Using plants to light the way

What if, instead of turning on the lights when it gets dark, you could read by the light produced by your plant? Not one, but two projects are currently working with plants for illumination, each in their own way. The start-up Living Light uses the electricity produced by plants, while researchers at MIT created plants that give off a dim light.

Living Light
The lamp Living Light created uses a living plant to generate its own electricity. Using microorganisms, the chemical energy that a plant naturally produces during photosynthesis is converted into an electric current. The lamp is designed to be self-sufficient so it can function off-grid.

The plants are encased inside a glass tube. As the plant photosynthesises, it releases organic compounds into a soil chamber. The organic matter is broken down by bacteria, which are fostered by a system that mimics bacterial interactions in nature. When this happens, electrons are created that are passed along a wire into the LEDs. These light up when a user touches the plant leaves.

According to Van Oers, the potential is enormous, as the system is applicable to all plants that live in wet ground. Streetlights, for example, could be connected to trees, so that places without electrical grid could be lighted as well.

Researchers at MIT have taken a different approach. By embedding specialised nanoparticles into the leaves of the plants, they induced the plants to give off dim light for nearly four hours.

The team uses luciferase, an enzyme that gives fireflies their glow. Luciferase acts on a molecule called luciferin, causing it to emit light. Another enzyme called co-enzyme A helps the process along by removing a reaction by-product that can inhibit luciferase activity.

The researchers’ early efforts at the start of the project yielded plants that could glow for about 45 minutes, which they have since improved to 3.5 hours. The light generated by one 10-centimetre watercress seedling is currently about one-thousandth of the amount needed to read by, but the researchers believe they can boost the light emitted, as well as the duration of light, by further optimising the concentration and release rates of the components.

The method developed by in the lab could be used on any type of plant. So far, they have demonstrated it with arugula, kale, spinach, and watercress.

For future versions of this technology, the researchers hope to develop a way to paint or spray the nanoparticles onto plant leaves, which could make it possible to transform trees and other large plants into light sources.

Photos: Seon-Yeong Kwak / Living Lights