Fuel Cells

A Fuel Cell is a device that generates electricity and heat by converting the energy of the chemical reaction between a fuel and an oxidant. Fuel cells consist of an anode, cathode, catalysts and most often an electrolyte. Fuel cells are combined into groups, called stacks, to obtain a usable voltage and power output.¹

Fuel cells emit almost none of the sulfur and nitrogen compounds released by conventional generating methods. Fuel cells can also utilize a wide variety of hydrogen-rich fuels: Natural Gas, coal-derived gas, landfill gas, bio-gas, or alcohols. Since fuel cells generate electricity electrochemically, rather than mechanically, they are more efficient over a wider load factor and can cut greenhouse gases by over 50 percent.²

Technology Basics

A demonstration of the working machenism of a full cell

A demonstration of the working mechanism of a full cell

Source: US DOE, Office of Energy Efficiency and Renewable Energy Author: http://p2library.nfesc.navy.mil/issu...5/fuelcell.jpg . Permission:DOE Public resource

A fuel cell works by catalysis, separating the electrons and protons of the reactant fuel (at the anode), and forcing the electrons to travel though a circuit, generating electrical power. At the cathode, another catalytic process takes the electrons back in, combining them with the protons, which have traveled across the electrolyte and the oxidant to form waste products (typically simple compounds like water and carbon dioxide).

In many fuel cells, the fuel is hydrogen and the oxidant is oxygen (as depicted in the image). But not always, for example the microbial fuel cell converts chemical energy directly into electricity using a substrate, such as glucose or waste water, as the fuel and bacteria as the catalyst.

Specific uses of fuels cells include: Heating District Building/Network, Hotel, Laboratory/Processing Plant, Manufacturer, Medical Facility, Military Housing/Facility,Office Building, University/School, Waste water Treatment. ³

Types of fuel cells

Fuel cells are most often defined by the electrolyte material used. The different types determine the kind of chemical reactions taking place, the catalysts required, the fuels used and other factors. The different fuel cells available include⁴:

Proton exchange membrane or Polymer Exchange Membrane (PEM)- see this video from Ballard
Molten Carbonate (MCFC)
Solid Oxide Fuel Cells (SOFC)
Alkaline (AFC)
Phosphoric acid (PAFC)
Direct Methanol (DMFC): a subset of PEM typically used for portable devices using under 100 watts of power.
Zinc Air
Protonic Ceramic
Microbial Fuel Cell- for a good overview see the microbial fuel cell website

Advantages

Fuel cells have various advantages compared to conventional power sources, such as internal combustion engines or batteries. Some of the following advantages are only valid for certain applications, most advantages are more
general.

Fuel cells are environmentally friendly. Fueled by pure “clean” hydrogen, fuel cells produce only pure water as a byproduct. Even when powered by fossil fuels, they produce far less pollution than conventional technologies.⁵
Fuel cells have high efficiency. Fuel cells extract more energy from a fuel due to the increase in efficiency of electrochemical conversion over combustion. There are no moving parts in a fuel cell stack itself so there are no mechanical inefficiencies.⁶
The production of potential fuel can be widely distributed. It is possible to produce hydrogen fuel from both renewable and traditional energy sources. In addition to hydrogen, it is also possible to run fuel cells on numerous other fuels, including fossil fuels and bio-fuels.⁷
Fuel cells have high power density. The power density of a generating system defines how much power can be produced per unit volume. With fuel cells, this value is usually given in kWh / l, which are high values. ⁸
Fuel cells have longer operating times than with batteries, since doubling the operating time needs only doubling the amount of fuel and not the doubling of the capacity of the unit itself. Similar to internal combustion engines, fuel cells can produce electricity and heat as long as fuel is available.⁹
Fuel cells usually operate quietly , compared to internal combustion engines. ¹⁰

Disadvantages

Fuel cells are not the perfect solution to the world’s energy needs. There are several obstacles facing developers and the
commercialization of fuel cells.

Fuel cells are still in a relatively early stage of development and even the few commercially available models have limited fleet operating experience. Also, the production, transportation,distribution and storage of hydrogen is difficult.¹¹¹²
Another big hurdle for fuel cells is cost. Although some fuel cell systems are in use today, very few are currently cost effective. For stationary fuel cells, typical capital costs for installed systems exceed $5,000 per kilowatt – well above the target capital cost of $1,000-$1,500 used by most energy generation developers.¹³
The refueling and the starting time of fuel cell vehicles are longer and the driving range is shorter than in a “normal” car.¹⁴

Applications

Fuel cells can be used for a wide range of applications, from producing electricity for the grid to powering portable devices, like lap tops, to vehicles.

Stationary power

The nearest term application for fuel cells is in stationary power. Many fuel cells are in use today producing power for off grid applications or on the grid.

Key initial markets include:

back-up power for critical infrastructure such as cell phone towers which require longer term back up than battery technology can provide
back-up power for locations that demand very reliable, high quality power such as data centers (generators are often less reliable and can take longer to start up)
power production for congested grid locations

Clean energy fuel cells, which meet renewable energy portfolio standards and greenhouse gas reduction targets, are also in use which produce power from waste water treatment plants and landfill gas.

