From: Ron Kean (ronkean@juno.com)
Date: Sat Jun 05 1999 - 00:09:27 MDT
On Fri, 4 Jun 1999 13:45:21 -0700 (PDT) Eugene Leitl
<eugene.leitl@lrz.uni-muenchen.de> writes:
>Chuck Kuecker writes:
>
> > If I recall right, large methane fueled fuel cells were proposed
>for
> > installation in New York City to generate power - and the waste
>heat could
> > then be used for process or building heat. Does anyone know if this
>scheme
> > was actually installed?
> >
> > Chuck Kuecker
I don't know specifically about that, but in some other countries,
especially those formerly communist, it is not uncommon for towns and
portions of cities to be heated from a central heating plant. In
Washington, DC, many of the older federal buildings are heated from a
central steam heating plant run by the General Services Administration.
The plant burns coal, which comes in by rail, and the heat is transferred
to the buildings thru insulated steam pipes running under the streets.
College campuses are often heated from a central steam plant.
All systems which produce electrical power from fuel generate lots of
waste heat. The thermal efficiency of the best coal-fired power plants
is no more than 45%, and 35% is more common. So in principle it may be
attractive to use that waste heat for building heat. But there are big
practical problems with actually doing that. Multi-building heating
systems are most economical for large buildings heavily concentrated near
each other, as in the downtown part of a city. But power plants are
generally not built in such areas, because the plant, with its
switchyards and transmission lines and infrastructure for fuel delivery
and handling takes lots of land, and the land is just too expensive
there. There are some cities where power plants were built downtown
(usually by a river) in the early years of the century, but those plants
are obsolete and not capable of meeting present power demands, and are
being closed to free up the land for other uses. Also, the waste heat
from a power plant is at a relatively low temperature, about 100 degrees
C or less, which makes it difficult to effectively deliver the heat any
significant distance while maintaining a temperature high enough to be
useful in building heating. It sometimes makes sense to locate an
industrial user of heat, such as a paper mill, near a power plant.
Georgetown University in Washington, DC has an existing central heating
plant for the campus, and they have been considering piggybacking
electric power generation into the heating plant system. The plan would
be to sell the power to the local electric utility.
Ron Kean
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.
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