Electrical Energy is Where You Can Find It
Sep 12 - Electrical Apparatus
A western city is putting in energy systems from hydroelectric to geothermal
SAN LUIS OBISPO, CALIF.-Alternative energy production may not be the tour de
force it should be with the crisis in oil production, but in the area of
municipal and county investment in new technology, it is beginning to make
serious headway. By designing systems to take advantage of natural resources at
hand, towns, cities, and counties are taking steps to produce energy or to
conserve it, and in either case are saving money.
Several county and municipal energy projects coming together have turned a
small central California region into a test bed for new ways to cut the power
bill. The city of San Luis Obispo, with a population of 50,000, is putting in
small-scale energy systems ranging from hydroelectric generation to geothermal
climate control.
The city's primary water source is above La Cuesta Summit, which rises more
than 1,500 feet in the Santa Lucia Mountain Range. The water falls 740 feet from
the source to the city's old water treatment plant. It was relatively easy as
well as profitable to put in a small hydroelectric system a generation ago. The
city sold power to the grid and offset some of the water department's
electricity costs.
Changing water flow
In 1985 a single turbine and a synchronous generator rated at 640 kW were
purchased from Shinko Electric Co. Ltd. of Japan and installed adjacent to the
water treatment plant. Nine years after the plant went online, it was shut down,
partly because a new water filtration plant was built a short distance
downstream, but mainly because water coming into the system had changed.
Previously having passed freely through an eight-foot-high tunnel through the
mountains, water flow changed when the California State Water Project ran piping
through the same tunnel. The pipe was laid within the flow, and state engineers
installed a concrete cover on it. While the addition did not impede the flow of
water to San Luis Obispo, it changed the hydraulics of the stream. Recent events
in the power industry deregulation have made retrofitting cost effective.
Under contract with San Luis Obispo, Dean Rubinson, an engineer with Black
& Veatch Consultants in Concord, Calif., ran a feasibility study for the
restart of the hydroelectric plant. He reported that the best option for the
city was to use the plant as it stands, but with new electronic controls.
Rubinson said the alternative "takes full advantage of the hydroelectric
generation potential of the raw water system at a minimum of capital
expense." San Luis Obispo City engineers agreed.
According to the city's water division manager, Gary Henderson, "The
water treatment facility takes a great deal of electricity to run. The city
spends $260,000 a year to do it, and we estimate that with the hydro plant we
can sell $52,000 worth of electricity to the grid during that same period.
That's an attractive payback, especially since the system is expandable for
future growth."
The retrofitted hydroelectric system will use a large open clarifier tank at
the decommissioned old filtration plant to store water, essentially creating a
small lake for steady inflow of water to the turbine.
This is not the only project where the city expects to save on power bills.
Copeland Sports Corp., a private company, is building a parking garage in the
downtown area that will be purchased by the city when it is finished. One floor
of the garage will contain offices with heating and cooling needs assisted by
geothermal technology. Pumps will circulate tap water through a system of looped
piping placed in fifty vertically drilled boreholes 300 feet deep.
Trenches for foundations of the San Luis Obispo City's new parking garage
include fifty 300-foot-deep holes drilled into the earth for piping loops to run
the geothermal heating und cooling systems for offices on one floor.
San Luis Obispo lies on the Pacific coast roughly halfway between Los Angeles
and San Francisco.
The pipe and fittings are made of high-density polyethylene plastic (HDPE).
Steve Best, owner of David's Plumbing, Heating & Air, Inc., is a local
specialty subcontractor for the job. He is enthusiastic about the new technology
and said, "For flexibility, resistance to corrosion, and expandability, for
this application HDPE is preferred to steel."
He goes on to say that during the Northridge earthquake near Los Angeles, not
one polyethylene line broke in hundreds of miles of underground piping while
there were hundreds of breaks in steel lines. Best makes sure the piping is
sealed in each borehole with a special thermally enhanced bentonite grout. This
allows for full contact between the pipe and the surrounding surface to optimize
thermal conductivity.
The circulating water, moderated by a consistent 620F temperature
underground, will keep the temperatures consistent in the offices of the new
building all year long. Sixteen pumps will move BTU's to or from the earth by
way of the ground loop heat exchanger.
The new system will use power, but for every one BTU equivalent of
electricity consumed, it will draw four to five BTU's out of the ground.
According to Dave Best, "Day after day, BTU's will be absorbed from the
earth and rejected into the earth to meet the heating and cooling needs of these
offices."
