A proposed solar power plant would have a "substantial adverse impact" on visual resources in Riverside County's Chuckwalla Valley, including the views from vantage points in two protected wildernesses and Joshua Tree National Park. That's according to the Final Staff Assessment (FSA) of the California Energy Commission (CEC) on the project, which was released Tuesday.
The Palen Solar Electric Generating System's impacts to visual resources are severe enough that they would not be mitigated even if the project proponents took all the remedial steps CEC staff recommends to counter them, according to the FSA.
The project would also have significant impacts on local biological resources, including birds and other flying wildlife, as well as species such as the Mojave fringe-toed lizard that depend on wind-blown sand corridors likely to be altered by construction.
The 500-megawatt solar thermal project, proposed by BrightSource Energy and Abengoa for 3,794 acres of public land, would include two 750-foot tall towers near Interstate 10 west of Blythe. The towers would be surrounded by 170,000 mirrored heliostats that would focus solar energy on boilers atop the towers.
The FSA for Palen is being released in sections. Tuesday's release includes the majority of the document. In addition to covering the plant's expected impact on visual and biological resources, Tuesday's section also includes the staff's assessment of the project's soil, public health, and transportation impacts, among other areas. The sections of the FSA covering the project's likely effects on air quality and cultural resources will be released later this month. Both of those areas are expected to be contentious: the cultural resources area in particular has already been the locus of conflict between CEC staff, who want more information, and the project's backers, who say that finding and providing that information will make them late for lenders' deadlines.
Palen's projected disruption to visual resources is no surprise: building 750-foot tall towers with extremely bright boilers at their tops at one end of a broad desert valley will obviously have significant effects on visual resources. Despite the subsequent change in the visitor experience for people in both Joshua Tree National Park and the nearby Palen-McCoy and Chuckwalla Mountains wildernesses, it's unlikely the CEC staff's observation of significant adverse impact will cause Energy Commissioners to spike the project.
However, it's the FSA's ambiguity over the degree of effects on birds and other flying wildlife that will likely cause BrightSource and Abengoa the most stress in the interval between the FSA's release and the CEC's final decision.
At issue is the concentrated solar energy -- solar flux -- that the heliostats will focus on the towers. Two years ago, the issue of solar flux was largely unmentioned in discussions of power tower solar thermal projects. The group Basin and Range Watch repeatedly introduced a decades-old study of solar flux injuries to birds at the old Solar One project in Daggett into CEC procedings on power tower proposals. Still, the topic didn't get much attention until the CEC staff started asking some tough questions as it examined BrightSource's proposals at Hidden Hills and Rio Mesa, now abandoned.
Palen's design is substantially similar to that of both Hidden Hills and Rio Mesa, so depending on the prevalence and behavior of local birds, the effects of solar flux on those birds may also be assumed also to be substantially similar to that the two shelved plants would have had.
According to the FSA, Palen's solar flux would pose a risk of injury and mortality to burrowing owls, eagles, and other "special status avian species." In each case, says the FSA, the impacts of that flux -- along with other risks such as collision with mirrors or other equipment and electrocution -- may "remain significant after mitigation." The recommended mitigation includes both operational practices (such as using raptor-safe transmission equipment) and paying to preserve bird habitat elsewhere.
The field of heliostats may also pose a threat to birds similar to that ReWire described at the nearby Genesis and Desert Sunlight power plants, in which birds apparently mistake large arrays of mirrors and photovoltaiic panels for bodies of water.
The CEC staff's assessment of Palen's risk to eagles is stated bluntly:
While the probability is uncertain, given that the site and surrounding areas are suitable bald and golden eagle foraging habitat, staff believes that operation of the [Palen] project could result in the take of bald or golden eagles, due either to collision with project facilities or to injury or mortality caused by flying through concentrated solar energy over the heliostat field. No mechanism is currently available to allow staff to quantify potential mortality for bald or golden eagles, or any other avian species. Because they are fully protected species, any take of bald or golden eagles is prohibited by law. The burden is on the project owner to avoid any such take.
The cultural resources section of the FSA is scheduled for release on September 16. The Air Quality section will be released within 30 days of its approval by the South Coast Air Quality Management District. Once the full FSA is released, the CEC will hold evidentiary hearings on the project before issuing a decision. BrightSource and Abengoa are keepiing their fingers crossed that a final CEC decision will come in time for the join venture to meet lenders' deadlines at the end of the year.
In the past, the Commission has regularly approved projects despite staff concerns about non-mitigatable environmental impacts, citing "overriding considerations" -- essentially saying that generating renewable energy takes precedence over protecting wildlife, cultural, and visual resources. Even if its on staff constructs a compelling argument against approving Palen, the CEC's Commissioners would be true to form if they went ahead and greenlighted the project anyway. But you never know.