If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.


Food Ingredients

Can start-ups succeed in making food from the air?

Gas-to-protein processes could disconnect food production from land and sea

by Alex Scott
September 20, 2020 | A version of this story appeared in Volume 98, Issue 36


Photo of a fermentation reactor.
Credit: Solar Foods
Solar Foods has just secured funds to build a larger version of this pilot plant for making its Solein protein from green hydrogen and CO2.

Feeding the world with protein made from air or industrial exhaust with minimal use of water and land, and without pesticides, fertilizer, or a thought for weather, seems fanciful. A handful of start-ups, though, say this scenario will become commercial reality in just a few years.

Their plan is to mass-produce proteins by using bacteria to ferment various gases. Once dried, the bacterium cell bodies form a flour with a protein content of about 70%.

Even though some of the firms have already shown that they can make edible—and even tasty—protein at lab and pilot scale, they have yet to prove their approach can compete in the real world against soy and other high-protein crops such as pea. If gas-to-protein processes can overcome this cost hurdle, the market opportunity is huge.

The mass production of protein from gases is being preceded by a new wave of so-called precision fermentation processes to make protein from starch and sugar. Such processes “are already starting to make their way into the mainstream food value chain,” says Catherine Tubb, senior research analyst for RethinkX, a San Francisco–based firm that analyzes technology’s impact on society.

Gas to protein by the numbers

60–70%: The protein content of biomass made by gas fermentation

7%: The reduction in greenhouse gas emissions from agriculture if gas-to-protein processes become widespread

<10%: The amount of water required to make protein from gas versus livestock

10 kg: The amount of CO2 Deep Branch consumes to make 7 kg of protein

Sources: Calysta, RethinkX, University of Queensland, Deep Branch Biotechnology.

Precision fermentation, which uses targeted fermentation systems, will cause a paradigm shift in agriculture, as it will be 100 times as land efficient, 20 times as time efficient, and 10 times as water efficient as industrial livestock production, according to a 2019 report authored by Tubb and colleagues at RethinkX.

Proteins made from bugs that feed on gases have the potential to leave an even smaller environmental footprint than those made from sugars, starches, or oils. In a world facing severe environmental and food security stress and a human population set to grow from 7.8 billion today to 10.9 billion by the end of the century, protein sourced from gases is essential, proponents say.

The Finnish start-up Solar Foods aims to be one of the first companies to make air-derived protein a commercial reality. “Our vision is to change the way food is produced. . . . The food of the future is not a utopia but is happening now,” Pasi Vainikka, CEO and cofounder of Solar Foods, says in a recent press release from the company.

The firm is developing a process that combines green hydrogen, made from water electrolysis powered by renewable electricity, with nitrogen and CO2 from the air. This mixture is fed into a fermentation tank and used to feed the protein-producing bacteria.

Solar Foods’ Solein product has a protein content of 65%. “It is yellow in color from β-carotenoid. It has a hint of carrot and an umami taste,” says Juha-Pekka Pitkänen, the firm’s chief technology officer. “Bake with it, and it tastes like carrot cake.”

A core challenge for Solar Foods is that producing hydrogen from water electrolysis and capturing CO2 from the air are both inefficient and expensive processes today. While farmers’ key costs include land and fertilizer, Solar Foods needs a lot of electricity to run its electrolyzer and a centrifuge for drying its protein.

But making the protein requires just 10% of the land needed for soy, and the carbon footprint is 1% of any animal or plant-based alternative, Solar Foods claims.

Like other leading players in the field, Solar Foods has chosen not to genetically modify bacterium so it can avoid regulatory hurdles, especially in Europe. Instead, the firm sifted through hundreds of samples containing hydrogen-oxidizing bacteria found in soil. “That is not to say organism selection is easy. There are so many boxes the organism needs to tick—it needs to be efficient, safe, and good for human consumption,” Pitkänen says.

The European Food Safety Authority is evaluating whether Solein is safe to eat, a process that could take a year, Pitkänen says.

At least three other European firms—Avecom, Calidris Bio, and Deep Branch Biotechnology—are also developing processes that use green hydrogen to make food. But Solar Foods appears to be ahead of the pack, having just raised $17 million to build a demonstration plant producing 300 kg of Solein per day. The plant is set to open in 2022.

Avecom, a small Belgian firm, has been working with KWR Water Research Institute for the past 5 years to ferment green hydrogen, oxygen, and waste CO2 into protein. The firm acknowledges that its process depends on the availability of renewable energy at the right price. “But we see a lot of progress in the green hydrogen sector and are convinced that the process will achieve its break-even point within the next few years,” says Stijn Boeren, Avecom’s director of business development.

Currently, the firm is running a demonstration unit that makes 1 kg of protein per day. It is working with Flanders’ Food, a Belgian industry organization, to direct its protein at human food applications.

Companies that plan to use carbon emissions or CO2 from the air to make protein could offset some of their costs by being paid for the CO2 they consume. Such payments will require that their processes are recognized by Europe’s Emissions Trading System, says Deep Branch CEO Pete Rowe. At today’s prices in Europe, each metric ton of CO2 consumed would earn firms about $29. Deep Branch says it consumes 10 kg of CO2 to make 7 kg of protein.

