The University of Cambridge uses cyanobacteria to generate electricity and run computers for a year

We know that IoT devices require a sustainable, affordable, decentralized source of electrical energy to power them. While the power consumption of a single IoT device is modest, ranging only from microwatts to megawatts, the number of IoT devices today is in the billions and is expected to increase to a trillion by 2035, which requires massive amounts of portable energy , such as a battery or an energy harvester.

But batteries mostly rely on expensive and unsustainable materials (such as rare earth elements) and eventually run out of charge.

Existing energy harvesters (e.g. solar energy, temperature, vibration), although lasting longer, are not environmentally friendly, such as the use of harmful materials in photovoltaic production.

So, is there an energy harvesting system that is portable, cheap and durable, and also protects the environment?

A research team at the University of Cambridge tells you: Of course there is!

It’s this container of blue-green algae that has powered a computer for up to a year!

The device is 6 cm high, 3.1 cm long, and 2.3 cm wide, which can be said to be very small. (I understand the truth, why does this picture look so big…)

Moreover, the materials it requires are simple, cheap and recyclable:plastic, aluminum, cyanobacteria, water.

Day and night, super battery life for more than six months

This energy harvester is aBiophotovoltaic Energy Harvesting System, which was developed by Professor Chris Howe and colleagues from the Department of Biochemistry at the University of Cambridge. The study, titled “Powering a microprocessor by photosynthesis,” has been published in the journal Energy&Environmental Science.

Paper address:

https://pubs.rsc.org/en/content/articlelanding/2022/EE/D2EE00233G

The researchers used aluminum and clear plastic to create a metal case the size of an AA battery, which housed a cyanobacterial flora called PCC 6803, commonly known as “cyanobacteria.”When cyanobacteria are exposed to sunlight, it can produce oxygen through photosynthesis.

▲ Cyanobacteria (Photo source ScienceDirect)

Staying on the windowsill of team member Paolo Bombelli’s home during the 2021 lockdown ARM Cortex-M0+ Continuous power supply.

▲ Arm Cortex-M0+ microprocessor

The ARM Cotex-M0+ chip comes from chip maker Arm, who has partnered with a research team at the University of Cambridge to provide it with test equipment and a cloud interface for data collection. This chip is not designed for research, but a microprocessor commonly used in IoT devices.The CPU of the Raspberry Pi Pico is it.

▲ The cyanobacteria power generation device that powers the ARM chip

The researchers thought that the system might stop working after a few weeks, but it worked day and night for 6 months, and after the experiment ended, the cyanobacteria continued to generate electricity, which has been running until now.

So how does this device generate energy?

The Magical “Alchemist”

There are theoretically two possible sources: either the cyanobacteria themselves generate electrons, which generate an electric current, or they create the conditions in which the aluminum anode in the container is corroded in a chemical reaction, which generates electrons and an electric current. In this experiment, there was no significant degradation of the anode, so the researchers believe that the cyanobacteria produced most of the current.

In recent years, seaweed has become the new darling of biofuels. Algae can generate hydrogen, purify wastewater, remove carbon dioxide from the atmosphere, etc., and become a great “alchemist”, with strong potential to develop clean technology.

The PCC 6803 used in this experiment is a strain of single-celled freshwater cyanobacteria belonging to Synechocystis sp. Like other plants, it can obtain energy from sunlight through photosynthesis and generate a weak electric current.

So as long as you put electrodes in the water tank, you can use the generated current as a battery. The processors of IoT devices only need very little power to drive, so using algae to power IoT devices is very suitable.

During the experiment, the algae-powered microcomputer performed some basic calculations, simulating the computational workload by summing consecutive integers in 45-minute cycles, consuming only 0.3 microwatts of power, and 0.24 microwatts on standby for 15 minutes. watts of electricity. The computer itself measures the current output by the device, and this data is stored in the cloud for researchers to analyze.

▲ Research team members Christopher Howe (left) and Paolo Bombelli (right), the picture comes from the University of Cambridge

Although the current generated by this device is relatively weak, it is enough to charge some small electronic devices. However, it is not enough to power an ordinary desktop computer. The actual energy consumption of a computer will vary depending on factors such as workload and age. If a computer consumes 100 watts of power per hour, then It takes about 333,000,000 algae “batteries” to run this computer. Therefore, further scale-up is required in the future to power devices that consume more power.

The current algae “battery” is a bit smaller, but Christopher Howe is particularly proud of the device’s battery life. “This photosynthesis device doesn’t run out as quickly as a battery.” Compared with traditional batteries or solar energy, algae are more sensitive to battery life. Low environmental dependence, continuous use of light as an energy source to provide continuous electricity.

The algae don’t need to be fed, they can “produce” their own food during photosynthesis, harvesting energy from natural sunlight. Moreover, in the absence of light at night, the device can continue to be powered by “eating” the electricity stored during the day. Algae are divided into autotrophic and heterotrophic types, the most common and easy to obtain is the photoautotrophic type. In other words, there is “light” to say anything.

Algae, so much more than pond scum

The device is currently only available inproof-of-concept stageIn the next step, researchers are likely to apply algae-powered chips to IoT devices. The Internet of Things has a large power gap, and it requires a continuous energy supply system like algal biopower generation, rather than a battery that simply stores energy.

In recent years, carbon has peaked and carbon neutrality has become very windy. Carbon sequestration and emission reduction are a key part of achieving global carbon neutrality. For example, using algae photosynthesis to power a certain machine equipment belongs to the category of “green computing”.

“Green computing” is disassembled and understood. Green is simply low-carbon and harmless, that is, environmentally friendly, resource-saving, and can be recycled efficiently. Computing can be understood as including terminal equipment, servers and related systems that combine software and hardware.

Algae is a common marine creature that has appeared 3.5 billion years ago, and it is also considered to be TopX, the most oxygen-releasing creature in the world. The utilization of algae energy belongs to “biophotovoltaics” (BPV), which is a biological way to utilize solar energy. It sounds as if a fresh wind is about to blow through the industrial land. Humans use the energy generated by microorganisms through photosynthesis to power equipment for the industry. Thinking about it, isn’t it a waste of billions of years of energy generated by microbial photosynthesis? The reclamation hoe needs to be swung more often.

Of course, the peacock still exposes its buttocks. This project is not without its shortcomings. For example, in addition to the small scale of algae “battery” production,Algae are extremely energy efficient – In the same scenario, solar panels absorb 20% of sunlight, while plants absorb 0.25%. This project clearly needs to be accompanied by a solution.

The good news is that researchers have found algae that produce higher currents, and combined with extremely low cost, sonext 5 yearsLarge-scale commercial applications are likely to be realized.

It is conceivable that in the near future, the vast sea area is covered with algae in the shape of huge lotus leaves, and their identity is the mobile power station of offshore wind farms.