Look at any nuclear, coal, gas or geothermal power plant, and you will spot a turbine – a chunky rotary mechanical contraption full of moving parts that require serious maintenance and that can break down. They convert heat – usually steam – into electricity, and in the inefficient process, they typically lose more energy than they transform.
So isn’t there a better way to morph all that warmth into electricity?
Matthew Simmons and his Hamilton, New Zealand innovation company, Arvus Group, believe there is.
“You convert the heat directly to electricity, with no moving parts,” says Simmons.
He’s working on a solid state thermoelectric technology he calls Thermagenz, which Arvus wll deploy first for geothermal power, but which Simmons believes could be a perfect match for the emerging “alternative” nuclear movement – especially for the high temperature reactors that could replace today’s conventional, lower temperature reactors.
“It’s all part of the rethink about nuclear,” says Simmons, who I spoke with via Skype today, and who I first met when he presented at the Thorium Energy Conference 2012 in Shanghai last October. Many proponents of thorium fuel advocate using it in high temperature reactors like those using molten salt and pebble bed designs, in order to optimize superior performance and safety features compared to conventional uranium reactors.
The idea of Thermagenz is simple: eliminate turbines altogether by running steam or some other heat source through a bank of “hybrid peltier” semiconductors, and out comes electricity. Say goodbye to moving parts and all the potential malfunctions that go along with them, a development that as Simmons points out means “the maintenance is almost zero.”
Arvus’ first installation of Thermagenz will be a trial, 2-kilowatt geothermal demonstrator starting soon in Taupo on New Zealand’s North Island, where Simmons says they only have to dig a meter to hit 200 degree C heat. It plans a larger, 100-t0-500 kilowatt geothermal trial in southeast Asia later this year, where it hopes to operate at least one megawatt-plus installation by the end of next year in partnership with a utility.
In the geothermal deployments, Arvus sinks a proprietary thermal superconducting material that Simmons says loses practically no heat for up to a mile. The material – which he declines to name – is “30,000 times more conductive of heat than silver,” Simmons claims (silver is a well known as an effective heat conductor).
RAISING THE TEMPERATURE
That heat feeds the solid state device, which can handle temperatures of up to 300 degrees C and which converts about 5-to-6 percent of the energy to electricity. Although that is much lower efficiency than what a turbine delivers, Simmons says the thermoelectric system as a whole offers huge advantages, including much lower operating and maintenance costs, as well as eliminating the need for precious water.
“The clean energy revolution isn’t really about efficiency. It’s about viability,” says Simmons.
But 5-to-6 percent efficiency and 300 degrees won’t cut it for high temperature nuclear applications, especially when many developers of MSRs, pebble beds and other alternative reactors are targeting temperatures of around 700-to-1,000 degreees C. (The good news is that Arvus’ high temperature superconducting pipe can deliver heat of up to 1,200 degrees, and can carry that heat up to a mile beyond the reactor, where it would hand it over to the semiconductors for conversion to electricty).
That’s not lost on Simmons, who spoke at the Shanghai thorium conference to help generate interest among the thorium crowd and to initiate the long process of collaboration to help advance Thermagenz for nuclear applications.
Simmons says that the threshold for Thermagenz to compete on a par with turbines is about 15 percent efficiency operating at between 700 and 1,000 degrees C.
Are reactor developers interested? “Yes,” says Simmons who adds that he has several meetings coming up with nuclear companies in Europe and elsewhere. He’s also working with semiconductor companies and university research teams.
“We want to develop a semiconductor that can work at the higher temperatures so that we can potentially back our Thermagenz not only onto geothermal, but also on the back end of high temperature reactors,” says Simmons.
Thermoelectric generation from nuclear heat is not a new idea. Spacecraft like the current Mars Curiosity use it, as did the Voyager from the 1970s. But those craft tap a highly costly and inefficient version which would not fly in commercial nuclear reactors.
Certainly plenty of technological and financial challenges lie ahead both with Arvus’ technology and with alternative reactor and fuel development.
“It’s a long arc,” says Simmons. “But it’s going to attract so many interesting companies, interesting problems and interesting people, and so it’s a really exciting hub of energy to be part of. Because this is a shift, a lot of people truly believe in the potential of thorium, and it’s giving rise to people to rethink about nuclear. “
It’s good to know that the blades of nuclear change are spinning not just on the fuel and reactor front, but in the generating room as well.
Image of Matthew Simmons is a screen grab from TED video via YouTube.