take a sterling heat engine, take the heat from a solar concentrator. use the motion of the engine to drive an electrical generator.
take a windmill, slap an electrical generator on it.
combine the two??
probably been done, just not very popular.. yet.
now, put photovoltaic cells all over your contraption.
but theoretically you can get several hundred watts per square meter of ground from the suns radiation, and several hundred watts per square meter of wind turbine area.
now, the efficiency of these things is not so great. but who cares, what is the efficiency of building a power plant shoving coal combustion products into the air, blowing up mountains to strip mine, destroying the water supply with tailings and acid mine drainage, you know? what is the effiency of that system? what is this obsession with efficiency?
my crackpot conspiracy side says the following.... stirling engines are/were safer than steam engines, but steam won out because it was more efficient. How much more? 5 percent? 10? 15? does that much efficiency really matter to the average bloke? clearly not, since we are almost all of us living in residences with massive cooling/heating losses due to our houses not being air-tight. the windows leak, the door jambs leak, our vents to the outside for our stoves, our plumbing, etc, it all leaks. thats good, supposedly, because it helps improve indoor air quality. but its an awful waste of energy since most of the energy most people use goes into heating or cooling their house.
im just saying. 15% efficiency... who cares... if you can take the initial energy input from the sun! but why did efficiency matter so much?
ok here is where my crackpot conspiracy side comes in. capitalism. these engines were used in factories. factories are run partly by people looking at statistics. if you can prove on paper that something is saving money, then nobody cares about your amorphous crying over the fate of the rain forests, etc. show me the numbers.
the capitalist factory has to care primarily about things like proving how much money they save. of course statistics can sometimes be misleading or miss out on the real picture of what is happening. every scientist, well most of them, the good ones, understand the difference between a mathematical model, statistics, numbers, and reality. and most people understand the phrase 'looks good on paper'... the mathematical model of the company or person or whatnot, vs reality, which is not so predictable.
like the guy who invented the 'save' statistic in baseball. for pitchers. before he did that, people did not recognize the accomplishments of those certain pitchers who 'saved' games. but this man pointed out the amazing nature of what a pitcher does, and how their actions can 'save' a game. baseball itself eventually adopted the idea.
now in factories, there are probably lots of things like the 'save' not being measured or understood properly. but they are there, in reality, and some people probably have noticed it, but apparently nobody has gotten to the point where they have been able to popularize it like the 'save' guy did his idea in baseball.
in capitalist factories, they looked at steam, they looked at sterling. what if steam has a 5-10 percent advantage over sterling? on paper? that 5 or 10 percent becomes a big number in a corporation. if inflation is 3 percent, if prices of other supplies rise 4%, you have to make up the difference somewhere. its a bunch of little numbers, added together, to make one big one. or, if you are the owner or shareholder, that 5% or 10% of , say, several ten million dollars of income, adds up to a lot of money.
this is what shareholders often end up wanting. maximized profits. CEOs are almost required by law to ignore anything that doesn't relate to short-term maximized profits.
and even on the discussions of modern wind power, you will find people talking about differences in design that increase or decrease efficiency by 1-2 %. in a huge windmill that can generate a megawatt, that 1% is going to be 1000/100, or 10 kilowatts, which is an extra house or so.
but those tiny percentages of efficiency dont really matter for a lot of things. in computer science, you stop worrying about one percent, because the guy in the next cubicle is redesigning the whole algorithm so that it will be faster by an order of magnitude, ie, the more stuff you feed to it, the faster the improvement becomes. maybe his algorithm runs in O(n^2) instead of O(n^3). thats, well, you give his algorithm 100 inputs, it might take 10 seconds, you give it 10,000 inputs, it might take 20, while mine would take 40 seconds. see the thinking there. who cares about 1% in the digital world of the algorithm?
only in certain areas of endeavor do we care.
but when you are trying to make something simple, cheap, effective, to withdraw a few hundred watts per square meter of power, for free, from the sun... maybe you dont need to worry about 15 percent or 10 percent. you might have to cut tv from the average 4 hours a day or whatever down to 3.6 hours. might have to have a 90 light candleabra instead of 100. 10 percent dont matter that much. besides you can make up the difference w some old fashioned fossil fuel, just stick it in a chamber underneath your stirling engine and burn it... you will still be using 90% less fossil fuels than you were before.
course if you -can- boost efficiency by 10% thats great. but if the tradeoff is more omplex manufacturing of the unit, less reliable design because its more complicated, etc, then why worry that you have sub optimal efficiency?
only a certain type of performance fetishist cares. but that's a whole nother story.