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Presto! Alaska inventor turns wood stove heat into electricity

Suzanna Caldwell
Courtesy Trista Crass

Looking at the warmth radiating from his friend's wood stove pipe, Alaskan Theo Graber had an idea. What if someone could take that heat and convert it into electricity? What if there was a way the noisy generator rumbling outside his friend’s cabin could be a thing of the past?

Years of research and engineering later, the founder of Alaska Dynamics came up with an idea to harness that energy through his Delta-T Wood Stove Generator. The device is part catalytic converter, part thermoelectric generator -- all inspired by space-travel technology created in the hope of powering remote Alaska residences.

Graber thinks the generator will be welcomed by weekend warriors looking for a more energy-efficient way to light their cabins and brew their coffee. But the generator could have bigger implications. Graber said the generator could be “fantastic” for Interior Alaska residents because the device's catalytic converter would not only burn wood more efficiently -- helping residents deal with the region's air quality woes -- but also help offset the high price of electricity.

Finishing the prototype

Production is still in very early stages. Graber, 42, is working on the prototype, thanks to a $5,000 Kiva Zip loan that's endorsed by the Anchorage Economic Development Corp. He hopes to finish the prototype next month and move forward on creating a product he can sell within a year.

Already, it's piqued Alaskans' interest. The generator was a finalist for prizes at both the Arctic Innovation Competition and the Alaska Energy Authority Emerging Technology Fund.

“People who own rural cabins love the idea of just starting your fire and the lights come on,” Graber said. “They're excited.”

Space technology

Graber, who's lived in Alaska since 1995, has always been a bit of tinker. Even as a child, he was fascinated by machines, constantly taking them apart, putting them back together and learning how to fix them. Despite studying anthropology in college, Graber went on to work as a machinist and welder, eventually learning 3D CAD modeling programs. He spent years developing X-ray technologies looking into everything from corrosion in pipelines to giant blocks of cheese. Graber spent two years helping design and build the Alaska Distillery still. All his those skills would come in handy when Graber decided to design the converter.

Graber said he was inspired by the thermoelectric generator used to power the Voyager I spacecraft that launched in 1977. He was amazed the craft was still operating after 30 years, powered by an electrical generator that uses thermal differentials between radioactive heat and the cold of outer space.

Using that principle, Graber moved forward on the idea for the converter. But there was a catch. Even the hottest wood stoves don't produce enough heat in their stovepipes to creat a temperature difference strong enough to generate electricity. So Graber added a catalytic converter, allowing the stove to reach higher temperatures faster.

While some catalytic converters can be hard to use, requiring tricky stoking of the stove and manual operation of the converter to find the right temperatures, Graber said his converter is designed to be automatic.

The generator is designed to be plugged into the base of the stove pipe. From there, he said users would just start and stoke their wood stoves as usual.

Power output

Graber expects the first version of the prototype to produce about 130 watts an hour while running, for a total of about 2 to 3 kilowatts a day. That’s enough to light up a room, run a small radio and charge your laptop.

The first versions of the generator would best supplement other power supplies such as solar panels or gas generator.

“I want to get the output to where it can be a full-source, power delivery system,” Graber said. “One of these devices would be enough to power" a cabin.

He hopes to get the price on the generator under $1,000 per unit. Materials have been ordered and within the next month, Graber expects to begin fabricating his generator. From there it will undergo extensive testing before he can consider putting a product on the market.

Jon Bittner, vice president of the Anchorage Economic Development Corp., thinks Graber's generator has great potential. The Kiva loan requires a trustee to endorse it, and AEDC is one of only two trustees in the state. The project is its first endorsement.

Graber "is one of those people who's constantly interested in the world and how things work,” Bittner said. “He has had an innate understanding of things, which allows him to create things using existing technology that are put together in a really unique way.”

Contact Suzanna Caldwell at suzanna(at)alaskadispatch.com