The computer powered by a colony of blue-green algae has worked for six months

Blue-green algae, a type of cyanobacteria, placed in a container on a window sill powered a computer continuously for six months through photosynthesis.


May 12, 2022

Al-Anode mini device.

A container containing blue-green algae that powered a computer

P. Bombelli

Blue-green algae sealed inside a small container has powered a computer for six months, and the researchers say similar photosynthetic power generators could run a range of small devices cheaply for years to come, without the need for the rare materials. and unsustainable that are used in batteries.

Christopher Howe of the University of Cambridge and his colleagues built a small enclosure about the size of an AA battery out of aluminum and clear plastic. Inside, they placed a colony of a type of cyanobacteria called synecocystis sp. PCC 6803, commonly known as “blue-green algae”, which produces oxygen through photosynthesis when exposed to sunlight.

The device was placed on a window sill in team member Paolo Bombelli’s home during a covid-19 lockdown in 2021, and remained there from February to August. It provided a direct current through its anode and cathode that powered an Arm microprocessor.

The computer ran in 45-minute cycles calculating sums of consecutive integers to simulate a computational workload, requiring 0.3 microwatts of power, and 15 minutes of waiting, requiring 0.24 microwatts. The microcontroller itself measured the current output of the device and this data was stored in the cloud for the researchers to analyze.

Not only were there no power outages for the entire six months, but in the six months since the experiment ended, the bacteria continued to produce power.

Howe says there are two potential theories for the source of the power. Either the bacterium itself produces electrons, which creates a current, or it creates conditions where an aluminum anode in the container corrodes in a chemical reaction that produces electrons. Because the experiment proceeded without significant degradation of the anode, they believe the bacteria are producing most of the current.

Howe says the approach could be extended, but more research is needed to know how far. “It’s not entirely easy,” she says. “So putting one on your roof is not going to provide the power supply for your house at this stage. There is quite a bit more to do on that front. But [it could work] in rural areas of low- and middle-income countries, for example, in applications where a small amount of energy can go a long way, such as environmental sensors or charging a mobile phone.”

The bacteria create their own food during photosynthesis, and the device can even continue to produce energy during periods of darkness, which the researchers believe is possible because the bacteria continue to process excess food.

The researchers have experimented with creating a similar enclosure from empty plastic bottles and believe that effective devices could be produced very cheaply, with a possible commercial application within five years. They have also found other species of algae that create higher currents.

Magazine Reference: Energy and Environmental SciencesDOI: 10.1039/D2EE00233G

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