature fuel cellsMCFC, SOFC

Polymer Electrolyte Membrane• Vehicles• Small-scale distributed power generation

UsesTypes of Fuel Cells

UsesApplications of Fuel Cells

UsesApplications of Fuel Cells

• Portable Devices (Direct Methanol)– Cell Phone– Laptops– Field Equipment for military

• Distributed Generation– Commercial and Residential stationary

• Light Duty Vehicles

UsesApplications of Fuel Cells

V. Ananthachar, J.J. Duffy / Solar Energy 78 (2005) 687–694

Energy/National Security

Total U.S. primary energy production and consumption, historical and projected, 1970 to 2025. SOURCE: EIA (2003)

U.S. primary energy consumption, by fuel type, historical and projected, 1970 to 2025.SOURCE: EIA (2003).

Energy Diversity

Environment/Climate Change

U.S. emissions of carbon dioxide, by sector and fuels, 2000. SOURCE: EIA (2002)

Environment/Climate Change

Estimated volume of carbon releases from passenger cars and light-duty trucks: current hydrogen production technologies (fossil fuels), 2000–2050. Source: NAS

Public Health

• Particulateair pollution

• Smog• Other air

pollutants

htttp://airnow.gov

Feasibility of a U.S. Hydrogen Economy

Steven SmrigaScripps Institution of Oceanography

                      

             

Policy and Political Milestones

• 2002: U.S. President Bush launches FreedomCAR, a partnership with automakers to advance research needed to increase practicality and affordability of hydrogen fuel cell vehicles

• 2003: Bush State of the Union Address announces $1.2 billion hydrogen fuel initiative to develop technologies for hydrogen production and distribution infrastructure needed to power fuel cell vehicles and stationary fuel cell power sources

• 2004: Governor Schwarzenegger launches California’s Hydrogen Highway Network initiative

• 2005: CA Senate Bill 76: $6.5 million in funding for state-sponsored hydrogen demonstration projects through 2006

Hydrogen Production using Domestic Resources

“The U.S. Department of Energy estimates that the hydrogen fuel initiative and FreedomCAR initiatives may reduce our demand for petroleum by over 11 million barrels per day by 2040 – approximately the amount of oil America imports today.”

Major driver: Reduction in dependence on foreign oil

“America imports 55 percent of the oil it consumes; that is expected to grow to 68 percent by 2025.”

-www.whitehouse.gov, January 2003

Hydrogen Production using Domestic Resources

Resource Consumption factor*

Coal 1.3

Natural gas 1.2

Biomass 2.4

Domestic oil ??

Wind 140

Solar >740

Nuclear 3.2

*Factor by which U.S. would need to increase current consumption of this resource to produce required hydrogen equivalent

Source: U.S. Dept. of Energy, H2 Posture Plan, 2004

Source: National Fuel Cell Research Center, UC-Irvine

Hydrogen: Toward Zero Emissions• Combined heat and power systems

• Carbon capture and storage

• Future energy sources: wave, geothermal, nuclear fusion

• Energy storage of renewables Modules that couple wind and solar with hydrogen production

Capture intermittent output Batteries may be superior for short term applications

Contributes to distributed generation

Making Fuel Cells Affordable

Barriers include:

durability

fuel supply (some FCs require extremely pure fuel), and

raw materials (e.g. platinum and other precious metals used as a catalyst)

Making Fuel Cells Affordable

Factors toward weakening these barriers:• Widespread fuel cell vehicle

demonstration projects– California Hydrogen Highway (e.g.

Chula Vista)– Canada, Japan, EU, others

• Fuel cells already used in stationary power backup systems

• Public-private partnerships and alliances setting goals– Solid State Energy Conversion

Alliance (SECA)

The overall U.S. hydrogen market is estimated at $798.1 million in 2005 and is expected to rise to $1,605.3 million in 2010.

The overall European hydrogen market is estimated to be about $368 million in 2005 and is expected to grow to $740 million in 2010.

Source: Fuji-Keizai USA, Inc.: 2005 Hydrogen Market, Hydrogen R&D and Commercial Implication in The U.S. and E.U.

Reduction in Carbon Emissions

• hydrogen fuel cell efficiency: 40-60% combustion engine efficiency: ~35%

• potential for cleaner energy production

Source: U.S. Dept. of Energy

Transition to Hydrogen Vehicles

Possible optimistic market scenario showing assumed fraction of hydrogen fuel cell and hybrid vehicles in the United States, 2000 to 2050. Sales of fuel cell light-duty vehicles and their replacement of other vehicles are shown. Source: The Hydrogen Economy: Opportunities, Costs, Barriers, and R&D Needs (2004); National Academies Press.

Source: Dept. of Energy, Hydrogen Posture Plan

             

Source: Dept. of Energy, Hydrogen Posture Plan

Challenges to the Hydrogen Economy

Two aspects:

1) Feasibility

2) Misalignment with goals

Ted Beglin

Can it happen?Feasibility

• Chicken and the Egg• Cost of infrastructure• Competition• Storage• Public Perception• Land Usage

Can it happen?Chicken and the Egg

• The FCV market depends upon the availability of a hydrogen infrastructure

• The hydrogen infrastructure must be promoted by hydrogen use

• Neither serves any purpose without the other

Can it happen?Cost of Infrastructure

• Replacement value of the current energy system and related end-use equipment would be in the multi-trillion-dollar range

• Both the supply side (the technologies and resources that produce hydrogen) and the demand side (the technologies and devices that convert hydrogen to services desired in the marketplace) must undergo a fundamental transformation.

