Can we really save the planet by making food ‘from air’ without farms? - New Scientist News

Solar panels and sheep — Could solar farms provide our food?

It is being claimed we could save the planet by turning renewable energy and air directly into food and rewilding all the farmland that is no longer needed. Could it really work?

In a TV documentary called Apocalypse Cow, and a Guardian column, environmentalist and journalist George Monbiot says food grown in vats using renewable energy could transform food production.

He highlights a Finnish company called Solar Foods that makes food from air. The process starts by splitting water into hydrogen and oxygen. The hydrogen then provides energy for bacteria to use to turn carbon dioxide and nitrogen in air into protein-rich organic matter, more efficiently than plants grow using photosynthesis.

“The land efficiency, the company estimates, is roughly 20,000 times greater,” Monbiot writes. “Everyone on Earth could be handsomely fed, and using a tiny fraction of its surface.”

Monbiot is absolutely right about the destructiveness of food production – but his numbers appear off.

The head of Solar Foods, Pasi Vainikka, tells me that the efficiency figure Monbiot cites applies only to the area of land taken up by the factories. If the energy were derived from solar, says Vainikka, then it would be only 10 times more land efficient than farmed soya.

Sadly, this suggests a claim reported by Monbiot in 2018 that all the protein the world now eats could be cultivated in an area smaller than Ohio is rather wide of the mark.

But we do need to do something about the impact of our food and even a small reduction in farmland could make a big difference. Habitat loss is the single biggest killer of wildlife, for instance, and it is largely due to farming.

Farming and land clearance also produces a third of all greenhouse gas emissions. And organic farming is even worse than the conventional kind.

Food production is also inefficient. Almost all the food we eat is derived from photosynthesis. This will be true for lab-grown meat as well, if made with nutrients obtained from plants.

Less than 0.5 per cent of the light energy falling on a field gets turned into food. By contrast, solar panels convert around 17 per cent of the light energy falling on them into electricity.

Solar Foods says it can convert electricity into food – via hydrogen – with an efficiency of 20 per cent. That is several times better than photosynthesis.

It is technically feasible. In fact, a company called Calysta is already producing animal feed from microbes fed on methane – but the methane comes from natural gas.

Solar Foods says its process is economically feasible, too, and that it will be able to beat the price of soya, the cheapest protein widely used for animal feed.

There are other issues though. There are grand plans to use hydrogen for everything from heating homes to powering aeroplanes. But we don’t produce enough hydrogen for this, and 99 per cent of it is made from fossil fuels, so using it won’t reduce emissions.

We don’t have renewable electricity to spare, and half the energy is lost when making hydrogen. So clean hydrogen is a limited resource and should be used wisely.

Putting huge amounts of renewable energy into producing hydrogen to make farm-free food could thus undercut other efforts to limit climate change – the other great threat to wildlife.

However, it would also eliminate greenhouse gas emissions and other forms of pollution from the farms that are replaced, so it might still be a win overall.

The bottom line is that it is still far from clear if farm-free foods can save the planet. But the potential rewards are so immense that we should be pouring vast sums of money into finding out.

In the meantime, we should do all we can to minimise the land needed for farming, such as eating less meat, stopping turning foods like palm oil into biofuels and embracing genetically modified supercrops.