County building upgrade
A stone's throw from the city's building complex site, the San Luis Obispo
County campus is undergoing its own energy makeover. When the county decided to
put air conditioning in the old courthouse, which had none previously, design
engineer Alien Crosby of Aircon Energy in Sacramento suggested it also look at
long-term energy savings by replacing lamps in the building for higher
efficiency and by adding motion sensors to turn lights on and off.
Tn addition, Aircon recommended the old boilers and chillers at the library
and courthouse annex be retrofitted or replaced with new, more efficient ones.
According to the county capital projects coordinator, Greg MacDougall,
heating and cooling, even with the additional 42,000 square feet of area in the
old courthouse, use less electricity than they did before.
A crew seals high-density polyethylene pipe connections with a thermal fuser.
The connections form the resulting water into virtually a single pipeline nearly
six miles long.
"Everyone's looking for ways to save on electricity costs, especially
government," MacDougall said. "Our budgets are getting whacked, but
people still need the services, so we have to find ways to deliver those
services cheaper. One way to do that is to lower operating costs."
The courthouse retrofit won an award from the American Society of Heating,
Refrigerating, and Air Conditioning Engineers.
The county hired Aircon to look into energy efficiency options in other
areas. The result is a new cogeneration system to cut power costs at the county
government campus. The system serves the old courthouse, the annex, and the
library. Across the street, a new county building under construction will also
be served by the new power plant.
The system, designed by consulting engineer Ron Blue of List Engineering in
Monterey, Calif., has three synchronous cogeneration units of 200 kilowatts
each, fueled by natural gas. Exhaust heat will be recycled for hot water in all
the buildings and to maintain comfortable temperatures in offices during winter.
The system will cool the buildings in summer through an absorption chiller.
The production of power on-site is expected to provide 45% to 55% of all
electricity needs for the county building complex. An incentive program through
the Public Utilities Commission has already brought the county a half-million
dollar rebate. The payback for the capital expenditure is expected to take seven
to nine years even with fluctuating gas prices. Engineers are also looking at
powering the jail with a similar system.
The new multi-story county building being built across from the courthouse
has energy consciousness built in. The floor consists of an air space sandwiched
between two inch-and-a-half slabs of concrete.
A blower system will take advantage of low nighttime temperatures, which
often fall into the 50's in the summer. The floors of one level are the ceilings
of the one below. The walls are broken up with windows so only the
floor/ceilings are used in the system.
The mountains in the background of this view of the San Luis Obispo hydro
plant provide a sense of the elevation from which water powering the plant
drops.
The special floor design is a part of the environmental package
recommendations. It also has the same kind of energy-efficient lamps and motion
sensors for on and off. This system can sometimes lead to unusual measures to
keep a meeting going. If people are not moving around much, sensors will turn
off the lights, and people will have to wave their arms to kick the sensor on
again.
Specially designed louvers on each window allow sunshine to enter the
building in winter and keep it out in summer. Pumps take advantage of the cool
summer nights by pulling in air to cool the slab and shell of the concrete
building afte\r dark, reducing some of the need for air conditioning during the
day.
The San Luis Obispo city engineering staff is looking to put solar electric
arrays on the roofs of two buildings. A city councilman, John Ewan, is a
supporter of green energy systems. He is in the solar energy business but is
prohibited from bidding on projects because of his position on the council.
Also in the design stage is a plan to offset the cost of electricity at the
city sewer plant with by-product methane produced on-site to power synchronous
microturbines.
The elimination of fossil fuel from the process may qualify the project for a
rebate from the Public Utilities Commission. Solar projects qualify for rebates
and that includes anyone in the state, private offices, manufacturing
facilities, homes, apartments, and anyone looking to reduce power off the grid.
The PUC gives their highest priority to promote projects that use fewer or no
natural resources such as gas assist backup by using hydroelectric, solar or
waste methane.
A hundred years ago electric power plants were small and scattered. That was
before the emergence of today's vast energy infrastructure of power grids and
fuel lines. Demand was small, too, before today's ever-expanding need for light,
heat, and fuel.
The growing movement to conserve electricity using public funds judiciously
by municipal and county entities with alternative distributed power demonstrates
leadership that deserves to be applauded and emulated.
The best option for the city was to use the plant as it stands, but with new
electronic controls
By Barbara Wolcott, EA Special Correspondent
Copyright Barks Publications Sep 2004