The Corpus Callosum

Decentralized Power, In Your Basement

Posted by Joseph j7uy5 on April 30, 2007
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IEEE Spectrum
(free registration required) has a nice little article about devices
that generate heat and electricity for the home.  This is a
good idea, except for two problems: one, it is more efficient, and two,
it is more reliable than the current system.

Micro-CHP (combined heat and power) systems eliminate the inefficiency
that is inherent in the process of transmitting power over very long
wires.  It also reduces the impact of a failure in any one
point in the power grid.  

href="http://spectrum.ieee.org/apr07/5010">A Power Plant for
the Home
Basement
furnaces generate electricity, too
By Prachi
Patel Predd


When
you flip on a light switch in an average
American home, the light bulb probably uses electricity generated in a
far-away power plant. But that is not the most efficient way to use
fuels—two‑thirds of their energy is lost as waste heat at the
plant and while traveling over power lines.

What if the power plant were sitting in your home’s basement
instead? Combined heat and power (CHP) systems can utilize up to 90
percent of a fossil fuel’s energy by simultaneously
generating heat and electricity on-site, reducing energy consumption
and slashing utility bills…

Micro-CHP systems typically consist of an internal combustion engine
and a furnace. The engine drives a generator to produce electricity,
and the heat created in the process goes to the furnace via a heat
exchanger module. Micro-CHP equipment can run on a range of fuels,
including coal and oil. The most popular systems, including Climate
Energy’s, run on natural gas.

Unlike solar panels, wind turbines, and fuel cells, CHP is, as Climate
Energy CEO Eric Guyer says, “an approach that’s
much more like the hybrid gasoline-electric automobile than an exotic
automobile such as one running on fuel cells. It’s a good
application of available technology—nothing extraordinarily
new, no new science, no new way of converting energy.”…


They cost a few thousand dollars more than a regular furnace.
 In cold climates, they pay for themselves in two years; in
warm areas, it could take 10 years.  

Later in the article, they say “traditional utilities still see home
power generation as a threat.”  

This is probably true.  I suspect that having
widely-distributed power generation capability, using a variety of
sources, would make it difficult to manipulate the energy market.
 It also would make the entire system less vulnerable to
disruption, either from a href="http://www.nytimes.com/2004/05/13/business/13blackout.html?ei=5007&en=42d824d56c573299&ex=1399780800&adxnnl=1&partner=USERLAND&adxnnlx=1113995683-LgfkQn6oBW+xdxSSott6Mg">system
failure, or from a href="http://en.wikipedia.org/wiki/Hurricane_Katrina">natural
disaster, or from title="America’s Vulnerable Energy Grid"
href="http://www.cfr.org/publication/13153/americas_vulnerable_energy_grid.html?breadcrumb=%2Fissue%2F135%2F">sabotage.
 It would put people more in control of their power.

Of course, only a cynic would think that our current government has no
interest in hardening the power grid against terrorism, or making
energy more affordable.

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Comments

  1. #1 Mustafa Mond, FCD
    April 30, 2007

    Combined heat and power (CHP) systems can utilize up to 90 percent of a fossil fuel�s energy by simultaneously generating heat and electricity on-site, reducing energy consumption and slashing utility bills…

    While heat and electricity production may be synergistic in winter, they are not during air-conditioning season.

  2. #2 Ben M
    April 30, 2007

    Mustafa Mond, that’s not strictly correct. Waste heat can be used to generate cooling as follows:

    1) Take a bucket of refrigerant with two phases (liquid, gas)
    2) Expose the gas phase to something that absorbs it (dry zeolite, miscible solvent, etc.)
    3) The pressure in the gas phase goes down, causing liquid to evaporate and cool.
    4) When you’ve exhausted your stock of liquid (and choked up your absorbent), you reverse the process: use waste heat from your generator to *heat up* the zeolite/solvent/whatever, driving the refrigerant back to the bucket, where it condenses.

    This is standard practice in large cogen plants; most or all of MIT’s chilled water supply (for labs, AC, etc.) is cooled by waste heat from the cogen plant. I’m not sure how well it adapts to micro-CG, but the principles are simple enough.

  3. #3 VJB
    April 30, 2007

    Mustafa Mond, you’re forgetting the old ammonia-cycle refrigerators there used to be before universal connection to the elecrical grid (and were in the early trailers, like Airstreams). They ran on kerosene. They’re so wonderfully counter-intuitive.