In a dreadful vision of a future cut off from the sun, the machine overloads into the Matrix film series turned to sleeping human bodies as sources of electricity. Had they had sunlight, seaweed would undoubtedly have been the best choice.
Engineers at the University of Cambridge in the UK ran a microprocessor for more than six months using nothing more than current generated by a common species of cyanobacteria. The method is intended to provide power to vast swarms of electronic devices.
“The growth of the Internet of Things needs an increasing amount of energy, and we believe this will need to come from systems that can generate energy, rather than just store it like batteries,” says Christopher Howe, biochemist and (we assume) mechanical non-human.
Unlike the side of the internet we use to tweet and share TikTok clips, the Internet of Things connects less opinionated things like washing machines, coffee makers, vehicles, and environmental sensors remotely.
In some cases, these devices operate far from a power grid. Often they are so far apart, or in such inconvenient places, that there is no easy way to insert a new battery when they run out, or repair their power source if it degrades. or break.
For technology that operates on a simple flicker of current, the solution is simply to absorb energy from the environment, capturing motion, carbon, light or even waste heat and using it to emit voltage .
Photovoltaic (solar energy) cells are an obvious solution in today’s world, given the rapid progress that has been made in recent years to extract more energy from each ray of sunlight.
If you want power at night, however, you’ll need to add a battery to your device, which not only adds bulk, but requires a mixture of potentially expensive and even toxic substances.
Creating a “living” energy source that converts materials in the environment, such as methane, results in a greener, simpler electric battery that doesn’t fade when the sun goes down. On the other hand, they will run out of juice the moment their food supply runs out.
Algae could be the solution that offers an intermediate option, acting as a solar cell and a living battery to provide reliable current without the need for nutrient supplements. Already explored as a power source for larger operations, algae could also provide power to countless small devices.
“Our photosynthetic apparatus doesn’t discharge like a battery, because it continually uses light as its energy source,” Howe explains.
Their bio-photovoltaic system uses aluminum wool for an anode, primarily because it’s relatively easy to recycle and less of an issue for the environment compared to many other options. It also allowed the team to study how living systems interact with energy-generating aluminium-air batteries.
The “bio” part of the cell was a strain of freshwater cyanobacteria called Synechocystselected for its ubiquity and the fact that it has been so widely studied.
Under perfect lab conditions, an AA battery-sized version of the cell managed to produce just over four microwatts per square centimeter. Even when the lights were off, the algae continued to break down food stores to generate a smaller but still appreciable current.
That might not seem like a lot, but when you only need a tiny bit of energy to function, algae energy can be the perfect solution.
A reduced instruction set 32-bit programmable processor commonly used in microcontrollers was given a set of chews for a 45-minute session, followed by a 15-minute rest.
Left in ambient lab light, the processor performed this same task for more than six months, demonstrating that simple algae-based batteries are more than capable of running rudimentary computers.
“We were impressed with how smoothly the system worked over a long period – we thought it might stop after a few weeks, but it kept going,” says biochemist Paolo Bombelli.
Given the rate at which we’re finding new ways to integrate electronics into everyday objects, it’s clear that we can’t keep making lithium-ion batteries to power them all.
And frankly, using sleeping human bodies to power vast swarms of computers is just plain overkill. Right, the machines?
This research was published in Energy and Environmental Sciences.