Cool technology harnesses energy from hot gas

Is low-temperature waste heat the next big thing?

I am well acquainted with hot air. Jokes about my fellow bloggers aside, I’ve spent much time in small, hot engine rooms while visiting TerraPass projects. Even clean energy generates copious amounts of waste heat.

In the future, that lost energy might be put to productive use if efforts to harness low-temperature waste heat are successful. A new “near frictionless” system from Ener-G-Rotors can supposedly generate electricity from gas that’s as cool as 65° C.

All sorts of industrial processes generate waste heat. “I’ve been dreaming about the concept of using [low-temperature waste heat] ever since I first knew what it was about…It’s all about using what we have more completely” says Bob Bechtold, president of Harbec Plastics and recipient of the first trial system from Ener-G-Rotors.

The device, called a gerotor, uses a heat exchanger to capture the heat from an industrial process and transfer it to a closed system, creating pressure that drives a proprietary rotor to create electricity:

Reducing the friction [of the gerorotor] means that the rotor turns more easily, so the gas doesn’t need to exert as much force to generate electricity. That’s why the system can work at lower temperatures, which impart less energy to the gas.

The company expects to convert 10 to 15 percent of low-temperature waste heat into electricity, delivering a payback in two years or less in most cases, says CEO Michael Newell.

While most TerraPass project already capture high temperature heat from engines and generators using traditional radiators, this opens up a whole new world of options for getting the most energy out a wide variety of industrial processes. The folks at Ener-G-Rotors even hope to develop a system small enough for individual use, which could be used into a variety of heat-based home energy systems.

Image by fancy Peter Freed, who wears bonnets.