Scientists Create Algae-Powered AA Battery That Powers a Microprocessor

A team of researchers in the U.K. has powered a microprocessor continuously for a year using blue-green algae, light, and water alone. 

Detailed in a paper published Thursday in the peer-reviewed journal Energy & Environmental Science, a group out of the University of Cambridge created a photovoltaic cell that generates electrical current using biological materials. Comparable in size to an AA battery, the cell is made primarily of recyclable materials and does not require the use of any rare earth elements such as lithium.

“Batteries rely largely on expensive and unsustainable materials,” the researchers write. “Existing energy harvesters are longer lasting but may have adverse effects on the environment.” 

By contrast, the device they’ve created harvests energy from the sun through photosynthesis, generating a current that interacts with an aluminum electrode that can then be used to power microprocessors: In this instance, they plugged it into an Arm Cortex M0+ that was run for six months before the researchers submitted their findings for publication. This is notable, because this small, energy efficient chip is often found in internet-connected devices. 

In that time, the researchers tested the photovoltaic cell in both domestic and semi-outdoor conditions amid natural light and temperature fluctuations, and the device stayed powered the entire time.

“We were impressed by how consistently the system worked over a long period of time,” Dr. Paolo Bombelli, postdoctoral researcher at the University of Cambridge department of biochemistry and first author on the paper said in a release. “We thought it might stop after a few weeks but it just kept going.”

Though light is a key ingredient in photosynthesis, the cell continued operating even at night, which the researchers posit is a function of the fact that algae continues to process its food even when there’s no light.  

The researchers hope the device could reduce the pressure placed on lithium-ion batteries as energy storage savior in the renewable transition: Their battery doesn’t require the mining of rare minerals, does not come with the same risks inherent to using volatile elements, and can, in fact, generate energy, rather than just store it.

“Our photosynthetic device doesn’t run down the way a battery does because it’s continually using light as the energy source,” said Christopher Howe, professor in biochemistry at the University of Cambridge and co-author on the paper. “The growing Internet of Things needs an increasing amount of power, and we think this will have to come from systems that can generate energy, rather than simply store it.” 

Bombelli told Motherboard he hopes to see the cell used in small devices in off-grid or remote settings. But first, he needs to replicate it “hundreds, if not thousands” of times in different systems to better grasp its kinks.

“In my futuristic view I could foresee more plausible to have algae-driven charging stations for mobile phones located in remote locations,” he said. “If algal systems could be used to power small electronic devices located off-grid, this could be part of our energy portfolio.”