A colony of blue-green algae can power a computer for six months

Researchers from the University of Cambridge have managed to run a computer for six months, using blue-green algae as a power source.

A type of cyanobacterium called Synechocystis sp. PCC 6803 – commonly known as “blue-green algae”, which produces oxygen through photosynthesis when exposed to sunlight, was sealed in a small container, the size of an AA battery, made of aluminum and clear plastic.

The research was published in the journal Energy and Environmental Sciences.

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Christopher Howe from the University of Cambridge and colleagues say similar photosynthetic energy generators could be the power source for a range of small devices in the future, without the need for the rare and unsustainable materials used in batteries.

The computer was placed on a windowsill in one of the researchers’ homes during the COVID-19 lockdown in 2021, and remained there for six months, from February to August.

The battery made of blue-green algae supplied direct current through its anode and cathode which operated a microprocessor.

The computer worked in cycles of 45 minutes. It was used to calculate sums of consecutive integers to simulate a computational workload, which required 0.3 microwatts of power, and 15 minutes of standby, which required 0.24 microwatts.

The microcontroller measured the device’s current output and stored that data in the cloud for researchers to analyze.

Howe suggests that there are two potential theories for the power source. Either the bacterium itself produces electrons, which creates a current, or it creates conditions where an aluminum anode in the container is corroded in a chemical reaction that produces electrons.

The experiment took place without any significant degradation of the anode and because of this, the researchers believe that the bacteria produces most of the current.

Further research is needed

Howe says the approach could be extended, but more research is needed to determine how far. He explains that installing one on your roof will not provide enough energy for your home. But in rural areas of low- and middle-income countries, in applications where a small amount of power could be beneficial, such as environmental sensors or cellphone charging.

The bacterium creates its food during photosynthesis and the battery can continue to produce energy during periods of darkness. Researchers believe this is possible because bacteria process excess food.

The researchers believe that effective devices could be produced at lower cost and that commercial applications will be possible within five years.

They also found other species of algae that create higher currents.

So it looks like we will soon be using algae as a source of living energy, just as the machines used humans as batteries in the Matrix.

Summary of the study:

Sustainable, affordable and decentralized sources of electrical energy are needed to power the network of electronic devices known as the Internet of Things. The power consumption of a single Internet of Things device is modest, ranging from μW to mW, but the number of Internet of Things devices has already reached several billion and is expected to reach one trillion by 2035, requiring a large number portable energy sources (for example, a battery or an energy harvester). Batteries are largely based on expensive and unsustainable materials (e.g. rare earth elements) and their charge eventually runs out. Existing energy collectors (eg, solar, temperature, vibration) last longer but may have adverse environmental effects (eg, hazardous materials are used in photovoltaic generation). Here we describe a bio-photovoltaic energy harvesting system using photosynthetic microorganisms on an aluminum anode that can power an Arm Cortex M0+, a microprocessor widely used in Internet of Things applications. The proposed energy harvester has operated the Arm Cortex M0+ for more than six months in a home environment under ambient light. It is comparable in size to an AA battery and is constructed using common materials that are durable, inexpensive and widely recyclable.

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