One of the best ways for us to generate power and fuel our vehicles from an emissions point of view is through a combination of renewable electricity and hydrogen. The European Union has set targets for 2020 for renewables to contribute 20% to the overall energy mix while simultaneously cutting carbon emissions by 20%. Currently Europe gets around 20% of its electricity from renewable energy, which includes a 5% contribution from wind energy. Increasing the contribution of variable renewables to any electricity grid can potentially cause instability and traditionally requires back-up generation in the form of spinning reserves of fossil fuel generators. In Europe two projects are demonstrating hybrid power plants, solving these issues and providing additional benefits.
The first project is a wind–hydrogen hybrid power plant, located in Prenzlau, Germany and opened on 25 October 2011, and is primarily a 6 MW wind power plant (above). ENERTRAG AG has partnered with DB Energie GmbH, Vattenfall and TOTAL Germany on the project with DB Energie seeking to use the electricity to contribute to decarbonising the railway network. The rail network needs a predictable and reliable source of power and it is encouraging to see DB Energie recognising the solution a combination of hydrogen and renewables can offer. In 2010 DB Energie reported that renewables contributed 19.8% of its traction energy mix, but by 2020 it wants a minimum 35% contribution.
When more wind power is available at the site than can be accepted by the network, a series of electrolysers are used to generate hydrogen which is stored on site. This stored energy, effectively acting as renewable base-load energy, is used in a number of ways:
- The hydrogen can be mixed with biogas and fed into cogeneration plants which produce electricity and heat. The electricity can then be fed back into the grid at times when little or no wind is available; the heat is fed into a district heating network, increasing the overall efficiency of the hybrid power plant.
- The hydrogen is also used as a fuel by TOTAL hydrogen refuelling stations in Berlin and Hamburg which support fleets of fuel cell vehicles.
Berlin Brandenburg Airport (BER) is also interested in using hydrogen from this project to fuel its vehicle fleet which is planned to be operational by June 2012.
The second project is located on the French island of Corsica, in the Mediterranean Sea, and combines solar power with electrolysers, hydrogen storage and fuel cells. Known as MYRTE (a French acronym for Renewable Hydrogen Mission for Integration into the Electric Grid) the project is a partnership between CEA (the French Nuclear and Alternative Energies Commission), energy company AREVA and the University of Corsica.
MYRTE contains a 560 kW photovoltaic power plant which has been connected to the Corsican electricity grid since December 2011. The system can provide electricity during the day but, using the electrolysers and AREVA’s hydrogen energy storage system, excess electricity can be stored and returned when required using fuel cells. The aim of this initial project is to prove the concept, but there are plans to develop the system further with a second phase planned for 2013. This will see the inclusion of AREVA’s Greenergy Box, an integrated, containerised hydrogen energy system housing electrolysers, fuel cells, fuel storage and heat management systems.
Both of these examples are positive steps for the future of Europe’s renewable energy sector. The successful integration of variable renewables into electricity grids while avoiding the need for curtailment will be vital to meeting future renewable electricity targets and decarbonising the grid. In addition, the potential for projects like these to provide hydrogen for nascent fuel cell vehicle fleets only adds to their attractiveness and cost effectiveness. Hopefully we will see more of these projects in the future and on larger scales making significant contributions to future clean energy.
Dan Carter Manager
Image Source: Römer Grafik, from TOTAL Germany website