The three power purchase agreements do not include projects already in the works, such as Ivanpah at the California-Nevada border, but will include two concentrating solar power future projects in Riverside and San Bernardino counties, said Kristin Hunter, a BrightSource spokeswoman.
BrightSource’s power tower solar thermal system uses mirrors to reflect the sun’s energy to a boiler on top of a tower. This produces high temperature and high pressure steam, which is used to turn a steam turbine that produces electricity.
With the addition of storage, the steam is directed to a heat exchanger, where molten salts are heated to a higher temperature — allowing for the storage of the energy for future use. When the sun is no longer out, yet electricity is needed, the heat stored in the molten salts is used to generate steam to run the turbine.
According to a prepared statement from BrightSource, electricity is most needed by utilities during the later hours of the day. Hunter said the addition of storage to future solar plants will allow utilities to use power when they need it. BrightSource signed power purchase agreements with Edison for seven different units, but the addition of storage means that the company can avoid building one of the units.
The Sibera plant will be constructed somewhere in San Bernardino County and the Sonoran West project will be constructed somewhere in Riverside County.
Both projects are still in the planning stages and not scheduled to come online until 2016 and 2017, said Hunter. The paperwork for the Siberia project is about a year from being filed, and Hunter said the company’s policy does not allow her to disclose the exact location of future plants until paperwork is filed. Construction at the Ivanpah concentrating solar thermal project is projected to finish in 2013.
KAREN JONAS, www.desertdispatch.com