The Internet of Things (IoT) is a vast and growing network of electronic devices – each using only a small amount of power. Sustainable, affordable, and decentralized sources of electrical energy are required to power this growing network. Powering trillions of Internet of Things devices using lithium-ion batteries would be impractical, and traditional photovoltaic devices are made using hazardous materials that have adverse environmental effects.
Now, Cambridge University 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.
The Cambridge team sealed Synechocystis, a type of non-toxic algae that harvests energy from the sun through photosynthesis, inside a transparent compartment. The tiny electrical current this generates then interacts with an aluminum electrode and is used to power an Arm Cortex M0+, a low-power microprocessor that’s commonly used in Internet of Things (IoT) devices.
It is comparable in size to an AA battery and is built using common, durable, inexpensive, and largely recyclable materials. This means it could easily be replicated hundreds of thousands of times to power large numbers of small devices as part of the Internet of Things. Also, it is likely to be most useful in off-grid situations or remote locations, where small amounts of power can be very beneficial.
The proposed energy harvester has operated the Arm Cortex M0+ for over six months in a domestic environment and semi-outdoor conditions under natural light and associated temperature fluctuations. The team argues that this type of solution can be used to guarantee the supply of electricity to various small appliances without the need for rare materials like batteries.
“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 in the University of Cambridge’s Department of Biochemistry, first author of the paper.
The team says that the device can even continue producing power during periods of darkness. They believe this is because the algae process some of its food when there’s no light, and this continues to generate an electrical current. This algae-based energy harvester doesn’t generate a huge amount of power, but it’s enough for IoT devices.