One of the downsides to large-scale solar power is finding space suitable for the installation of a large area of PV panels or mirrors for CSP.  These are long-term installations, and will have impact on the land and it’s uses.  There are potential objections to committing areas of undeveloped or pristine land to solar power. 

Solar Energy on Reservoirs:

Floating arrays have been installed on surfaces such as water reservoirs as these “land areas” are already committed to a long-term purpose.  Solar power is considered a good synchronistic fit, and most recently work was completed in England seeing “23,000 solar panels on the Queen Elizabeth II reservoir at Walton-on-Thames”.   (1)

Water utilities are the first to see the benefit of solar panel installations as the power generated is generally consumed by the utilities operations for  water treatment and pumping.  This of course offsets demand requirements from the electrical utility and reduces operating costs with a ROI from the installation.  Possible government or other industry incentives and subsidies may enhance benefits.  Last year a 12,000 panel system was installed on a reservoir near Manchester (UK) and was the second of it’s kind in Britain, dwarfing the original installation of 800 panels.  (2)  (3)

Image #1:  World’s largest floating array of PV Solar Panels in Japan (4)

Currently Japan has the most aggressive expansion plans for reservoir installations, with the most recent being the world’s largest of it’s kind.  Recent changes in energy policies and the ongoing problems associated with Nuclear Power has propelled Japan into aggressively seeking alternative forms of energy.

“The 13.7-megawatt power station, being built for Chiba Prefecture’s Public Enterprise Agency, is located on the Yamakura Dam reservoir, 75 kilometers east of the capital. It will consist of some 51,000 Kyocera solar modules covering an area of 180,000 square meters, and will generate an estimated 16,170 megawatt-hours annually. That is “enough electricity to power approximately 4,970 typical households,” says Kyocera. That capacity is sufficient to offset 8,170 tons of carbon dioxide emissions a year, the amount put into the atmosphere by consuming 19,000 barrels of oil.” 

“[…]“Due to the rapid implementation of solar power in Japan, securing tracts of land suitable for utility-scale solar power plants is becoming difficult,” Toshihide Koyano, executive officer and general manager of Kyocera’s solar energy group told IEEE Spectrum. “On the other hand, because there are many reservoirs for agricultural use and flood-control, we believe there’s great potential for floating solar-power generation business.”

He added that Kyocera is currently working on developing at least 10 more projects and is also considering installing floating installations overseas.” (4)

Solar Energy on Brownfields:

A Brownfield is defined generally by the EPA  (5)

A brownfield is a property, the expansion, redevelopment, or reuse of which may be complicated by the presence or potential presence of a hazardous substance, pollutant, or contaminant. It is estimated that there are more than 450,000 brownfields in the U.S. Cleaning up and reinvesting in these properties increases local tax bases, facilitates job growth, utilizes existing infrastructure, takes development pressures off of undeveloped, open land, and both improves and protects the environment.

Image #2:  6-MW solar PV array on the site of the former Palmer Metropolitan Airfield (6)

Traditionally most solar projects have been built on “Greenfields”, however, on further analysis it makes far more sense to install solar on “Brownfields”.

The U.S. is home to more than 450,000 brownfields – unused property that poses potential environmental hazards. Eyesores as well as potential health and safety threats, brownfield sites reduce urban property values. Rehabilitating them pays off, and in more ways than one, according to a July, 2014 National Bureau of Economic Research (NBER) working paper entitled, ¨The Value of Brownfield Remediation.¨ […]

NBER researchers determined that remediation increased the value of individual brownfield sites $3,917,192, with a median value of $2,117,982. That compares to an estimated per-site cost of $602,000. In percentage terms across the study’s nationally representative sample, EPA-supported clean-ups resulted in property price increases of between 4.9% and 32.2%. (6)

In another example where a Brownfield remediation effort has payed off utilizing a Solar Power upgrade is at the Philadelphia Navy Yard according to a June 2011 report by Dave Levitan (7) where it says:

“The Navy Yard solar array is just one of a growing number of projects across the U.S. that fall into the small category of energy ideas that appear to have little to no downside: turning brownfields — or sites contaminated

Every solar project that rises from an industrial wasteland is one that won’t be built on pristine land.

or disturbed by previous industrial activity — into green energy facilities. Among the successfully completed brown-to-green projects are a wind farm at the former Bethlehem Steel Mill in Lackawanna, New York; a concentrating solar photovoltaic array on the tailings pile of a former molybdenum mine in Questa, New Mexico; solar panels powering the cleanup systems at the Lawrence Livermore National Laboratory’s Superfund site in northern California; and the U.S. Army’s largest solar array atop a former landfill in Fort Carson, Colorado.”

