Anonymous
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Because Stirling engines, solar photovoltaic, geothermal, biomass, and other sources of energy are not cheaper than burning fossil fuels.
Until alternative sources of energy cost less than petrochemicals, natural gas, wood, etc., they will not successfully compete without huge tax breaks and incentives- which just hit the pocketbook every 15 April instead of every time at the pump.
Simple economics.
There is a start-up in Phoenix making do with Stirling engines, but they have a long way to go before they can compete (reference 1).
Roadkill
Do the math, I though the same thing and went to work on it. After all a sterling engine can operate with a temperature difference of only a few degrees.
Problem is the surface area required to build an engine that has the ability to develop any significant power output forces the engine an impractical size. For example one capable of a few horsepower might be the size of house. The cost of building it just isn't practical.
There are some engines that use the sterling cycle but they aren't using low grade waste heat, or they are the ones that run on the heat from the palm of your hand. If you could measure the horsepower of the little lab models its barely enough to spin a small fan.
Esperanza
1
andyoptic
Although Sterling engines are efficient I am not sure if the sun's energy can be gathered well enough to make it economic
the4nhustla
Because this would put the oil companies out of business. They are paying the government to keep fussel fuel cheaper than anything that would put them out of business.