Scientists at the University of Cambridge, Università degli Studi di Milano, Scottish Association for Marine Science, and the Norwegian University of Science and Technology, working with United Scientists CORE and Arm, have created a computer powered by photosynthesis — turning algae into functional solar energy harvesters for electronics.
"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," says Christopher Howe, professor at the University of Cambridge's biochemistry department and joint co-author of the paper. "Our photosynthetic device doesn’t run down the way a battery does because it’s continually using light as the energy source."
Slightly bigger than a AA battery, the energy-harvesting device the team has created doesn't use photovoltaic cells in the traditional manner; it's instead built using blue-green algae and aluminum wool, turning sunlight into electricity through photosynthesis.
To prove the concept, the team put the device to work powering a test-bed microprocessor board based on an Arm Cortex-M0+ core and transmitting sensor readings to a remote server via a Raspberry Pi. Situated in domestic and semi-outdoor conditions with access to natural light, the device operated continuously for six months before the paper was written and submitted — and has since been running for six months more without rest, even operating in complete darkness.
"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," says first author Paolo Bombelli, PhD and first author of the paper.
The team is eager to see the technology pushed still further, claiming it to be a realistic solution to the problem of powering the growing Internet of Things — calculating that projections pointing to a trillion IoT devices online by 2035 would require three times as much lithium as is produced globally each year for battery power, while traditional photovoltaic panels use materials far more hazardous than blue-green algae.
The team's work has been published in the journal Energy & Environmental Science under closed-access terms.