Fuel cells

Looking towards the next decade, the source of heat and power for many homes could well be the fuel cell. This is an electrochemical device which feeds on hydrogen to produce electricity, heat and water (see Chapter 13 'Energy options'). In January 2004 the first UK domestic-scale fuel cell began operation at West Beacon Farm in Leicestershire.

The most common fuel cell at the moment is the proton exchange membrane type (PEMFC) which feeds on pure hydrogen. It has an operating temperature of 80°C and at the moment is 30 per cent efficient. This is expected to improve to 40 per cent.

The farm is owned by the energy innovator Professor Tony Marmont. Rupert Gammon of Loughborough University is the project leader as part of the Hydrogen and Renewables Integration Project (HARI). It is designed to provide entirely clean energy.

The hydrogen is extracted from water by means of an electrolyser which splits water into oxygen and hydrogen by means of an electric current (Figure 7.8).

The electricity for the electrolyser is provided by wind, PV and micro-hydro generation. An alternative is to extract H2 from natural gas by means of a reformer but then it is no longer zero carbon.

The fuel cell installation is compact and can fit into a cupboard. It has no moving parts and is therefore almost silent. At the moment it is producing 2 kW electricity and 2 kW heat. A second 5 kW fuel cell from Plugpower is in the process of being commisioned (Figure 7.9).

Figure 7.8

Electrolyser at West Beacon Farm

Figure 7.8

Electrolyser at West Beacon Farm

Figure 7.9

Fuel cell installation, West Beacon Farm (courtesy of Intelligent Energy 2004)

The production and storage of hydrogen as the energy carrier are the problems still to be solved satisfactorily. Cracking water into hydrogen and oxygen by electricity is analogous to the sledge hammer and the nut. An alternative method of producing hydrogen is to extract it from ethanol derived from biowaste as has recently been demonstrated at the University of Minnesota.

The reactor is, in effect, a compact fuel cell hydrogen generator which would be ideal for vehicle application. It can be scaled up to provide the hydrogen for grid-connected fuel cells using ethanol fermented from both biowaste and energy crops.

Sanyo plans to launch a domestic fuel cell using natural gas or propane in 2005. It will be used to power TVs, air conditioners, refrigerators and PCs as well as catering for domestic hot water requirements. It plans to export the system to the US and Europe. Other companies like Mitsubishi Heavy Industries Ltd and Matsushita Electrical Industrial Co. are developing a similar system also due on the market in 2005.

Currently under development is a microbial fuel cell which avoids the need for hydrogen. It converts sewage to electricity. Bacterial enzymes break down the sewage liberating protons and electrons. The system then behaves like a proton exchange membrane fuel cell with protons passing through the membrane and electrons diverted to an external circuit to provide useful electricity (see pp. 255-256).

Renewable Energy Eco Friendly

Renewable Energy Eco Friendly

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable.

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