> PV users) are dependant on the grid for "storage" of the power we 
> generate
> from the solar panels. Batteries are NOT cost effective and the sun 
> has this
> bad habit of going behind the planet...

Electrolytic hydrogen.
Gasometer storage.
Reconvert to electricity using, @@[cough]@@, Stirling or other less 
efficient technology. Use balance of non reconverted energy for 
heating.

For such static applications a large buried flywheel may be 
acceptable.

English (and no doubt other) stately homes at one stage used a wind up 
weight system to generate power, powered  usually no doubt by servant 
input. Food to electricity! Such a system may be rendered practical by 
modern means - electric motor energy mass storage. One Watt second =~ 
0.1 kg.m. So to store 1 kWh = 360,000 kg.m. eg 10m x 36 tonne. An 
annoyingly large amount for about $0.20 worth of electricity. More 
with inefficiencies. This could be water pumped to a reservoir - 
entirely practical and actually done on large scale. Only attractive 
if you have a lake and a hill to hand.

"Larnoch Castle" in Dunedin NZ has an interesting structure out-back 
which is not mentioned except in most peripheral passing in guidebooks 
etc. On inspection it is clear that they made Methane gas from their 
own sewage. Don't know if they had a Stirling engine though :-).

BTW -James recent query about any one large Stirling engine design 
that was commercially viable is arguably exampled by those built by 
the original inventor :-).



        Russell.


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