Q&A: How the roots of living plants can power your wifi

How can we generate energy from plants without hurting food production? Marjolein Helder, the CEO of the Dutch company Plant-e and a World Economic Forum Technology Pioneer, uses living, growing plants to power LED lights and Wifi hotspots. She talked to us for our XxXX interview series, which profiles ten inspiring women in science and technology.

What do you do?

We produce electricity from living plants while the plant is growing. That means we can harvest electricity without harvesting the plant.

How does it work?

Every plant produces organic matter via photosynthesis. Some of this is used for its own growth, and what's left over is excreted through the roots. Bacteria then feed on the organic matter and release electrons. We use electrodes to harvest these electrons, a process that doesn't harm the plant. It requires a fairly wet environment, for example wetlands, rice paddies, mangroves or peatlands, and it works in both freshwater and saltwater areas.

Are people already using this in daily life?

Yes. We built the first commercial system here in the Netherlands in 2014, and now have several projects at home and abroad. We are working on two systems, a modular system and a tubular system.

The modular system comes as a box that you can use with any plant species that grows in a wet environment. We use four boxes per square metre, which generates about 0.1 watts - enough to light a small LED lamp. Once the plants grow taller, you can't see the boxes.

Our larger-scale tubular system is for existing wetlands. The tubes are inserted into the soil, around the roots. Last year, we started our first pilot project for that, and this year we're going to add another one. Both are in the Netherlands, one in peatland and one on sandy soil.

Who are your clients?

Our largest modular projects are in the Netherlands, including one in a children's play area. It's next to a school, and the children use the energy to power their wifi connection. This summer, we are starting our fourth 100 square meter project in the Netherlands with the Dutch Ministry of Economic Affairs. They are going to install our boxes in their flowering courtyard. We always try to plant native species, and they have to be suited to wet environments - so grasses and irises, for example.

We have clients in the US, Luxembourg and Singapore and are working on a project in Germany. We do a lot of educational work, too. It's really nice to see young people experiment with this new technology. After all, they're the ones who will be installing our systems in the future.

How could this change the way we use and think about energy?

With solar power or biofuel, you are always competing against other ways of using the land. Our population is growing, but our planet will stay the same size. So we will need to use the land more efficiently.

Our approach doesn't force you to decide between growing food and growing fuel. For example, you could use the same paddy to grow rice and produce electricity. There's an extra economic benefit for the rice grower, and in remote locations that lack access to electricity, the plants could power LED lights and other appliances. This could really improve lives.

Another option is to use green roofs to collect rainwater, generate electricity from plants, and increase biodiversity in cities. That's the kind of multiple land use we should be thinking about.

So in the future, will we all be growing our own energy?

We're going to need many different sources of energy, and hopefully ours will be an important part of that mix. I think we are going to approach our energy needs very differently. We will look at a location and say: we need this amount of power, what are the circumstances, what's the most suitable system? If it's hot, dry and sunny, the answer is probably solar. If it's cool and wet, it could be ideal for plant-generated power.

Everything is going to be a lot more linked than it is now. Energy will be only one factor in people's decisions, along with water management, biodiversity and air quality. Sometimes there'll be a trade-off, and people will decide to use a system that generates less energy, but also uses less water.

What are your main challenges?

There is still a lot of fundamental research to be done. This started as a project at the University of Wageningen. In 2007, we found out that the principle worked. Since then, we've tried to figure out why it works and how it works.

We also need to build more trust in the market. We are the first to work on this technology, so there is no one to compare us to. People compare our systems to solar panels, but solar panels have been developed over the past eighty years. Our system has been around for eight years.

So we're still developing it, it's still expensive - but it works. And that's a major breakthrough.

What are your next goals?

We want to lower the price of our boxes and make them available in remote, low-income areas where they could really improve the standard of life. We are also working on our tubular system, which will hopefully be ready for the market in three to five years.

You are a successful female entrepreneur and scientist in an area still dominated by men. What can we do to attract more women to the STEM fields?

That's an interesting question. Here in the Netherlands, there is a relatively level playing field between men and women. I just did what I liked and what I thought would be good for the world, and it brought me to the place where I am now. My parents taught me to believe in myself and to be confident, and I've had many mentors. Ultimately, you should pursue your passion. If you're passionate about something, you're probably good at it.

Interview by Sophie Hardach

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