Delivering Big Solar with a Small Footprint

While the world's energy demand increases at an unparalleled rate, the need to meet that demand with cleaner sources of energy is growing even faster. Solar energy offers an abundant and sustainable energy supply, but as the New York Times reported, expectations are growing that the solar technologies themselves must also have a low carbon footprint – from the materials used to manufacture panels to the water and land required to produce solar energy.   In comparing the various technologies used to create electricity from the sun, concentrator photovoltaic (CPV) solar technology has the lightest environmental impact.
Solar power’s environmental impact is of critical concern, especially in regards to water and land use. In California, Senator Dianne Feinstein is reintroducing the California Desert Protection Act. The legislation proposes to set aside new lands in the Mojave Desert for conservation, recreation, and other purposes. The “California Desert Protection Act of 2011” proposes the following:

• Create the Mojave Trails National Monument, protecting 941,000 acres of federal land. 
• Create the Sand to Snow National Monument, encompassing 134,000 acres of federal land.
• Add adjacent lands to Joshua Tree National Park, Death Valley National Park, and the Mojave National Preserve. 
• Protect nearly 76 miles of four important waterways. 
• Designate five new wilderness areas. 
• Designate approximately 250,000 acres of Bureau of Land Management wilderness areas near Fort Irwin.

Environmental stewardship is a value that today’s solar industry leaders must hold in high regard. Solar companies must be committed to providing the world with a viable solution for clean energy throughout the solar equipment’s lifecycle, from cradle-to-cradle. In the instance of CPV technology, the combination of high efficiency systems and a small amount of photovoltaic material make the technology environmentally advantaged in a number of ways including the fastest energy payback – 6 months compared to nearly 2 years for silicon PV.
An advantaged environmental footprint for systems, however, doesn’t just happen – it has to be strategically considered from concept to commercialization. For example, at the inception of both product design and manufacturing, engineers should take into account key environmental concerns – climate change, water use, habitat impact, and end of life recyclability. With the rapid deployments planned for solar, inclusion of sustainability factors in the product definition is absolutely critical to assure that clean energy is indeed “clean.”
Minimising land use
Capable of flexible site layouts, CPV power plants can be deployed on odd-shaped parcels and on land with up to 23% grading. Photo courtesy of SolFocus.In addition to energy payback, one of the key metrics in measuring environmental impact is land use.  With the increased efficiency offered by advanced solar technologies such as CPV, land use is optimized with minimal land coverage and disruption, protection of animal and flora ecosystems, flexibility of field layouts, and no use of water to produce electricity.
Increasing recycled content
As new products are developed, a minimum of 90% recyclability (we aimed for over 97% at SolFocus) with low levels of embodied green house gases should be minimum acceptable standards. Sustainable equipment is no longer a nice option, it is part of our day jobs as solar professionals. Optimized land use and best cradle?to?cradle model result in the highest level of environmental stewardship. Tracking technologies (again, CPV is one) are mounted on trackers (dual-axis for CPV) and follow the sun continuously throughout the day.  As a result, energy production is higher and there is no permanent shadowing of the ground’s surface reducing the impact on the animal and plant ecosystems, including with proper planning minimal disruption of migratory wildlife patterns at an installation facility.
Reducing water use
New solar projects must reduce land erosion from continual water runoff in fixed patterns. Globally, nearly half of water withdrawals are for the production of electricity.  Polysilicon, thin film and CPV systems, with the direct conversion of sunlight to electricity using photovoltaic cells, do not use water in the production of electricity as do most concentrating solar power (CSP) plants.  Those technologies that use passive cooling as do the SolFocus CPV systems, use water only for panel cleaning and not for energy generation.  With the growth of solar in the high solar resource regions of the world, which typically have limited water supply, this feature is very important in having a technology that does not consume precious natural resources.
CPV systems require no water consumption in the production of electricity, and a significantly smaller amount just for the cleaning of panels Stabilizing our global climate is paramount. Overconsumption of limited water supply and rapidly increasing greenhouse gas emissions, the key contributors to devastating climate change, are largely the result of continued reliance on traditional fossil fuel sources and generation technologies for energy. Choosing advanced technology solutions that do not exacerbate this process is critical for climate stability.