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The Role of Fuel Cells in an Integrated Sustainable Energy Infrastructure

One of the major impediments to the adoption of renewable energy sources such as wind, wave and solar is that they cannot produce power on demand.  This means that they must be coupled to a storage system (usually an electrical battery).  Furthermore they are limited in their long term energy output by prevailing environmental conditions and so must be backed up by a fossil-fuelled generator.

Fuel cells offer freedom from these limitations.  By utilising a reversible fuel cell (one which can convert hydrogen rich fuel to electricity and vice-versa) the renewable power source can be used to generate hydrogen whenever supply exceeds demand and can consume hydrogen whenever demand exceeds supply (i.e. the fuel cell plus hydrogen storge tank replaces battery charging equipment and batteries); AND should long term demand exceed production (i.e. the hydrogen tanks are emptied) the fuel cell can be supplied with  fuel (such as natural gas or more favourably imported renewable hydrogen or bio-gas) to make up the shortfall.  Hence the fuel cell acts as both battery storage system and back up generator.  A further advantage is that (providing space is availiable) considerably more energy can be stored in hydrogen tanks than could economically be stored in batteries, allowing for greater fluctuations in supply-demand ratio which allows the overall system size to be reduced.

PROBLEMS

For an introduction to small scale regenerative fuel cells see this US government site .

For more outrageous space applications see this paper from NASA .