Since 2006, Cool Energy Inc., a Boulder-based company, has been developing technology to help capture the excess or wasted heat generated by commercial and industrial processes and convert it into electricity.
“We take heat that is otherwise wasted and turn it into energy, and the market opportunity is enormous in that space,´ said Sam Weaver, Cool Energy’s president and chief executive.
To achieve that, Cool Energy’s seven full-time employees and two contractors are developing a new type of Stirling engine in the company’s Boulder workshop.
The principles behind the Stirling engine have been known since the early 19th century. Gases and fluids inside a Stirling engine are heated and cooled, and can move a piston as they expand and compress. The piston can be attached to a generator, which will create electrical power.
A lot of industrial equipment such as ovens and kilns generate sufficient waste heat to power Stirling engines. The equipment is used in industries such as brick, glass and ceramic manufacturing, and about 20 percent to 50 percent of the energy used in their processes can be lost to waste heat. The U.S. waste-heat recovery market is worth about $15 billion annually, Weaver estimates.
The major thing that makes Cool Energy’s Stirling engine unique is that it doesn’t take much heat to make it work, Weaver said. Relatively low temperatures in the 100- to 300-degree Celsius range are enough. Other Stirling engines require much more heat to function.
Cool Energy only needs to develop technology that could be adopted by a small number of companies to become very profitable, Weaver said.
Cool Energy’s strategy is to keep its engines small. Its fourth-generation engine can generate 3 kilowatts and is small enough to be paired with a common diesel generator. Not many other companies are working in that market segment.
“We’ve started at the small end of the scale because there’s less competition there,” Weaver said.
Cool Energy is looking to India and nations in Africa to try to get a slice of the market.
As those nations develop, more residents are using mobile phones, either for their convenience or because building a mobile network is easier than building landlines in rural areas.
Many of the antenna towers in those nations are essentially off the electric grid, Weaver said. They are powered instead by on-site diesel generators, and Cool Energy believes there are 650,000 powered by diesel generators.
Cool Energy’s small Stirling engines would attach to the diesel generators and convert their waste heat to electricity that would be added to the cell tower’s power supply. Cool Energy’s managers think the company can reduce the cost to operate a tower by 10 percent to 15 percent, Weaver said.
Weaver has spent the past few months contacting clients and potential funders. Telecommunications equipment companies in the developing world have expressed interest in the technology and Cool Energy, he said.
“It’s a good sign we’ve gotten the meetings with telecom companies because it shows they understand the potential,” Weaver said.
“It feels like we’re on the verge of making a big breakthrough. We’re getting a lot of traction with potential customers and potential manufacturers.”
Cool Energy is looking to raise about $5 million from private investors to finance its next stage of growth. So far, it has received grants from the National Science Foundation, the U.S. Department of Energy, the U.S. Environmental Protection Agency and the Colorado Governor’s Energy Office.
Back in Colorado, Cool Energy’s employees are putting its latest models through field tests.
“We need to make sure we get it as bulletproof as possible before we move forward,´ said Dave Georgis, director of operations. “There are hundreds of things you just never find out until you put it out in the field.”