Isegoria

Lonnie Johnson, inventor of the Super-Soaker squirt gun, did not have much luck selling his new idea to the Office of Naval Research in Arlington, Virginia:

Johnson had traveled there from his home in Atlanta, seeking research funding for an advanced heat engine he calls the Johnson Thermoelectric Energy Converter, or JTEC (pronounced “jay-tek”). At the time, the JTEC was only a set of mathematical equations and the beginnings of a prototype, but Johnson had made the tantalizing claim that his device would be able to turn solar heat into electricity with twice the efficiency of a photovoltaic cell, and the Office of Naval Research wanted to hear more.
[...]
Mild-mannered and bespectacled, Johnson opened his presentation by describing the idea behind the JTEC. The device, he explained, would split hydrogen atoms into protons and electrons, and in so doing would convert heat into electricity. Most radically, it would do so without the help of any moving parts. Johnson planned to tell his audience that the JTEC could produce electricity so efficiently that it might make solar power competitive with coal, and perhaps at last fulfill the promise of renewable solar energy. But before he reached that part of his presentation, Richard Carlin, then the head of the Office of Naval Research’s mechanics and energy conversion division, rose from his chair and dismissed Johnson’s brainchild outright. The whole premise for the device relied on a concept that had proven impractical, Carlin claimed, citing a 1981 report co-written by his mentor, the highly regarded electrochemist Robert Osteryoung. Go read the Osteryoung report, Carlin said, and you will see.

End of meeting.

Then he came back with a different approach:

Instead of presenting the JTEC as an engine, he would frame it as a high-temperature hydrogen fuel cell, a device that produces electricity chemically rather than mechanically, by stripping hydrogen atoms of their electrons. The description was only partially apt: though both devices use similar components, fuel cells require a constant supply of hydrogen; the JTEC, by contrast, contains a fixed amount of hydrogen sealed in a chamber, and needs only heat to operate. Still, in the fuel-cell context, the device’s lack of moving parts would no longer be a conceptual stumbling block.

Indeed, Johnson had begun trying out this new pitch two months before his naval presentation, in a written proposal he submitted to the Air Force Research Laboratory’s peer-review panel. The reaction, when it came that May, couldn’t have been more different. “Funded just like that,” he told me, snapping his fingers, “because they understood fuel cells—the technology, the references, the literature. The others couldn’t get past this new engine concept.” The Air Force gave Johnson $100,000 for membrane research, and in August 2003 sent a program manager to Johnson’s Atlanta laboratory.

The JTEC turns heat transfer into useful work — in an unusual way:

A steam engine, for example, converts heat into electricity by using steam to spin a turbine. Steam engines — powered predominantly by coal, but also by natural gas, nuclear materials, and other fuels — generate 90 percent of all U.S. electricity. But though they have been refined over the centuries, most are still clanking, hissing, exhaust-spewing machines that rely on moving parts, and so are relatively inefficient and prone to mechanical breakdown.

Johnson’s latest JTEC prototype, which looks like a desktop model for a next-generation moonshine still, features two fuel-cell-like stacks, or chambers, filled with hydrogen gas and connected by steel tubes with round pressure gauges. Where a steam engine uses the heat generated by burning coal to create steam pressure and move mechanical elements, the JTEC uses heat (from the sun, for instance) to expand hydrogen atoms in one stack. The expanding atoms, each made up of a proton and an electron, split apart, and the freed electrons travel through an external circuit as electric current, charging a battery or performing some other useful work. Meanwhile the positively charged protons, also known as ions, squeeze through a specially designed proton-exchange membrane (one of the JTEC elements borrowed from fuel cells) and combine with the electrons on the other side, reconstituting the hydrogen, which is compressed and pumped back into the hot stack. As long as heat is supplied, the cycle continues indefinitely.

“Lonnie’s using temperature differences to create pressure gradients,” says Paul Werbos, an energy expert and program director of the National Science Foundation. “Only instead of using those pressure gradients to move an axle or a wheel, he’s forcing ions through a membrane.” Werbos, who spent months vetting the JTEC and eventually awarded Johnson’s team a $75,000 research grant in 2006, describes the JTEC as “a fundamentally new way, a fundamentally well-grounded way, to convert heat to electricity.” Regarding its potential to revolutionize energy production on a global scale, he says, “It has a darn good chance of being the best thing on Earth.”
[...]
When I spoke to [Karl Littau, a materials scientist with PARC], he ticked off the potential advantages of the JTEC over typical heat engines: no moving parts, which means the engine is more reliable and virtually silent; the safety of hydrogen, which is essentially benign (unlike, say, Freon); and the lack of waste produced (the JTEC gives off no carbon or — unlike a fuel cell — even water, which, although environmentally harmless, can corrode equipment). All of these advantages mean longer-lasting performance and potentially higher energy-conversion efficiencies.

Commercial photovoltaic solar cells convert approximately 20 percent of received solar energy into electricity. The best solar-energy systems today — thermal-power plants that concentrate the sun’s heat to drive turbines — operate at a rate of about 30 percent efficiency. The JTEC, Johnson claims, could double that figure, cutting the cost of producing solar power in half from its current average of 25 cents per kilowatt-hour, and making it competitive with coal.

Posted in Technology | 1 Comment »