Generating renewable electricity is an important way to reduce carbon dioxide (CO2) emissions and many countries are installing wind and solar power plants to help meet targets for cutting CO2. One drawback of these energy sources is their variability: the wind tends to blow intermittently and solar power is only available during the daytime. Hence renewable power plants either have to be over-engineered to take account of this lower capacity factor, or they must be supported by spinning reserve power stations, typically fast-response open-cycle gas turbines – which goes against the environmental aims of the projects.
Ideally, excess renewable energy generated during times of plenty can be stored for use during periods when sufficient electricity is not available. But storing this energy is a difficult task: batteries and similar technologies perform well over short timescales, but over periods of weeks or months a different approach is necessary. Energy storage in the form of hydrogen is one such possibility: excess electricity is fed into an electrolyser to split water into its constituent parts, oxygen and hydrogen. The hydrogen is then used in fuel cells to produce electricity when needed, releasing the stored energy back to the grid.
This information sheet explains the key benefits that fuel cells can offer in this application, the fuel cell types used in the application today, and case studies of a solar-to-hydrogen project in Corsica and a wind-to-hydrogen hybrid power plant in Berlin.