Hydrogen from RES: pressurised alkaline electrolyser with high efficiency and wide operating range
Key Objectives of the project
The project RESelyser develops high pressure, highly efficient, low cost alkaline water electrolysers that can be integrated with renewable energy power sources (RES) using an advanced membrane concept, highly efficient electrodes and a new cell design.
The project is to develop a prototype of an improved electrolyser. In this innovative materials and components, especially electrodes and separators will be utilised. These are to enhance the efficiency, reliability, durability and to reduce the costs of the electrolyser when operated variably and intermittently, as is demanded by integration into energy networks with renewable energy.
High efficiency, i.e. small loss of energy when transforming electrical to chemical energy (hydrogen), will be demonstrated. A stability of this efficiency during long term operation in on/off cycles, as needed when operated with RES, will be demonstrated with an extrapolation to a lifetime of 10 years. In the same time low costs for the system are the target.
Alkaline water electrolysis for hydrogen production is a technique well established with electrolysers in a wide power range being commercially available. Hydrogen production by electrolysis is increasingly studied as a way to smoothen the fluctuating power output of renewable energy sources not correlating with the electrical energy demand. However for this purpose present electrolysers have to be improved for fluctuating power operation and the system costs have to be decreased to reach a low cost energy conversion.
To address these challenges in the project RESelyser a new separator membrane with internal electrolyte circulation and an adapted design of the cell to improve mass transfer, especially gas evacuation, is investigated and demonstrated. Intermittent and varying load operation with RES will be addressed by improved electrode stability and a cell concept for increasing the gas purity of hydrogen and oxygen especially at low power operation as well as for very high pressure. Also the system architecture will be optimized for intermittent operation of the electrolyser.
New materials, especially membrane diaphragms and electrodes, are first developed, demonstrated and tested in a small scale before being scaled up to technical size and to preparation techniques suitable for commercial products. Electrolysers with new concepts are also first realised at small scale, later at intermediate scale, in the end at technical scale. In the same time the stack pressure is increased which means increasing demands in technical realisation. To operate an electrolyser system components are needed apart from the electrolyser itself. These are considered in the project and a system concept for integrating electrolysers with solar fields is developed. A cost estimate for the components and the complete system will be made. The project runs from November 2011 to October 2014.
Expected socio and economic impact
Ambitious targets have been decided upon for the use of renewable energy within the European Union to reduce the emission of greenhouse gases. Today it turns out more and more that without substantial investments in the electrical power grid and techniques for management of variable loads the targets can hardly be met. Using surplus electrical energy for the production of hydrogen via alkaline water electrolysis will, in the same time, help starting the hydrogen-based electrical propulsion using fuel cells. Alkaline electrolysers today however do not yet meet the technical and cost requirements for this purpose.
The outcome of this project will be an electrolyser fitting in these requirements. A major market for this product is expected in the next years. Hydrogenics already today produces and sells alkaline water electrolysers that are also operated coupled to RES. However an improvement in costs, partial load operation, efficiency and life time will substantially increase the market possibilities.
Material screening for electrodes catalysts and membrane materials as well as first tests are presently performed.