Events & Media

We Need Solar Power…So Where Do We Put the Facilities?
Bren School—based project seeks lowest-impact installation sites in California desert

One of the ironies of the law requiring California utilities to secure one-third of the state’s electricity from renewable sources by 2020 is that popular actions to address one element of sustainability – reducing greenhouse gas emissions (GHGs) –  may negatively impact another: desert conservation.

To meet the state’s 2050 GHG reduction goals, however, will require solar arrays be constructed on some 65,000 to 97,000 hectares of California desert. But the desert is home to numerous rare, threatened, and endangered species. Thus, even as developers rapidly file for permits to install solar arrays on public and private desert sites, they, along with government agencies, environmental organizations, residents, and other stakeholders are also seeking to ensure that sites for development are selected to minimize impacts on biodiversity.

To address the competing interests of desert development and conservation, the California Energy Commission (CEC) and other agencies are creating the long-range, multi-stakeholder Desert Renewable Energy Conservation Plan (DRECP), which is expected to be approved in May 2013. The agency then asked Bren professor Frank Davis to develop new methods for assessing cumulative impacts of large-scale solar installations on biodiversity. Those methods could then be used to identify lands that are more – and less – appropriate for solar-energy installations.

As the first part of the project, Davis partnered with Bren School professional researcher David Stoms (now at CEC) and Bren alumnus and Defenders of Wildlife staffer Stephanie Dashiell (MESM 2011) to identify sites where solar-energy development is most compatible with conservation interests. The researchers used “compatibility” to mean the absence of conflict between energy development and goals relating to the conservation of biological resources.

The team developed a spatial model and produced maps identifying the relative degree of compatibility of solar development with biodiversity conservation at any given location. Developing projects on lands that are less compatible increases not only the likelihood of conservation impacts, but also the risk that solar developers will face stiff opposition or incur high mitigation costs for whatever impact their projects have.

After excluding urban areas, where residents commonly oppose energy projects, and steep slopes that are unsuitable for construction, the study mapped 282,000 hectares as most compatible. But the majority of that land is currently being used or was recently used for agriculture, so even if those lands are of low value for biological conservation, they serve other interests.

To determine biological conservation value for their model, the researchers used two main sets of criteria developed by environmental organizations. The first states that the least conflict will occur on sites that are the most ecologically degraded and therefore have low conservation value. The second emphasizes the desirability of siting solar arrays near existing power-transmission infrastructure to minimize new impacts.

For conventional research projects, it is sufficient to publish results in a peer-reviewed scientific journal, but the mapped results of the Bren team's project had to be usable by a wide spectrum of stakeholders having varying degrees of technical training. Those users, Stoms says, need a visualization tool that enables them to locate the sites on the maps and query the database about the factors that determined compatibility of a given site.

The Bren team developed two versions. The first was a map with overlays that can be viewed with Google Earth, the free map-viewing application that quickly downloads digital imagery and topography as a base map. The second option is a web mapping service hosted by the Mojave Desert Ecosystem Program in Barstow ( This version is similar to Google Earth but also lets users add other map layers from the DRECP and other agencies to the view and to easily download all input data and model documentation.

Several tasks remain, according to Stoms. The team will develop a software application to locate sites for mitigation projects to account for the impacts of solar projects that cannot be mitigated on the project site or avoided altogether. The final task will be to develop a tool for modeling the cumulative impacts that solar development scenarios will have on biological resources. That assessment methodology will incorporate impacts of future urban growth and climate change as context for impacts caused by energy development. Bren alumnus Jason Kreitler (PhD 2011), who is now at the USGS Western Geographic Science Center in Boise, is involved in these tasks, and Bren adjunct professor Lee Hannah is also an investigator on the project, focusing on species distribution modeling and climate change impacts.