What is sustainable protein?

Sustainable protein is protein made without the land, water and emissions that livestock needs. Livestock uses 83% of the world’s farmland but supplies only 18% of its calories (Poore & Nemecek, 2018). There are four main alternatives, each with its own page, and all of them have a part to play in a balanced, sustainable diet:

Form	What it is	Main hurdle	Where it stands (October 2026)
Plants	Protein eaten straight from crops, or made into meat-like foods	Farmland, weather and season	Mainstream; plant-based meat sales have dipped
Precision fermentation	Microbes make one specific protein (whey, casein, rennet), which is purified out	Purification cost	Approved in the US and Israel; no animal protein approved in the EU or UK yet
Single-cell protein	The whole microbe is the food: fungi, algae or bacteria	Scale, cost and approvals	Mycoprotein mainstream (Quorn, ENOUGH, Nature’s Fynd); SoF1, Solar Foods’ proprietary hydrogen-oxidising strain (Solein), approved in Singapore and sold in the US
Cultivated meat	Animal cells grown in bioreactors	Cost of the growth medium; scale	Approved in Singapore, Israel, the US and Australia; UK pet food only

Insects are another option (the EU has authorised four species), but they are farmed animals, and the largest insect farming company in 2025 went into liquidation, so we don’t cover them here.

Why we are working on hydrogen-oxidising bacteria

Hydrogen-oxidising bacteria (HOB) are single-cell protein with one big difference: they don’t need crops. Fungi and precision fermentation are usually fed sugar, which has to be grown. HOB make protein from hydrogen, oxygen and carbon dioxide, and hydrogen and oxygen can be made from water and electricity.

• Land and water: powered by solar panels, HOB could make about ten times as much protein per hectare as soya, the most efficient protein crop (Leger et al., 2021), with about a tenth of its water (Sillman et al., 2019). Both are models, not measurements.
• Anywhere: no sunlight, soil or season, so protein can be made where crops fail.
• Simple to process: the whole cell is the food, so there’s no purification step. That makes it a good fit for small, local, open source production.

The challenges we’re working on:

• Energy: HOB need a lot of electricity, so their carbon footprint is only low when that electricity is low-carbon (Järviö et al., 2021).
• Digestibility: early lab tests suggest HOB protein is moderately digestible (Caliskan et al., 2026); human data are still needed.
• Processing: bacterial biomass is high in nucleic acids, which have to be reduced before it is eaten in quantity.
• Regulation and money: novel foods take years to approve, and two start-ups making protein from hydrogen and carbon dioxide, NovoNutrients (with bacteria) and Arkeon (with archaea), closed in 2025 after running out of capital.

A note on closed source companies

We mention a number of commercial companies in these pages. We support their efforts, and commercial competition has brought many good innovations to market. But good companies and their patents can be bought by less benevolent ones, and shareholder primacy means the world’s poorest, in the most challenging environments, may not benefit from the innovations they need most. If it can gain the required funding, open source work like ours benefits everyone, companies included, while making sure the results stay available to all.