Two German scientists, Dr Gerhard Knies and Dr Franz Trieb, calculate that covering just 0.5% of the world's hot deserts with a technology called concentrated solar power (CSP) would provide the world's entire electricity needs, with the technology also providing desalinated water to desert regions as a valuable byproduct, as well as air conditioning for nearby cities.
Any temperature difference will power a Stirling engine and the term "external combustion engine" often applied to it is misleading. A heat source may be the result of combustion but can also be solar, geothermal, or nuclear or even biological. Likewise a "cold source" below the ambient temperature can be used as the temperature difference. (see liquid nitrogen economy). A cold source may be the result of a cryogenic fluid or iced water. Since small differential temperatures require large mass flows, parasitic losses in pumping the heating or cooling fluids rise and tend to reduce the efficiency of the cycle.
Because a heat exchanger separates the working gas from the heat source, a wide range of combustion fuels can be used, or the engine can be adapted to run on waste heat from some other process. Since the combustion products do not contact the internal moving parts of the engine, a Stirling engine can run on landfill gas containing siloxanes without the accumulation of silica that damages internal combustion engines running on this fuel. The life of lubricating oil is longer than for internal-combustion engines.
The U.S. Department of Energy in Washington, NASA Glenn Research Center in Cleveland, and Stirling Technology Co. of Kennewick, Wash., are developing a free-piston Stirling converter for a Stirling Radioisotope Generator. This device would use a plutonium source to supply heat.
TheDude wrote:Maybe some of you get the Peak Oil.com News feed, which sent me this story: How mirrors can light up the world, about using CPS to provide for the world's power needs using a pittance of desert land:
Alternating current cables, which now form the main electricity grids in Europe, are not suitable for long distance transport of electricity because too much is lost on the way. Dr Trieb, of the German Air and Space Agency, says the advantage of DC cables is that the loss in transport is only about 3% per 1,000 kilometres, meaning losses between North Africa and Britain of about 10%.
JRP3 wrote:I always thought it was the other way around, that AC had less transport loss and that's why it's used.
Frank wrote:JRP3 wrote:I always thought it was the other way around, that AC had less transport loss and that's why it's used.
AC does have less losses - I didn't read the link but if that's what they're saying then they're screwed-up.
small_steps wrote:
DC will have less loss than AC transmission lines, but the main reason that DC is used for longer distances is that the transmission of power is no longer limited by the inductive reactance of the line. That is, you can control it easier.
Frank wrote:JRP3 wrote:I always thought it was the other way around, that AC had less transport loss and that's why it's used.
AC does have less losses - I didn't read the link but if that's what they're saying then they're screwed-up.
canuckinczech wrote:The idea I'm after is avoid using the solar panels and just using the focusing power of the Fresnel lens directly on Stirling(...sorry mis-spelled that earlier) engine. As seen here;
http://youtube.com/watch?v=fUrB7KRvxUk
canuckinczech wrote:The idea I'm after is avoid using the solar panels and just using the focusing power of the Fresnel lens directly on Stirling(...sorry mis-spelled that earlier) engine. As seen here;
http://youtube.com/watch?v=fUrB7KRvxUk
Vegas wrote:http://www.stirlingenergy.com/default.asp
Heat-based solar collector. Mirrors and engines seem easier to scale up than silicon based stuff, though I could be wrong.
Desperation is the mother of all invention.
mos6507 wrote:
The one thing I don't like about stirling engines is the mechanical components. Aside from solar trackers, there is nothing more reliable than photovoltaics because they are completely solid state (except for organic solar cells which have an electrolyte in them).
Rollout of solar beyond a certain scale will be a maintenance nightmare. Imagine hundreds of thousands of these solar collectors spread out over many square miles. There will always be a certain percentage of them breaking down and a long trip required to get to and repair them. You really need something you can set up and largely forget about.
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