How turning electricity directly into food could help save the planet

Technologies being developed now could help us grow food without the need for direct sunlight

Dabarti CGI/Shutterstock

What breakthroughs are you most looking forward to in the next 70 years? That’s the question we’ve been asking here at New Scientist as our 70th anniversary nears. For me, there’s one clear answer: solar foods, made by turning renewable electricity directly into food.

This is already being done on a small scale. The big challenges are to make it efficient enough to compete with conventional foods on price, and delicious enough that people choose to buy it. When it comes to taste, perhaps the most promising approach is electro-ag, or growing plants on electricity instead of sunlight. In principle at least, all the fruits and veg we love – strawberries, avocadoes, olives, you name it – could be grown in the dark.

Why would we want to do that? Because farming is the most destructive of all human activities, driving the two major crises we face, global heating and biodiversity loss. And yes, I do mean all farming, including organic. Less-intensive forms of farming generally yield less food per land area, which ultimately means cutting down more forests somewhere in the world.

Every year, we have more mouths to feed. Not only is the world’s population still growing, but people are eating more meat as they become wealthier. So, we’ll need to grow more and more food each year for ourselves and the animals we eat, yet that’s going to get harder and harder as global heating drives more extreme weather. Yields of staple crops like wheat have been rising thanks to technological advances, but they would have been even higher without the increasing losses due to climate change. The danger is that global yields could start to decline, as happened in Europe this year. That means even more land will have to be cleared for growing crops, resulting in even more greenhouse gas emissions.

In other words, we are likely to end up in a vicious cycle in which global heating driven partly by farming will hit food production ever harder, leading to ever higher farm emissions and yet more warming as we try to compensate for escalating food losses. That’s a rather terrifying prospect.

What can we do about it? Some claim the answer is growing crops in closed environments under artificial lights, known as vertical farming. Unfortunately, it’s a non-starter, as I reported way back in 2015 – and as evidenced by company after company going bust.

The fundamental problem is that plants are terrible at turning sunlight into food. Typically, less than 1 per cent of the solar energy hitting a crop ends up in the food we eat. When sunlight is free, it doesn’t matter if more than 99 per cent of it is wasted. But if you’re paying for electricity for grow lights, it becomes a massive issue.

There’s also a land use issue. Yes, layers of plants can be stacked up, but every hectare of growing area requires around 13 hectares of solar panels to power the lights, so overall land use per unit of food increases. This could be avoided by using nuclear power, say, but nuclear power is neither cheap nor going spare.

Hence the interest in turning air, water and electricity directly into food, to reduce the need for land by taking advantage of solar panels being way more efficient than plants. Standard solar panels turn more than 20 per cent of the energy hitting them into electrical energy, and some experimental panels achieve more than double this.

Electrochemical plant food

The general idea is to convert electricity into a chemical that microbes can feed on, for instance by electrolysing water to produce hydrogen gas. This is what Solar Foods in Finland is doing. Its process relies on one of the many microbes that can use hydrogen as an energy source.

Solar Foods grows these bacteria in vats, also supplying CO2 as a carbon source and ammonia as a nitrogen source, along with other essential nutrients. The idea is to use CO2 from direct air capture and ammonia made from the hydrogen, making the process nearly carbon neutral if it’s powered by solar or wind.

Solar Foods grows Solein protein inside bioreactors

Solar Foods

The bacteria are dried to produce a yellow powder called Solein that is up to 80 per cent protein. It can be made into protein bars or drinks, or added to foods such as pastries and pasta to replace eggs. Products containing Solein are already available in the US and Singapore, and the company is hoping for approval in the European Union soon, too, says co-founder Pasi Vainikka.

The company’s small demonstration factory is working even better than expected, says Vainikka. “It has scaled really well. It’s almost five times more productive than we thought early on.” Solar Foods now aims to build a second factory with a capacity of 6400 tonnes a year. It wants to get the cost of making Solein down to a few dollars per kilogram and hopes to sell it for more than twice that, helped by recent jumps in the market prices of protein.

Several other start-ups, including Jooules, Air Protein and Aerbio, also aim to produce proteins from microbes fed on gases.

There’s no reason to doubt that gas fermentation, as this process is known, can be scaled up hugely – because it already has been. Between 1999 and 2005, a Norwegian company called Norferm produced 110,000 tonnes of microbial protein from methane, which was used as fish food. Norferm halted production because it wasn’t profitable at the time, but with protein prices rising, several companies are now making microbial proteins this way for use as animal feed. US firm Calysta has built a 20,000-tonne-a-year factory in China, for instance, while Unibio in Denmark is constructing a 50,000-tonne-a year-plant in Saudi Arabia.

The big “but” here is that these companies are using methane from fossil fuel sources. This does have some advantages – such as requiring much less land than, say, growing soya – but all the fossil carbon ends up in the atmosphere. The issue is that making hydrogen, methane and ammonia from renewable energy costs more, for now at least, so there’s little incentive to go green, especially when making a low-value product such as animal feed – though Calysta tells me it is looking at using biogas instead.

