An electric seaweed generator to supply our electronic equipment in an environmentally friendly way

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The search for green, sustainable energy sources without significant impacts on the environment is one of the great challenges of our time. Climate change is accelerating, resources are running out, while all the technologies that unite our ultra-connected way of life and ecology are on the rise. Recently, American researchers demonstrated the ability of certain algae to keep a computer processor running for almost a year! These promising results could indicate a potential solution to the growing energy demand of our electronic equipment.

The Internet of Things (IoT) or IoT in English (internet of things), is the interconnection between the Internet and objects, places and physical environments. The term refers to an increasing number of objects connected to the Internet, thus allowing communication between so-called physical goods and their digital stocks. Therefore, sustainable, affordable and decentralized energy sources are needed to power this network of electronic devices.

The power consumption of a single device connected to the Internet is often modest, and requires power ranging from μW (microwatt) to mW (millwatt). But the number of devices has already reached several billion and is expected to reach one trillion by 2035, requiring a large number of portable power sources (batteries or power collectors). However, batteries are largely based on expensive and unsustainable materials (rare earth elements), and their carrying capacity runs out. Existing energy sensors (solar, temperature, vibration) last longer, but can have adverse effects on the environment. In particular, hazardous materials are used in photovoltaic production.

In this context, a team from the University of Cambridge, led by Christopher Howe of the Department of Biochemistry, has developed a system capable of generating energy with algae. His work has been published in the journal Energy and environmental science.

Photosynthesis as an engine

In order to create a photosynthetic device capable of generating energy on its own, the team studied a non-toxic alga called Sinecocystis, or “blue-green algae”, used especially in medical research. It naturally uses the sun’s energy through photosynthesis and produces oxygen. But the question was whether that would be enough to power small electronic devices, and that, in a sustainable way.

In simple terms, the system, comparable in size to an AA battery, contains the algae that do photosynthesis. The weak electric current generated in this way interacts with an aluminum electrode and is used to power a microprocessor.

In one experiment, the device was used to power an Arm Cortex M0 +, a microprocessor widely used in connected devices. Specifically, the system only powers the Cortex-M0 + processor on the test chip, with a minimum power of 0.3 µW. The electronic test card verifies the operation of the processor and measures the potential and intensity of the electrical output of the photosynthetic device. The data is transferred to a cloud system, using a Raspberry-pine and a router. The rest of the test chip, apart from the Cortex-M0 + processor, and all the other electronics on the test board, the Raspberry-pi and the router are powered on the grid.

Experimental device with photosynthetic device, test card, Raspberry-pi, and cloud connection. © C. Howe et al., 2022.

Initially, the photosynthetic apparatus was tested in laboratory conditions with exposure to light for 6 hours, then 6 hours in the dark, at a constant temperature of 22 ° C. Second, it operated in a domestic environment, with semi-outdoor conditions with natural light and associated temperature fluctuations. The set produced, for six months, enough electricity to run the processor. The latter worked in cycles: 45 min in calculation mode and 15 min in standby mode, to simulate conventional use.

Cycle of operation of the experimental device. © C. Howe et al., 2022.

Dr Paolo Bombelli, of the Cambridge University Department of Biochemistry and lead author of the study, said in a statement: ” We were impressed with the smooth running of the system for a long time – we thought it might stop in a few weeks, but it went on. “In fact, after 6 months of experimentation, the device continued its activity for another 6 months, which lasted a total of almost a year.

Multiple, durable and economical applications

The system is made of common, cheap and widely recyclable materials. This means that it could easily be replicated hundreds of thousands of times to power a large number of small devices as part of the Internet of Things. Researchers believe that it is likely to be more useful in off-grid situations or in remote locations, where such small amounts of power output can be very useful. C. Howe points out: Our photosynthetic device does not discharge like a battery, because it continuously uses light as a source of energy. “.

In addition, algae do not need to be fed, because it creates its own food during photosynthesis. And although photosynthesis requires light, the device continues to produce electricity during periods of darkness. Researchers believe that this is because algae process part of their food when there is no light, which continues to generate electricity.

The use of other recyclable materials, which are found in abundance on Earth, would support the spread of this technology in areas where energy is scarce and where economic means are equally scarce. However, more research is needed to put this breakthrough into action for future marketing. They can also be used to find other species of algae with a higher yield.

Source: Energy and Environmental Science

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