Solar Energy: Friend Or Foe Of The Environment?

Solar energy is a renewable, clean, and efficient energy source that harnesses the power of the sun to generate electricity, heat buildings, and perform many other functions. As interest in solar energy as a clean power source surges, it is important to consider its environmental impact. While solar energy does not produce emissions that contribute to climate change or air pollution, there are potential environmental impacts associated with its production and use, including land use and habitat loss, water use, and the use of hazardous materials in manufacturing.

Solar panels can contain hazardous materials and metals

Solar panels are often touted as an environmentally friendly alternative to fossil fuels. However, there is growing awareness that solar panels, like other forms of renewable energy, are not without their environmental costs. One significant concern is the presence of hazardous materials and metals in solar panels, which can pose risks to the environment if not properly handled and disposed of.

The manufacturing process for photovoltaic (PV) cells involves the use of several hazardous materials, including hydrochloric acid, sulfuric acid, nitric acid, hydrogen fluoride, 1,1,1-trichloroethane, acetone, and silicon dust. These chemicals are necessary for cleaning and purifying the semiconductor surface. While some of these chemicals are common in the semiconductor industry, their use in PV cell manufacturing must be carefully managed to avoid releasing them into the environment.

Thin-film PV cells, in particular, contain higher levels of toxic materials than traditional silicon photovoltaic cells. These include gallium arsenide, copper-indium-gallium-diselenide, and cadmium-telluride. If not properly handled and recycled, these materials could pose serious environmental and public health risks. For example, cadmium-based modules have been known to fail hazardous waste tests and require treatment at specialised facilities.

Additionally, some solar panels release nitrogen trifluoride (NF3) into the atmosphere, a chemical compound that is significantly more harmful than carbon dioxide. As of 2015, manufacturers were still working on methods to contain its release. Solar thermal systems may also use potentially hazardous fluids for heat transfer, and leaks of these fluids could harm the environment.

The proper disposal and recycling of solar panels at the end of their useful life are crucial for mitigating these risks. However, recycling solar panels can be costly, and the absence of valuable metals and materials in the panels can result in economic losses. As a result, many solar panels end up in landfills, where broken panels can release toxic materials into the soil. To address this issue, several U.S. states have enacted laws to encourage the recycling of PV panels, and efforts are being made to recover and recycle materials used in their manufacture.

Solar panels can be recycled or disposed of as hazardous waste

Solar panels can be recycled, but the process is tedious and requires advanced machinery. The glass, aluminium, and copper in solar panels can be recovered through crushing, shredding, and milling processes, while the silicon solar cells may be incinerated. Glass makes up about 75% of a solar panel's weight, and glass recycling is a well-established industry. Other easily recyclable materials include the aluminium frame, copper wire, and plastic junction box.

However, other materials within the solar cells may be more challenging to recycle. Silver and internal copper are valuable but are only present in small amounts. Toxic metals like lead and cadmium may also be present in solar panels, and panels with these metals are considered hazardous waste in North Carolina. Thin-film cadmium-telluride panels, which are a smaller part of the solar market, undergo a different recycling process. At least one US manufacturer runs dedicated recycling facilities for these panels, recovering the semiconductor material (cadmium and tellurium) in addition to glass and copper.

The US Department of Energy is supporting efforts to address end-of-life issues related to solar energy technologies, including recovering and recycling materials used to manufacture photovoltaic (PV) cells and panels. Several states have enacted laws that encourage recycling PV panels. California, which has the most solar installations, allows panels to be dumped in landfills but only after being verified as non-hazardous. As of July 2022, California had only one recycling plant accepting solar panels. Washington State has also passed a solar product stewardship law, and New Jersey and North Carolina are taking steps to address PV waste.

Despite the recyclability of solar panels, the recycling rate in the US and the EU is around 10%. This is partly due to the difficulty of extracting valuable materials from panels. However, as more panels reach the end of their useful life, recycling is expected to become more prevalent, providing recyclers with valuable materials to sell. By 2030, the global value of recoverable raw materials from end-of-life panels is estimated to be about $450 million, equivalent to the cost of raw materials needed to produce 60 million new panels.

Solar energy systems require land, impacting habitats and ecosystems

Solar energy is a renewable resource, which means it can be naturally replenished over time. It is a more environmentally friendly option than traditional forms of energy generation because it emits no harmful emissions. However, solar energy systems require land for the installation of solar panels, and this can impact habitats and ecosystems.

