A truly green way to power our devices

The digital clock says it’s 2:42 – the blinking colon counting the seconds below a mysterious green box. At a time when ‘being green’ matters more than ever, a team of Cambridge researchers has devised a way to power electronic devices that’s taken the brief quite literally.

“We’ve found a way to tap into a natural process in algae, and use it to generate continuous electricity 24/7 without harming the plant at all,” says Dr Paolo Bombelli in the University of Cambridge’s Department of Biochemistry. He’s scientific lead of a project that began two decades ago - and his self-confessed obsession with algae shows no sign of letting up.

The algae are ‘photosynthetic cyanobacteria’: ancient, aquatic microorganisms that harvest sunlight and take carbon dioxide out of the air to power their growth. This process involves a continuous flow of electrons - essentially electricity - and the team has worked out how to tap off a fraction of it and use this to power electrical devices.

Better than conventional batteries?

“Disposable batteries, which you just throw away when they stop working, are very bad for the planet and we want to use our biocells as a replacement,” says Professor Chris Howe, Principal Investigator of the project in the Department of Biochemistry.

Conventional chemical batteries are built with mined materials like lithium that cause a range of environmental issues: extraction methods are energy-intensive, release greenhouse gases and cause local ecological degradation and habitat destruction. In contrast the biocells are made of common, inexpensive and largely recyclable materials.

The power output of the biocells is low, so the technology can’t be used for devices that need lots of power. The team’s idea is to use it to power large numbers of devices that would normally be powered using small, disposable batteries – for example remote controls or smoke alarms.

“Our technology could replace millions of small disposable batteries with a much a cleaner source of energy – that’s a huge environmental benefit and a really exciting prospect,” says Howe, adding, “there are so many potential applications.”

The technology holds promise for electricity provision in rural, off-grid locations, and Howe says that providing readily available power in low-income countries could be life-changing. In sub-Saharan Africa, for example, mobile phone ownership and coverage is wide, but charging facilities can be very limited in remote rural areas. If the technology can be scaled up to charge mobile phones this improves not only communication, but access to information and online tools.

The team also sees potential to use biocells to power environmental sensors, for example to monitor water quality in remote locations. These require a long-lasting, uninterrupted supply of power and, as they’re often in hard-to-access locations, must run reliably without human intervention to change batteries when they run out.

From lab to market

Now it’s time to prove the biocells have a competitive edge over chemical batteries - and move them into the commercial realm. Grants from the University’s BBSRC Impact Acceleration Account have enabled the team to develop their ideas further by bringing in bio-designer Lucia Giron and electrical engineer Lifu Tan. “Knowing how the technology works is one thing, but transforming it into a product is a very different ball game,” says Bombelli.

The algae clock was Giron's creation, and she’s also produced a temperature sensor interface and a beautifully designed demonstrator cell. Via its start-up company e-Pho, the team is currently in talks with potential clients about specific applications and while these remain confidential, they have several ideas they can showcase. One uses a biocell to keeps tabs on a potted plant in the lab.

Since the team set to work in 2006, a number of other teams across the world have begun investigating similar ideas, but Howe says his has a march on them. “We’ve been one of the most significant places in the world for development and research into this technology, and our continued experiments and refinements have enabled us to increase the power output of the biocell over 20-fold since we started,” he says.

Inspiring future scientists

In a different branch of their efforts, the team has developed a ‘living toolkit’ and dedicated website that they use to run very popular classroom workshops in secondary schools. They also run smaller community events, such as Makespace workshops, for adults.

“School pupils love the chance to build a fully functional system step by step, to grow the algae and run their own experiments,” says Bombelli. “They learn how the system works and how the materials they use affect the results, and they get an insight into different subject disciplines - from biology and electronics.”

Howe adds: “My view is that the school plant science curriculum isn’t very inspiring or contemporary. We want to give schools something that demonstrates the significant applications of plant science in the modern world. Hopefully our workshops will inspire more interest in plant science, and encourage more young people to study it at university and have careers in it.”

Race against time

The team’s two-pronged approach reflects their commitment to helping meet our energy demands more sustainably for the long-term. Commercialising the biocell for greener energy production must go hand in hand with reducing overall energy demand through education and behavioural change. The algae-powered clock continues to tick.