Electro-ag: the race to make food directly from renewable electricity

The article, written by New Scientist columnist Michael Le Page to mark the magazine's 70th anniversary, makes a personal bet: the advance he is most excited about for the coming decades is not a gadget but so-called "solar foods" — food made by converting renewable electricity directly into edible organic matter, without going through traditional cultivation under the sun.

The starting point is a harsh diagnosis of today's agriculture: according to the author, it is the most destructive human activity there is, the main driver of both global warming and biodiversity loss, and that includes organic farming, since its lower yields per hectare force more forest to be cleared somewhere else on the planet to compensate. Add to that a growing world population and an increasingly meat-rich diet as wealth rises, which is driving up demand for food just as climate change begins to weigh on harvests: yields of staple crops such as wheat are still rising thanks to technology, but they would have grown more were it not for warming-related losses, and this year has already seen yields fall in Europe. The fear expressed in the article is a vicious circle: warming driven in part by agriculture itself hits food production, which leads to more land being ploughed up and more agricultural emissions, generating still more warming.

Against this backdrop, the author rules out vertical farming under artificial light from the outset, something he says he already criticized in 2015 and which the string of bankruptcies in the sector confirms. The underlying problem is that plants are very inefficient at converting light into food: typically less than 1% of the solar energy reaching a crop ends up in the food we eat. When sunlight is free that doesn't matter, but if you have to pay for electricity to run grow lights, the waste becomes unaffordable. There is also a land-use problem: even if layers of plants can be stacked, every hectare of crops under artificial light requires on the order of 13 hectares of solar panels to generate the necessary electricity, so total land use per unit of food goes up rather than down (and nuclear power, an alternative in theory, is neither cheap nor abundant).

Hence the interest in another route: converting air, water and electricity directly into food, taking advantage of the fact that solar panels are far more efficient than plants (more than 20% energy conversion, versus less than 1% for photosynthesis, with some experimental panels exceeding 40%). The general idea is to turn electricity into a chemical compound that microbes can feed on, for example by electrolysing water to produce hydrogen.

That is exactly what the Finnish company Solar Foods does: it grows in bioreactors a bacterium that uses hydrogen as its energy source, along with CO2 (captured from the air) as a carbon source and ammonia (made from that same hydrogen) as a nitrogen source, making the process almost carbon-neutral if the electricity is solar or wind. The bacteria are dried into a yellow powder called Solein, with up to 80% protein, already sold in the United States and Singapore in bars, drinks or as an egg substitute in baking and pasta, and for which the company expects approval in the European Union soon. According to co-founder Pasi Vainikka, the demonstration plant is running better than expected, nearly five times more productive than initially estimated, which has led the company to plan a second factory with a capacity of 6,400 tonnes a year, aiming to bring production costs down to a few dollars per kilo and sell it for more than double that, helped by the recent rise in protein prices. The article mentions other start-ups pursuing the same idea of protein from microbes fed on gases, such as Jooules, Air Protein and Aerbio.

This so-called "gas fermentation" is not just theory: it has already been done at scale. Between 1999 and 2005, the Norwegian company Norferm produced 110,000 tonnes of microbial protein from methane to feed farmed fish, and although it halted production because it wasn't profitable at the time, today's higher protein prices have revived interest: U.S.-based Calysta has built a 20,000-tonne-a-year plant in China, and Denmark's Unibio is building a 50,000-tonne-a-year factory in Saudi Arabia. The important caveat is that these plants use fossil-derived methane, which reduces land use compared with growing, say, soya, but releases fossil carbon into the atmosphere; making hydrogen, methane or ammonia from renewables is still more expensive, so for now there is little incentive to "green" a low-value product like animal feed, although Calysta says it is looking into using biogas.

