The profile of nature-based solutions to greenhouse gas removal is growing. Earlier this month, the Times visited Professor Luke Mackinder in his York labs to understand just how his research is aiming to turbocharge the CO2 removal processed of plants. They also spoke with CTRF’s CEO Dave Hillyard about the importance of funding innovative research right now to ensure that solutions can be found and scaled by the time we really need them. Here’s what they discovered.
The Times
Science
Carbon Capture is vital to fighting climate change- and promising methods include modifying trees, sinking plankton and burying wood in the desert
by Ben Cooke
Thursday November 30 2023
12.01am
Each year humanity chucks an enormous amount of carbon into the atmosphere — ten gigatonnes, or the weight of about 55 million blue whales. But as vast as this amount is, it’s quite small compared to the amount circulating through the natural world. Every year, trees, plants and algae suck about 120 gigatonnes out of the atmosphere through photosynthesis. Almost all of this is released again through respiration and decomposition. But some is locked up in trees, some in rocks and some, as dead algae, falls to the sea floor.
As the world has dithered in its effort to limit global warming, it’s become clear that if we are to stop it, we’ll need to mimic nature’s vast carbon clean-up. The National Academy of Sciences estimates that to limit warming to 1.5C we’ll need to be removing 10 billion tonnes of carbon dioxide from the atmosphere a year by the middle of the century to compensate for those emissions too difficult to stop at source, such as those from planes. Ten billion tonnes of CO2 is roughly three billion tonnes of pure carbon.
Nobody knows yet what the best way of removing all that carbon will be, but scientists around the world are developing a smorgasbord of methods. Some, like those at the Swiss company Climeworks, are building big extractor fans to sift carbon atoms from the breeze.
But other scientists are looking to nature’s carbon cycle for inspiration. They’re looking for ways to tweak it, speed it up and help it take more carbon out of the air permanently.
One of those scientists is Professor Luke Mackinder, a plant biologist at the University of York. His research into carbon removal is inspired by ocean algae. “About half of carbon absorption takes place in the ocean,” he says. “Algae are extremely efficient at absorbing it.”
Mackinder explains that, because carbon diffuses more slowly in water than in air, algae have had to work far harder to acquire it for photosynthesis. To do this, they have evolved a feature called a pyrenoid, which Mackinder describes as a “CO2 turbocharger”. The pyrenoid bunches up carbon atoms alongside an enzyme called rubisco, which turns them into energy. This allows the algae to grow far more efficiently.
Together with his team at York and researchers in Edinburgh and Princeton, Mackinder is working out how to put pyrenoids into other plants that do not have them, helping them to absorb carbon faster. If he succeeds, then he thinks he could increase their growth rate by up to 30 per cent.
To do this, his team has studied the genetic code of algae to work out which genes give rise to the pyrenoid. He believes they have now figured this out. “Now we have this parts list, we can start thinking about how to assemble them in different organisms,” he says. “We insert the genes into the genome of the other plant. It’s genetic modification.”
Mackinder’s collaborator at the University of Edinburgh, Alistair McCormick, has already succeeded in putting a pyrenoid into the thale cress plant. Mackinder anticipates adding them to a range of crops and trees. The resulting increased yields could be good for food security. Alternatively, they could help to reverse climate change. It all depends on what we do with the carbon once it’s captured in those plants. Eating them would quickly return it to the atmosphere. But if instead we find ways to store it, we could keep it out of the atmosphere for good. Mackinder says there are several ways to do this.
“One possibility is you could turn those crops into something called biochar,” he says. Biochar is a charcoal-like residue, created by heating biomass in an oxygen-free environment. It can be spread on fields to improve soil structure. Another way of storing plant-based carbon is to turn it into building materials. “There’s crops like hemp, which can be turned into materials for insulation, and also into something called hempcrete, which is like breeze blocks.”
There are also wackier ideas for storing carbon. The California-based startup, Kodama Systems, is taking waste wood from forest management, and burying it beneath the Nevada desert to stop it degrading.
While none of these methods require genetic engineering, all could be enhanced by it. The quicker plants grow, the more carbon they take in, and the more can be sequestered. “You would need less land for the same amount of carbon removal, or with the same amount of land you could achieve a lot more.”
Businesses in Britain would not be allowed to sell crops that have had a pyrenoid added to them. The law was recently relaxed to allow the commercial development of crops with genes from other varieties of the same species, but those with genes from other species are still prohibited. Mackinder says that “as a society we’re going to have to make some big decisions. Do we want to use this new technology to improve carbon capture and help solve global warming? What I should say is that there are already large parts of the globe, like the US, where GM is accepted. I can’t see anything going wrong [with GM crops].”
Growing plants and storing them isn’t the only way that scientists around the world are tweaking nature’s carbon cycle. The Israeli start-up, Gigablue, has found a way to sink more plankton to the bottom of the ocean, where their carbon remains inert for thousands of years. Ninety-nine per cent of plankton would normally be eaten before reaching the ocean floor. To counteract this, the company spreads nutrient particles in the ocean, which attract plankton that then sink to the depths before predators can eat them.
Meanwhile, the Dutch company, greenSand, is selling ground-up olivine for use in urban landscaping. This dark green mineral naturally absorbs carbon dioxide in a process similar to iron going rusty. By grinding it up and increasing the surface area exposed to the air, greenSand speeds up this process.
Dave Hillyard, chief executive of the Carbon Technology Research Foundation that is funding Mackinder’s research, says that it is important to fund work on a wide array of carbon removal methods, because “some will not get the results they’re looking for and some will succeed. There’s a lot of opportunity here but very little funding and research going into it.”