Can Methane Act as a Storage Medium for Renewable Energy?

Photo: Karlsruhe Institute of Technology

Researchers from the Karlsruhe Institute of Technology (KIT) in German have demonstrated a novel method of converting the outputs of biogas facilities into methane. The new type of methanation plant can fit inside a standard shipping container, and could be combined with renewable energy production as a means of storing the excess and intermittent supply that is inherent to wind and solar power.

“As conventional methanation processes reach their limits at this point, we have developed a new reactor concept,” said Siegfried Bajohr, the leader of the new project, in a press release. The concept takes the products of biomass gasification—hydrogen, carbon dioxide, and carbon monoxide—and uses a nickel catalyst to produce methane and water. The catalysis is done in a “honeycomb catalyst carrier,” already used as catalytic converters in cars, which are “characterized by a high thermal conductivity and mechanical robustness.”

When connected to the electricity grid or production facilities using wind or solar power, this mobile plant can use that power for electrolysis and production of additional hydrogen. That means almost all of the carbon stored in the initial biomass feedstock can be used, and the volume of the biomass plant can double. Even the waste heat produced by the catalyst could be used.

At its best, this idea would mean a clever linkage of the electricity and gas grids. By using the renewable energy to turn biomass outputs into methane, and then transporting the methane through the existing gas infrastructure, that renewable energy is not wasted as it would be without any form of storage available. The methane, in a way, becomes a battery. That gas can be sent along through impressive gas grids in the U.S. and Europe, say, where it could be used by any end-user or burned into electricity at natural gas power plants.

The pilot plant, known as DemoSNG, has been fully tested at KIT and will now be moving to Köping, in Sweden, where it will connect with a biomass gasification plant that uses wood residues. “DemoSNG shows the way to storing green power and transporting it in our gas grids in the form of methane, “said Thomas Kolb, also of KIT.

Each plant is small, but that’s not such a bad thing: the European Biogas Association reports that there are more than 14,500 biogas plants in Europe alone, and that number is increasing. The small size and scalability of this idea means that even small facilities could pair with small wind or solar farms in decentralized fashion to produce methane. Of course, burning methane still produces carbon dioxide emissions, but those emissions are grabbed from the biomass gasification processes.

The other issue is that natural gas wells and pipelines tend to leak like crazy, and methane is a much more potent greenhouse gas than carbon dioxide. Increased scrutiny on gas infrastructure, though, could help remedy that issue, and any idea to make better use of increasing amounts of wind and solar power is worth a look.

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