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Tribal Energy and Environmental Information Clearinghouse: Environmental resources for tribal energy development
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Solar Energy Operations: Resource Requirements and Impact Sources

Minimal land-disturbing activities are anticipated during the operations phase.

Routine activities would include operation of the solar development to produce power, and regular monitoring and maintenance activities to ensure safe and consistent operation. Routine mirror washing would be required (e.g., every few weeks). In most cases, mirror washing would occur during evening hours. Both on- and off-site maintenance of access roads may be required after rainfall events (e.g., blading and sediment removal from culverts). Vegetation maintenance would be required within the solar collector field and within the transmission line, gas pipeline, and water pipeline rights-of-way.

The following factors could affect whether an environmental impact could occur at a solar energy project and whether it would be considered an adverse effect.

  • Acreage – Acreage needs for a parabolic trough or compact linear Fresnel reflector development would average about 5 acres/megawatt (MW), while acreage for the other solar technologies would average about 9 acres/MW. Acreage needs increase if the solar field is oversized to take advantage of thermal or electrical storage. For example, a parabolic trough development could increase the field size from 5 acres/MW to 10 acres/MW. Also, facilities with two-axis tracking would require increased spacing to avoid shadowing effects (e.g., photovoltaic plants could double in size, requiring up to 10 acres/MW). The transmission line right-of-way would be about 150 feet wide, while pipeline rights-of-way would be about 25 to 50 feet wide.
  • Emissions - Solar energy operations would generate pollutants that include emissions from the operation of vehicles and the periodic operation of diesel-fueled emergency generators for preventative maintenance purposes; fugitive dust from vehicle travel on unpaved roads or wind erosion from bare soils; and minor release of volatile organic chemicals (VOCs) from on-site storage of diesel fuel, and various maintenance and cleaning operations. Criteria and greenhouse gases could also result from use of heating, ventilation, and air conditioning systems. Particulate emissions would be released from cooling tower drift if wet cooling is used. Air emissions from hybrid facilities would be proportional to the relative percentage of the power generated from the fossil-fueled portion of the project. Fires, accidents, and broken photovoltaic (PV) modules could also be a source of air emissions.
  • Waste Generation – Small amounts of gear oil and lubricating oils; transmission and glycol-based coolants and lubricants; and paints or coatings for corrosion control. Hazardous chemicals would be present in blowdown. The only hazardous materials used in dish engine systems are the antifreeze used in the cooling system and a small amount of oil lubricant used in the engine. The hydrogen gas used as the heating fluid is sealed inside the engine; the small amounts that escape over time is non-toxic and diffuses rapidly into the atmosphere.
  • Water Needs – Parabolic trough, compact linear Fresnel reflector, and power tower technologies would require up to 15 acre-feet per year per megawatt (ac-ft/yr/MW) (nearly 13,400 gallons per day per MW) for wet cooling or up to 1.5 ac-ft/yr/MW (about 1,350 gallons per day per MW) for dry cooling. Cooling water would not be required for dish engine or photovoltaic technologies. Water required for mirror washing would be about 0.5 ac-ft/yr/MW (nearly 450 gallons per day per MW) for all solar technologies. Water would likely be brought to the site by a pipeline or obtained from an on-site well.
  • Workforce – Full-time operational or maintenance crews would be required at the project site. The number of full-time equivalent employees would be about 10 to 160 or more, depending upon the type and size of the solar project.
  • Utility and Emergency Power Requirements – Although the primary purpose of a solar development is to deliver power to the transmission grid, it may also use power to function optimally. To ensure safe shutdown of all systems in the event of grid connection interruption, and to ensure the continued operation of safety-related devices such as aviation safety lights, solar developments would be equipped with emergency alternating current (AC) power generation, typically in the form of a diesel-fueled emergency generator, and emergency direct current (DC) power in the form of lead-acid storage batteries. Energy would also be required to operate the power block, cooling towers and fans, provide lighting and heat, and so forth.