Fuel Cells
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Hydrogen is fed in to the fuel cell and a catalyst on the anode converts hydrogen gas into negatively charged electrons (e-) and positively charged hydrogen ions (H+). The H+ ions move through the cell to the cathode where they combine with oxygen and the electrons (e-) to produce water. The flow of electrons through the cell produces electricity. Individual fuel cells are arranged in "stacks” to increase the amount of power produced. Fuel cells can also supply heat and cooling via absorption chillers. Hydrogen fuel is most often produced from natural gas (methane), but can also produced from biogas or by converting water into hydrogen and oxygen (which requires energy input).
Types
- Various technology
- Portable/stationary
- Range of sizes
Other components
- Natural gas reformer or hydrogen fuel supply
- Hot water cylinder (thermal store) for CHP operation
Typical saving
Electrical efficiency is high, at 40-55% (better than normal gas CHP), but CO2 savings limited if natural gas used as fuel.
Indicative cost
High capital cost and cost of replacing fuel cell stack every five years. Currently only financially viable for nice applications such as uninterruptable power supplies, unless grant funding available. Ongoing fuel costs. Main issues affecting feasibility
Heat and power demand: Most efficient if heat can be used, so year round heat demand ideal.
