Fuel Cell Operation
Fuel Cells work by passing Hydrogen across a special membrane in a Fuel Cell Stack. A catalyst on the anode side causes the hydrogen to split into hydrogen ions (protons) and electrons. The membrane is permeable to the protons and so allows them to pass through to the cathode, but the electrons have to pass through an external circuit – thus providing useful power. At the cathode the hydrogen ions and electrons combine with oxygen (from the air) to produce water vapour (the exhaust).
A feature of the operation is that unlike many other power sources (such as diesel generators) there is no combustion. The process is a chemical one and this provides numerous benefits:
- Quiet operation
- Extremely high reliability because there are few moving parts, and none of these is ever stressed
- Quick start-up
- Tracks the load so only generates as much power as the load requires
- High efficiency so no special cooling is required
- Very low maintenance
- Environmentally sound
All Fuel Cells use hydrogen to generate electricity, but the hydrogen can come from a number of sources, and Fuel Cell manufacturers have developed several types of Fuel Cells which use a variety of fuels.
The most obvious fuel is Hydrogen. It can be directly deployed into a Fuel Cell and has zero emissions. Sefca works with Acta (Italy) to generate hydrogen on site via solar power – providing a truly green solution. We call this Bottled Sunshine because we effectively "bottle" the sunshine for later use.
Hydrocarbons can also used as fuel. Their suitability derives from the fact that all hydrocarbons are chains of hydrogen and carbon. The attraction of hydrocarbons is that they are very dense with hydrogen and are easy to store. The hydrogen is used to produce electricity in the stack with the normal water vapour exhaust; and a small amount of CO2 is also produced.
Sefca uses methanol based fuel cells from EFOY. A 10 litre methanol cartridge provides 11.1kWh of power
Our Fuel Cells are used both as prime power sources and for power backup. Typical loads range from 50W for SCADA networks and security/surveillance applications, up to 10kW for telecommunication, signalling and radio transmitter supply backup.
Power Backup systems are used in both On-Grid and Off-Grid installations. In an On-Grid installation the Fuel Cell automatically and continuously monitors the load being drawn from a backup battery. If the mains supply fails, the Fuel Cell immediately starts to produce power, automatically tracking the amount of power required. Once the grid is restored, the Fuel Cell returns to its standby mode, ready to provide power when there is another power disruption.
In an Off-Grid installation there is no mains power available, and the Fuel Cell is teamed with a photo-voltaic (solar) array. On days of good radiation the PV array provides plenty of power for the load. During times of poor solar radiation – winter and very cloudy days, insufficient power is provided by the PV array and the Fuel Cell generates power to satisfy the load.