Over the past three years, WACKER has been working on a major project in partnership with other renowned companies and research institutes: storing energy generated by renewable sources. The researchers want to convert surplus green electricity into methane gas. This would allow the energy to be stored easily in the natural-gas grid or in gas caverns. The greenhouse gas carbon dioxide acts as an aid.

Storing Energy Generated by Wind, Sun or Biomass

December 2014 was a stormy month, so German wind turbines generated more electricity than ever before. 14 powerful low-pressure areas – from Alexandra to Zoe – and numerous new offshore wind farms ensured that 8.9 billion kilowatt hours were fed into the German power grid. As a result, wind energy even outperformed nuclear power.

But what happens when the sun isn’t shining and the wind doesn’t blow? Fluctuating green electricity yields are one of the energy transition’s unsolved problems. Experts are desperately searching for a solution that will allow energy generated by wind, the sun or biomass to be stored. Just like a squirrel stocks up on winter supplies, it should be possible to store solar energy for when the days are short. After all, we want electricity to be available from our sockets at all times, wherever we are – regardless of whether the sun is shining or not.

Dr. Alexander Zipp hopes to solve this problem. “I’ve always been somewhat environmentally minded,” he says modestly. Over recent years, the young chemist has enthusiastically supported the iC⁴ project at WACKER, in which science and industry are joining forces to research the conversion of green electricity into synthetic natural gas (see box). “Storing energy is obviously a major problem,” says Zipp, his expression serious behind his protective glasses. “This makes it even more exciting to be involved in finding a solution.”

Opportunities for the Chemical Storage of Energy

How can surplus energy generated by wind and the sun be stored long-term? There are various different approaches. “But only the existing gas grid and gas reservoirs really make sense for seasonally storing large amounts of energy,” says chemistry professor Bernhard Rieger of the Technical University of Munich (TUM). In his opinion, batteries can, at best, store large quantities of electricity short-term, while new pumped storage power plants are unpopular with the general public, and building huge new hydrogen tanks would entail enormous effort and expense.

That’s why the iC⁴ project partners have opted for chemical storage. Here, the first step involves water being separated into its components oxygen and hydrogen with the aid of surplus green electricity. Electrolysis plants for this are already available on an industrial scale. The hydrogen is then converted into methane with the aid of carbon dioxide, obtained, for example, from coal-fired power stations, cement factories or biogas plants. This step is important, because, unlike hydrogen, methane can easily be stored in large volumes. It is the main constituent (over 80 percent) of natural gas and can thus be fed into the gas grid or one of the many underground gas reservoirs.

The chemistry underlying this power-to-gas technology has long been established. However, carbon dioxide reacts so slowly that, for a long time, nobody seriously considered commercializing methanation. The process was not economically feasible. The researchers of the iC⁴ group are now putting their hearts and souls into optimizing key components for the process in order to make methanation more cost-effective.

Dr. Christian Anger is one of the young WACKER employees involved in the global competition for energy storage systems of the future. The 30-year old works in a modern building on the grounds of WACKER’s central R&D facility – the Consortium – in Munich’s Obersendling area. Here, over 160 employees are working on megatrends, such as battery components, better processes for photovoltaic materials, and higher-performance materials for wind power. And materials for energy-storage systems.

As part of the iC⁴ project, Anger and his team have developed a membrane for separating carbon dioxide from waste gas. This will allow the greenhouse gas CO₂, which is generated in power plants, cement factories and biogas plants, to be recycled. “Our goal was to develop a membrane that separates gases better than any other membrane process,” says Anger. The membrane is still being put through its paces by cooperation partner Linde. “We already know that our silicone materials are quite well suited to the support structure of the membrane,” says research group head Dr. Jürgen Stohrer. “However, it is not yet clear if and where they will be used to develop products.”

Catalysts Are at the Heart of the Process

A few doors down, Zipp is shaking a screw-top jar full of hollow ceramic cylinders, irradiated by sunlight passing through his lab’s long window front. “This could be the key to economical methane production,” says the 39-year-old. The small, white, hollow cylinders made of HDK^® pyrogenic silica constitute the support from which catalysts for the conversion of hydrogen and carbon dioxide into methane are made.

These small catalysts must be able to do a lot: they have to convert the starting materials into methane as completely as possible. Furthermore, they must be able to withstand moisture, temperature fluctuations, and any impurities in the carbon dioxide. “CO₂ from power plants is not pure, but contains substances that can affect the catalyst,” explains Stohrer. Moreover, the catalysts must work well for years. “After all, a catalyst charge for a production reactor costs several million euros,” explains Zipp.

Even though Zipp and his team are only looking after one aspect of the iC⁴ project, it is an important part. “Tailor-made catalysts and catalyst supports are at the heart of the process,” says Stohrer, who is coordinating iC⁴ work at WACKER with key project partners. The company can offer decades of knowledge here, as the chemical group has been manufacturing pyrogenic silica since 1969.

Is it possible that the success of the transition toward renewable energy sources actually depends on these inconspicuous catalyst supports? Prof. Rieger believes this to be a likely possibility. “WACKER has developed completely new support systems for the catalysts,” says the renowned scientist, who heads the iC⁴ project. “This has allowed us to make considerable progress with this type of electricity storage.” The chemist sees iC⁴ as one of his most successful projects: “Here, the right people are at the right place at the right time.”

That’s music to Dr. Arndt Schlosser’s ears. He is responsible for innovation management at WACKER and establishes research partnerships with top-class scientists around the world. To him, the iC⁴ project fits in very well with corporate strategy, since energy is a key growth market for WACKER. “Avoiding CO₂ emissions and storing electricity are strategic, future-oriented topics,” he explains. “Over the coming years, nobody will exactly be doing major business in this field,” says Schlosser. “But anyone who wants to be involved in these topics in the future must get on board early.”

“Because we really believe in what we are doing here.”

iC⁴ is one of the long-term topics in WACKER’s innovation portfolio. “Here, we are free to look at more than just the next set of quarterly figures,” says research manager Schlosser. The prudent chemist believes that this is an important prerequisite for sustainable business practices, as such projects do not just benefit the environment. “When we look for long-term business models that will allow us to continue earning money and providing jobs for our employees in the future, we are acting in a totally sustainable manner,” says Schlosser, adding with a smile: “This is, after all, how WACKER has managed to succeed for 100 years.”

His colleague Stohrer is not normally inclined to be emotional about these things. He is a scientist, after all. Nevertheless, his expression reveals that he is impressed with the WACKER researchers’ commitment over recent years. “Our young project managers and their teams have really gotten involved – it’s a highly emotional affair,” he says. “Because we really believe in what we are doing here.”

Stohrer shares the feeling that iC⁴ is a special project. “Something has to be done about climate protection, we all know that,” he says emphatically. He believes that the work on chemical storage has paid off: “We now know how it works and that it works.” However, according to Stohrer, when and if this will be commercialized depends on politics and energy prices. TUM professor Rieger definitely sees potential. He says: “Pilot plants could be up and running by 2020. And the technology must be well-established by 2030.”