Deep Branch: from CO2 to salmon
Deep Branch uses CO2 as a raw material for animal feed ingredients, especially for fish farming. A pilot plant will start next year at Chemelot, a demonstration plant is in the planning.

It is late 2026. On your plate is sushi. Chances are that the salmon in it has been fed with a CO2 made ingredient, from the company Deep Branch. The product is called Proton and will be produced on a pilot scale of ten tonnes per year at Chemelot from May 2023. The basis is essentially a very old fermentation process, says CEO and co-founder Peter Rowe. "In fermentation, you usually use sugar. You dissolve that in water, provide a hydrogen source and nutrients, and the micro-organisms then have everything they need to grow and, under the right conditions, such as acidity, deliver the desired product. The difference is that instead of sugar, we use CO2 and use hydrogen."

It sounds simple, but it is not. "You have to provide an excellently controlled fermentation environment through bioprocess engineering and fermentation science, while creating a completely safe application of hydrogen and oxygen, a potentially explosive gas mixture, for which you have to deal with ATEX standards. Combining the two in one process is our innovation."

Power station
In the continuous production process in the bioreactor, the micro-organisms multiply and build up more and more proteins. It produces a milky liquid. Rowe: "We harvest that, we dry it, and what remains is a batch powder of what the microbes were. That's our product: dried microbes full of protein, up to seventy per cent." The product is supplied to animal feed companies, which combine it with other ingredients and additives and supply the final product to salmon farms, for example, in the form of pressed pellets. Trout and shrimp farms and poultry farms are also among the potential customers.

The CO2 comes from various sources, mostly flue gases from industry, and is only used in a purified way, as the final product must be suitable for food consumption (food grade). The pilot at Chemelot uses CO2 of Carbolim, a joint venture between Air Liquide and Air Products dedicated to purification and conditioning of CO2. Source is an ammonia plant of OCI. Previously, purified CO2 from a power plant in the UK is used, and Rotterdam's industrial cluster is being looked at.

For now, they are all fossil sources. "The considerations for these are mainly pragmatic at the moment," says Rowe. "In the future, we want to start looking more at other sources, such as biogas and in the distant future perhaps direct air capture (CO2 get out of the air immediately - ed)."

Salmon farm

The pilot plant at Chemelot will be followed in two to three years by a demonstration plant, which will produce 250 to 500 tonnes, as a prelude to reaching 100,000 tonnes by the end of the decade. A number of potential sites in north-western Europe that have the necessary infrastructure have been looked at for this purpose. "We have several sites in mind, including Chemelot," said Rowe. "In a few months, we will announce the choice."

The first Proton-lined will then be available on the market by the end of 2026. Whether Deep Branch will thereafter sell the technology to third parties or run its own factories depends on several factors. "The first factory will be run by us anyway, to fine-tune everything. We still need to do a lot of business and market development. After that, we will look at it on a case-by-case basis. In any case, important factors are the availability of CO2 and hydrogen and proximity to fish farms. These are mainly in Norway, Chile, Scotland and Australia."

Soya flour
Rowe argues that in the context of geopolitics and climate change, it would be good for the Netherlands and Europe to become more self-sufficient in proteins too. "There is no soya production in the Netherlands, which is true for most EU countries. Europe is a net importer of protein. Only three countries are exporters: Brazil, Argentina and the US."

He sees Deep Branch's market opportunities as rosy, depending on the price of CO2 and hydrogen. "The demand for protein is increasing and our feedstock, CO2 and green hydrogen, is becoming increasingly available. We cannot compete against the extremely low price of soybean meal, which is also high in protein, but we are not looking to replace soybean meal either. We can hardly compete in northern Europe with agriculture-based animal feed in hot regions that have two growing seasons a year. We can, however, counter that with a more biotechnologically sustainable alternative that does not take up valuable agricultural land." For fishmeal, made from fish and widely used as fish feed, Proton does represent a good alternative in terms of price. And again in terms of sustainability, because wild fish is used for fishmeal.

The beauty of Deep Branch's biotechnology process is that it does not rely on high-value carbon sources in a sugar-based economy. "We offer CO2-based high-value products for the food chain that do not use agricultural land." And who knows, these might eventually replace soy as a protein ingredient for animal feed.

Deep Branch
Deep Branch was founded in 2018 by three PhD students at the University of Nottingham, including Peter Rowe. All three studied gas fermentation, where you use gases instead of sugar for the carbon and energy needed.

"The microorganisms we use and their functioning are similar to how the first life on Earth developed," Rowe says. "And then if you look at what happened on the deep sea floor, where life developed that produced CO2 used, and then came the microorganisms that could use their CO2 for photosynthesis, a trick that plants later copied from them... The microorganisms we use go back to the time before photosynthesis, they form the deepest branch of the tree of life. Hence the name Deep Branch."

It currently employs 30 people, 18 of them in the Netherlands. The parent company is a British Ltd. In Nottingham, Deep Branch has a small R&D facility, while the rest of the company is in the Netherlands: a pilot plant in Geleen and a small office at the Biotech Campus Delft (DSM has part of the shares).

This article was written by Igor Znidarsic and previously appeared in Chemie Magazine.