• In no prior case has the government attempted to promote the replacement of an entire, mature, networked energy infrastructure before market forces did the job

• Market pressures from lacking petroleum supplies and/or US participation in a CO2 credit-trade market are needed to push this forward NAS, 2004

Can it happen?Competition

• Incumbent technologies do not stand still, but continue to improve.

• The cost of the current energy infrastructure is already sunk, favoring technologies that use it.– Gasoline, Diesel, and CNG Hybrid Vehicles– Bio-diesel and Ethanol

Can it happen?Competition

NCEP, 2004

Can it happen?Storage

Goals for Hydrogen On-Board Storage to Achieve Minimum Practical Vehicle Driving Ranges

Energy DensityGeneral Motors Minimum Goals

Compressed/Liquid Hydrogen (Currently)

DOE Goal

Megajoules per kilogram

6 4/10 10.8

Megajoules per liter 6 3/4 9.72NOTES: Energy densities are based on total storage system volume or mass. Energy densities for compressed hydrogen are at pressures of 10,000 psi.SOURCES: DOE (2002b, 2003b)

Can it happen?Storage

• Compressed gas tanks– Lacks energy to volume ratio– For example, for more than a 200-mile driving range,

today’s natural gas vehicles usually require two 5,000 psi tanks or one 10,000 psi tank, taking up most of the trunk. (NAS)

• Cryogenic liquid hydrogen tanks – About 30% of the energy in the hydrogen is wasted in

the liquefaction and filling process– Emptying equipment is both complex and costly– Boil-off rate is such that the liquid can only be stored

for a few days at most. (Rand, Dell 2005)

Can it happen?Storage

• Advanced methods may have to provide the solution, but are still in development– metal hydrides– chemical reactions (e.g. hydrolysis)– nanomaterials

• Public perception of safety is affected by Hindenburg Syndrome

• However, it is not clear that H2 is any more dangerous than natural gas or gasoline

• Irony: Because of high diffusion, it may be safer

Can it happen?Public Perception

Addison Bain, NASA veteran presented compelling evidence in 1997 that the Hindenburg’s cotton covering was coated by a substance with similarities to rocket fuel. The same ship filled with inert helium still would have burned.Peter Hoffman, Tomorrow’s Energy, 2001

Can it happen?Land Usage

• New transmission lines are increasingly difficult to build, largely because of public opposition.

• The transmission system is being used for purposes for which it was not originally designed, and upgrades are not keeping pace with the increasing loads on it.

• Unless this situation is corrected, it may hamper the use of electrolyzers in distributed hydrogen generation facilities.

• Building pipelines to carry hydrogen may encounter some of the same sitting problems.

Should it happen?

• Reliance on Natural Gas rather than Oil• Carbon Sequestration• Picking a winner

Should it happen?Energy/National Security

• We could be trading one foreign dependency for another

• The initial hydrogen economy would most likely depend upon the reforming of natural gas

• If natural gas is used to produce hydrogen, and if, on the margin, natural gas is imported, there would be little if any reduction in total energy imports, because natural gas for hydrogen would displace petroleum for gasoline.

NAS, 2004

Should it happen?Environment/Climate Change

• Two sources of carbon stand out– Coal burned for

electricity– Petroleum burned

in transportation fuels

• Hydrogen must address both to benefit the environment

U.S. emissions of carbon dioxide, by sector and fuels, 2000. SOURCE: EIA (2002)

Should it happen?Environment/Climate Change

• Successful carbon sequestration is necessary, otherwise CO2 from petroleum will come from fossil fuel reformation to produce hydrogen

• Energy shifted from oil could result in massive coal mining to make up the difference

• Energy/National security would be addressed but not greenhouse gases

• Conservation, advancement of renewables, and nuclear power would be the only emission free hydrogen if CO2 sequestration is not realized

Should it happen?Public Health

• Although fuel cells only emit water, internal combustion use produces NOx, leading to smog

• Unintended consequences of H2 leakage may include reduction in global oxidative capacity, increase in tropospheric ozone, and increase in stratospheric water that would exacerbate halogen induced ozone losses (Dubey, Los Alamos National Laboratory, 2003)

Should it happen?Energy Diversity

• Quite the opposite, it could reduce us to predominately rely on coal

• The hydrogen economy needs support from some combination of increased renewable power, reinvigoration of nuclear power, and conservation to promote diversity

Should it happen?Energy Diversity

• Picking winners?• The track record

– 50s Nuclear power “too cheap to meter”– Late 70s, early 80s oil price assumptions to justify

large amounts of spending– 90s battery powered cars

• Other technologies, should funding favor H2?– Battery technology– Biomass based fuels

• alternatives to gasoline engines:– clean diesels– gasoline-electric hybrids– hydrogen internal

combustion engines (H2ICE)

– hydrogen fuel cell vehicles (FCV)

• Physical and regulatory infrastructure– Safety codes and standards– Public awareness about fueling systems– Training for fuel distribution personnel

Types of Fuel Cells• Alkaline Fuel Cell (AFC)• Molten Carbonate Fuel Cell (MCFC)• Phosphoric Acid Fuel Cell (PAFC)• Proton Exchange Membrane Fuel Cell

(PEMFC)• Solid Oxide Fuel Cell (SOFC)• Direct Methanol Fuel Cell

• Fuel cell types are generally characterized by electrolyte material. The electrolyte is the substance between the positive and negative terminals, serving as the bridge for the ion exchange that generates electrical current.