One of the arguments often used to denegrate solar power is that they don't work when it is cloudy or at night. But a new demonstration project in Hawaii proves this isn't so. Keahole Solar Power has installed an array of Sopogy "Micro-scale Concentrating Solar Power Concentrators" at the Holaniku Solar Farm on Hawaii's Big Island- a thousand solar collectors covering 3.8 acres, with a thermal energy of 2 megawatts.
They use the output to heat 8,000 gallons of water which runs through Electratherm "green machines"- the organic rankine cycle waste heat generators we have shown hooked up to geothermal and other sites. The result: according to Keahole, "firm, fixed power which has been deemed as the holy grail for renewable energy."
Electratherm waste heat generators
The ElectraTherm units are called Waste Heat Generators and run on a temperature difference of only 20 degrees, while the output of the Sopogy array is anything but waste heat- it is hot enough to run turbines, adsorption air conditioners (shown in video below) and even make steam. However the addition of ElectraTherm units squeezes a lot more energy out of it and improve system efficiencies. Robert Hoover of ElectraTherm tells us that "ElectraTherm's generation of electricity consumes only a small portion of the Btu generated by the concentrators."
Hot water storage tanks
But if all the waste heat left over after using the high grade stuff is used to heat water, there is more than enough to run the Green Machines day and night, cloudy or sunny. "Holy Grail" may be overstating the case, but it is certainly a big step forward.
How The ElectraTherm Generator works:
"ElectraTherm power systems use a closed-loop organic Rankine cycle (ORC) to create pressure by boiling EPA-approved chemical working fluids into gas. The gas expands in a one way system and turns a patented Twin Screw Expander, which drives a generator to ultimately put out electricity." more info at ElectraTherm
More at Keahole Solar Power and ElectraTherm
More on ElectraTherm in TreeHugger
Put Your Waste Heat To Work With a Green Machine
Green Machine Hooked Up to Geothermal Heat Source Makes Electricity Almost Free
How the Sopogy System Works:
If you are interested in this technology, here are promotional videos prepared by Sopogy:
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