The amount of land required for solar energy systems can vary depending on the technology used, the topography of the site, and the intensity of the solar resource. According to the DOE's Solar Futures Study, solar energy development could require up to 5.7 million acres of land, or about 0.3% of the contiguous US, by 2035. While some areas are more suitable for solar panel installation than others, any area that has been cleared and developed for this purpose is considered a lost habitat. This can have significant impacts on local ecosystems, especially when coupled with the construction of roads and transmission lines necessary for large-scale solar energy development, which can fragment habitats.

To minimize these impacts, solar developers typically evaluate multiple sites, site designs, and operation strategies during the siting and permitting of solar projects. They assess the environmental impacts of their projects by complying with relevant laws, soliciting input from regulators, and performing impact assessments and mitigation measures. Strategies to minimize impacts include siting utility-scale solar systems at lower-quality locations such as brownfields, abandoned mining land, or existing transportation and transmission corridors. Smaller-scale solar PV arrays, which can be built on homes or commercial buildings, also have a minimal land use impact.

Additionally, placing solar panels on existing structures can help avoid habitat loss. The US Department of Energy's Solar Energy Technologies Office (SETO) supports research to better understand how solar energy installations, wildlife, and ecosystems interact and to identify strategies that maximize benefits to the local environment and host communities. SETO-funded research projects are led by collaborative groups of stakeholders, which may include representatives from the solar industry, communities, governments, universities, environmental and conservation non-profits, and the agriculture industry. Through technical assistance programs, SETO also encourages information sharing among stakeholders on environmentally responsible solar deployment.

Solar energy systems use water for cleaning and cooling

Solar energy is widely regarded as a clean and sustainable electricity source that does not contribute to toxic pollution or global warming emissions. However, solar energy systems do have some environmental impacts, including land use, habitat loss, water use, and the use of hazardous materials in manufacturing.

Solar energy systems may require water for cleaning and cooling, depending on their design and location. Solar photovoltaic (PV) cells do not use water for electricity generation, but water is used during the manufacturing process and for maintenance, such as cleaning the panels. The amount of water used for cleaning can be minimized by turning off the hose when not in use or filling a bucket to control water consumption.

Concentrating solar thermal plants (CSP), on the other hand, require water for cooling. The amount of water used depends on the plant design, location, and cooling system. CSP plants with wet-recirculating technology and cooling towers can withdraw between 600 and 650 gallons of water per megawatt-hour of electricity produced.

In arid locations, using large volumes of groundwater or surface water for cleaning solar collectors and concentrators can impact the ecosystems that depend on these water resources. Therefore, careful consideration of water usage is essential, especially in regions with high solar energy potential and dry climates.

Solar panels can help conserve water once they are operational, as they do not require water for electricity generation, unlike traditional power plants that use water for cooling. By reducing the reliance on traditional power sources, solar panels can help households save a significant amount of water annually, contributing to the preservation of aquatic ecosystems and water resources.

Solar energy systems do not produce emissions

Solar energy is a renewable energy source that is vital to the U.S. effort to reduce fossil fuel use. Solar energy systems do not produce emissions that contribute to climate change or air pollution. This makes solar energy a much safer choice for those living near power plants, compared to other energy sources.

Photovoltaic (PV) cells convert sunlight into electrical energy with very high efficiency rates. Solar energy can be used to generate electricity, heat buildings and water, and run cars. However, the manufacturing process of PV cells includes hazardous materials, which must be carefully handled to avoid releasing them into the environment. These chemicals include hydrochloric acid, sulfuric acid, nitric acid, hydrogen fluoride, 1,1,1-trichloroethane, and acetone. The amount and type of chemicals used depend on the type of cell, the amount of cleaning required, and the size of the silicon wafer.

Some solar thermal systems use potentially hazardous fluids to transfer heat, and leaks of these materials could be harmful to the environment. U.S. environmental laws regulate the use and disposal of hazardous materials. The U.S. Department of Energy is supporting various efforts to address end-of-life issues related to solar energy technologies, including recovering and recycling materials used to manufacture PV cells and panels. While solar energy systems themselves do not produce emissions, there are emissions associated with other stages of the solar life cycle, including manufacturing, materials transportation, installation, maintenance, and decommissioning and dismantlement.

The environmental impact of solar energy systems can be further mitigated by carefully selecting installation sites. For example, installing solar energy systems on land with marginal agricultural value or integrating them into farms can provide economic and environmental benefits to farmers. Additionally, placing solar panels on existing structures can help avoid habitat loss.

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