There is “green energy” and then there is really GREEN energy, or rather, blue-green energy† A colorful colony of photosynthetic cyanobacteria, also known as blue-green algae, has successfully powered a computer microprocessor for more than six months. published a study Thursday in the journal Energy & Environmental Science.
The small bio-based battery alternative could serve as a way to power small electronics without rare earth elements and lithium, materials scarce and under growing demand, the study researchers said. In addition, the system could also help bridge the electricity gap, by providing a new power supply for people in rural areas or low-income countries, said senior author Chris Howea biochemist at the University of Cambridge, in a press statement†
During a pandemic lockdown, the algae computer system was placed in the window of another Cambridge biochemist, Paolo Bombelli’s. It sat there from February to August 2021, and all the while it worked, according to report from New scientist. In the six additional months following the official testing, the scientists said the algae machine and computer continued to run.
Although the microprocessor has since been disconnected, the cyanobacteria apparatus continues to produce power. “It’s still running and I hope it lasts for a very long time. Given the right conditions of light, temperature and water, I can’t predict when it will stop,” Bombelli said in an email to Gizmodo. To which Gizmodo says: Good luck with microbes!
Cyanobacteria extract energy from sunlight and use it to make food for themselves. For this study, the researchers placed the energy-providing microorganisms (in particular Synechocystis sp.) in a plastic and steel case, about the size of an AA battery, along with an aluminum anode.
Throughout the experiment, the attached microprocessor was programmed to perform a lot of calculations and then check its own work. It did this in 45 minute increments, followed by 15 minutes of standby, continuously for months with the cyanobacteria unit as the sole power source.
The researchers offered two hypotheses for how their system created power. In the so-called “electrochemical” model, the microbes simply produced the right conditions for the aluminum anode to oxidize — or release electrons, which then create an electrical output. In the “bioelectrochemical” model, the cyanobacteria themselves generated electrons that were transferred across bacterial membranes to the aluminum anode, creating a current. Because the aluminum anode didn’t seem to degrade much over time, the scientists think the latter explanation is more likely than the former.
Although the algae depended on a light source to feed, the biosystem continued to produce enough power to run the microprocessor in the dark. The scientists actually attributed this phenomenon to leftovers. When it was light, the cyanobacteria cooked an abundance of food, and when it was dark, the microorganisms kept munching on the extras.
The computer, a microprocessor called the Arm Cortex-M0+, drew an average of 1.05 microwatts and an electrical current of 1.4 microamps, with a voltage of 0.72 V from the cyano cube over the course of the experiment. In comparison, a standard AA battery starts its life at 1.5V, which decreases with use.
While the results of the experiment are promising, it’s important to keep in mind that the computer processor tested consumes very little power — it only requires 0.3 microwatts. For context, even an energy-efficient, LED bulb uses about 10 watts† More research is needed to know exactly how much the small device the size of an AA battery could scale, How told New scientist. “If you put one on your roof, it won’t provide the power for your home at this stage.”
Update 13-5/20225:08 pm ET: This post has been updated with additional commentary from biochemist and 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.
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