JTEC May Bring 60% Efficiency to Solar Power

It's amazing what $100 dollar a barrel oil costs can bring out in American Ingenuity.

This from Popular Mechanics, it appears that Lonnie Johnson, the inventor of the Super Soaker hasn't been resting on his toy royalties, no in fact the former NASA scientist has been working with the help of money from the National Science Foundation to shake up the future of Solar Energy in the United States.

While his work has primarily focused on better Li Ion battery systems, he now is working on a prototype of his JTEC (Johnson Thermoelectric Energy Conversion) System. Similar to a Fuel Cell in that it has no moving parts, rather it consists of two MEA (membrane-electrode assemblies) stacks, one hot, one cold. Energy is produced by hydrogen moving between the two stacks, in response to the stacks temperature differential and the larger the temperature differential between the stacks the higher the efficiency.

Johnson hopes a high temperature version of the JTEC will double the efficiency of today's best solar systems which now reach 30%. How soon we don't know, but he hopes to have a low temperature version of the JTEC working later this year.

For more information take a look at Popular Mechanics - Super Soaker Inventor Cuts Solar Power Costs - Johnson Thermoelectric Energy Conversion System - Heat Engine:

Here’s how it works: One MEA stack is coupled to a high- temperature heat source (such as solar heat concentrated by mirrors), and the other to a low-temperature heat sink (ambient air). The low-temperature stack acts as the compressor stage while the high-temperature stack functions as the power stage. Once the cycle is started by the electrical jolt, the resulting pressure differential produces voltage across each of the MEA stacks. The higher voltage at the high-temperature stack forces the low-temperature stack to pump hydrogen from low pressure to high pressure, maintaining the pressure differential. Meanwhile hydrogen passing through the high-temperature stack generates power.

“It’s like a conventional heat engine,” explains Paul Werbos, program director at the National Science Foundation, which has provided funding for JTEC. “It still uses temperature differences to create pressure gradients. Only instead of using those pressure gradients to move an axle or wheel, he’s using them to force ions through a membrane. It’s a totally new way of generating electricity from heat.”

The bigger the temperature differential, the higher the efficiency. With the help of Heshmat Aglan, a professor of mechanical engineering at Alabama’s Tuskegee University, Johnson hopes to have a low-temperature prototype (200-degree centigrade) completed within a year’s time. The pair is experimenting with high-temperature membranes made of a novel ceramic material of micron-scale thickness. Johnson envisions a first-generation system capable of handling temperatures up to 600 degrees. (Currently, solar concentration using parabolic mirrors tops 800 degrees centigrade.) Based on the theoretical Carnot thermodynamic cycle, at 600 degrees efficiency rates approach 60 percent, twice those of today’s solar Stirling engines.

This engine, Johnson says, can operate on tiny scales, or generate megawatts of power. If it proves feasible, drastically reducing the cost of solar power would only be a start. JTEC could potentially harvest waste heat from internal combustion engines and combustion turbines, perhaps even the human body. And no moving parts means no friction and fewer mechanical failures.

Or check out Johnson's JTEC website.

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