Skip to content

Greener Solar Developments

August 15, 2010

A major new solar power plant proposal is in the works that makes better sense than siting solar power on previously undisturbed lands. The Westlands agricultural district in the San Joaquin Valley encompasses thousands of acres of salinated land, which is degraded and rendered unproductive for agriculture after decades of agricultural irrigation (Figure 1).1 The Westlands project is underway to build a 5,000 MW solar park on these degraded lands (“brownfields”).

Figure 1. Salination of agricultural land, southern San Joaquin Valley

A project of this size will take decades to buildout, and depends on major upgrades to the electrical transmission system,2, 3 but use of degraded lands is a much better idea than current projects in the Mojave Desert on little-damaged public lands (see our pdf on Fast-Tracking Solar Development in the Desert). Whether a photovoltaic (PV) or solar thermal plant will generate the electricity is not yet clear, but since cooling and cleaning water would have to be imported, PV is the likely choice.

Another 5,000 MW project proposed for a site on Owens Dry Lake, southeast of Westlands, is more contentious. The site’s disturbed lands are on large parts of the dry lake surface and adjacent flatlands. Although disturbed, the flatlands have a mature vegetative cover, so grading to install PV arrays would open a new source of dust and sand for the area’s frequent high winds to transport.

The proposal supposes that installing solar panels will reduce dust yield and offset the current need for periodic shallow flooding to reduce dust transport. PV arrays on the dry lake surface would reduce (but not eliminate) the size of the dust fetch (the area contributing dust during windy intervals) (Figure 2).

Figure 2. Multiple dust sources, minor dust storm, Owens Lake, CA

The solar panels also will create surface roughness, like vegetation, so reducing wind velocity and hence its dust-carrying capacity and overall dust transport. But the near-surface wind turbulence induced by the solar array also would likely cause severe problems of dust impacts on the panels themselves. And if PV panel systems are tracking types (panels constantly turn to maximize solar gain), the amount of land exposed to dust yield is larger than for fixed panel arrays.4

An issue for the Owens Lake proposal is the composition of the dry lake surface, where corrosive materials have been found that have a potential to degrade the panels more severely than plain dust. This discovery has apparently dampened interest in building a solar mega-project, limiting the current proposal to a 50 MW pilot project. The risk of occasional natural flooding, which could weaken the stability of panel supports, has not yet been addressed .

Endnotes

1. Howard G. Wilshire, et al., Geologic Processes at the Land Surface, U.S. Geological Survey, Bulletin 2149, 1996

2. The American Society of Civil Engineers recently gave the U.S. electricity grid a grade of D (American Society of Civil Engineers, U.S. Electric Power Grid, 2005: http://apps.asce.org/reportcard/2005/page.cfm?id=25).

3. See also The Oil Drum, The U.S. Electric Grid: Will It Be Our Undoing? – Revisited, The Oil Drum, 6 August, 2010: http://www.theoildrum.com/node/6817#more. This article considers the current grid inadequate for carrying additional electricity, which is hoped to come from renewable sources

4. Tracking arrays require greater spacing between solar collector panels to avoid the shading effects caused by the sun-tracking movement of the modules.

Advertisements
No comments yet

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: