A 130MWh pilot plant testing the use of volcanic rock as a medium of storing energy as heat has just been launched in Hamburg-Altenwerder, Germany.

Siemens Gamesa Renewable Energy, best known as designer and manufacturer of wind turbines and wind power facilities, launched the project this week at a ceremony attended by German State Secretary for Energy, Andreas Feicht. The new application for the ancient materials could enable the storage of large amounts of energy cost-effectively, Siemens Gamesa claims. In turn, they could also provide a ’second life’ purpose for old thermal power plants, the company also said.

Around 1,000 tonnes of volcanic rock are contained inside the heat storage facility. Electrical energy is converted into hot air using a resistance heater, getting the rock up to a temperature of 750 degrees centigrade. When the energy is then needed again, such as during times of peak demand on the grid, the heat from the rock is used to drive steam turbines to create electricity once again.

According to Siemens Gamesa, the facility should be able to stop energy thermally for a week, claiming that the storage capacity of the system “remains constant throughout the charging cycles”. With the aim of scaling up the solution to store and deliver back “energy in the range of several gigawatt hours in the near future”, Siemens Gamesa said it will extensively test the capabilities and effectiveness of the solution.

The project is part of ‘Future Energy Solutions’, a programme funded by the Federal Ministry of Economics and Energy, and is partnered by the Institute for Engineering Thermodynamics at Hamburg University of Technology and local utility Hamburg Energie, which will be responsible for putting the thermally stored energy to use in electricity markets. Hamburg Energie has developed its own software and aggregation platforms for aggregating distributed energy resrouces on its networks into so-called ‘virtual power plants’.

Siemens Gamesa also claimed “standard components” could be used to convert conventional fossil fuel plants into this type of facility. Energy-Storage.news recently spoke with another company, Lumenion, which is trialling the storage of energy as heat in steel structures, claiming it can store energy cost-effectively up to 48 hours, which again, the company claims can be cheaply replicated and scaled up. Lumenion’s technology is currently being trialled by Vattenfall, also in Germany. Others are also racing to commercialise similar concepts, such as storage in composite material similar to concrete.