This solar collector in Spain uses a point focus parabolic mirror and has a Stirling engine at the center.
Wikimedia Commons
Posted on 06/10/2010 10:32:21 PM PDT by neverdem
An updated version of a two-hundred-year-old invention is turning sunlight into electricity.
Promising new solar technology to generate electricity is almost a cliche these days. Let's look at some promising old technology. Today, on Engineering Works! Listen to the podcast.
When people talk about solar energy, they usually mean one of two things. Photovoltaic panels or solar concentrating plants. Some engineers are trying something else. An updated version of a two-hundred-year-old invention to turn sunlight into electricity. This old technology is something called a Stirling engine. A Scottish clergyman named, you guessed it, Stirling, invented it in 1816.
The idea is simple. A Stirling engine has two cylinders and pistons. Kind of like a two-cylinder motorcycle engine. The space above the pistons is filled with a fluid, usually air or helium. Heat the gas in one cylinder and it expands, moving the piston. The gas cools and moves to the other cylinder, where it moves that piston and flows back to the first cylinder, where it's heated again and the whole cycle starts over. It's more complicated than this, but you should get the idea. They're a lot more efficient than conventional internal combustion engines and need only a little outside heat to keep the cycle going.
In solar power plants, sunlight provides the heat that makes the gas expand. Sunlight is focused on the Stirling engine by a concentrator that looks like a big, shiny satellite TV dish. Stirling engines spin electric generators the same way turbines or diesel engines do.
Whew! It's getting hot in here. We'll see you next time.
Engineering Works! is made possible by Texas A&M Engineering and produced by KAMU-FM in College Station.
Stirling engines work, but they tend to be rather low power, low torque devices.
But they’re definitely a solution for .023% of our energy problems, and certainly ripe material on which to write many grant requests, conduct studies, and get tremendous government funding.
Very astute analysis! LOL.
Al Gore said last month that the center of the earth is several million degrees and all we have to do is dig a few holes a couple miles deep to get unlimited free energy.
With Al’s luck he would hit oil first.
The demonstration engines certainly are low power/torque devices, but they don’t have to be.
What is needed (and feasible in a fix/stationary situation like this) is to get the temperature differential as wide as possible, and set it up with as long a stroke as possible.
The attraction here is high thermal efficiency in converting an external heat source to mechanical energy - ie, at better efficiencies than many solar cells are going to do for you today.
[But they’re definitely a solution for .023% of our energy problems,]
Yup, low power, low torque, usually with high operating pressures required.
Reminds me of those toy drinking birds.
Earthquakes and sinkholes so far, oil is prolly next if they can find another place to drill.
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People have been trying to get Stirling engines to work in this role since about forever. Fail.
Miniature Stirling engines have numerous applications. Large scale Stirling engines probably have no more utility than large breasts on a boar/
On the other hand, you can take one with you on camping trips and read books in the dark with nothing but starlight.
......write many grant requests,......
Green jobs go English Majors.
No Selma Hayak pictures!
Take that lil’ gal out in the Sun and watch her pump eh!
The big problem is cutting holes in the rock (it's very hard and very acidic, and therefore corrosive).
In many places you only need to drill 100 feet or so.
In Southern Indiana and in much of Kentucky it is a common practice to stick one end of a heat pump system into a cave. Where the caves are filled with sand you just dig a borehole and plant an "immersion" system in to work as your heat sink. Now that doesn't give you free energy, but it gives you exceedingly inexpensive heating and air conditioning.
No, I was referring to “as useless as big breasts on a boar.”
The practice is commonly done, at least on the Eastern side of the Appalachians, to provide cold, not warmth. It’s a heat sink. But, combined with solar panels and a fireplace, it can provide a very comfortable home “off the grid.”
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