Nutrition from fermented CO₂: Tiny organisms with a huge impact

Food product on a table

Finnish company Solar Foods has developed a protein that is made from the microorganisms in hydrogen and carbon dioxide. Known as Solein, the protein could be produced anywhere in the world, having a positive impact on the climate while only minimally altering our diet. One of the founders shares with us a vision that promises a completely new food. 

A third of all global greenhouse gases are attributable to food production, and 80% of that figure comes from the meat and dairy industries. This proportion is so immense that we run the risk of missing the 1.5-degree target – even if all other emissions dropped to zero at a stroke. This realisation was motivation enough for two scientists – Dr. Pasi Vainikka and Dr. Juha-Pekka Pitkänen – from the VTT Technical Research Centre in Finland. Vainikka has been conducting research into renewable energy for years. 


Pitkänen’s focus is on the opportunities opened up by fermentation processes. The two therefore decided to pool their knowledge and get to the root of the problems facing the food industry. They asked themselves how they could use electricity to transform climate-damaging CO₂ into something climate-friendly. The solution they found is a protein called Solein, which is derived from fermented CO₂. At Solar Foods, the Finnish scientists are thus pursuing the ambitious goal of producing food in a resource-friendly way and in harmony with nature – even in the midst of landscapes that are hostile to life. 

Woman in laboratory working with pipet
Solein is based on specific microbes. With carbon dioxide from the air and green hydrogen, these are stimulated to multiply.

A raw material for in vitro meat, too 

Fermentation is a process that was already being used to make wine in ancient Egypt. Yeast transforms the sugar in grape juice into alcohol. “Instead of sugar, we give our microorganisms hydrogen as an energy source and also feed them with CO₂, nitrogen and mineral nutrients,” Dr. Vainikka explains. The organisms convert the hydrogen and carbon dioxide to water and carbon, just as plants do in the process called photosynthesis. “This is how our special microorganisms grow and multiply.” One major advantage is the sheer simplicity of the production process: “Fermentation is not bound by any particular climatic conditions,” Dr. Vainikka says. “So, Solein can be produced anywhere – even in the desert.” CO₂ reacts poorly with other substances. Like hydrogen, it is a gas, so it escapes quickly. Special equipment is therefore needed: “We use a closed tank as a bioreactor to create the mix of gas and liquid that sets the reaction in motion.” 

Man looking at bioreactor where a fermentation process is ongoing
The CO₂ is subjected to fermentation in a bioreactor filled with soil bacteria, along with nitrogen and hydrogen, as well as phosphorus, calcium, and other minerals.

Solein is made up mostly of protein with some saturated fatty acids. It looks like a flour-like yellow powder and has a mild umami taste, somewhere between savoury-spicy and meaty. It is as easy as soy to process as a meat substitute or for protein drinks. “In principle, it can be used anywhere where milk or meat have been consumed up to now,” Dr. Vainikka affirms. “But you can also use it in soups, as an egg substitute in pasta, as a sandwich spread and in mayonnaise.” Further down the line, Solein could also serve as a raw material for in vitro meat. And it could even be an exciting option in the context of space travel, especially with a view to landing on Mars: Conventional plants will not grow readily in the Martian atmosphere – but Solein probably will. Before finding the microorganisms they now use to make Solein, the scientists went through a systematic screening process. They went out and collected soil samples, adopting the trial-and-error method in their search for suitable microorganisms. Then, having successfully produced Solein, Drs. Vainikka and Pitkänen then had to prove that it was suitable for nutrition. 

“We have spent two years and over 1.5 million euros proving that Solein is safe as a food. It has passed all the tests with flying colours,” Dr. Vainikka says. “I have fed myself a Solein-based diet. And we also regularly invite investors and people from the press, to whom we serve food containing Solein.” 

Yellow protein powder coming from microorganisms
The result is an increasingly thickening mass, from which a slurry can be skimmed. Upon drying, the final product is Solein- a yellowish powder.

In the shops this year 

The company is committed to interdisciplinary collaboration. “We use hydrogen, as does the petrochemical industry. We use fermentation, as in winemaking,” Dr. Vainikka says, listing the steps involved. “We also create textures, as you would in conventional food production.” Although it is a food company, Solar Foods sees itself primarily as a clean tech enterprise: “We only need about a tenth of the space a plant would need to photosynthesize, and only 1% of the space you need to produce meat,” the Finn reports. This calculation also includes the space needed to generate electricity, which is essential for this foodstuff, so Solein could also serve as an alternative to conventional livestock farming. Plant-based agriculture would be retained, but meat growers could shift their focus. “We don’t expect consumers to change their behaviour,” Dr. Vainikka explains. “People don’t need to accept compromises.” While Solein is obviously not perfectly comparable to meat from animals, it would allow many existing end products to stay around. The only difference is that the production process would be much kinder to the environment – kinder even than in the case of soy. At between 5 and 10 euros per kilo, Solein is already significantly cheaper to buy than meat. Compared with other protein nutrients, it ranks in mid-table. “I myself am a flexitarian,” the 45-year-old says, “but not because of any idealistic considerations.  I don’t see consuming meat as intrinsically wrong. This has just been a natural progression for me.” Giving up carnivorous habits is also a generational issue, he points out: “Red meat is a status symbol for my parents. But for my daughter, it is something you don’t post on social media. I am somewhere between these two realities. When I one day sit in my rocking chair and my grandchildren see meat in my fridge, that will be strange for them – because Solein could be the new normal by then.” 


Right now, the company is building its first factory to demonstrate that large-volume production is also feasible. The aim is for Solein to be available in the shops before the end of this year. If you happen to be in or around Helsinki anytime soon, take the opportunity to see how Solein is produced – and have a taste – in the company’s showroom. “We want to encourage people to try it for themselves,” Dr. Vainikka smiles. “Then they can decide whether Solein is something they would like to incorporate in their regular diet.” 

Scientist in front of equipment, specialized in the development of a pilot plant for air-based fuel production
Dr. Pasi Vainikka holds a master's degree in energy systems, another in energy economics, and a doctorate in process chemistry. He is an associate professor at Lappeenranta University of Technology and previously served as a senior scientist at the Technical Research Centre of Finland. In addition to his role at Solar Foods, Vainikka is involved in various projects, including the development of a pilot plant for air-based fuel production.

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