In message ,
"IMM" wrote:


"NickW" wrote in message
om...

Solar thermal however, I think should be exploited first as it seems
to yield the big numbers for something as simple as heating air.

Air heaters are very efficient. have one on the back wall of a conservatory
with the heat rising into the house, or loft and ducted down.

What is very efficient and economical, is a sun tracker focusing the sun via
lenses onto a heat exchanger and producing very hot water. These can also
produce steam and run a small steam or Stirling engine/generator. Even in
cloudy weather very hot useful water can be produced. Steam or Stirling
engines can be very small for high large torque. There is research in the
USA on sun trackers/heat generators for CHP applications, or cogen as the
Yanks say, and it appears more cost effective and efficient than most other
methods: PV cells, flat plate collectors, etc.




Can I ask a couple of questions?

1: If suntrackers are so efficient, why is it that the only one at the
Centre for Alternative Technology is about 25 years old? Why haven't
they installed more? Is it perhaps that the reflectors are a waste of
time?

2: Are you *sure* Stirling engines have high torque? The ones I've seen
certainly don't - they are very efficient, but only when operating high
speed/low torque.

Just interested :-)

Hwyl!

M.

--
Martin Angove (it's Cornish for "Smith") - ARM/Digital SA110 RPC
See the Aber Valley -- http://www.tridwr.demon.co.uk/abervalley.html
.... To hell with the prime directive, let's kill something.