In Hembrug, Netherlands, a crowd stood in a park and looked up into the evening sky, waiting for lights to shine. This month more than 300 LED lights were illuminated by the Dutch company Plant-e in a new energy project called “Starry Sky.” Although the bulbs were ordinary, the electricity running through them derived from a new process that harnesses the power of living plants.
Plant-e’s technology is the first to produce electricity from plants without damaging them.
“Starry Sky” and a similar project an hour’s drive away, near Plant-e’s Wageningen headquarters, are the two first commercial installations of the company’s emerging technology. Both power lighting, but the company also sells Wi-Fi hot spots, mobile chargers, and rooftop electricity modules, all fueled by the byproducts of living plants.
Plant-e’s co-founder and CEO, Marjolein Helder, believes that this technology could be revolutionary. Using plants to generate electricity brings a new clean energy option to the table, but even more exciting, the company plans to expand the technology to existing wetlands and rice paddies where electricity can be generated on a larger scale. This could give power to some of the world’s poorest places.
Although the idea of using plants and photosynthesis to extract energy is not a new one—for decades middle schoolers have been engineering clocks made from potatoes, which run on a similar principle—Plant-e’s technology is the first to produce electricity from plants without damaging them.
Using plants to generate electricity brings a new clean energy option to the table.
Helder was working on her master’s thesis in environmental technology at Wageningen University when she first began to research plant energy. She had aspirations to be an entrepreneur and agreed to research the technology only if she could spend time each week pursuing her business interests. The two endeavors came together when Helder started working on a business case for what is now Plant-e.
Both projects that lit up the Netherlands this month involved native aquatic plants that were supplied by local greenhouses. The process involves plants growing in modules—two-square-foot plastic containers connected to other modules—where they undergo the process of photosynthesis and convert sunlight, air, and water into sugars. The plants use some of the sugars to grow, but they also discharge a lot of it back into the soil as waste. As the waste breaks down, it releases protons and electrons. Plant-e conducts electricity by placing electrodes into the soil.
Graphic by Jim McGowan.
Harvesting electricity from plants is no easy feat. Ramaraja Ramasamy, an adjunct professor at the University of Georgia College of Engineering, said that what Plant-e uses is called a “sediment microbial fuel cell.” He cautions readers that this technology is not advanced enough to compete with solar panels and wind turbines, which have been in development for years.
“It’s not making enough energy to have any reliable commercial product. That doesn’t mean that it will not be. We are too early in the research,” Ramasamy explained. “If I come to you and say, ‘Do you want to power that 100-watt bulb?’ You probably need an acre of land and dirt to get the electricity from. Is that feasible? No.”
Although it may not be practical in the United States, where households use high amounts of electricity, it could work in other parts of the world.
The next step for Plant-e is using existing wetlands to generate electricity.
Helder says that a one-square-meter garden should be able to produce 28 kilowatt-hours per year. According to the U.S. Energy Information Administration, the average amount of electricity used by a home in a year was 10,837 kilowatt-hours in 2012. This means in order to power a home in the United States, it would take approximately 4,000 square feet of space, the size of a large backyard.
But in the Netherlands, the average household uses 3,500 kilowatt-hours of electricity per year, according to a press release from Plant-e. This means a home in the Netherlands could be powered by an area of Plant-e modules about a third of the size of what the U.S. home would require.
As is the case with solar and wind energy, plant energy yields vary based on climate. In the Netherlands, Plant-e’s installations stop producing electricity for one to two weeks during the coldest part of winter because the technology doesn’t work when the ground freezes. As Plant-e expands to larger markets, this detail could dictate where the product is best marketed.
The next step for Plant-e is using existing wetlands to generate electricity. Engineers would place a tube horizontally below the surface of a wetland, peat bog, mangrove, rice paddy, or river delta, and use the same process as the modular system.
The company created a prototype tubular system last year and was scheduled to start a pilot in July, but it ran into trouble with financing.
Roughly one home in the Netherlands could be powered by one-fourth of the size needed in the United States.
“Modular systems are interesting, but you can only scale up to a certain size because it’s pretty labor- and material-intensive,” Helder said. “A tubular system can just be rolled out through the field and it just works because the plants are already there. So for the longer term, for the really large scale, that’s much more interesting.”
The tubular system is still years away from production. Helder said that although the company hopes to start its field pilots soon, the product will need two to three more years to complete the demo stage and have a commercial product ready for market.