PV And Concentrating Solar Try To Hook Up

Editor’s note: This story has been edited since its original posting to clarify the technology planned for use.

Boasting both a state Solar Initiative and a New Solar Homes Partnership, California has become prime real estate for solar developers.

Florida-based cleantech company GDT Tek announced on March 1 that it had purchased 109 acres in Desert Hot Springs, Calif., in order to develop a 20-megawatt (MW) commercial-scale solar photovoltaic (PV) system. That will take up 100 acres of the site. The other nine acres? That will be used to build what the company calls “a pilot thermal solar system” that combines concentrating solar power with a waste-heat technology. That system, the company said, could be 40 percent more efficient than current PV technology.

image via GDT Tek

Heat to electricity technology is not completely new, especially to GDT Tek. Its 50 percent-owned subsidiary, Steriwave-GDT Tek, a JV company with Steriwave Hungary, specializes in creating heat capturing devices (like the one pictured above) that reuse the heat to create electricity. Steriwave-GDT Tek even has a patent pending for underwater technology that captures methane hydrates from undersea reserves to be resued for electricity generation.

For California, the installation is another step toward a statewide goal of reaching 1,940 MW of installed solar capacity by 2016. The California Solar Inititative (CSI)—run by the California Pubic Utilities Commission (CPUC) and with a total budget of $2 billion over the next 10 years—set the goal and provides cash back incentives for solar systems.

CSP plants can work in a few different ways, but are always based on the concept of heating a liquid, which is why they are often also called solar thermal plants. One common system, called power tower, uses big mirrors—heliostats—to direct sunlight at the top of a tower several hundred feet high. The energy is received by the tower and used to heat water, generating steam and then power. There are plants like this already operating in Europe, and several are either under construction or planned for construction in the United States, including some that use molten salts to store the heat that’s been gathered so it can be used to produce power long after the sun goes down. Parabolic reflector systems use curved mirrors that direct the heat toward receiver tubes positioned along the focal line of each parabolic mirror.

It’s unclear exactly how the solar thermal aspect of the GDT Tek system will work. In a statement, company president Bo Linton says it will use a “new solar thermal style panel that the GDT Tek waste heat to electricity system employs.”

“Waste-heat” typically refers to systems that capture heat lost from operating motors—like this system in Alberta that we reported on last November. And in materials and a video describing its technology GDT Tek references harnessing heat from a gas-powered engine.

But in this case, it appears that GDT Tek intends to use solar heat—captured by its “new solar thermal style panel”—as the heat source in an organic Rankine cycle system. This is a process in which, first, heat is captured and used to heat a fluid that has a much lower vaporization temperature than water. This fluid—now a hot vapor under high pressure—is then employed to spin a turbine connected to a generator, producing electricity. According to the National Renewable Energy Laboratory, these systems are often paired with parabolic trough collectors.

“Our CTO, Ralf Horn, has estimated that our system will prove to be 40 percent more cost efficient and productive than current PV technology,” Linton said. “Once we build it side by side the proof will show right on the meters for the entire world to see. It’s our goal to become the frontrunner in solar farm technology and this site is a major step in getting us recognized as what we believe to be the best solar farm technology on the planet.”

Shifra Mincer is a freelance journalist and passionate tweeter (@Shiframincer) currently living in Israel. Before moving to Israel to apprentice with a homebirth midwife, Shifra worked as Associate Editor of AOL Energy, and was a member of the launch team that got the site up and running. Shifra has over a half a decade of experience in journalism and has written on women's health, green technology, politics and regulation of the energy industry, energy financial news, and local news. While studying for her B.A. at Harvard College, Shifra worked as a news editor for the Harvard Crimson. Shifra is also a yoga teacher and a birth doula and is hoping to create an active Jewish birth community through her web venture www.layda.org.

    • George

      Please note: CSP plants heat water to generate steam to run a steam turbine, not a gas turbine.
      Sorry, but this story is full of missunderstoods

      • Pete Danko

        George, thanks for your note. We’ve updated the story.

        • George

          Congrats, much better now.
           I see GDT Tek doesn’t want to explain clearly how it works, but I hope this will be succesful

    • Kennethdanis

      The California Solar Inititative (CSI)—run by the California Pubic
      Utilities Commission (CPUC) ….

      The California pubic utilities commission arranged this hookup?

      • Pete Danko

        That paragraph in the story was simply providing background on one tool California is using to pursue its solar power goals. We know of no role on the part of the PUC in this planned project beyond any customary regulatory/approval role.