At Imperial College London’s new campus in West London, some rooftops will soon hold bright green “biosolar” panels covered with algae. The plants suck carbon dioxide out of the air and produce fresh oxygen at a rate 100 times faster than trees covering the same amount of land–and then the microscopic organisms can be harvested to be used in food.

“We call it a ‘BioSolar Leaf,'” says Julian Melchiorri, CEO of Arborea, the company that designed the new technology. “It uses solar energy, but instead of converting solar energy into electricity [like a solar panel], we convert solar energy into food.”

Melchiorri, who graduated from a joint masters program at Imperial College London and the Royal College of Art in 2014, is primarily focused on using the technology at a larger scale to produce ingredients. It’s a way to produce more protein in a given area than any other type of food production; the algae are also a source of antioxidants and other nutrients. In pasta, for example, the algae can be used to add protein. The algae can also create natural food coloring. “Let’s say you have blue M&Ms,” he says. “The blue [algae], instead of being synthetic and having all of the issues related to colorants, actually has more antioxidants than you can find in an apple.”

Microalgae are already used in food, but the new panels use a proprietary production process that makes growing them less expensive, more scalable, and results in a higher quality product, Melchiorri says. “We reinvented how we can grow cells by radically changing culturing techniques,” he says. The company, which recently launched a Series A round of financing, plans to soon open a demo plant in San Diego. But Imperial College London saw an opportunity to pilot a rooftop system that would take advantage of the algae’s ability to clean the air.

“Our new campus is a brownfield site, and that means that it’s going to be difficult to grow trees to green it,” says Neil Alford, associate provost at Imperial College London. “But what we can do is use this technology to supplant the trees. We’ll have the ability to create oxygen within London, which isn’t a bad idea, but we can do something which per area will produce maybe 100 times more oxygen than trees will.” Algae naturally absorb CO2 and release oxygen faster than other photosynthetic organisms, and the panel growing system makes it possible to perform this process anywhere. “You can put them on the sides of buildings or the roofs of buildings, and that is something that is interesting for us.”

A city could potentially have a network of sites with the biosolar panels, beginning on buildings with sprawling roofs, such as supermarkets or warehouses, or next to industrial plants emitting carbon dioxide. The pilot plant at Imperial College London, which is now under construction, will test how well the system works to clean the air. Arborea will also continue to move forward with the panels at larger production plants. Because the panels can be used on infertile land, the process can avoid some of the sustainability challenges inherent in other food production–like the deforestation often caused when land is cleared to raise cattle or grow soy. The climate pollution avoided by producing protein with algae is even more significant than the algae’s ability to suck CO2 from the air, Melchiorri says. “[Our] primary function is to produce the most sustainable protein.”