The Department of Energy has issued a conditional loan guarantee to Solar Trust worth $2.1 billion to help the world's largestsolarplant get off the ground.

The loan will help build the first 484 megawatts of the 1-gigawatt Blythe project being put together by Solar Trust and its subsidiary Solar Millennium near Blythe, a town in Riverside County, California. (The company also has another gigawatt of projects in the rest of the Southwest.).

The plant will be a parabolic trough solar thermal power plant in which curved mirrors capture heat from the sun to make steam. Other solar thermal technologies such as 'power tower' are newer and can convert heat more efficiently to power, according to its advocates. Solar Trust, however, has noted that parabolic trough plants have been producing electricity for decades and over 90 percent of the solar thermal projects on the books today involve parabolic troughs.

Here is a rundown on the specifications for Blythe. When complete, the 1-gigawatt plant will cover 5,960 acres and have a capacity factor, or functional uptime, of 26 percent. It will operate at 14-percent-plus efficiency and will generate approximately 2.2 gigawatt-hours of power a year. As an added bonus, the system will be air-cooled to reduce water consumption. (Cooling is required to condense the fluid that transmits heat from the mirrors to the steam operations.)

The project will create 1,000 construction jobs, but only 80 operational jobs. Basic access roads and some preliminary construction on the plant have already taken place. (The Department of Interior signed off on the project last October.) Primary construction will begin in the spring. Power should start to be produced toward the middle of 2013.

"When we rev up the American innovation machine, we can outcompete any other nation," said Energy Secretary Steve Chu during a conference call. Chu further noted that the DOE wants to back 27 projects. BrightSource Energy, building a power tower system in near Ivanpah that will generate 370 megawatts when complete, received a $1.6 billion loan guarantee. Ivanpah will cost north of $2 billion. The DOE also issued a conditional loan guarantee to build the 250-megawatt California Solar Ranch, which relies on PV panels.

The call is going on right now. One of the more interesting tidbits: Jerry Brown, California's governor, says he wants to see California get 40 percent of its power from renewable sources. Last week, Brown signed a bill to raise the renewable portion of California's grid to 33 percent by  2020. No deadline for 40 percent given. By 2020, Brown wants to see California to have 12 gigawatts of PV capacity and 8 gigawatts of thermal capacity.

Solar thermal power plants appear to be emerging from a difficult period. Back in 2007, solar thermal plants were viewed by many as the most cost-effective solar technology and one of the best opportunities for renewables. Then came the recession. PV prices began to plummet. Solar thermal companies found it difficult to raise the hundreds of millions required to move forward on their projects. Lawsuits filed by environmental groups, meanwhile, also threatened to delay some projects.

Now, hope is emerging again. Areva, which bought a weakened solar thermal company called Ausra last year, recently landed a small 44-megawatt solar thermal project in Australia and is expected to announce more deals.