...the Ivanpah Solar Electric Generating System (ISEGS) will boast 173,000 heliostats that will concentrate the sun's rays onto a solar tower standing approximately 450 feet (137 m) tall. The plant commenced construction in October 2010 and is expected to generate 392 MW of solar energy following its projected completion in 2013.

Although Solar Power Tower Development is currently less advanced than the more common trough systems, they offer higher efficiency and better energy storage capabilities.

Parabolic Trough Systems consist of parabolic mirrors that concentrate sunlight onto a Dewar Tube running the length of the mirror through which a heat transfer fluid runs that is then used to heat steam in a standard turbine.

Solar power tower systems such as the ISEGS on the other hand focus a large area of sunlight into a single solar receiver on top of a tower to produce steam at high pressure and temperatures of up to 550 ° C (over 1,000° F) to drive a standard turbine and generator. The ISEGS also uses a dry-cooling technology that reduces water consumption by 90 percent and uses 95 percent less water than competing solar thermal technologies.
Water is also recirculated during energy before being reused to clean the plant's mirrors.

The energy generated from all three plants will be enough to supply more than 140,000 homes in California during peak usage hours...

The size of the investment reflects Google's faith in the technology and it hopes that other companies will follow its example and make similar investments in renewable energy.

LINK:
www.gizmag.com/google-invests-168-million-in-solar-power-tower/18383/