Turning air into carbon into food

Gas fermentation isn’t the only approach to making food from air. Some researchers think there is a better way. “Hydrogen hardly dissolves at all in water, so it is very difficult for microorganisms to get hold of,” says Remko Boom at the University of Copenhagen in Denmark.

This limits growth, says Boom. Methane is only a bit more soluble. The alternative is to turn CO2 into simple carbon compounds that are highly soluble, such as acetate. It takes more energy to produce acetate than it does to make hydrogen, but the idea is that this is compensated for by faster growth.

Boom is part of the Acetate Consortium, a project that has already shown that some microbes can be grown on acetate. “In principle, we can go to quite large scales,” he says. “So, it could be a significant source of proteins over the world, and that would mean that we can decouple this type of food production from the use of land.”

The challenge is to turn what emerges from bioreactors into appealing foods, he says. There are two broad routes. One is to use the microbes as a food ingredient with minimal processing, as Solar Foods is doing. Here, the Acetate Consortium has focused on microbes already approved for food use, such as yeast, thus avoiding the often slow process of getting novel foods approved. (Solar Foods has been waiting five years for approval in the EU.)

The other is to use genetically modified microbes to produce specific proteins, such as the casein proteins found in cheese. Purifying proteins is much more expensive than using entire cells, says Boom, so this approach would only be suitable for high-value products.

There’s no reason why microbes couldn’t be used to produce carbohydrates, too, he says. “However, we don’t expect a shortage of carbohydrates, while we do expect a shortage in protein.”

So, when it comes to microbial foods, a lot of progress has already been made. The big question is whether consumers will embrace them. Even if they do, people won’t want to live on microbes alone.

Replacing sunlight with electricity

A prototype system for electro-agriculture

Feng Jiao

This is where electro-ag could come in. The idea is to grow plants on acetate instead of sunlight.

In 2022, a team including Robert Jinkerson at the University of California, Riverside, made acetate from CO2 via electrolysis and used the acetate to grow yeast, mushrooms and algae. Turning sunlight into acetate and then into yeast was almost 18 times as efficient as standard farming, the team calculated. For algae, it was nearly four times as efficient. These are absolutely gigantic leaps in efficiency.

The team envisages growing crops in buildings covered in solar panels. The electricity generated would be used to make acetate on-site that would be supplied to the plants in the dark below via their roots. With technological improvements, the efficiency of plant production could be boosted tenfold, Jinkerson and his colleagues estimated in a 2024 follow-up paper.

If s0, we could grow around 10 times as much food per land area, freeing up huge tracts for rewilding. Growing food in this way would also help prevent food shocks caused by extreme weather and allow food to be produced anywhere. What’s more, growing food in closed systems can largely prevent pest and disease outbreaks, which massively reduce yields worldwide.

This all sounds great, but, of course, it isn’t so simple. The first obstacle is that plants cannot simply be fed acetate – using it efficiently requires a chemical pathway active only in seedlings. Jinkerson’s team is now genetically modifying plants to do this, and a spin-out company called Nolux has been set up.

There’s no fundamental reason to think this couldn’t be done. After all, some plants already grow in the dark – many parasitic plants rely entirely on nutrients stolen from other plants. Plants also put a lot of energy into growing structures like stems and leaves that we often don’t eat. Ideally, then, we would also modify these plants to get rid of superfluous structures. Again, parasitic plants such as the giant-flowered Rafflesia, which has no roots or leaves, show what is possible.

Another way to go would be to grow plant cells on acetate, rather than entire plants or microbes. A number of companies are already working on making food by growing plant cells in vats. For instance, last year I reported on efforts to make chocolate this way. I tried some of it, too, and it was pretty good.

At present, these cells are being grown in culture mediums containing things like sugars derived from conventionally grown foods, so they still have a significant environmental footprint. Deriving the culture medium entirely from renewable energy would change this. It seems to me that a huge array of foods could be made this way, from flour to guacamole.

Yet another option is to cut out living cells altogether. A US start-up called Savor is converting syngas – a fossil fuel-derived mix of hydrogen and carbon monoxide – into edible fats to create a butter-like product. The hydrogen and carbon monoxide could be produced by renewable electricity instead.

Savor’s “butter” made from synthetic vegan fat derived from carbon

Savor

All these different approaches may have a part to play. “We will probably not rely on one particular route,” says Boom.

No one is expecting food made from air and electricity to replace conventional crops and livestock farms anytime soon, not least because it would require more renewable electricity than we currently generate. But if we can make a decent proportion of food this way in the coming decades, it will make a huge difference, helping to limit global heating, protect wildlife and feed the world.

This is why governments should be doing much more to encourage solar foods, from funding research to easing regulatory obstacles and helping make these foods competitive on cost. As individuals, we can all help too by buying solar foods. Perhaps when people get together to celebrate New Scientist’s 140th anniversary, everything they eat and drink will have come from thin air.