Solar Energy on Landfills:

Building solar power projects on top of closed off landfills appears to be a good idea, however, there are additional considerations and requirements which must be met which would exceed those of a normal type of undisturbed geology.

“Construction and ongoing operation of the plant must never break, erode or otherwise impair the functioning integrity of the landfill final closure system (including any methane gas management system) already in place.”  (8) […]

Image #3:  Prescriptive Landfill Capping System

In general, the features of a conventional “Subtitle D” final protection barrier cover system on USA waste sites are shown in the illustration above and include the following layers added on top of a waste pile:

1. First, a foundation Layer – usually soil—covers the trash to fill and grade the area and protect the liner.
2. Then typically a geomembrane liner or a compacted clay layer .is spread over the site to entomb the waste mass in a water impermeable enclosure.
3. A drainage layer (i.e. highly transmissive sands or gravels or a manufactured “Geonet”) is next added– especially in areas with heavy rainfall and steeper slopes. This is to prevent the sodden top layers of dirt from slipping off the impermeable barrier (a.k.a. a landslide).
4. Next, typically 18 inches of soil is added as a “protection layer.”
5. Finally, an “erosion layer” of soil – typically 6 inches of dirt of sufficient quality to support plant growth (grasses, etc., etc.) which the waste industry calls a “vegetative layer.”

Image #4:  Established Solar Energy Projects on Closed Landfills (9)

As of 2013 we can see that there already have been a number of solar installations and that this number is still growing through to the present as more municipalities seek ways to convert their closed landfills into a renewable resource and asset.

Summary of Solar Energy Project Types by Site

A greenfield site is defined as an area of agricultural or forest land, or some other undeveloped site earmarked for commercial development or industrial projects.  This is compared to a brownfield site which is generally unsuitable for commercial development or industrial projects due to the presence of some hazardous substance, pollutant or contaminant.

While a water reservoir is not a contaminated site, it is generally rendered useless for most purposes, however provides an ideal site for locating solar panels as they provide relatively large areas of unobstructed sun.  Also reservoirs provide water cooling which enhances energy efficiency and PV performance.  Uncovered reservoirs can be partially covered by floating arrays of PV panels, of modest to large sizes in the 16 MW range.  Installations can be found throughout the world, including England and most recently Japan where interest in alternative energy sources is growing rapidly.

A brownfield site is considered ideal for the location of a solar plant as a cost-effective method of an otherwise useless body of land, such as a decommissioned mine, quarry, or contaminated site.  A landfill is one form of brownfield site which could be suitable for the installation of solar power where provision has been made to protect the cap on the landfill.  Municipalities have been showing growing interest in landfill solar as a means to offset operational costs.

Abbreviations:

PV – Photo Voltaic

CSP – Concentrated Solar Power

ROI – Return On Investment

UK – United Kingdom

NBER – National Bureau of Economic Research

EPA – Environmental Protection Agency

References:

1. http://www.theguardian.com/environment/2016/feb/29/worlds-biggest-floating-solar-farm-power-up-outside-london
2. http://www.telegraph.co.uk/finance/newsbysector/energy/11954334/United-Utilities-floats-3.5m-of-solar-panels-on-reservoir.html
3. http://www.telegraph.co.uk/news/earth/energy/solarpower/11110547/Britains-first-floating-solar-panel-project-installed.html
4. http://spectrum.ieee.org/energywise/energy/renewables/japan-building-worlds-largest-floating-solar-power-plant
5. https://www.epa.gov/brownfields/brownfield-overview-and-definition
6. http://microgridmedia.com/massachusetts-pv-project-highlights-benefits-of-solar-brownfields/
7. http://e360.yale.edu/feature/brown_to_green_a_new_use_for_blighted_industrial_sites/2419/
8. http://solarflexrack.com/a-simple-guide-to-building-photovoltaic-projects-on-landfills-and-other-waste-heaps/
9. http://www.crra.org/pages/Press_releases/2013/6-3-2013_CRRA_solar_cells_on_Hartford_landfill.htm