As more countries pledge to achieve net zero carbon emissions, there will be a greater reliance on renewable energy sources such as wind turbines and solar energy. However, there is very little evidence on the impacts large-scale solar farms have on the local environment. Now, scientists using satellite technologies have discovered that large-scale solar parks have a cooling effect on the land surrounding them.
The team of scientists, from Lancaster University, Ludong University and the University of California, Davis, focused on two large-scale solar parks located in arid locations: the 300 MW Stateline solar park in California and the 850 MW Longyangxia solar park in China. Using land surface temperature data derived from Landsat satellite images — an approach not previously applied to solar parks — the team was able to compare the land surface temperatures around solar parks before and after the solar parks were constructed. The satellite data was supplemented by on-the-ground temperature measurements around Stateline solar park.
The researchers found that the parks produced ‘cool islands’ extending around 700 m from the solar park boundaries. The temperature of surrounding land surface was reduced by up to 2.3°C at 100 m away from the solar park, with the cooling effects reducing exponentially to 700 m. The researchers hypothesise this is due to the solar arrays shading and insulating the land surface, as well as energy being converted into electricity by the solar panels, although further studies are needed to determine the exact mechanisms that cause the cool island effect and how it might vary with location and solar park design.
Published in the journal Renewable and Sustainable Energy Transition, the team’s discovery is important as it shows solar parks could impact ecological processes, including productivity, decomposition and ultimately the carbon balance, in the surrounding landscape — an effect that will depend on the location and could be positive, negative or inconsequential. For example, previous studies have shown that lower surface temperatures on the Tibetan Plateau could potentially reduce the amount of methane lost to the atmosphere. However, in the Mojave Desert, lower temperatures resulted in fewer seeds germinating, which may mean fewer plants surviving to adulthood, reducing biodiversity.
The new findings therefore highlight the need for greater consideration to be given to where solar parks are built around the world, as well as their design, to minimise any negative impacts and boost positive effects.
“Most studies examine the impacts of land use change for solar parks inside the site boundaries,” said Dr Alona Armstrong, co-lead author on the study from Lancaster University. “Here, we found a temperature effect that is evident up to around 700 m away, suggesting that ecological processes may also be impacted.
“This heightens the importance of understanding the implications of renewable energy technologies on the hosting landscape — we need to ensure that the energy transition does not cause undue damage to ecological systems and ideally has net positive consequences on the places where we build them.”
Image L–R: Stateline solar park; Dr Alona Armstrong taking a soil surface measurement.