Concentrated solar power projects are becoming a more considered means of generating power from solar energy. The primary plant designs are solar trough, linear Fresnel and power tower plants. All three of these technologies use mirror configurations to concentrate a large area of sunlight onto a small area.

By Michelle C. Kales and Amy M. Steinfeld

The concentrated light is typically used to heat a transfer fluid (e.g., water or molten salt), which is then used to generate power using conventional turbine technology.  Projects using a variety of CSP technologies have been built or are currently being proposed and considered throughout the southwest, including Nevada, Arizona and California.  For example, in 2007, Nevada Solar One - a 64 megawatt CSP plant  - was completed in Boulder City, Nevada. The 400-acre plant produces enough energy to power more than 14,000 homes and brings Nevada closer to its renewable energy goal.  It is only the second solar thermal plant built in the United States in more than 16 years, but several other CSP plants are in various stages of planning and development throughout southwest.  The increasing demand for CSP development in the southwest is driven by state-mandated renewable energy portfolio requirements and an abundance of land ideal for solar power generation. 

WATER, A LIMITING FACTOR

Another natural resource, however, is putting the brakes on many CSP projects in these states.  While the sunshine is abundant throughout the southwest, water is not only scarce, but it is heavily regulated.  Although concentrated solar is becoming more efficient as technology improves, producing more power with smaller land area, the most efficient and least expensive type of CSP technology still requires relatively large quantities of water for heat transfer fluid and cooling purposes.  Currently, all operating CSP plants in the United States employ some form of evaporative water cooling.  As with fossil fuel plants, this type of wet-cooling is used to condense steam and much of this water is lost to evaporation.  Because of water scarcity, many pending projects are shifting to new dry-cooling technologies, which can reduce water use by up to 90 percent.  However, dry-cooling is still typically more expensive and can be less efficient when air temperatures are high.

Throughout the southwest, water woes have slowed the pace of solar development.  State resource agencies, local governments, environmental groups and local residents have all voiced opposition to the siting of any solar project in their states that comes with large water demands.  For instance, in California - a state with one of the most aggressive renewable energy portfolio requirements - solar developers have been forced to find new technologies when local water officials refused to sign-off on projects because of water needs. 

In July 2010, NextEra Energy Resources, the developer of a CSP project in California’s Sonoran Desert, agreed to switch to a dry-cooling system after the California Energy Commission (CEC) recommended against using wet cooling.  Likewise, CSP projects being developed on federal land, such as the Ivanpah solar plant in California’s Mojave Desert, plan to use dry-cooling.  In response to concerns by local citizens and state agencies, some solar developers, such as Arizona’s Mohave Sun Power, are considering the viability of using reclaimed water for cooling purposes to avoid expensive dry-cooling. 

STATE ACTION

California has tried to address this and other stumbling blocks to renewable energy development by creating a streamlined certification program for solar projects over 50 megawatts.  This program, administered by the CEC preempts local groundwater ordinances and state water supply assessment requirements for projects falling under the California Environmental Quality Act, which requires development projects to submit documentation of their potential environmental impact. 

Since some local groundwater ordinances limit and highly regulate the extraction of groundwater in the area, and water supply assessments require developers to engage in a lengthy and costly process to demonstrate adequate water supplies for the project, the CEC’s streamlined process appears on its face to avoid difficult water rights issues.  As part of its review process, the CEC thoroughly evaluates water supply and quality issues, and requires that an applicant’s proposed use of water conforms to all state water-related laws and policies.

While the CEC’s official policy provides that it will approve the use of potable water for solar plant cooling purposes only where alternative water supply sources are “environmentally undesirable” or “economically unsound,” in practice the CEC is not currently permitting large-scale CSP projects to use large quantities of potable water.  

LOOKING AHEAD

As conflicts over water increase, other states may follow California’s lead in regulating the use of water for solar projects and in discouraging the use of wet cooling.  In a recent report on the nexus between water and solar, Arizona Senator Jon Kyl recommended that Arizona require CSP plants to be dry-cooled or to use reclaimed water for cooling purposes.  For that reason, solar project developers must have a clear understanding of a property’s water rights, including the reliability of existing water supplies, the existence of any relevant water law restrictions, and the type and quality of water used.  This will assist developers in purchasing or leasing decisions for a site, and help establish a project’s budget, efficiency, and ultimate feasibility.  In the increasingly parched southwest, demonstrating adequate water supplies could be a difficult hurdle in the permitting process for solar energy projects.  By implementing dry-cooling technologies or by using reclaimed water and other non-potable supplies, developers may limit environmental challenges to a project’s water use.  Moreover, knowing a state’s tolerance for water intensive projects up front and planning for water needs in advance of site and technology selection will help minimize delay and unnecessary expense. 

Michelle Kales is a shareholder in Brownstein Hyatt Farber Schreck’s natural resources group. As chairperson of the Renewable Energy practice group she focuses on environmental and energy law, litigation, and land use for a variety of clients, including utilities, energy development companies, residential developers and other real estate developers. As an associate in Brownstein’s water and public lands group, Amy Steinfeld works a broad range of water issues, including legal transactions, litigation, groundwater adjudications and environmental quality projects.