Algae used to power electrical devices

Initiative could mean algae replaces batteries in the future

Professor Christopher Howe and Dr Paolo Bombelli with their algae device and a flask of algae. Photo: Paolo Bombelli

Scientists at Cambridge University have created a way to power electrical devices using algae, in a move which could eventually mean it replacing batteries.

Researchers have used a widespread species of blue-green algae to power a microprocessor continuously for over a year using nothing but ambient light and water.

Their system has the potential to be a reliable and renewable way to power small devices in the future.

The system, comparable in size to an AA battery, contains a type of non-toxic algae called Synechocystis that naturally harvests energy from the sun through photosynthesis.

The tiny electrical current it generates then interacts with an aluminium electrode and is used to power a microprocessor.

The system is made of common, inexpensive and largely recyclable materials and the researchers believe it will enable the initiative to be replicated hundreds of thousands of times to power large numbers of small devices as part of the Internet of Things.

The Internet of Things is a vast and growing network of electronic devices — each using only a small amount of power — that collect and share real-time data via the internet.

Using low-cost computer chips and wireless networks, many billions of devices are part of the network — from smartwatches to temperature sensors in power stations.

“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 like batteries,” said Professor Christopher Howe in the University of Cambridge’s Department of Biochemistry, joint senior author of the study paper.

“Our photosynthetic device doesn’t run down the way a battery does because it’s continually using light as the energy source.”

In the experiment, the device was used to power an Arm Cortex M0+, which is a microprocessor used widely in Internet of Things devices.

It operated in a domestic environment and semi-outdoor conditions under natural light and associated temperature fluctuations, and after six months of continuous power production the results were submitted for publication.

“We were impressed by how consistently the system worked over a long period of time — we thought it might stop after a few weeks but it just kept going,” said Dr Paolo Bombelli, from the University of Cambridge’s Department of Biochemistry, first author of the paper which has been published in the journal Energy and Environmental Science.

The algae does not need feeding, because it creates its own food as it photosynthesises and despite the fact that photosynthesis requires light, the device can continue producing power during periods of darkness.

The researchers think this is because the algae processes some of its food when there’s no light, and this continues to generate an electrical current.

The Internet of Things is expected to grow to one trillion devices by 2035, requiring a vast number of portable energy sources.

The researchers say that powering trillions of Internet of Things devices using lithium-ion batteries would be impractical.

They say it would need three times more lithium than is produced across the world annually and traditional photovoltaic devices are made using hazardous materials that have adverse environmental effects.

The work was a collaboration between the University of Cambridge and Arm, a company leading the design of microprocessors.

The research was funded by the National Biofilms Innovation Centre.