A reliable and renewable biological photovoltaic cell

A reliable and renewable biological photovoltaic cell

Biological Photovoltaic Cell

This system, which contains blue-green algae, fed a microprocessor continuously for a year using nothing but ambient light and water. Credit: Paolo Bombelli

Algae-fed calculus

Scientists have used a widespread species of blue-green algae to power a microprocessor continuously for a year – and in large numbers – using nothing but ambient light and water. Their system has the potential as a reliable and renewable way to power small electronic devices.

The system, comparable in size to an AA battery, contains a type of non-toxic alga called Sinechocystis which harvests energy naturally from the sun through photosynthesis. The small electric current it generates then interacts with an aluminum electrode and is used to power a microprocessor.

“Our photosynthetic device does not work like a battery, because it uses light continuously as a source of energy.” – Chris Howe

The system is made of ordinary, cheap and largely recyclable materials. This means that it could easily be reproduced millions of times to power a large number of small devices as part of the Internet of Things. Researchers say it is likely to be most useful in off-grid or remote locations, where small amounts of electricity can be very beneficial.

“The growing Internet of Things needs more and more energy, and we believe that it will have to come from systems that can generate energy, rather than simply storing it as batteries,” said Professor Christopher Howe of the Department of Biochemistry at Cambridge University. main co-author of the paper.

He added: “Our photosynthetic device does not work like a battery, because it uses light continuously as a source of energy.”

In the experiment, the device was used to power an Arm Cortex M0 +, which is a microprocessor widely used in Internet of Things devices. It operated in a home and semi-outdoor environment in conditions of natural light and associated temperature fluctuations, and after six months of continuous energy production, the results were submitted for publication.

The study is published in the journal on May 12, 2022 Energy and Environmental Science.

“We were impressed with how consistently the system worked for a long time – we thought it might stop after a few weeks, but it kept going,” said Dr. Paolo Bombelli of the Department of Biochemistry. of the University of Cambridge, the first author of the paper. the paper.

Algae do not need feeding because they create their own food as they photosynthesize. And despite the fact that photosynthesis requires light, the device can even continue to produce energy during dark periods. Researchers believe that this is because algae process some of the food when there is no light, and it continues to generate electricity.

The Internet of Things is a vast and growing network of electronic devices – each using only a small amount of energy – that collect and share real-time data over the Internet. Using low-cost computer chips and wireless networks, billions of devices are part of this network – from smart watches to temperature sensors in power stations. This figure is expected to increase to one trillion devices by 2035, requiring a large number of portable power sources.

Researchers say that powering trillions of Internet of Things devices using lithium-ion batteries would be impractical: they would need three times more lithium than is produced annually worldwide. And traditional photovoltaic devices are made using hazardous materials that have negative effects on the environment.

The work was a collaboration between the University of Cambridge and Arm, a company that runs the design of microprocessors. Arm Research developed the ultra-efficient Arm Cortex M0 + test chip, built the board, and configured the cloud-based data collection interface shown in the experiments.

Reference: “Powering a microprocessor by photosynthesis” by P. Bombelli, A. Savanth, A. Scarampi, SJL Rowden, DH Green, A. Erbe, E. Årstøl, I. Jevremovic, MF Hohmann-Marriott, SP Trasatti, E. Ozer and CJ Howe, May 12, 2022, Energy and Environmental Science.
DOI: 10.1039 / D2EE00233G

The research was funded by the National Biofilm Innovation Center.

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