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I've looked around quite a bit before I got here and haven't found
much of an answer. So here goes.

First, imagine if you took two alpha engines and stuck the two cold
cylinders back to back, and the two hot cyliders back to back.
Ignoring the regenerator, would this still run? If so, is there any
significant drawbacks to this over other types of engines? I've
tried doing the math myself, but I'm not a physicist and I couldn't
find enough info.

Second, does it sound reasonable to place Stirling engines on
special bouys in the ocean (not too far off the coast) to generate
power? Assuming that the top side of the bouy was under a glass
dome and had solar absorbing paint/panels, does this sound cost
effective?

Thanks in advance.

I'm not sure what is meant by placind two alpha engines 'back to back.'
You can place the two displacer cylinders next to each other with the hot and cold ends together, but this is nothing more that a single displacer cylinder of larger areas and volume.

Ocean bouy mounted Stirling engines might under the most favorable conditions generate enough power for a system to warn of their presence. There simply is not sufficient temperature difference available at sea to drive an SE to produce signifigant outputl

Sorry, by back to back, I meant one cylinder and one piston seperating two volumes of gas.

Joshua,

I haven't got years of experience to base this answer on, but I think the answer to the first question is yes. The design you're talking about would be called a "double-acting piston" alpha Stirling engine. I think companies have gone for a "free-piston" design instead, which also uses the space above and below a piston in a single chamber but in a beta Stirling configuration. I have been thinking about double-acting piston Stirling engines, too, and to the extent that they provide more opportunity for insulation between the hot and cold cylinders and the opportunity for more efficient regeneration, I think they may have advantages over a free-piston design.

As for your second question, I think the previous answer was a bit too narrow. You can make a concentrated solar Stirling engine work on land, and I don't see why you couldn't float one on the sea#except it would be harder to keep it aimed at the sun for maximum efficiency, the sea near shore is often covered with clouds and/or fog, and you'd have to make the cable that delivered the power to shore withstand any wave action your power station might encounter. I don't think using the vast body of seawater to cool the cold chambers provides sufficient reason to put one at sea, there are plenty of ways to cool the cold cylinder on land.