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re: utility costs
5 apr 1999
tim dierauf wrote:
>nicksanspam@ece.vill.edu says...
>
>hi nick,
hi tim,
>...you must also consider the stack. well designed cogen systems can get
>to ~80% (lhv) efficiency. the 20% is lost out the stack. what is the stack
>loss of the oil heater in your house?
pretty low, since i unplugged it a few years ago. intelligen's 11 hp diesel
cogen system had a measured stack loss of 7%. with a 150 f exhaust gas temp,
93% of the fuel oil's heating value stayed in the house (as measured by
brookhaven national labs.) i guess that might have improved with a larger
exhaust gas heat exchanger.
>a better approach would be to run the steam turbine at a higher back
>pressure (to raise the exhaust temperature). the power plant would be
>less "efficient", but the overall power/heating cycle would be more
>effective -- and, this is commonly done (in some places)!
sure. scandinavia, siberia... as i recall, there's a new system heating
a significant part of berlin. it may happen here again someday soon :-)
or maybe we'll skip that step, and cover australia with pvs to make
liquid hydrogen that's pumped round the world in tankers.
nick
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