In a strange fantasy about a future left off by sunlight, the Matrix film series shifts to sleeping human bodies as sources of electricity. It''s unlikely that algae would have been the better choice if they had sunlight.
Engineers from the University of Cambridge in the United Kingdom have operated a microprocessor for more than six months, utilizing nothing more than the actual actual generated by a common species of cyanobacteria. The method is intended to provide power for vast swarms of electronic devices.
"The growing Internet of Things requires an increasing amount of power, and we believe this will need to come from systems that can generate energy rather than just store it like batteries," says Christopher Howe, a biochemist and (we assume) a non-mechanical human.
And unlike the side of the internet we use to tweet and share TikTok clips, the Internet of Things connects less advanced items such as washing machines, coffee makers, automobiles, and remote environment sensors.
In some cases, these devices operate far from a power grid. Often they''re so distant, or in certain awkward situations, there''s no easy way to get in a fresh battery when they run down, or fix their power source if it degrades or breaks.
For computers that run on a simple flicker of current, the solution is to simply soak up energy from the environment, capture movements, carbon, light, or even waste heatand removing it in order to set out a voltage.
Given the rapid advances that''s been made in recent years in squeezing more energy from every ray of sunshine, photovoltaic cells (solar power) are an obvious solution in today''s society.
Depending on whether you want power at night, you''ll need to add a battery to your device, which doesn''t only add mass, but also adds a variety of potentially costly and even harmful chemicals.
A ''living'' power source that converts material in the environment, such as methane, makes for a greener, simpler power cell that will not weaken as the Sun sets. On the other hand, they will run out of juice the moment their food supply is out.
Algae might be the solution that provides a middle-ground capability, acting as a solar cell and living battery to provide a reliable current without a need for nutritional breakdowns. Now being explored as a source of energy for larger organizations, algae may also provide power for countless tiny devices.
"Our photosynthetic device doesn''t run down the way a battery does, because it is constantly using light as the energy source," says Howe.
Aluminum wool is used as an anode in their bio-photovoltaic system, which is designed to be relatively simple to recycle, but it is less of a problem for the environment compared to other methods. It provides the team with an opportunity to explore how living systems interact with power-generating aluminum-air batteries.
The ''bio'' portion of the cell was a strain of freshwater cyanobacteria called Synechocystis, which was selected for its ubiquity and the fact it''s been so extensively studied.
Fortunately, a AA-battery-sized cell grew by just four microwatts per square centimeter. Even as the lights were out, algae continued to break down food resids to generate a smaller but still noticeable current.
It may not sound much, but when you only need a tiny bit of power to operate, algae-power might be the perfect choice.
A programmable 32-bit reduced-instruction-set processor used in microcontrollers was given a set of sums to chew on for a 45 minute session, followed by a 15 minute rest.
Left in the ambient light of the lab, the processor completed the same task for more than six months, demonstring that simple algae-based batteries are more than capable of operating rudimentary computers.
"We were amazed by how consistently the system worked over a long time, which we thought would stop after a few weeks," says journalist Paolo Bombelli.
Given the speed at which we''re looking for new methods to transform electronics into everyday items, it''s evident we can''t keep churning out lithium-ion batteries to power them all.
This is simply overkill if you are to be able to assemble sleeping human bodies for vast amounts of computing. Is it not working, machines?
This study was conducted in Energy and Environmental Science.