Green Metroplex Defines Distributed Generation
(Includes variations and systems for Net Metering, Decentralized Energy and related topics)
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The web address of this page is http://www.green-metroplex.com/factoids/PV/Distributed.html
Created: 7/11/2007 Revised: 11/11/2007
Distributed generation means electricity from many small energy sources. It has also
been called on-site generation, dispersed generation, embedded generation, decentralized
generation, decentralized energy or distributed energy.
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Currently, industrial countries generate more than 99% of their electricity in large power
plants, the majority of which burn coal. Some countries also use efficient generators burning
natural gas, nuclear reactors or hydro power.
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These plants have excellent economies of scale, but usually transmit electricity long distances.
Coal plants do so to prevent pollution of the cities. Nuclear reactors are thought too unsafe to
be in a city. Dam sites are often both unsafe, and intentionally far from cities. The coal and
nuclear plants are too far away for their waste heat to be used for heating buildings.
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Low pollution is a crucial advantage of combined cycle plants that burn natural gas or that
gasify coal or that harvest and burn methane as from solid waste facilities. The low pollution
permits the plants to be near enough to a city to be used for district heating and cooling.
Power generation from solid waste methane also helps a municipality to reduce its carbon
footprint by using methane for fuel instead of being burned as it otherwise escapes into the
atmosphere.  Focused solar generators with thermal mass storage capability for extended
night operations and Photovoltaic panels for daylight operations during peak loads, are other,
non-polluting sources of distributed generation.
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Wind Turbine generators qualify as candidates for Distributed Generation, but in a practical
sense, they compete with coal fired plants at night when the wind is statistically most
abundant. Coal fired generators must remain at their peak temperatures at all times in order to
protect the firebricks from massive temperature changes, which damage them during no-load
periods if allowed to make rapid temperature fluctuations such as a full shut down and restart,
later. In Texas, wind turbines erected close to the deep oil shale areas where electric pumps
draw oil from great depths and inject heated water to liquefy the heaviest oil, are most cost
competitive by virtue of being in close proximity to their Distributed Generator sources.
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Plug-in capable hybrid (PHEV) and electric only vehicles (EV's) currently are an integral
part of Bay Area Rapid Transit system planning (which uses overhead electric lines and third rail
power), in the San Francisco, California basin.
BART wants to attract electric vehicle and
hybrid parking by their owners
so much that it is providing 115 volt receptacles for their
patrons to plug-in and charge their batteries free of charge.
During peak load periods,
BART will barrow back 30% of the energy in these vehicles
batteries, rather than buy it
from the grid at punitive, peak-load commercial kWh rates. Transformers in parallel with
BART's electric lines supply both energy to or from the 115 volt plug-in receptacles in BART's
parking lots.
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Any municipality can adapt a Distributed Generation system to their particular needs and
budgets. For example,
BART also instituted so called soft purchase orders for hybrid or EV
vehicles for municipal fleets for the purpose of plugging them in during peak loads or for
emergency energy generation for their buildings and facilities, once these vehicles can be had
in bulk. Mainstream auto manufacturers need only start building these vehicles to enable
purchases by ready-made markets; who plan to make them a part of their Distributed Energy
grid.
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Mainstream auto makers appear reluctant to make the switch, however, due to the higher
reliability of EV's in particular. Their after-market repair and spare parts sales will suffer, without
doubt.
Sherry Boschert the award winning former medical reporter turned eco-advocate said
that it may take laws patterned after the seat-belt, air-bag, safety glass and other laws of
decades past, to force PHEV's and EV's delivered en mass by major auto makers. She points
out the fact that Toyota with its Prius Hybrid,
does not deliver a Plug-in version that they have
had for years, to Americans, because they hold
that option in reserve as a competitive weapon
for market share.
There are currently two proven Li-Ion battery
variants that have
100% reliability
characteristics, which buries any concerns that
these batteries might be a fire hazard as an
argument against making them an integral part
of vehicles used for energy storage on a
Distributed Energy Net Metering grid...
Some municipalities have gone so far as to
put a bounty on Ni-Cad and Li-Ion batteries that
have dropped to 80% capability, to add to their own enormous energy storage banks, in
order to reduce their demand during peak load periods in which they must pay punitive rates
for their power.
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Distributed Generation reduces the amount of energy lost in transmitting electricity because
the electricity is generated very near where it is used, perhaps even in the same building. This
also reduces the size and number of power lines that must be constructed.
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See also:
Net Metering