United Kingdom: Green innovations: Algae and sunlight power computing

As the race towards more green tech solutions continues, researchers from the University of Cambridge have announced that they have been working on an interesting energy innovation that could, in the future, replace batteries in small off-grid Internet of Things devices. The device was found to be significantly cheaper to make than a traditional battery, with a much greener footprint. 

Dr. Paolo Bombelli and Professor Christopher Howe of the University of Cambridge’s Department of Biochemistry developed the system, which is the size of an AA battery and made from common, inexpensive, and largely recyclable materials. The system used a species of blue-green algae (a colony of a type of cyanobacteria called Synechocystis sp. PCC 6803) to generate a tiny electrical current while photosynthesizing sunlight into energy. Some of this energy was captured to run an Arm Cortex M0+ microprocessor, which even ran at night. According to Professor Howe, this is likely due to the algae storing the food created during the photosynthesis process and consuming this at night. 

Beginning in February 2021, for six months, the system sat on Dr. Bombelli’s windowsill, powering the Arm processor. This processor, according to the researchers, ran in cycles of 45 minutes calculating integer sums (needing 0.3 microWatts), followed by 15 minutes on standby (using 0.24 microWatts). Following the success of the research project, the scientists submitted their results to the Energy and Environmental Science journal. 

While, currently, the device is still in the experimental phase, and the researchers haven’t proposed any industrial uses, the project shows great potential, which could be scalable. Professor Howe commented: “It’s not entirely straightforward.” Adding: “So putting one on your roof isn’t going to provide the power supply for your house at this stage. There’s quite a bit more to do on that front. But [it could work] in rural areas of low and middle-income countries, for example, in applications where a small amount of power might be very useful, such as environmental sensors or charging a mobile phone.”

Reflecting on the project’s success, Dr. Bombelli, said: “We were impressed by how consistently the system worked over a long period of time – we thought it might stop after a few weeks but it just kept going.” And, the system is still working to this day. The researchers posit two explanations; the first is that the cyanobacteria produce electrons themselves, which in turn creates a current, or that they create conditions where the aluminum anode in the container is corroded. Considering that the researchers witnessed no significant degradation of the anode, for now, the scientists have decided the former explanation is the most plausible.