Photosynthesis: How researchers used algae to power computers for months

©Dr. Paolo Pompelli, University of Cambridge

Atlantico: You recently published the results of your study “Powering a microprocessor through photosynthesis” in Energy & Environmental Science. How Have you been able to run the chip for six months ? What mechanism did you create?

Paulo Bombelli and Christopher J. Howe: We used algae, which are common single-celled photosynthetic organisms. Photosynthesis works by using energy from the sun to generate tiny electric currents in the body’s cells. These currents are used to convert carbon dioxide into sugars, and oxygen is produced as waste. However, a small amount of electrical current can be exported from the algae cells, and we can harvest it using an electrode. In our systems, algal cells form a layer, sometimes called a biofilm, on an electrode. We used aluminum for the electrode, although many other materials could be used. The electrode collects current which is then used to power the microprocessor.

How did you come up with the idea that algae could power a microprocessor?

It has been known for several years that algae can generate these tiny extracellular currents. Together with other scientists from around the world we have studied the following important questions: Why do algae do this, if we can increase the amount of current they produce, and what this current can be used for. We thought the microprocessor would be a good example of a “real world” device that could operate with one of these algae systems, and our colleagues at Arm worked with us using one of their microprocessors. We were surprised by the efficiency of the system, which managed to keep the microprocessor working for several months and even then.

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Can your work actually be used tangibly at this point? Or is it too experimental? Or a very limited power?

The power produced is quite low, but it is enough to power this microprocessor used in the Internet of Things. We’ve also used these algae devices to power LED lights and environmental sensors. We like to use larger devices to power mobile phones. But wherever you are on this planet, there are plenty of situations where even a little bit of energy can really come in handy. We are also very keen on creating educational tools based on these devices. They can be used in schools to help people learn more about photosynthesis, renewable energy, and the effects of pollution on photosynthetic organisms.

In the context of a growing need for energy and technological devices, is food by photosynthesis an opportunity for the future? Could you someday power bigger devices?

There will be an increasing demand for sustainable sources of small amounts of energy as the Internet of Things expands. So if we could use our algae systems to power devices in the Internet of Things, there would certainly be many possibilities. We also think that algal systems will be particularly useful where small amounts of energy at off-grid sites can be beneficial. These might be rural communities in low-income countries, for example. In Africa, mobile phones are very important for the delivery of health care. If we could actually use our algae-based devices to charge cell phones, the applications could be many.

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Looking at the numbers, a modern electric shower consumes about 10 kW, so for a small village of only 100 households, the power consumption can reach 1 MW. We do not plan to use seaweed for this. By contrast, environmental sensors can operate at a power of a few thousand watts, and a large number of them, spread over a large area, can be powered by algae.

Are you optimistic about the future of research in this field?

There are many exciting questions we need to answer. How does electric current flow from cells? Can we increase the amount of energy produced, and how do we measure devices? Often, in science, the transition from the laboratory to real-world applications is one of the most difficult steps, and this transition depends on appropriate support from funders. It would also be difficult to convince people associated with conventional solar power generation systems, photovoltaics, that algae-based systems could also be beneficial. But we are excited about this technology and optimistic about its future.

To find the monograph specifically signed by Paulo Bombelli and Christopher J. Howe: click here