The engines are powered by the movement of spores in response to humidity.
As Earth’s surface warms, evaporation rates speed up. A new device designed at Columbia University harnesses the power generated by evaporation. If produced in large-scale, the device has the potential to make evaporation an important global source of renewable energy.
The research, “Scaling up nanoscale water-driven energy conversion into evaporation-driven engines and generators” is published in the journal Nature Communications. The article is open-access and can be read in its entirety. Columbia University has filed a patent for the energy generation device.
Ozgur Sahin, Ph.D, lead author on the research, explains the discovery relies on bacteria spores that expand and contract in response to humidity. In this way, the spores are powered by the water in the air and perform similarly to a muscle. The spores have the ability to generate movement, which can be manipulated by changing humidity conditions.
The scientists designed two different water devices to harness the energy. The paper explains, “These engines start and run autonomously when placed at air–water interfaces.” When testing the small-scale devices, they were able to propel a toy car. On a larger scale, one pound of dried spores could produce enough energy to lift a car.
The first uses a pressure-driven piston engine placed in a plastic box. The spores are glued to a strip enclosing the box. The spores contract when they are exposed to dry air and form a wavy shape. When exposed to humidity, the strip straightens out and produces a tugging motion.
The second device, called the Moisture Mill, functions similar to a wind turbine. The spores are placed on the ends of small strips. The strips are attached to a wheel. One-half of the wheel is exposed to humidity, and the other is exposed to dry air. The spores power the wheel as they move in response to the humidity or air.
In the article, uses are proposed for the technology, such as “Evaporation-driven engines may find applications in powering robotic systems, sensors, devices and machinery that function in the natural environment.” Dr. Sahin claims that harnessing evaporation will combat climate change by providing clean energy and keeping moisture close to the earth.