Environmental Engineering Reference
In-Depth Information
Existing Large-Scale Solar Thermal Energy Storage Systems
SolarOneandSolarTwoMojaveDesert,California
— The first commer-
cial concentrating solar power tower system was a 10 MW pilot plant called
Solar One that included a TES tank used to test the performance of thermal
storage within oil, rocks, and sand media. Eventually, molten salt at 565°C
was determined to be the best storage material. The project produced 10 MW
of electricity using 1,818 mirrors of 40 m² each, with a total area of 72,650 m².
Solar One was completed in 1981 and operational from 1982 to 1986.
In 1995, Solar One was converted into Solar Two by adding a second ring
of 108 larger (95 m²) heliostats around the existing Solar One for a total of
1,926 heliostats with an area of 82,750 m². The new Solar Two plant could also
produce 10 MW. Solar Two used molten salt (a combination of 60% sodium
nitrate and 40% potassium nitrate) as an energy storage medium. It was
decommissioned in 1999 and converted by the University of California Davis
into an Air Cherenkov Telescope in 2001 to measure gamma rays entering
the atmosphere.
SolarEnergyGeneratingSystems(SEGS),MojaveDesert,California
—In
1985, Luz International built the first SEGS at Kramer Junction in the Mojave
Desert. There are now nine SEGS plants and together they comprise the
world's largest solar energy generation facility. SEGS I is a 13.4 MW plant
with 3 hours of thermal storage capacity using Caloria mineral oil.
Table 7.13 compares the SEGS I and Solar One and Two systems along with
other industrial TES applications. Further development of storage technolo-
gies such as TES is required for baseload power to be provided by renewable
energy sources.
Building and Industrial Process Heat
Thermal energy storage techniques can be used on a smaller scale in buildings
and industrial processes. Tables 7.14 and 7.15 list common applications for TES
within building and process heating applications, respectively. For example,
cleaning processes are required in many industries. Cleaning bottles, cans,
kegs, and process equipment consumes most of the energy used by food
industries. Metal treatment (galvanizing, anodizing, painting, etc.) plants use
energy to clean parts and surfaces. Textile plants and laundries clean fabrics,
and service stations clean cars. All these operations require warm (about 60 to
100°) water and provide excellent applications for TES. The storage and inte-
gration into existing heat supply systems is rather easy because they already
have storage tanks for water that serve as the main medium [16].
Seasonal Heating
Seasonal heating is an application of TES designed to retain heat deposited
during the hot summer months for use in colder winter weather. The heat is
