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Powering computers with algae

TECHNOLOGY/ENVIRONMENT

Scientists from the University of Cambridge in the UK have been using a common species of blue-green algae to power a microprocessor computer chip continuously for a year — and counting — using nothing more than ambient light and water. They argue such a system has the potential to power billions of small devices both reliably and renewably.


The team took a colony of non-toxic algae — called Synechocystis — that naturally harvests energy from the sun through photosynthesis and sealed it inside a metal enclosure the size of an AA battery, which was then left on a windowsill to generate an electrical current. The algae didn’t need feeding, rather it gathered all its energy needs from natural sunlight, and was even able to continue producing power at night drawn from energy stored during the day. The team thinks this is because the algae processes some of its food when there’s no light, and this continues to generate an electrical current.


The system is made of common, inexpensive and largely recyclable materials, meaning it could easily be replicated hundreds of thousands of times to power large numbers of small devices as part of the Internet of Things. While this is only a proof of concept, its creators say algae-powered chips have an advantage over traditional batteries or solar power because it has a smaller environmental footprint and could potentially provide continuous power. They say it’s likely to be most useful in off-grid situations or remote locations, where small amounts of power are required.


“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 Professor Christopher Howe from the Department of Biochemistry, joint senior author of the study, which has just been published in the journal Energy & Environmental Science after the system ran continuously for six months. “Our photosynthetic device doesn’t run down the way a battery does because it’s continually using light as the energy source.”


Dr Paolo Bombelli, also from the university’s Department of Biochemistry and first author of the study concurs, saying, “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.”


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, this network comprises many billions of devices from smartwatches to temperature sensors in power stations. This figure is expected to grow to one trillion devices by 2035, requiring a vast number of portable energy sources.


The researchers say powering so many devices using lithium-ion batteries would be impractical: 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.


Although using algae in this way is definitely unusual, it’s also part of a growing area of research known as biophotovoltaics, a field that aims to harness the power generated by biological microorganisms that naturally convert light into electricity through photosynthesis. Although so far extremely inefficient — with plants absorbing only 0.25 percent of the energy of sunlight, compared to 20% absorbed by solar panels — advocates argue biophotovoltaics could be cheap to produce and environmentally friendly. Some even imagine, in the future, giant “lily-pads” that float on water could be coated in algae to act as mobile power stations alongside offshore wind farms.


TOP Chris Howe (left) with the algae device and Paolo Bombelli (right) holding a flask of algae

BOTTOM A colony of algae was enclosed in a unit the size of an AA battery

PHOTOS Paolo Bombelli/Creative Commons


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

Chris Howe


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