At the 6th Lautrer Energy Forum on March 12, 2014, at the 1. FC Kaiserslautern press center, experts considered the question of how energy from renewable sources can best be stored.

Electricity-to-gas technology

Because wind and sun are not available at all times, fluctuations in the amount of electricity generated have to be managed – both to ensure a steady supply of electricity and to guarantee the stability of the power grid. If generating systems are not to be left idle at some times then it is necessary to store power from renewable sources.

Electricity-to-gas technology offers one way of achieving that. It involves the conversion of renewable energy to hydrogen or methane for storage in the natural gas supply system. A variety of battery systems already offer an alternative.

Thüga Group pilot project

Jakob Brendli of Thüga AG, Munich, explains electricity-to-gas technology. By 2050 the need for storage could reach more than 50 terawatt hours (TWh). Only long-term chemical systems can be used to store TWh-level volumes of electrical energy. The conversion of power to gas offers many advantages. The infrastructure and storage systems already exist, and the technology is familiar. All that is missing is functional testing.

He presented a pilot project carried out by the Thüga group in which 13 companies joined forces to invest in electricity-to-gas storage technology. The plant in Frankfurt am Main began testing at the end of November 2013, supplying hydrogen to the gas supply network for the first time. If functional testing of the plant is successful, the gas network could represent the battery of tomorrow.

A contribution to climate protection

Dr. Peter Missal, Managing Director of e-rp GmbH, Alzey, considered the question of the conditions that would be required for the conversion of electricity to synthetic gas to become economical. The decisive factors will be investment cost and the period and frequency of use.

Under present conditions, such plants would not be profitable. However, that could change quickly if costs are reduced and the period of use increases. It should not be forgotten that electricity-to-gas plants could make a considerable contribution to climate protection, as they are climate neutral. The political environment also needs to change so that incentives for such technology are created.

Storage using batteries

Jürgen Heller of NextGen Technologies & Innovations presented the redox flow battery, a system that already allows electricity from renewable sources to be stored. The system uses batteries that communicate with the grid and can be used for medium-term storage. That allows them to smooth out peaks in power generation and bottlenecks in the grid.

They can be used by individual family homes, businesses, manufacturers and energy providers. Redox flow batteries store electrical energy using a chemical medium, fluid electrolyte, almost without loss. The technology is simple and easily scalable. Now the focus is on reducing cost and improving overall performance.