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July 29, 2021 | Tom Ballard

SMTI secures $4 million Canadian to move very close to commercialization of heat pump

By Tom Ballard, Chief Alliance Officer, PYA

A little more than two years ago, we posted this article on teknovation.biz where Michael Garrabrant said, “We can see a light at the end of the tunnel, but we still have a lot of work to do.”

Fast forward a little more than 27 months, and we received some really exciting news from the Chief Executive Officer of Johnson City-based Stone Mountain Technologies Inc. (SMTI). The news release and follow-up email exchanges suggest that the tunnel opening is clearly in sight.

The company announced yesterday that Enbridge Inc., a leading North American energy infrastructure company, has invested $4 million in Canadian dollars in the late stage start-up. The funding provides key support for SMTI’s final steps toward the market release of its Thermally Driven Heat Pump (TDHP) technology, currently planned for 2022.

“I started the company a decade ago in order to develop a low-cost, mass-scalable gas heat pump that doesn’t suffer the weaknesses of electric heat pumps in cold climates,” Garrabrant said in the announcement. “Decarbonization of space and commercial water heating loads is very difficult to electrify without increasing end-user utility costs and a massive infrastructure build-out that will take decades to achieve, if at all. We are very excited about the potential of our family o, f heating products to offer immediate CO2 emission reductions while decreasing costs for our customers, in addition to providing a credible path to net-zero as the gas grid decarbonizes over the next decade.”

Enbridge, located in Calgary, Alberta, joins two other strategic investors supporting SMTI. In response to an emailed question, Garrabrant added that the latest round of funding “is slightly larger than our first seed round from back in early 2018 (and that) puts us at about $6 million U.S. total outside investment.” He said that non-equity funding like grants exceeds $12 million.

“With this round closed, we are now working on a larger A1 round that will provide funds for capital equipment/tooling,” Garrabrant added.

SMTI’s low-cost heat pump technology is driven by heat instead of electricity and is well-suited for colder climates such as the northern half of the U.S., Canada, and Europe. The design uses a 150-year old thermodynamic cycle with an extremely long track record of success, re-engineered for optimum heating performance and low-cost manufacturing to take place in North America.

SMTI’s technology has many advantages, according to Garrabrant. They include: (1) requiring no additional backup energy sources to keep residents warm and comfortable at winter temperatures as low as minus 40 degrees; (2) reducing energy use, operating cost, and CO2 emissions for space and water heating by 30 to 50 percent with one-third of the total heating output derived from renewable energy (from the atmosphere or ground); (3) avoiding the need for significant and expensive infrastructure changes to buildings as compared to an electricity delivery system that would result in a mass-scale adoption of electrically driven heat pumps; and (4) offering a fast path to net-zero heating by utilizing and leveraging the impact of low-carbon renewable gas and hydrogen blends that are poised to become an increasing part of North America’s gas delivery system.

Garrabrant adds that SMTI’s Thermally Driven Heat Pumps are “future proofed” because they utilize a 100 percent natural refrigerant with zero Global Warming Potential.

“Advancing the commercialization of low-carbon technologies for building heat is one example of the initiatives Enbridge is undertaking to lead the transition to a low carbon energy future,” said Cynthia Hansen, Corporate Executive Vice President and President of the company’s Gas Distribution & Storage business line.

SMTI completed four years of field trials in residential space and water heating along with commercial water heating applications to refine the product design, third-party verification of a 140 percent AFUE (Average Fuel Utilization Efficiency) rating, and certification to California’s low-NOx emission requirements. In addition, Garrabrant says that extensive market testing with homeowners, building managers, and installation contractors shows a strong likely market acceptance, owing to the relatively simple ability of the system to replace existing gas heating appliances with a technically straight-forward and economically sound solution.


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