The U.S. Army conducts key fuel cell research and construction at the Engineering Resource Laboratory (CERL) in Champaign, IL

Transportation

Fuel cell operated cars exist today in prototype form and most car manufacturers are currently developing fuel cell prototypes. Most fuel cell cars, however, are still at least a few years away from mass production. Perhaps the nearest term use of fuel cells in vehicles is for fork lifts in large warehouses.¹⁵

However, fuel cell vehicles are rapidly appearing all over the globe in the past less than 10 years.Fuel cell vehicles have gone from mere research novelties to operating prototypes and demonstration models.government and industry have teamed up to invest billions of dollars in partnerships intended to commercialize fuel cell vehicles。Significant government and industry partnerships are operating in at least 11 major countries and the European Union. These partnerships are pursuing a variety of projects, including the development of “hydrogen highways,” fuel cell buses, and fuel cell bicycles and scooters.¹⁶

Portable and micro power

There is a large market for using fuel cells for portable power.

Fuel cells can provide power where no electric grid is available。Portable fuel cells are also being used in emergency backup power situations and military applications. They are much lighter than batteries and last a lot longer, especially important to soldiers carrying heavy equipment in the field.¹⁷

Fuel cells will change the telecommuting world, powering cellular phones, laptops and palm pilots hours longer than batteries. Companies have already demonstrated fuel cells that can power cell phones for 30 days with out recharging and laptops for 20 hours. Other applications for micro fuel cells include pagers, video recorders, portable power tools, and low power remote devices such as hearing aids, smoke detectors, burglar alarms, hotel locks and meter readers. These miniature fuel cells generally run on methanol, an inexpensive wood alcohol also used in windshield wiper fluid.¹⁸The first consumer fuel cell was released in 2008. Check out this fuel cell cell phone/ipod charger here.

Manufacturers

UTC Power, Connecticut, USA (PAFC and PEM).Based in Hartford, Conn., UTC provides high-technology products and services to the building and aerospace industries.
Plug Power, LLC, New York, USA (PEM). Plug Power Inc. (NASDAQ: PLUG) develops, manufactures, integrates and services proprietary fuel cell solutions, providing clean, reliable energy for customers throughout the world.
FuelCell Energy, Connecticut, USA (DFC).Based in Danbury, CT (USA), FuelCell Energy (NASDAQ: FCEL) manufactures Ultra-Clean stationary fuel cell power plants that generate electricity with up to twice the efficiency of conventional fossil fuel plants – and with virtually no air pollution.
More information about manufactures.

Footnotes

1. CLIMATE CHANGE FUEL CELL PROGRAM,U.S. Department of Defense.

2. CLIMATE CHANGE FUEL CELL PROGRAM,U.S. Department of Defense.

3. CLIMATE CHANGE FUEL CELL PROGRAM,U.S. Department of Defense.

4. Types of Fuel Cells, EERE, DOE.

5. Fuel Cell Technologies, Fuel Cell Market.

6. Fuel Cell Technologies, Fuel Cell Market.

7. Fuel Cell Technologies, Fuel Cell Market.

8. Fuel Cell Technologies, Fuel Cell Market.

9. Advantages - Disadvantages (pdf), Education Kit 9, FuelCellToday.com. Accessed May 19, 2010.

10. Advantages - Disadvantages (pdf), Education Kit 9, FuelCellToday.com. Accessed May 19, 2010.

11. Advantages - Disadvantages (pdf), Education Kit 9, FuelCellToday.com. Accessed May 19, 2010.

12. Advantages - Disadvantages (pdf), Education Kit 9, FuelCellToday.com. Accessed May 19, 2010.

13. Fuel Cells,Massachusetts Technology Collaborative Renewable Energy Trust.

14. Advantages - Disadvantages (pdf), Education Kit 9, FuelCellToday.com. Accessed May 19, 2010.

15. Early Markets: Fuels Cells for Material Handling Equipment (pdf), DOE Hydrogen Program, November 2008. Accessed September 19, 2010.

16. Fuel Cell Vehicle, World Survey 2003, Breakthrough Technologies Institute.

17. Fuel Cell Basics, Applications, FuelCells.org.

18. Fuel Cell Basics, Applications, FuelCells.org.

Resources

NOVA Science Now Fuel Cell Site This site provides a great video with an overview of how fuel cells work and the challenges facing the technology.
DOE animation This animation gives a simple overview of how fuel cells work[1].
Fuel cell animations and learning materials from minHydrogen.dk provide an easy to understand overview of how different types of fuel cells work.
Education Kit from Fuel Cell Today. This series of documents provides provides easy access to information about the fuel cell industry, its key players, the technology and general data.
Fuel Cells 2000- An extensive online information resource for fuel cells.
A interactive picture of fuel cell car,ScienceNow.