efficient means of producing electricity
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efficient means of producing electricity
what is the most efficient means to produce electricity in space??
Response to efficient means of producing electricity
Take a nuclear power plant with you?
You'll need to be a bit more specific. Since we're on a Stirling forum, I assume your question is actually, "What's the most efficient engine for converting solar energy into usable power," where usable power may be electricity.
The answer to that is complex and frought with dangerous misconceptions. First and foremost, you have to understand that the "cold" vacuum of space isn't cold at all. It's simply empty. And empry means that there's nothing to pass on those molecular vibrations we call "heat". Instead, we have to rely on objects getting hot enough to release heat via photons. This is similar to when your electric stove heats up. Eventually it will develop a red glow from the heat. That red glow is how its getting rid of heat it can't exchange with the nearby atmosphere.
The result of this revelations is that we need LOTS and LOTS of surface area for our space generator. Make sure all that surface area is pointed away from the Sun, or you'll defeat your own intent.
Now that we have that figured out, which method works best for translating solar energy into usable energy? Well, we can begin by assuming that you'll use large mirrors to reflect sunlight directly on your engine. This means that your "hot" side can be smaller in size and further from the Sun.
Now we need to figure out our output. For 50-100 KW, a Stirling Engine may make more sense. In theory it is more efficient than any other cycle, and is completely closed. In reality, there tends to be some engineering issues concerning the stresses on the parts, but we'll assume for a moment that it's doable.
Unfortunately, that only takes us up to about 100KW maximum. Generally, the fewer power producing stations you have, the lower your overall costs. So what can we do to hit the multi-megawatts range? Well, I'm glad you asked!
It just so happens that there's another cycle that is already being used daily for high power outputs from a fairly small engine. It can also be used in either an open cycle or closed cycle configuration. That cycle is the Brayton Cycle. While most people think that the Brayton Cycle requires combustion of some sort of fuel (i.e. a gas turbine), the truth is that it only needs a powerful heating source to quickly expand the gasses. In this case we'll use the power from the Sun to provide that heat.
Now we need a cooling source. In gas turbines, the working fluid would normally be exhausted out into the Earth's atmosphere. We want a closed cycle, however, so we need to cool the working fluid before feeding it back into the compressor. The solution is to feed the working fluid through the radiator section of the generator (i.e. the part pointed away from the Sun) so that it can heat up the radiator vanes and expell heat via infrared light. Voila! Multi-megawatt power!
Of course, there's still plenty more engineering issues that could cause problems, but you should now have a better overall sense of how solar power production in space might work.
Does that answer your question?
You'll need to be a bit more specific. Since we're on a Stirling forum, I assume your question is actually, "What's the most efficient engine for converting solar energy into usable power," where usable power may be electricity.
The answer to that is complex and frought with dangerous misconceptions. First and foremost, you have to understand that the "cold" vacuum of space isn't cold at all. It's simply empty. And empry means that there's nothing to pass on those molecular vibrations we call "heat". Instead, we have to rely on objects getting hot enough to release heat via photons. This is similar to when your electric stove heats up. Eventually it will develop a red glow from the heat. That red glow is how its getting rid of heat it can't exchange with the nearby atmosphere.
The result of this revelations is that we need LOTS and LOTS of surface area for our space generator. Make sure all that surface area is pointed away from the Sun, or you'll defeat your own intent.
Now that we have that figured out, which method works best for translating solar energy into usable energy? Well, we can begin by assuming that you'll use large mirrors to reflect sunlight directly on your engine. This means that your "hot" side can be smaller in size and further from the Sun.
Now we need to figure out our output. For 50-100 KW, a Stirling Engine may make more sense. In theory it is more efficient than any other cycle, and is completely closed. In reality, there tends to be some engineering issues concerning the stresses on the parts, but we'll assume for a moment that it's doable.
Unfortunately, that only takes us up to about 100KW maximum. Generally, the fewer power producing stations you have, the lower your overall costs. So what can we do to hit the multi-megawatts range? Well, I'm glad you asked!
It just so happens that there's another cycle that is already being used daily for high power outputs from a fairly small engine. It can also be used in either an open cycle or closed cycle configuration. That cycle is the Brayton Cycle. While most people think that the Brayton Cycle requires combustion of some sort of fuel (i.e. a gas turbine), the truth is that it only needs a powerful heating source to quickly expand the gasses. In this case we'll use the power from the Sun to provide that heat.
Now we need a cooling source. In gas turbines, the working fluid would normally be exhausted out into the Earth's atmosphere. We want a closed cycle, however, so we need to cool the working fluid before feeding it back into the compressor. The solution is to feed the working fluid through the radiator section of the generator (i.e. the part pointed away from the Sun) so that it can heat up the radiator vanes and expell heat via infrared light. Voila! Multi-megawatt power!
Of course, there's still plenty more engineering issues that could cause problems, but you should now have a better overall sense of how solar power production in space might work.
Does that answer your question?
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stan.hornbaker
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efficient means of producing electricity
Most efficient is not necessarilly the most appropriate for the specific application. Isotope powered Stirlings, PV cell arrays, and other solutions have their place. Jerason Banes has discussed another.