Dean Kamen tried and failed to change the world with the Segway personal transport. Now he’s taking another shot at it, this time with a 200-year-old technological curiosity, and with the unlikely encouragement of one of the cable industry’s technology leaders, Mike LaJoie, CTO of Time Warner Cable. This time, Kamen might actually pull it off.
Kamen has been working with Stirling engines. The Stirling engine, conceived in 1816, is in essence a heat engine, operating by cyclic compression. They have several drawbacks, including practical limitations to how big (in terms of energy output) they can be. Though Stirling engines have been successfully used, no Stirling engine has ever been successfully commercialized – not for long, anyways.
In most circumstances, energy from Stirling engines will be far more expensive than energy from almost every other extant power generation system. Most circumstances, but not all.
Stirling engines are highly efficient generators and can be run not only with any energy source, but they can be run with different energy sources changed on the fly – kerosene, diesel, alcohol, it doesn’t matter, Kamen said, because it relies on external combustion.
They’re quiet, and they can run anywhere – they don’t need to be connected to the grid.
And they can be run continuously without wearing out. Kamen’s Stirling engines have no pistons, and therefore no seals. They act as brushless DC motors, with wires the only thing inserted in the cylinder chamber to draw off the electricity generated, he explained to a group of journalists after his keynote at Cable-Tec Expo.
But in order to make it all practical, he and his company, Deka Research, need economies of scale. Kamen said it costs about $250,000 to build one generator today, essentially on a custom basis; he thinks that with volume, they could be made for as little as $10,000 each.
So Kamen was looking for an application where the advantages of his Stirling engines can be exploited and the disadvantages do not apply.
And that’s where the cable industry might – might – come in. Cable has to have backup power; the very biggest companies have literally thousands of generators (typically diesel engines), most of them sitting idle 90 percent of the time. What if those generators were replaced with Kamen’s 10 kW Stirling engines?
A cable operator could run the generator on whatever fuel was the cheapest available at the time. Furthermore, they don’t rely in any way upon the grid – they will be absolutely reliable in a power outage, as long as the fuel holds out – and remember, it can run on any fuel, even alcohol.
The U.S. utility industry is talking about building more than 100 new power plants in the next 10 years, each at the approximate cost of $100 million. What if cable operators volunteered to run their Stirling engine “backup” generators to help satisfy peak power demand, thereby alleviating new energy plant requirements?
We’re asking these questions anyway, LaJoie said, and he’s got Kamen and his own engineers trying to figure out if the approach might be practical.
“Dean has a system, and if it has downstream benefits, I’m thrilled,” he said.
Now about all that waste heat. Kamen has built a Stirling engine into a water purifier that requires heat to purify water. If he can get enough volume on Stirling engines to reap economies of scale, his water purifiers could end up becoming practical in Third World countries where pure water is at a premium and a variety of water-borne illnesses and diseases are endemic.
“Coca-Cola is interested in these,” Kamen noted. If Coca-Cola finds a practical way to distribute these machines in Third World countries, it could be directly responsible for reducing the occurrence of well over half of all diseases in the world. The soft drink manufacturer currently has an order in with Deka for 50 of the machines. “Coca Cola has the potential to be the largest health care provider in the world.”
That could truly change the world.