[Tfug] OT: Big Oil? Windows Vista!

[Ronald Sutherland]

On Sun, May 25, 2008 at 8:09 PM, Bexley Hall <bexley401 at yahoo.com> wrote:

>
> There's a firm with a Stirling engine coupled to
> a 20KW genset -- I think they were targeting
> $20K.  Missed their mark, IMO.  Need a small
> 3-5KW unit that could be roof mounted (the 20KW
> unit uses a 20ft collector!).  Even if it just
> carried the ACbrrr load it would be a BIG win!
>
> Although I like the Stirling engine, it has some problems, for example its
power output is much like PV, but delayed, and filtered with thermal
capacitance. When the sun goes behind a cloud the Stirling will operate on
its thermal capacitance for a short while, where as PV just stops dead.
But the bad thing is when I have a peak demand, for example when something
is started, the Stirling like PV can not respond to the peak, it has no
potential reservoir to draw from. A computer power supply has capacitors
just after the PFC rectifying stage (I hope you all have PFC?), an
intermediate stage, where power is stored that gives your UPS enough time to
react during a lose of power. In a Rankine engine the compressed (a.k.a.
high pressure) steam is a potential reservoir, and turbine implementations
with De Laval nozzle valves can quickly adjust steam expansion rate to
handle peak loads. The steam pressure like an intermediate voltage drops
when peak loads occur, but the peaks do not last.

http://en.wikipedia.org/wiki/De_Laval_nozzle
in a steam turbine a valve is pushed into the nozzle from the high pressure
side to adjust the restriction. Such a responsive throttle in a car would
feel like an instant on electric motor.

My AC is about 5hp (2.5kW) average and requires about 4-8kW during startup
(I've not checked but it's in that range). If I produce 3kW solar for 5-6hr
in the day that would be enough to run my AC, everything else is low power.
With net metering I can bank the power into the grid and then use what I
need, but what if I don't trust the grid.
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