Ideas Generated for Transforming the Electric Infrastructure
May 2005, page 13
Clark
Gellings and Kurt Yeager, in their article "Transforming the Electric Infrastructure" (PHYSICS
TODAY, December 2004, page 45), propose "distributed energy resources" as part of the solution
to transforming and modernizing the electric power infrastructure. They recommend "small generation
and storage devices distributed throughout" the system, but suggest only "fuel cells and batteries"
and offer no details of how the cells and batteries could be created economically or how they would
be integrated. Much more appropriate devices already exist and are currently proliferating—namely,
hybrid gasoline–electric vehicles, such as the Toyota Prius.
Although nominally designed as transportation, hybrid
vehicles normally perform that function for only an hour or so per day. The rest of the time they are
small standby generator plants. With their capacious batteries, they could supply tens of kilowatts
of instantaneous power to cover peak demands for electricity. The continuous power output of hybrids
is several kilowatts, commensurate with the power required not just to drive down the highway but
also to run a house.
On the power-receiving end, vehicle "docking stations"
with DC-to-AC inverters and transfer circuits could turn a house, a factory, or even a community
into a self-sufficient entity. Although such facilities aren't free, their cost is much less than
that of the typical power station and, if mass produced, might come in under $1000 plus professional
installation. Given the many power emergencies and inconveniences during this past hurricane
season, I can see at least one section of the country jumping at the opportunity.
Consider what could be accomplished as the hybrid fleet size increases and its power is harnessed:
Individual homeowners could sign up for voluntary disconnection from the grid. With continuous internet connections common, a utility could almost instantaneously request that customers go off-line and revert to their hybrid-vehicle power source if part of the utility's generating or transmission capacity fails.
Even without notice from the utility, homeowners would have a backup generator in the event of a power failure, and the neighborhood would have sources of emergency power.
Much of the time that the vehicle isn't at home, it is likely to be at work. If tens or hundreds of employees' cars are available to provide instantaneous emergency power, diffusion furnaces won't even hiccup, and the wheels of industry will continue to turn.
These benefits can be provided economically, given that
hybrid vehicles are already being produced and purchased in record numbers. Cooperation from
vehicle manufacturers is what is needed, primarily in including control software that will allow
the batteries to provide power and be recharged through external instruction and power demand.
That software, plus a power connector, should be sufficient on the vehicle. Neither should affect
its cost noticeably.
We're all accustomed to the necessity of installing an uninterruptible
power source for each computer. Maybe it's time to consider installing a UPS for the house as well.
In
their interesting article on the electric infrastructure, Clark Gellings and Kurt Yeager got
most of it right. However, in 1879, three years before Thomas Edison's Pearl Street Station, the
first electric company opened in San Francisco. It provided electric energy to arc-light customers.
Edison did his best to prevent the commercialization of
alternating current. Through an agent, he staged cruel public demonstrations electrocuting
dogs, cats, horses, and even an elephant, to show that AC was unsafe. He even purchased AC apparatus
to construct the first electric chair at Auburn Prison in New York. It was Nicola Tesla's polyphase
AC, promoted by George Westinghouse, that made possible the large transmission systems of today.
Edison's direct-current systems were largely obsolete by 1940.
Over the past 100 years, efficiencies of generators have
steadily increased because of scale economies.1 The efficiency of Edison's generators
in 1882 was estimated to be only 8%. It took the building of transmission lines and the increase in
unit sizes up to 500 000 kW or more over 70years to boost the efficiency to 38% for coal-fired
steam turbines.
These economies could only have been realized by connecting
giant generating stations to thousands of small loads over a very wide area, using transmission
lines to reach substations at many load centers and then distribution lines between the substations
and the small loads. The principal reason for constructing and operating transmission systems
is to permit the use of giant generators, which are more efficient in converting coal to electricity,
use far less fuel per kilowatt, and have far lower costs per kilowatt of generating capacity.
