Google no longer plays in the solar fields of the lord.

As the year draws to a close, Google is shutting down several projects that haven’t panned out as the company hoped. Perhaps most notably, the search giant is ending its foray into solar thermal energy.

“At this point, other institutions are better positioned than Google to take this research to the next level,” Urs Hölzle, Google’s senior vice president of operations said in a blog post.

Google’s “Renewable Energy Cheaper Than Coal” program started in 2007, aiming to reduce the costs associated with heliostats — mirrors used to reflect sunlight — as well as the efficiency of solar thermal power systems in general. Google had invested $168M in Brightsource’s Ivanpah Solar Electric Generating System (ISEGS), a project set to produce 392 MW of clean solar energy by the time it’s completed in 2013.

The centerpiece of the ISEGS is what the company calls a “solar power tower.” The tower stands at the center of a field of heliostats, which redirect the sun’s light onto a solar receiver at the tower’s apex. The receiver heats up, and the concentrated energy is converted to electricity that could power a town — or a data center.

This setup seems a lot like a Rube Goldberg machine when compared with a system based on photovoltaic (PV) cells — standard solar panels — which convert sunlight directly into electricity on the panels, avoiding the loss of energy that comes with heliostats. The price of PV cells has fallen dramatically in recent years, making it the winner — at least for the moment — in the race between the two ways of squeezing energy from the sun. IHS iSuppli, a technology research outfit, says that installation of photovoltaic cells will grow 200 percent from 2010 to 2011.

Data centers — massive consumers of power — underpin Google’s business. A study by Jonathan Koomey, a Stanford University professor, found that the consumption of data center electricity slowed to about 56 percent from 2005 to 2010, after doubling in usage from 2000 to 2005. Total electricity use by data centers in 2010 was about 1.3 percent of all electricity use for the world and two percent of all electricity use for the US. Google has long expressed interest in finding better sources of energy, striving to be completely dependent on renewable sources.

In September, the Google published some statistics on its data centers’ Power Usage Effectiveness (PUE). While usage can vary, many studies assume a national average PUE for other data centers at 2.0, meaning that for every watt of power consumed by the system, an additional watt is consumed to dissipate the energy. As of Q3 of 2011, the company was running at 1.14 PUE, which means that for every watt of IT power, an additional 0.14 watt is consumed to cool and distribute power to the IT equipment.

Photo: Bilfinger Berger Group/Flickr