I notice that people here occasionally mention Stirling Engines, when talking about the possible exploitation of anomalous heat (sometimes it gets misspelled as 'Sterling').
If you happen to be in the UK, want to have a look at some working examples of these peculiar heat engines, and chat to some people who build them as a hobby, there is an opportunity next month. The Stirling Engine Society will be running a stand at the Midlands Model Engineering Exhibition from 13th-16th October.
The majority of the engines on show will be relatively low power units, using air as their working fluid. However, there may well be examples of pressurised engines, and those running with alternative fluids, such as helium. There is also a small active group within the society that has been developing engine systems for powering riverboats – either as direct replacements for the usual steam or IC engine units, or as Stirling-Electric hybrid drives.
Unfortunately, Stirling cycle engines are often misrepresented as some mysterious technology that will revolutionise the world's energy systems. But since it is over two centuries since the original patent by Robert Stirling, that revolution is taking a long time in coming. As usual, of course, ideas turn out to be the easy bit. Making devices work – economically, efficiently, reliably, and durably – is hard. It also doesn't help that accurate thermodynamic analyses of the cycle are far from trivial, and textbook examples can be slightly misleading for the unwary.
Actually, Model Engineering shows are good places to see what can be achieved in small home workshops, using tiny budgets. They are also useful places to pick up unusual tooling and sensible quantities of materials, as well as getting hints, tips, and ideas for possible future projects.
I know this online Forum mainly concentrates on laboratory-oriented topics, but all labs need occasional workshop support. It can be frustrating if you have an idea for a particular experiment, or device, but are stymied by an inability to source or build the necessary equipment. Events like this help to show how some R&D equipment log-jams can be overcome, at a hobby scale and budget.
(p.s. Yes, I am a member of the Society, and will be helping on the stand during the first couple of days )