Martin wrote:

With a little added complication, you could use the waste heat to
pre-heat the water going into your hot water tank. You could even give a
boost using a heat pump. Although, I doubt that such complications would
be worthwhile.

I was thinking smoething similar myself.

I still favour the evaporative cooling ideas as discussed on here some
time ago... Should get rid of the cooling fans noise also.

Never saw that thread...

I have, however, seen a evaporation cooled diesel engine in real life :-)
The cooling water went out a pipe, and followed a metal net downwards,
before falling into a bucket of some sort, from where it was sucked into
the engine again. Lots of steam coming from the metal net.

Not a very usual engine though, it idled at less than 1 rpm (with no load on
it, of course). :-)