Hydrogen Fuel Cells Fact Sheet


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Hydrogen Fuel Cells

H2 DOE Hydrogen Program

Overview
Hydrogen is a versatile energy carrier that can be used to power nearly every end-use energy need. The fuel cell — an energy conversion device that can efficiently capture and use the power of hydrogen — is the key to making it happen.
4Stationary fuel cells can be used for backup power,
power for remote locations, distributed power generation, and cogeneration (in which excess heat released during electricity generation is used for other applications).
4Fuel cells can power almost any portable application
that typically uses batteries, from hand-held devices to portable generators.
4Fuel cells can also power our transportation, including
personal vehicles, trucks, buses, and marine vessels, as well as provide auxiliary power to traditional transportation technologies. Hydrogen can play a particularly important role in the future by replacing the imported petroleum we currently use in our cars and trucks.
Why Fuel Cells?
4Fuel cells directly convert the chemical energy in
hydrogen to electricity, with pure water and potentially useful heat as the only byproducts.
4Hydrogen-powered fuel cells are not only pollution-
free, but also can have two to three times the efficiency of traditional combustion technologies.
• A conventional combustion-based power plant typically generates electricity at efficiencies of 33 to 35 percent, while fuel cell systems can generate electricity at efficiencies up to 60 percent (and even higher with cogeneration).
• The gasoline engine in a conventional car is less than 20% efficient in converting the chemical energy in gasoline into power that moves the vehicle, under normal driving conditions. Hydrogen fuel cell vehicles, which use electric motors, are much more energy efficient and use 40-60 percent of

the fuel’s energy — corresponding to more than a 50% reduction in fuel consumption, compared to a conventional vehicle with a gasoline internal combustion engine.
4In addition, fuel cells operate quietly, have fewer
moving parts, and are well suited to a variety of applications.
How Do Fuel Cells Work?
A single fuel cell consists of an electrolyte sandwiched between two electrodes, an anode and a cathode. Bipolar plates on either side of the cell help distribute gases and serve as current collectors. In a Polymer Electrolyte Membrane (PEM) fuel cell, which is widely regarded as the most promising for light-duty transportation, hydrogen gas flows through channels to the anode, where a catalyst causes the hydrogen molecules to separate into protons and electrons. The membrane allows only the protons to pass through it. While the protons are conducted through the

A Single Fuel Cell

e–

e–

e–

H2
Hydrogen
H2
e–

e– e– e–
e–

Bipolar Plate Anode Electrolyte Cathode Bipolar Plate

H+
H+ H+

O2
O2 Oxygen
O2
Water H2O + Heat

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Hydrogen Fuels Cells

membrane to the other side of the cell, the stream of negatively-charged electrons follows an external circuit to the cathode. This flow of electrons is electricity that can be used to

Did you know…

do work, such as power a motor.

On the other side of the cell, oxygen gas, typically drawn from the outside air, flows through channels to the cathode. When the electrons return from doing work, they react with oxygen and the hydrogen protons (which have moved through the membrane) at the cathode to form water. This union is an exothermic reaction, generating heat that can be

Hydrogen is an energy carrier, not an energy source, meaning that it stores and delivers energy in a usable form.

used outside the fuel cell.
The power produced by a fuel cell depends on several factors, including the fuel cell type, size, temperature at which it operates, and pressure at which gases are supplied. A single fuel cell produces approximately 1 volt or less — barely enough electricity for even the smallest applications. To increase the amount of electricity generated, individual fuel cells are combined in series to form a stack. (The term “fuel cell” is often used to refer to the entire stack, as well as to the individual cell.) Depending on the application, a fuel cell stack may contain only a few or as many as hundreds of individual cells layered together.

Hydrogen can be produced using abundant and diverse domestic energy resources, including fossil fuels, such as natural gas and coal; renewable energy resources, such as solar, wind, and biomass; and nuclear energy.

This “scalability” makes fuel cells ideal for a wide variety of applications, from laptop computers (50-100 Watts) to homes (1-5kW), vehicles (50-125 kW), and central power generation (1-200 MW or more).

Using hydrogen as a form of energy can not only reduce our dependence on imported oil, but

Comparison of Fuel Cell Technologies
In general, all fuel cells have the same basic configuration — an electrolyte and two electrodes. But there are different types of fuel cells, classified primarily by the kind of electrolyte used. The electrolyte determines the kind of chemical reactions that take place in the fuel cell, the temperature range of operation, and other factors that determine its

also benefit the environment by reducing emissions of greenhouse gases and criteria pollutants that affect our air quality.

most suitable applications.

The President’s Hydrogen

Fuel Cell Type
Alkaline (AFC)
Phosphoric Acid (PAFC)

Operating Temperature
90–100ºC 194–212ºF
150–200ºC 302–392ºF

System Output
10kW–100kW
50kW–1MW (250kW module typical)

Efficiency
60–70% electric
80–85% overall with combined heat and power (CHP) (36–42% electric)

Applications
• Military • Space • Distributed generation

Fuel Initiative accelerates the research and development of fuel cells and hydrogen production, storage, and delivery infrastructure technologies needed to support hydrogen fuel

Polymer Electrolyte Membrane or Proton Exchange Membrane (PEM)*

50–100ºC 122–212ºF

<250kW

50–60% electric

• Back-up power • Portable power • Small distributed generation • Transportation

cells for use in transportation and electricity generation.
Under the President’s Hydrogen

Molten Carbonate (MCFC)

600–700ºC 1112–1292ºF

<1MW

85% overall with CHP (60% electric)

(250kW module typical)

• Electric utility • Large distributed generation

Fuel Initiative, the DOE Hydrogen Program works with

Solid Oxide (SOFC)

650–1000ºC 1202–1832ºF

5kW–3 MW

85% overall with CHP (60% electric)

• Auxiliary power • Electric utility • Large distributed generation

industry, academia, national laboratories, and other federal and international agencies to

Source: Argonne National Laboratory

overcome critical technology

*Direct Methanol Fuel Cells (DMFC) are a subset of PEMFCs typically used for small portable power applications with a size range of about a subwatt to 100W and operating at 60–90°C.

barriers, address safety issues

Challenges and Research Directions
Reducing cost and improving durability are the two most significant challenges to fuel cell

and facilitate the development of model codes and standards, validate hydrogen fuel cell

commercialization. Fuel cell systems must be cost-competitive with, and perform as well

technologies in real world

or better than, traditional power technologies over the life of the system.

conditions, and educate key

Ongoing research is focused on identifying and developing new materials that will reduce the cost and extend the life of fuel cell stack components including membranes, catalysts, bipolar plates, and membrane-electrode assemblies. Low cost, high volume manufacturing

stakeholders who can facilitate the use of hydrogen and fuel cell technology.

processes will also help to make fuel cell systems cost competitive with traditional technologies.

Increase Your H2IQ! Visit www.hydrogen.energy.gov

For print copies of this fact sheet, please call the DOE Energy Efficiency and Renewable Energy Information Center at 877-EERE-INF(O)/877-337-3463.

October 2006

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Hydrogen Fuel Cells Fact Sheet