Protein made using CO₂ and electricity

RESEARCHERS in Finland have successfully produced a batch of single-cell protein using electricity and carbon dioxide, which could be used as food or as animal fodder.

Juha-Pekka Pitkänen, principal scientist at VTT Technical Research Centre of Finland and Jero Ahola, a professor of energy efficiency at Lappeenranta University of Technology (LUT), say that the technology can be used anywhere that renewable energy is available. The technique is not dependent on the environment, such as the right temperature, light or soil type, and the researchers say it could help relieve famine. For example, a mobile reactor could be transported to areas where food is needed. As well as food, the technique could be used to produce animal fodder, potentially allowing land to be used for other purposes.

The initial idea to grow single-celled protein using electricity was first trialled in the 1960s, as scientists involved in the space race sought ways to feed astronauts and cosmonauts. The idea never really took off, but as Pitkänen points out, this was long before the days of affordable renewable energy, for example from solar panels or wind turbines. This, he says, makes the process much more viable.

The researchers use what is known as “Knallgas bacteria” (literally “bang-gas”), which can oxidise hydrogen directly. They place the bacteria in a bioreactor, which also contains electric water-splitting equipment. The reactor also contains nutrients for the bacteria, including ammonia, phosphorus and some inorganic salts. The bacteria use the hydrogen and oxygen from the water as it splits, and carbon dioxide as a carbon source, to make the proteins needed for growth.

The powdered product they make is 50% protein, with around 25% carbohydrate, with some fat and nucleic acids. Pitkänen told The Chemical Engineer that it could be used as it is, or be processed further to make pure protein. The concept is similar to that of Quorn mycoprotein, which is also a type of single-cell protein, although the microbes used to produce Quorn require sugar to grow.

At present, the amount of protein that can be created is relatively small. Producing 1 g of protein takes about two weeks. Pitkänen says that in total, the process requires about 24 kWh of electricity per kg of cells, but the technique is currently just proof of concept and the researchers are working to improve this. One of the things they will look at is the level of electrical current necessary to split the water that the bacteria can grow in.

“We are currently focusing on developing the technology: reactor concepts, technology, improving efficiency and controlling the process. Control of the process involves adjustment and modelling of renewable energy so as to enable the microbes to grow as well as possible. The idea is to develop the concept into a mass product, with a price that drops as the technology becomes more common. The schedule for commercialisation depends on the economy,” said Ahola.

He and Pitkänen are now planning to begin pilot production, which would make enough protein to test in food and fodder products.

A research paper is currently in progress, but Pitkänen told The Chemical Engineer that he and Ahola were keen to get the news out that they have got the process working.