Soil becomes battery

Soil becomes battery. In addition to foundations and a source of food, the soil is also increasingly becoming a source of new technology. As an alternative power source for example.

It has something magical. When Dr. Marjolein Helder in the office of her Wageningen company Plant-e, if you connect an LED light to two wires protruding from a planter, the light will spontaneously turn on! “And no, there is no battery in the soil,” laughs Helder. “This planter is part of our modular system. You can link several of these planters, up to a system of one hundred square meters. There are now such systems in various places in the country. For example, the municipality of Ede has an illuminated crash barrier that receives its power from one hundred square meters of these planters. For example, a company can also use that hundred square meters to power a Wi-Fi hotspot.”

*This barrier in Ede is illuminated on the basis of the current from the soil of an adjacent wet green strip.*

BACTERIA

Strictly speaking, there is of course a kind of battery in the soil of the planter. Bacteria around the roots of plants live on the nutrients they receive from that plant. These so-called exudates consist for a large part of sugars, which are broken down by the bacteria. In that process free, negative electrons and positive hydrogen ions are formed. "What we do is nothing more than draining charged particles with the help of electrodes." Clearly it sounds surprisingly simple, but the principle is not really obvious. At the time it was so innovative that there is now a patent that is in the hands of Plant-e, the company that Helder founded together with David Strik in 2009.

Not all plants seem suitable to play in the socket, explains Helder. "It is important that no oxygen reaches the roots. If there is oxygen, then those free electrons from the bacteria prefer to sit on the oxygen atoms, then on our electrode. This means that you can only get electricity from plants that are completely submerged with their roots. This ensures oxygen-free conditions and at the same time makes the electrons flow easily via the water to the poles of our 'generator'. "

SUSTAINABLE

The technique of electricity extraction from plants and bacteria is extremely sustainable, says Helder. "There are also gadgets that draw power from, for example, an apple. By putting a copper and a zinc electrode in an apple you can also gain a little bit of electricity. But in that process the two electrodes dissolve very slowly. Then you bring copper and zinc into the environment. We use inert electrodes. Nothing happens during the electricity production. And also the plant and the bacteria are no different. They continue to grow as hard as ever. No extra manure is required. The system runs for 100% on the sunlight where the plants get their energy from. "

On the roof of the Netherlands Institute of Ecology in Wageningen, planters supply electricity via the wires protruding from the front.

PEAT GENERATOR

In addition to the switchable planters, Plant-e has now also produced a kind of pipes, incorporating all the necessary technology. "This summer we have dug these pipes in a peat meadow area in South Holland as an experiment, and we will also do this in a wet nature area in Brabant. Our dream is that we can lay these pipes in the soil of much more existing wet nature areas. In this way you can extract electricity from the plants without affecting that nature. "

Slightly further away in Wageningen, on the roof of the Netherlands Institute for Ecology, the NIOO, Plant-e has already built the first electricity-producing green roof in the world. There are plants in a layer of water that actually supply electricity. "The honesty area to say that this roof does not yet provide much electricity, but this was above all a proof of the principle. We barely maintain the system, but it already delivers a bit of power. In winters with freezing cold, the system also stopped for a while after the thaw started again. But for us this roof was the prelude to more electricity-generating green roofs that we want to develop together with, for example, construction companies. "

"Although Plant-e's products are still under development and are still quite pricey, the company already has products for consumers," explains Helder. "You can purchase your own plant batteries as a Do-It-Yourself package via the webshop."

This article is a publication of Foundation for Life Sciences and Society.
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