A new study finds that there could be unintended consequences of building massive solar farms in deserts around the world. Revealing research claims that large solar farms, such as those in the Sahara, could lead to environmental crises, including altering the climate and causing global warming.
The study was conducted by Zhengyao Lu, a researcher in Physical Geography at Lund University, and Benjamin Smith, research director at the Hawkesbury Institute for the Environment at the University of Western Sydney. The results of their research were published in a February 11 article in The Conversation.
Solar panels are darker colors, such as black and blue, to attract and absorb more heat, but they are usually much darker than the ground around the solar panel. The publication cites an article that states that most solar panels are 15-20% efficient at converting sunlight into usable energy. The researchers claim that the rest of the sunlight is returned to the surrounding environment in the form of heat, “affecting the climate.”
The article notes that to replace fossil fuels, solar farms would have to be huge, covering thousands of square miles, according to this article. Solar farms of this magnitude potentially have environmental consequences, not just locally but globally.
The authors of a 2018 study say that climate models show that installing a large number of wind turbines would double precipitation in the Sahara desert, and solar panels would increase precipitation by 50%. The researchers came to this conclusion by determining that solar panels and wind turbines would decrease albedo at the Earth’s surface. Albedo is the fraction of light that a body or surface reflects.
From the conversation:
The model revealed that when the size of the solar farm reaches 20% of the total area of the Sahara, a feedback loop is triggered. The heat emitted by darker solar panels (compared to the highly reflective desert floor) creates a strong temperature difference between the land and the surrounding oceans which ultimately lowers the air pressure at the surface and causes humid air rises and condenses into raindrops. With more monsoon rains, plants grow and the desert reflects less energy from the sun, as vegetation absorbs light better than sand and soil. With more plants present, more water evaporates, creating a more humid environment that causes vegetation to spread.
Turning the Sahara desert into a lush green oasis could have climatic ramifications across the planet, such as affecting the atmosphere, ocean, land, changing entire ecosystems, altering rainfall in Amazon rainforests, inducing droughts, and potentially triggering more tropical cyclones.
The well-intentioned effort to lower the world’s temperature could do the opposite and increase the planet’s temperature, according to the researchers.
Covering 20% of the Sahara with solar farms raises local temperatures in the desert by 1.5 ° C according to our model. With a 50% coverage, the temperature rise is 2.5 ° C. This warming eventually spreads around the world by the movement of the atmosphere and oceans, raising the global average temperature by 0.16 ° C for 20% coverage and at 0.39 ° C for 50% coverage. However, the global temperature change is not uniform: the polar regions would warm more than the tropics, increasing the loss of sea ice in the Arctic. This could further accelerate warming, as melting sea ice exposes dark water that absorbs much more solar energy.
The authors conclude their article by stating that renewable energy solutions “can assist society in the transition from fossil energy, but studies of the Earth system like ours underscore the importance of considering the many coupled responses of the atmosphere, oceans and the land surface by examining its benefits and risks. “