An experimental technology to purify the air will be rolled out in London, it has been announced, in a “world first” way to tackle pollution. Scientists are confident their pioneering “biosolar leaf” technology can do the work of 100 trees, while only using the surface area of one – something vital in big cities.

Air pollution is the world’s top killer, a new global air quality index revealed last year. According to the World Health Organization (WHO), 4.2 million people die each year from ambient (outdoor) air pollution, and 91 percent of the world’s population lives in a place that exceeds the WHO’s guideline limits.

With that in mind, Imperial College London has teamed up with biochemical tech startup Arborea to test out its biosolar leaf technology to offset its west London White City campus, while also demonstrating how sustainable solutions can address the vital environmental and social issues of today in real-world conditions.

So, what is a biosolar leaf and how does it work? The secret is algae.

Arborea researchers developed a cultivation system that allows microscopic plants like microalgae and phytoplankton to grow on large solar panel-like structures that can be installed on land, buildings, and anywhere with a roof in a built-up city to improve the surrounding air quality.

Inspired by the natural process of photosynthesis, the biosolar panels allow the microorganisms to absorb CO₂ from the surrounding area and generate breathable oxygen back out again. And they help produce a nutritious, sustainable plant protein with tiny environmental impact – Arborea's other focus – at the same time.

“When I founded Arborea my goal was to tackle climate change while addressing the critical issues related to the food system.,” Arborea founder and CEO Julian Melchiorri said. “This pilot plant will produce sustainable healthy food additives while purifying the air, producing oxygen and removing carbon dioxide from the surrounding environment.”

Melchiorri has already had some success with his astonishing 'Exhale' project, the world's first living bionic chandelier, which uses the same technology. The light of the chandelier stimulates photosynthesis of the microorganisms on the leaf-shaped modules, absorbing the CO₂ inside and releasing oxygen back into the room. The chandelier currently holds pride of place in London's Victoria and Albert Museum's permanent collection.  

The biosolar panels, on the other hand, use natural sunlight and are infinitely scalable, so crowded busy cities won't have to make room for the panels. Instead, they can utilize already existing rooftop space that is not being used.  

“Air pollution is one of London’s most urgent challenges, and Imperial is committed to finding sustainable and resilient solutions to this threat," Professor Neil Alford of Imperial College added. "This collaboration with Arborea is an exceptional opportunity to showcase the power of Cleantech."