Electricity to Gas: A New Storage Model?


The technologies, fuel choice scenarios and implications of better electricity storage models was described in the previous article. A new concept was recently unveiled with potential seismic repercussions: Can we really – efficiently – turn electricity into gas?


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an renewable electricity be transformed into a substitute for natural gas? Until now, electricity was generated from gas. But a German-Austrian cooperation wants to


go in the opposite direction. In the future, these researchers and entrepreneurs would like to store surplus electricity – such as from wind power or solar energy – as climate-neutral methane, and store it in existing gas storage facilities and the natural gas network. Throughout the world, electricity generation is based more


and more on wind and solar energy. So far, the missing link for integrating renewable energy into the electricity supply is a smart power storage concept. Because when the wind is blowing powerfully, wind turbines generate more electricity than the power grid can absorb. German researchers have succeeded in storing renewable


electricity as natural gas. They convert the electricity into synthetic natural gas with the aid of a new process – developed by the Center for Solar Energy and Hydrogen Research Baden- Württemberg (ZSW), in cooperation with the Fraunhofer Institute for Wind Energy and Energy System Technology IWES. Currently, Solar Fuel Technology, an Austria-based partner company, is setting up the industrial implementation of the process. One advantage of the technology:


it can use the existing natural gas infrastructure. A demonstration system built on behalf of Solar Fuel in Stuttgart is already successfully operating. And by 2012, a substantially larger system – in the double-digit megawatt range – is planned to for launch. For the first time, the process of natural gas production combines the technology for hydrogen-electrolysis with methanisation. “Our demonstration system in Stuttgart splits water using surplus renewable energy using electrolysis. The result is hydrogen and oxygen,” explains Dr. Michael Specht of ZSW. “A chemical reaction of hydrogen with carbon dioxide generates methane – and that is nothing other than natural gas, produced synthetically.” With the rapid expansion of renewable energies, the need


analysis of the process. “Surplus wind and solar energy can be stored in this manner. During times of high wind speeds, wind turbines generate more power than is currently needed. This surplus energy is being more frequently reflected at the power exchange market through negative electricity prices.” In such cases, the new technology could soon keep green electricity in stock as natural gas or renewable methane. “Within the development of this technology, ZSW has been


guided by two core issues,” explains Michael Specht: “Which storage systems offer sufficient capacity for compensating fluctuating renewable energies that depend on the wind and weather? And which storage systems can be integrated into the existing infrastructure the easiest?” The storage reservoir of the natural gas network extending


The new technology aims at


through Germany is vast – more than 200 TWh – enough to satisfy consumption for several months. The power network has only a capacity of 0.04 TWh by itself. The integration into the infrastructure is simple: The natural gas substitute can be stored like conventional natural gas in the supply network, pipelines and storage systems, in order to drive natural gas cars or fire natural gas heating systems. The new technology aims at


facilitating the integration of high shares of fluctuating power generation from renewable energies into the energy system


facilitating the integration of high shares of fluctuating power generation from renewable energies into the energy system. One goal is to structure the delivery of power from wind parks on a scheduled and regular basis. “The


new concept is a game changer and a new significant element for the integration of renewable energies into a sustainable energy system,” adds Sterner. The efficiency of converting power to gas equals more than 60 percent. “In our opinion, this is definitely better than a total loss,” says Michael Specht. A total loss looms if, for instance, wind power has to be curtailed. The predominant storage facility to date – pumped hydro power plants – can only be expanded to a limited extent in Germany. In order to push the new energy conversion technology


for new storage technologies grows massively. This is of special interest for energy utilities and power companies. “So far, we converted gas into electricity. Now we also think in the opposite direction, and convert electricity into ‘real natural’ gas,” explains Dr. Michael Sterner of Fraunhofer IWES, who is investigating the engineering aspects and energy system


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forward, the two German research institutes have joined together with the company Solar Fuel Technology of Salzburg. Starting in 2012, they intend to launch a system with a capacity of approximately 10 MW. This team may have the best integration of renewable power


generation to the economy seen to date. One just wonders where or how they will get all that CO2? ■ For more information visit:


www.fraunhofer.de/en/research-topics/energy worldPower 2010


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