Yes, We Can—Make Energy From Water Vapor

In the future, this newly created film might be able to harvest energy when placed above a lake or river.
An animated view of the polymer film in action. (Dr. Ning Zhang)
Jan 18, 2013
A former Gourmet staffer, Lawrence enjoys writing about design, food, travel, and lots of other stuff.

I sometimes think scientists and biotechology engineers have the coolest jobs around. They can be conducting an experiment looking, or hoping, for a particular result and end up with something totally unexpected and, well, cool.

For example: Generating electricity by harnessing the power of water vapor.

“Initially, we planned to develop a strong and flexible polymeric electrode for tissue engineering purposes,” Mingming Ma, a postdoc at MIT’s David H. Koch Institute for Integrative Cancer Research and lead author of a paper describing the discovery, told TakePart. “We designed our material based on well-studied polypyrrole [a chemical compound], but also added the second polymer component: polyol-borate.”

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“We found that this new composite material was highly responsive to water vapor, which was unexpected and unique. Then we studied the mechanism of its water-responsive property and designed a generator that can harvest energy from low-temperature water vapor to generate electricity.”

Ma explained that when the polymer film the researchers created lies on a surface that contains even a small amount of moisture its bottom layer absorbs evaporated water, which then forces the film to curl away from the surface. “Once the bottom of the film is exposed to air, it quickly releases the moisture, somersaults forward, and starts to curl up again. As this cycle is repeated, the continuous motion converts the chemical energy of the water gradient into mechanical energy,” said Ma.

MIT News noted that this type of film could act as either actuators (a type of motor) or generators. “The researchers demonstrated that a 25-milligram film can lift a load of glass slides 380 times its own weight, or transport a load of silver wires 10 times its own weight, by working as a potent water-powered “mini tractor.’ ”

Asked how this was possible, Ma explained: “It’s like the power of ants. Ants can lift objects much heavier than themselves. What happens is that when the film is absorbing water and curling, there is a strong force, or stress, generated inside the film. This force is strong enough to lift heavy objects. That’s why this type of material is called artificial muscle.”

While Ma noted that real-world applications are at least five years off, the possibilities are extremely diverse.

“Potential applications include large-scale water-vapor power generators, or small generators to power wearable electronics,” he said. “If used to generate electricity on a larger scale, the film could harvest energy from the environment—for example, while placed above a lake or river. Or, it could be attached to clothing, where the mere evaporation of sweat could fuel devices such as wearable physiological parameter monitoring sensors (for blood pressure and heart rate). On a smaller scale, the film could power microelectrical mechanical systems, including environmental sensors, or even smaller devices, such as nanoelectronics.”

As if all of that weren’t enough, because the new polymer film uses so little water, it’s also environmentally friendly.

Can you imagine other ways this new material might be used? Let us know in the COMMENTS.

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