Lonnie Johnson invented the Super Soaker, which has sold over $1 billion dollars since 1992. He has invented tons of things but his latest could be the most useful. The Johnson Therm-Electrochemical Converter System (JTEC) sounds cool:
“It uses temperature differences to create pressure gradients,” says Paul Werbos, program director at the National Science Foundation, which has provided funding for JTEC. “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.”
It works like a fuel cell – but unlike a fuel cell it doesn’t need fresh hydrogen all the time. It cycles using pressure gradients created from a heat source (for instance solar heat) moving to a heat sink (ambient air):
Once the cycle is started by an electrical jolt, the unit starts producing a current. Heat in, electricity out.
Johnson claims a energy conversion of 60% – more than twice that of a Stirling Engine.
Further reading… JTECs page at Johnson Electro-Mechanical Systems.
A ton of cool stuff is in the invention pipeline. I just hope our political class can NOT BLOW it before the scientists save their bottoms.
December 2nd, 2008 at 8:53 pm
Sunshine just isn’t that strong – about 1000 w/m2 under the best conditions. Take 60% of that (my guess a way optimistic estimate), assume a 6 sq-meter solar collector always clean and always optimally pointed to the incident sunshine, and ask how steep a hill would be too steep for a usefully sized auto to climb. At 745 w per horsepower, that’s about 4 HP on the good days. Better stick with fixed installations in the low latitude deserts or next to some really hot waste heat source.
One ugly fact of thermodynamics is that you need a lot of heat to get useful work. And then you have to deal with friction losses in real machines.
I have another question about the supply of ions. You might get something from pushing ions through a membrane from some fluid source, but you would need a steady supply of such ions unless you have a perpetual motion machine that magically recycles the ions to the upstream side of the membrane with their initial energy.
Go ask a real engineer for an estimated average power and cost from such a device.
December 4th, 2008 at 7:22 am
Hope for solar cars, if you have room for big solar arrays.
“POZNAN, Poland – The first solar-powered car to travel around the world ended its journey at the U.N. climate talks Thursday, arriving with the message that clean technologies are available now to stop global warming. The small two-seater, hauling a trailer of solar cells” http://www.startribune.com/business/35530244.html?elr=KArks:DCiU1OiP:DiiUiD3aPc:_Yyc:aUU
December 4th, 2008 at 8:23 am
Saw that. A bit impractical. Slow too. Cars have to wait for better batteries.
June 18th, 2009 at 3:46 pm
Why not apply this to waste heat streams. There’s plenty of those with lots of potential. If this thing can actually get a 60% conversion ratio – it’ll be a game changer