Laboratory for Chemical Technology proposes alternative use of biogas

(29-05-2018) The subsidy of biogas combustion is expensive and prevents better use of it. Another approach that uses biogas as a raw material for the production of chemicals instead of as a fuel is cheaper for companies, government and the environment.

Subsidies for green electricity

Biogas is released during the fermentation of organic waste. That gas is burned, so that energy is released. This process now supplies about 10% of our green electricity.

This form of green electricity is widespread because governments distribute subsidies: at a European level, the subsidy of biogas combustion varies from 20 to no less than 276 euros per megawatt hour. The value of the electricity is actually only about 40 euros.

More expensive than the market price

According to scientists at UGent (Center for Microbial Ecology of the faculty of Bio Engineering and Technology and Laboratory for Chemical Technology of the faculty of Engineering and Architecture) this approach does not make any sense.

"Incineration is traditionally the easy way to convert a raw material into energy," explains Prof. Korneel Rabaey. "But only one third of the energy in the biogas can be converted into electricity. The other two thirds are lost as residual heat. "

The production of biogas and the subsequent incineration therefore yields electricity that is a lot more expensive than the market price. "Subsidies will therefore continue to be necessary to maintain this practice, especially now that the production of electricity from, for example, wind and solar energy has become much cheaper," says Rabaey.

No fuel, but raw material

In order to prevent the biogas sector from remaining a subsidy channel for green electricity forever, the researchers propose an alternative solution that is more positive for all parties.

They propose not to incinerate the biogas, but to upgrade it to bio-natural gas and then inject it into the existing natural gas network. Companies can use this network to purchase bio-natural gas and convert it into CO, one of the building blocks for the chemical industry. For example, biogas is no longer used as fuel, but as a raw material. It also ensures that the biomass is processed locally, but that its product, bio-natural gas, is available everywhere without the need for transport.

The researchers describe the technology behind this in a study that they recently published in the leading journal Science.

Less CO2 emissions

"This method allows companies to reduce their carbon footprint because they replace part of their fossil natural gas with bio-natural gas," says Prof. Korneel Rabaey.

"With a view to reducing CO2 emissions by 2030, we can cover four times the world demand of methanol, one of the world's most-produced chemicals, using EU natural gas. Of course, the reality will be a mix of products: our estimate is that we can capture more than half of the global CO2 emissions of the industry in CO through the use of bio-natural gas, ie through the smart use of biomass. "

"Ultimately this will ensure that biomass is processed without subsidies and that chemicals with a limited ecological footprint are produced," Prof. Rabaey concludes. "This would certainly be a good step towards deep decarbonisation."

The researchers argue that governments should support the transition of the biogas sector in this direction as much as they do now with green electricity.

Scientific articles on which these conclusions are based

  1. Lukas Buelens, Vladimir Galvita et al. 2016. Super-dry reforming of methane intensifies CO2 utilization via Le Chatelier’s principle. Science 354: 449-452.
  2. Kristof Verbeeck, et al. Upgrading the value of anaerobic digestion via chemical production from grid injected biomethane. Energy & Environmental Science, 2018, DOI: 10.1039/C8EE01059E
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