Some researchers believe there is a better route than hydrogen. According to Remko Boom of the University of Copenhagen, hydrogen barely dissolves in water, which makes it hard for microorganisms to use, and methane is only slightly more soluble. The alternative is to convert CO2 into simple, highly soluble carbon compounds such as acetate: it takes more energy to produce than making hydrogen, but the idea is that this is offset by faster microbial growth. Boom is part of the Acetate Consortium, a project that has already shown certain microbes can be grown on acetate and which, he says, could be scaled up significantly, decoupling protein production from land use. The challenge, he notes, lies in turning what comes out of the bioreactors into appetizing food, and he sees two paths: using the microbes themselves as an ingredient with minimal processing (as Solar Foods does), focusing on microorganisms already approved for food use, such as yeast, to avoid the slow "novel foods" approval process — Solar Foods has been waiting five years for EU clearance; or genetically modifying the microbes so they produce specific proteins, such as the caseins in cheese, a more expensive route because of purification costs and therefore reserved for high-value products. Boom also points out that carbohydrates could technically be made this way, although no shortage of these is expected, unlike protein.

The second major avenue the article explores is so-called electro-agriculture (electro-ag): instead of feeding microbes, the idea is to grow plants directly — strawberries, avocados, olives, any fruit or vegetable — using electricity instead of sunlight, in practice growing them in the dark. In 2022, a team including Robert Jinkerson of the University of California, Riverside, made acetate from CO2 by electrolysis and used it to grow yeast, mushrooms and algae; by their calculations, converting sunlight into acetate and then into yeast was nearly 18 times more efficient than conventional agriculture, and in the case of algae almost four times more efficient. The team envisions buildings covered in solar panels that would generate electricity to make acetate on site and supply it through the roots to plants grown in the dark on the building's lower floors. In a 2024 follow-up paper, the same researchers estimated that with technological improvements the efficiency of this plant production could increase tenfold, yielding about ten times more food per unit of area and freeing up vast stretches of land for rewilding. Growing food this way would also cushion food shocks caused by extreme weather, allow food to be produced anywhere and, as closed systems, largely avoid the pests and diseases that drastically cut global harvests today.

The article itself acknowledges this is not straightforward: plants cannot simply "eat" acetate, since using it requires a chemical pathway that is only active in young seedlings. Jinkerson's team is genetically modifying plants to achieve this, and has created a spin-off called Nolux for the purpose. The text notes there is no fundamental reason to think this is impossible, since some parasitic plants grow entirely in the dark today, feeding on nutrients stolen from other plants; indeed, it suggests that in future crops could also be genetically modified to eliminate superfluous structures such as stems and leaves that aren't eaten, taking as a reference extreme parasitic plants like the giant-flowered Rafflesia, which has no roots or leaves.

Another, different route, already under way according to the author, is growing plant cells in bioreactors instead of whole plants or microbes: he mentions that last year he tried chocolate made this way and found the result quite good. Today these cells are still grown in media containing sugars from conventional crops, so they retain a significant environmental footprint, but if that growth medium could be derived entirely from renewable energy (via acetate, for example), the impact would change, and in his view a wide variety of foods could be made this way, from flour to guacamole.

A third, even more radical option dispenses with living cells altogether: the U.S. start-up Savor converts synthesis gas (syngas) — a mixture of hydrogen and carbon monoxide currently derived from fossil fuels — into edible fats to create a butter-like product; according to the article, that hydrogen and carbon monoxide could in future also be produced with renewable electricity.

The piece ends on a measured note: Boom stresses that there will probably be no single dominant route but a combination of all of them, and the author himself warns that no one expects these foods made from air and electricity to replace conventional crops and livestock any time soon, not least because they would require more renewable electricity than the world generates today. Even so, he believes that if a decent share of food could be produced this way in the coming decades, the difference would be enormous for limiting global warming, protecting wildlife and helping feed the world. He therefore calls on governments to do much more to promote these "solar foods," from funding research to easing regulatory hurdles and helping make them price-competitive, and encourages consumers themselves to support the process by buying such products when they become available. The article closes on a light note, imagining that when the magazine celebrates its 140th anniversary, everything eaten and drunk at the party could come literally "from thin air."