This algae fed a computer for a year with only water and sunlight

Nearly three billion years ago, oceanic mats of cyanobacteria called blue-green algae transformed Earth’s atmosphere by converting carbon dioxide into the oxygen we breathe in complex animals. In their time on the planet, they have survived five mass extinctions using only light and water. And now, in a small tank on a windowsill in England, this billion-year-old piece of biotechnology lends its expertise to a relative novice.

Built by Cambridge scientists, the tank is about the size of an AA battery and features four plastic windows in a simple aluminum frame. Inside, a colony of algae takes in sunlight and converts it into food through photosynthesis. In doing so, they produce a small electrical current, which makes its way to electrodes in the aluminum frame. To this, the researchers attached a low-power computer chip programmed to run in cycles — 45 minutes on and 15 on standby — and left this curious device alone for six months.

To their surprise, it trudged on incessantly and without complaint.

“We were impressed with how consistently the system worked over a long period of time — we thought it would stop after a few weeks, but it just kept going,” said Paolo Bombelli, a Cambridge biochemist and lead author of a paper on the subject. work.

The system is not just a simple power source constructed from readily available parts and materials, it works day and night (unlike solar energy). The algae, the team thinks, are producing too much food during the day, so they continue to nibble happily and produce electricity all night. Although the article covers their findings from that initial six-month period, their algae-powered computer has been running continuously for a year (and still is).

It’s a pretty neat trick, but some scaling is probably in order. The system produces a small amount of power. The chip, an Arm Cortex M0+ commonly used in Internet of Things applications, only uses 0.3 microwatts per hour to perform very simple calculations. if The edge notes, if your average laptop uses about 100 watts per hour, you’ll need millions of these algae energy harvesters to check your email or go out in a Zoom meeting.

But the researchers are not focusing on laptops. Rather, they believe that future iterations would find a niche application powering the billions or trillions of simple sensors and chips of the Internet of Things. For example, they can measure local conditions in remote locations, or they can charge a small device.

†[Scaling] is not entirely self-evident. So if you put one on your roof, it won’t power your home at this stage,” said lead author Christopher Howe. new scientist† “There is still a lot to do in that area. But [it could work] in rural areas of low- and middle-income countries, for example in applications where a small amount of power can be very useful, such as environmental sensors or charging a mobile phone.”

But there is room for improvement. There are thousands of species of cyanobacteria, and the team found that some products are more topical than others. In previous research, the team also genetically modified cyanobacteria to produce electricity more efficiently.

Other benefits are more immediately visible. The required materials are recyclable, cheap and scalable. While batteries and solar cells are dirty to produce and require materials that are not always readily available, such as lithium and rare earth elements, aluminum, plastic, algae and water are easier to obtain with less mess. The team even tested a model of the system that reuses regular plastic water bottles.

The hope is that these types of systems can be replicated hundreds of thousands of times to power edge devices and may be commercially viable within five years. Whether that turns out to be true remains to be seen, but it seems we need alternative forms of power anyway. The team estimates that trillions of devices running on lithium-ion batteries require three times the amount of lithium produced each year. And as Stewart Brand recently told The New York Timesprogress is all about “add options”.

Anyway, wouldn’t it be appropriate if the organism that gave us the air we breathe helps us measure, among other things, and also keep it clean?

Image credit: Paolo Bombelli

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