A non-profit public media organization is reporting that there are calls for a moratorium on solar power towers.
According to KCET, an official with the Palm Springs office of the U.S. Fish and Wildlife Service (FWS) has suggested that the California Energy Commission (CEC) and other agencies involved in approving desert renewable energy facilities allow “at least a couple years” of research on already-approved concentrating solar power tower facilities before approving any new projects of that design. Or at least limiting new approvals until the studies are done.
The suggestion was made in a letter from Pete Sorensen. He is Division Chief of the FWS’s Palm Springs office. The letter included a list questions regarding potential threats to bird and bat species from two projects planned by BrightSource Energy, the Hidden Hills and Rio Mesa solar projects in Inyo and Riverside counties.
There are reports that both the Rio Mesa and the Hidden Hills sites have been identified as significant bird areas. KCET says each of the projects would surround 750-foot tall towers with tens of thousands of mirrored heliostats. A heliostat is an instrument that contains a movable or driven mirror. It is used to reflect sunlight in a fixed direction. The potential threat to flying animals comes from the intense radiation near the towers, termed “solar flux,” which some wildlife biologists fear may injure or kill wildlife through blinding, burns, or even incineration.
Apparently there have been earlier studies of bird mortality at the now-decommissioned Solar One power tower facility. KCET notes that biologists found a significant number of burn injuries among birds found dead on the site.
Sorensen’s letter was recently made public on the CEC’s website.
“We are concerned about the increasing number of power tower projects that are proposed or undergoing permitting review, given the outstanding questions about the impacts of utility-scale application of this technology. As such, it would be beneficial to the permitting process for pending and future projects, including Hidden Hills and Rio Mesa, to gather monitoring data that answer some of the questions about avian physiological tolerance and behavioral response to power towers, from already approved projects, before approving more projects. Increasing our knowledge about potential impacts from this technology would further our ability to complete science-based analyses of direct, indirect, and cumulative effects to the avian community, as required by our joint public trust responsibilities. Therefore, we suggest that the Agencies limit the number of power tower projects that are considered for permitting and development until we obtain a more detailed understanding of this technology and its impacts, based on at least a couple years of scientifically robust monitoring. Deploying technology of this scale in multiple places and on a short timeframe without such an understanding compromises our ability to make informed decisions on projects that would permanently and cumulatively impact species and the extensive tracts of desert habitat upon which they depend.”
Most active solar power tower proposals in the U.S. have not yet been approved.
Meanwhile, BrightSource has defended its position with a statement on its website for the company’s Ivanpah project. The company says it has designed its systems to minimize the threat against birds:
“Our technology has been specifically designed to avoid harming birds. Unlike older technology, when our mirrors are not focused at the top of the tower, the light is focused in a diffuse ring around the top of the tower, at concentration levels too low to have any detrimental effect on birds. We have also reduced the size of the heliostats and placed them lower to the ground to avoid collisions, and we avoid siting projects adjacent to actively farmed and irrigated agricultural land or standing water that might attract insects and birds.”