Biocatalysts Produce Methane from CO2 and H2

BioCat
Demonstration system in Copenhagen, © Electrochaea

Producing hydrogen in a completely natural way is something of a Rosetta Stone in science. Many have tried over the past decades, but rarely have they been able to announce a breakthrough in this field. Electrochaea, a startup based in a town west of Munich, could now have taken a big leap toward economic feasibility. This spring, the 20-staff company declared its intention to build power-to-gas bioreactors with a capacity of up to 50 megawatts. By 2025, output could theoretically hit the gigawatt mark if others are willing to join in.

The use of renewable energy, especially bioenergy, to create hydrogen could become an entirely clean method for ensuring supply security. At least, that is the vision of Electrochaea, headquartered in Planegg.

Frugal microbes

More specifically, the company is planning to use electrolyzers powered by solar and wind energy to create the gas. The hydrogen, though, will not be consumed immediately but undergo a biocatalytic process. Microscopic organisms called methanogenic archaea will convert it into biomethane through the addition of carbon dioxide. Mich Hein, Electrochaea’s chief executive, said that the company’s bioreactors were “turnkey systems to store a renewable energy surplus and carbon dioxide in the form of synthetic gas.” Its customers and partners would be able to put carbon dioxide to good use, either on-site or by injection into natural gas pipelines. As examples, he named garbage disposal, wastewater treatment, biogas and geothermal facilities. Industrial companies, too, produced large amounts of carbon dioxide, he said.

Electrochaea has claimed that it possessed the world’s most efficient archaeon strain and extensive expertise in biocatalysts in the form of exclusive licenses on patents by the University of Chicago. The microbe, one of the oldest organisms on earth, is found in oxygen-free habitats, such as moors, swamps and the digestive tracts of humans and cows.

The company started up its first industrial-scale demonstration system with 1 megawatt of capacity in summer 2016 at a site near Denmark’s capital Copenhagen. In the same year in fall, it inked a deal for building a power-to-gas system with a capacity of 10 megawatts in Hungary. In partnership with energy supplier Magyar Villamos Művek, it formed a joint venture called Power-to-Gas Hungary. Zsolt Bertalan, the chief executive of the energy supplier’s subsidiary Smart Future Labs, said at the time that the German startup had come up with an idea to store renewable energy but ensure a “permanent reduction of climate-damaging carbon dioxide. The potential of this disruptive technology is enormous.” More recent information about the system could not be obtained from any of the organizations involved.

In late 2017, it was said that a pilot and demonstration system would be constructed in Solothurn, Switzerland, as part of Store&Go, a project funded by the EU’s Horizon 2020 program.

Simpler than Sabatier reaction

One advantage of the single-cell organisms is that they require little to do their work. Not only can they convert less-than-pure carbon dioxide produced by biogas plants, but they flourish at a temperature of as little as 65 °C and ambient pressure. The company said that the microbes would have no difficulty coping with variable intake rates either. By contrast, standard methanation processes are much more demanding. Higher purity grades are just one issue. Operating conditions are more difficult to maintain as well: temperatures range between 300 °C and 550 °C, pressure needs to be above 10 bars and catalysts have to be made of nickel. On top of that, continuous operation is a must.

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