There is “green energy” and then there is really GREEN energy, or rather blue-green energy. A colorful colony of photosynthetic cyanobacteria, known as blue-green algae, successfully powered a computer microprocessor for more than six months, according to a study published Thursday in the journal Energy & Environmental Science.
The small bio-based alternative battery could serve as a means of powering small electronic devices without rare earth elements or lithium, materials in short supply and in growing demand, according to the study’s researchers. What’s more, the system could also help bridge the electrical divide, providing an alternative power supply to people in rural areas or low-income countries, said lead author Chris Howe, a biochemist at the University of Cambridge, in A press release.
During a pandemic lockdown, the algae computer system was placed in the window of the house of another Cambridge biochemist, Paolo Bombelli. He stayed there from February to August 2021, and throughout that time, according to reports by New Scientist. In the additional six months since official testing, scientists said the device and algae computer continued to work.
Although the microprocessor has since been disconnected, the cyanobacterial device continues to produce current. “It still works and I hope it will work for a very long time. Given the right light, temperature and water conditions, I can’t predict when it will stop,” Bombelli said in an email to Gizmodo. To which Gizmodo says: Well done germs!
Cyanobacteria harvest energy from sunlight and make it their own food. For this study, the researchers placed the energy-providing microorganisms (specifically, Synechocyst sp.) in a plastic and steel case, the size of an AA battery, with an aluminum anode.
Throughout the experiment, the attached microprocessor was programmed to do a bunch of calculations and then check its own work. He did this in 45 minute increments, followed by 15 minutes of sleep, continuously for months with the cyanobacteria unit as his only power source.
The researchers offered two hypotheses about how their system created current. In the so-called “electrochemical” model, the microbes have simply created the right conditions for the aluminum anode to oxidize – or release electrons, which then create an electrical output. In the “bio-electrochemical” model, the cyanobacteria themselves generated electrons which were transferred through the bacterial membranes to the aluminum anode, creating a current. Because the aluminum anode doesn’t seem to degrade much over time, scientists think the latter explanation is more likely than the former.
Even though the algae depend on a light source for food, the bio-system continued to produce enough energy to run the microprocessor in the dark. Scientists have basically attributed this phenomenon to the remains. When there was light, the cyanobacteria cooked an overabundance of food, and when it was dark, the microorganisms kept munching on the extras.
The computer, a microprocessor called Arm Cortex-M0+, drew an average of 1.05 microwatts and an electric current of 1.4 microamps, with a voltage of 0.72 V from the cyano-cube during the experiment. For comparison, a standard AA battery starts life at 1.5V, which decreases with use.
Although the results of the experiment are promising, it is important to keep in mind that the processor of the tested computer consumes very little power, requiring only 0.3 microwatts to operate. For context, even an energy-efficient LED bulb uses around 10 watts. More research is needed to find out exactly how far the tiny AA battery-sized device could scale, Howe told New Scientist. “Putting one on your roof won’t provide power to your home at this point.”
Update 5/13/20225:08 afternoon ET: This post has been updated with additional commentary from biochemist and study researcher Paolo Bombelli.
Editor’s note: The release dates in this article are based in the US, but will be updated with local Australian dates as soon as we know more.