Now, however, the relatively tiny 250-kW molten-carbonate
fuel cell is more efficient than even the largest central station, particularly when transmission
and distribution losses are taken into account and the high price of natural gas relative to coal
makes gas no longer as useful for generating base-load energy. Base-load generators, which are
on line most of the time, have the more expensive generating capacity per kilowatt but have the lowest
fuel costs per kilowatt hour. Even though they constitute only about 40% of all generating capacity,
they supply 80% or more of all kilowatt hours. Intermediate and peaking generators that use more
fuel per kWh supply the remainder when the base-load generators are being fully used.
With mass production, fuel cells' hardware cost will drop
dramatically, perhaps 20% with each doubling of production, and the full fuel-cell energy cost—including
the costs of both fuel and hardware—will become competitive with that of central-station
power from the grid.
Moreover, apart from their cost advantages, fuel cells
can provide highly reliable power. They can cut toxic pollution emissions by some 99% and greenhouse
gases by a lower percentage, and can do away with the transmission lines snaking through wilderness
or through Connecticut suburbs.
The fuel cost of electric power from giant central stations
has been so low over the past 100 years that, even after paying all the costs of transmission and distribution,
central-station power has been the most economical. With the advent of the fuel cell, that fuel-efficiency
advantage of large central stations over small ones has disappeared. The costs of new transmission
and distribution that are necessary if large central stations remain the source of power are skyrocketing—from
an average of $500 per kilowatt cost of all those currently installed to about $1500 per kilowatt
for those installed in the last few years before control of transmission no longer gave control
of the market.
I think that distributed generation with fuel cells will
likely be the direction that our power supply will take for the future.
Gellings and Yeager reply: We thank Wallace Brand and Richard Factor for providing additional
insights about the electric infrastructure. A few points deserve clarification.
Several electric ventures did, indeed, open in the US and
the UK in the late 1870s and early 1880s before Thomas Edison's Pearl Street Station. However, we
highlighted Edison since his was the first true utility "system" of substantial size, serving
multiple functions and users.
The efficiency of the transmission system has increased
over the years, largely through the use of higher-voltage AC transmission lines and, in a few
selected situations, high-voltage DC transmission. Little has changed in transmission technology,
though, except for a few applications of power electronics, and growth in demand continues to exceed
the rate of capacity expansion.
The cost of electricity steadily declined in real terms
from the birth of the industry to about 1970. Most of that cost reduction came from increases in power-plant
size and efficiency—a trend that has slowed over the past 30 years and has been more than offset
by fuel cost increases and the cost of retrofitting coal-fired power plants with environmental
controls such as selective catalytic reduction and flue gas scrubbers.
The average fuel efficiency of central-station power
does continue to increase, albeit slowly. The increase is mostly due to the recent addition of new
plants, based on combustion turbine technology, that are only slightly more efficient than the
average fleet of existing plants. Regrettably, the recent run-up in natural gas prices has rendered
many of these plants uncompetitive. And so far, the costs of small generation devices such as fuel
cells remain marginally competitive at best, despite their potential efficiency advantages,
and they should be considered a complement to, not a replacement for, central-station generation.
The solution to our electric energy needs may include fuel
cells—but realistically it will also require increasing the utilization efficiency of
electricity and use of advanced nuclear reactors, cleaner combined-cycle coal combustion, and
renewable energy resources.
Adapting hybrid vehicles to become plug-in hybrid vehicles
is an exciting potential way to reduce overall energy needs even further, reduce emissions, and
provide the lowest vehicle life-cycle costs to consumers. Several such vehicle con_1figurations
are being demonstrated in the US and Europe.
Today's power system remains the most complex machine ever
invented by humankind. Adapting it to meet tomorrow's needs will require a portfolio of solutions
and renewed investment. No matter how well-intended, efforts to promote individual solutions
outside the context of a robust portfolio only distract and delay the essential comprehensive
effort.
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