In January, Deep Branch started up a pilot facility for its process using waste CO2 from a power plant in Drax, England. The company plans to use the $6.5 million it has raised so far from investors to open a bigger pilot plant next year at a site in mainland Europe that it has yet to disclose.

Although firms like Deep Branch have their eyes on the human food market, in the near term some of them plan to sell their product as animal feed, a large market with room for environmental improvement.

Producing microbial protein from ­gases has the potential to replace 10–19% of conventional crop-based animal feed protein, according to modeling by Ilje ­Pikaar, an associate professor at the School of Civil Engineering at the University of Queensland. In a 2018 study published in the journal Science of the Total Environment, Pikaar and colleagues forecast that cropland area, nitrogen losses from croplands, and agricultural greenhouse gas emissions can be decreased by 6, 8, and 7%, respectively, if gas-to-protein technologies are widely deployed.

A photo of a scoop of animal feed.
Credit: Calysta
Calysta's FeedKind animal feed

Avoiding the application of fertilizer alone would deliver huge environmental and economic benefits compared with standard farming methods, according to Pikaar’s research. Another benefit of making protein from gases is that the approach can be rapidly scaled up with a minimal footprint on land.

The California start-up Calysta is one of those firms initially targeting animal feed markets. In Calysta’s case, the animal is fish and the gas being consumed by microbes is natural gas. CEO Alan Shaw estimates that a large plant making its FeedKind protein would use less than 1% of the land that the equivalent product made from soy would.

At the same time, FeedKind could hugely benefit ocean habitats and overfished wild fish populations, Shaw says. Currently, a quarter of the world’s annual wild fish catch of 85 million metric tons (t) is used as feed for farm-raised fish. “A 100,000-metric-ton plant making FeedKind could mean that half a million tons of wild-caught fish could stay in the ocean,” Shaw says.

The environmental benefits outweigh any greenhouse gas emissions resulting from the use of natural gas, Shaw says. “We can’t keep feeding people soy and using more land and more water like the planet is going out of business,” he says.

Calysta has been running a FeedKind pilot plant in Teesside, England, for over 2 years with a capacity of 50 t per year. FeedKind contains all 10 amino acids essential to fish, the firm says.

In June, Calysta and the feed additive producer Adisseo, a subsidiary of ChemChina, formed a joint venture called Calysseo. The venture plans to build a FeedKind plant with a capacity of 20,000 t per year in Chongqing, China, by 2022. Once this plant is running successfully, Calysseo plans to increase capacity by another 80,000 t per year.

Shaw was instrumental in acquiring gas fermentation technology from the Norwegian oil company Statoil and using it to cofound Calysta in 2012. “The reason we are able to go to the market first is because Statoil started doing work on this in the ’90s,” Shaw says. “We are a decade ahead of our next competitor.”

He praises the environmental principles of companies developing alternative protein processes using green hydrogen and industrial CO2 emissions but warns that such processes will be prohibitively expensive for the foreseeable future.

A 100,000-metric-ton plant making FeedKind could mean that half a million tons of wild-caught fish could stay in the ocean.
Alan Shaw, CEO, Calysta

Shaw’s assertion is firmly rejected by Deep Branch’s Rowe. “We have come a long way quickly,” Rowe says. “Just because Calysta has a 10-year head start doesn’t mean we are 10 years behind.” Deep Branch aims to raise enough money by year-end to commission a larger demonstration plant with an annual capacity of 5,000 t by 2023.

Rowe also challenges Shaw’s assertion that green hydrogen will be too expensive as a raw material for making protein. Deep Branch’s modeling shows its process for converting waste CO2 and green hydrogen to protein will be competitive with conventional protein-based animal feed in Europe in the next few years, Rowe says.

While hydrogen accounts for a significant proportion of Deep Branch’s costs for its Proton brand of protein, the firm says it can squeeze these costs by colocating with major hydrogen projects. Many such projects are in line to receive substantial subsidies, Rowe points out.

While Deep Branch and others are still working on their commercial plans, LanzaTech, a start-up formed in 2005, is already producing and selling multi–ton quantities of gas-based protein to the animal feed industry.

In its process, waste carbon monoxide is fermented to ethanol by using a bacteria originally found in rabbit droppings. The protein is a coproduct. LanzaTech is producing an undisclosed amount of the protein along with 46,000 t of ethanol per year from the CO exhaust of a steel plant in Jingtang, China.

“Having two products doesn’t completely change the business case, but it certainly improves it,” says Sean Simpson, LanzaTech’s cofounder and chief technology officer.

LanzaTech is looking to apply its technology worldwide and says it is seeking approval for its protein to be used in the US aquaculture market.

Like its competitors, LanzaTech wants its protein to eventually go into human foods. While public acceptance of protein from bacteria has yet to be tested, proteins made via precision fermentation may smooth the way. A wave of companies is starting to convert starches and sugars into protein for substitute-meat products. Chicago-based Nature’s Fynd, for example, is doing it with fungus.

If gas-to-protein companies can create their products at the right price, the market should be primed for them to deliver their extraordinary message that, for the first time, food can be made independent of the land and sea.


This article has been sent to the following recipient:

Chemistry matters. Join us to get the news you need.