What are fuel cells?
Fuel cells are devices for generating electric power. They share many of the characteristics of a battery - silent operation, no moving parts and an electrochemical reaction to generate power. However, unlike a battery, fuel cells need no recharging and will run indefinitely when supplied with fuel. The cells produce electricity by combining hydrogen (the fuel) and oxygen (from air) over a catalyst such as platinum.
There are several different types of fuel cell but the most researched type is the proton exchange membrane (PEM) fuel cell, which contains platinum catalysts. PEM fuel cells are capable of being used in power generation for buildings, instead of batteries or generators in portable equipment and as replacements for the internal combustion engine in a vehicle.
Fuel cells for transport
In 1997, Daimler-Chrysler, Ford and Ballard Power Systems joined together in a consortium to build fuel cell engines and drive trains for cars. DaimlerChrysler, Ford, Honda and Toyota now have small demonstration fleets of cars in operation. A total of 30 fuel cell buses built by DaimlerChrysler and Ballard went into service around Europe in 2004. This project was designed to demonstrate the technology and increase public awareness of fuel cells.
In 2009, six major automakers - Toyota, Hyundai, Daimler AG, Ford Motor Company, General Motors Co. and Honda - signed a memorandum of understanding to develop fuel cell light duty vehicles and encourage introduction of the necessary hydrogen infrastructure. These companies plan to commercialise fuel cell vehicles by 2015 and are tareting key locations, such as Germany, Japan and the USA, for infrastructure development allowing the rollout of fuel cell vehicles.
Why fuel cells for vehicles?
The advantages of fuel cells for transport
are both environmental and economic. The only emissions from a fuel cell vehicle come from the generation of hydrogen. Fuel cell cars have similar range and performance to cars with internal combustion engines, but the superior energy efficiency of fuel cell engines brings a significant reduction in carbon dioxide, a greenhouse gas, for every mile travelled. If fuelled directly by hydrogen, there will be no tailpipe carbon dioxide emissions at all.
Fuel cells for stationary power
Fuel cells can also provide electric power for homes and offices
. In these applications, heat produced by the cell can be circulated like the heat from a conventional boiler. Using the combined heat and power in this way considerably raises the efficiency of the system. More than 10,000 such units are already in use in Japan, the USA and Europe to power hospitals and industrial plant and to provide grid-independent, uninterrupted power supply.
Portable fuel cells
Fuel cells can compete with batteries and generators for portable use
, from a few kilowatts to power a mobile home down to a few watts to power a laptop computer. Methanol fuel cells designed to provide ancillary power to camper vans and boats are selling commercially and hydrogen-fuelled external charging devices for consumer electronics became available in 2011.
Fuels for fuel cells
to run the fuel cell can be stored as a compressed gas, as a liquid or in a chemically-combined form, such as a metal hydride. It can also be produced by reforming a hydrocarbon such as gasoline, methanol or natural gas. For transport, high pressure hydrogen storage and delivery has been developed to allow vehicles to refuel at conventional filling stations.
Barriers to fuel cells
Today the biggest obstacle to fuel cell commercialisation is cost. Research is being focused on improving cell performance and developing low cost materials which will enable fuel cells to compete on price: at first against batteries and later against conventional engines and generating plant.