Especially for those regenerative energy sources with the highest growth rates, i. e. wind and solar power, the produced energy flow usually strongly fluctuates over time. Hence, there is a fast growing need for means which can adapt to these fluctuations and store or use the amounts of electrical energy which can not be absorbed by the public grid at the times when they become available and also quickly release them with minimum losses when needed.
One concept of dealing with this surplus in electrical energy is the transformation into chemicals. The base or first step of practically all of these transformation schemes is the generation of hydrogen via electrolysis cells. Through electrolysis considerable amounts of electrical power can be absorbed and the electrolysers seem to be able to adapt fairly fast to load changes. However, the generation of large amounts of hydrogen would only shift the storage problem from electricity to hydrogen which would be nearly as costly due to its gaseous state and its low density. The natural gas grid can not offer a solution to this problem since only a few percent of hydrogen can be added to the natural gas flow due mainly to safety reasons. The overall amount which can be stored in the entire public gas grid is limited. Hence, a further transformation into – preferably liquid – chemicals is required.
The presentation gives an introduction into the processes for the production of possible candidates and in particular presents ammonia as the potentially most economical alternative. The presentation also investigates the problems associated with a considerably fluctuating supply of the hydrogen required for the synthesis of ammonia and presents possible compensating measures.