Electricity in your garden

 By RP Siegel

We know that energy can be produced from fertile soils. After all, that’s where most of the energy that powers our bodies comes from. But can soil directly produce electricity? In Perù, researchers at Universidad de Ingeniería and Tecnología (UTEC/Engineering and Technology University) have developed “Plant Lamp,” a system that taps into nutrients in the soil to collect electricity which is used to charge a battery—enough to run an LED light for a few hours. These lamps are being deployed in rural communities with little or no access to electricity…

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Usually, when we think about sources of clean energy, we don’t think about dirt. But a team of researchers in Peru have found a highly innovative way to combine the two. The result of this convergence is a Plant Lamp, an intriguing contraption that can bring light to some of Peru’s most impoverished areas such as the highlands and the southern jungle. It’s not that there is no power grid in those areas. There is one, though it’s old and unreliable. One of the main problems is the ceaseless growth of the jungle that wreaks havoc with power lines. But clever minds have found a way to turn this problem into a solution.

The Universidad de Ingeniería and Tecnología (UTEC) is an engineering and technology school just outside of Lima. According to Umberto Polar, chief creative officer of FCB Mayo who worked with UTEC on the project, UTEC has a mission to promote engineering and STEM education, so they are constantly on the lookout for projects with a sizzle factor, that will catch the attention of young people, such as billboards that produce clean drinking water from desert air or eliminate pollution.

So, in 2012, when they were looking at ways to provide lighting to remote areas, they took advantage of this opportunity to create something really unique — which they’ve now developed.

According to Elmer Ramirez, Professor of Energy Engineering, one of the researchers on the project, “Based on principles and findings documented in other countries, we developed our own prototype, using a clean energy system. To make this possible, we used what we have in abundance in the rainforest: plants and soil. Every plant produces nutrients, and these nutrients—in contact with microorganisms in the earth called geobacter—undergo an oxidation process, generating free electrons that are captured by electrodes. These electrodes are in a grid. This energy is stored in a conventional battery to be used to light an LED light bulb.”

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At first glance it looks like one of those overhead projectors that you used to see in classrooms and lecture halls. It’s a rectangular box about 18 inches (46 cm) in each direction with a pivoting arm supporting a lamp in front. On top, instead of a flat glass platen, where the transparencies would go, a green plant grows in the soil contained in the box. Beneath the soil are electrodes that collect electric current and a battery to store it. The system collects enough power each sunny day to power the lamp through the night. Inexpensive and simple to maintain, it is being deployed in the area of Nuevo Saposoa. All you need to do is to water the plant and keep it healthy.

The idea was first discovered by Dr. Derek Lovley of the University of Massachusetts, Amherst in 2009. He was doing research for the Office of Naval Research. They were looking for ways to power sensors at the bottom of the ocean, so they didn’t have to keep going down to replace the batteries. They had found that sticking an electrode in the ocean floor sometimes produced a tiny current and asked Dr. Lovley to investigate further. He identified the cause as geobacter, which also thrives on the nutrient-rich ocean bottom.

We asked Dr. Lovley to explain this to a non-biochemist. He said that the bacteria were not so much feeding on the nutrients, which he said included iron oxide, but rather breathing it. That is how these anaerobic bacteria get their oxygen. Electrons are given off in the process.

Lovley has continued to work with geobacter, whose fine protein filaments behave like nanowires, and has found ways to increase their power by a factor of ten.

It raises the question of whether larger plots could not be utilized to produce larger amounts of clean power. That’s exactly what Plant-e has done in Wageningen, Netherlands where they have created the world’s first green electricity roof. According to Marjolein Helder, founder of Plant-e, a complete green electricity roof should be able to produce half the electricity needed in a household.

about the author
RP Siegel
Skilled writer. Technology, sustainability, engineering, energy, renewables, solar, wind, poverty, water, food. Studied both English Lit.and Engineering at university level. Inventor.