Going green with an algae-powered microprocessor computer

Researchers from the University of Cambridge, U.K., have created a computer system that is powered by algae that harvests energy from the sun. About the size of a AA battery, the cell uses the microscopic organism Synechocystis which photosynthesizes sunlight to generate electrical current. Although the current generated is very small, it is enough to power a microprocessor, and the system had been running continuously for a year.

The biological photovoltaic cell uses Synechocystis algae to harvest energy from the sun.
The biological photovoltaic cell uses Synechocystis algae to harvest energy from the sun. Paolo Bombelli

The system would be most useful for powering small devices in remote locations, according to the researchers. “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 one of the lead researchers, Christopher Howe, in a statement. “Our photosynthetic device doesn’t run down the way a battery does because it’s continually using light as the energy source.”

The algae used in the system doesn’t need any additional food other than sunlight, and it even continues to produce power at night because it continues the process of photosynthesis for a time even when there isn’t light present. The electrical current generated by the algae is sent to an aluminum electrode from where it can be sent to the processor.

To test the system, the researchers hooked up the device to an Arm Cortex M0+ microprocessor, a highly efficient processor which is typically used in Internet of Things devices. It was left in semi-outdoor conditions with typical variations in temperature and sunlight, and it performed even better than the researchers expected.

“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 lead author Paolo Bombelli.

The researchers hope that systems like this one, which is made from cheap and widely available materials, could help replace expensive lithium-ion batteries or traditional photovoltaic systems which use environmentally hazardous materials, especially with the predicted growth of Internet of Things devices.

The research is published in the journal Energy & Environmental Science.

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