Chinese researchers have found that large-scale deployment of photovoltaics in the Taklamakan Desert could change regional climate dynamics and worsen water stress in the already arid Tarim Basin, despite the area’s vast solar potential.
A research team from China has assessed the climatic impact of a massive PV deployment in the Taklamakan Desert in the Tarim Basin, one of the driest major deserts in the world, characterized by extremely low precipitation and very high evaporation rates. Water availability in the region is highly dependent on meltwater from surrounding glaciers and seasonal snow, which feed the river systems of the Tarim Basin. However, as regional glaciers continue to retreat, the long-term reliability of this water supply is under increasing pressure.
The researchers assumed a scenario in which most of the basin would be covered by utility-scale PV installations, with total electricity generation exceeding current global demand. Despite this extreme setup, their results indicate that even much smaller-scale implementations in the region could intensify existing water stress.
“The novelty of our approach lies in the use of a high-resolution 9 km process-based modeling framework that combines the regional climate system with dynamic vegetation cover,” says corresponding author Zhengyao Lu. pv magazine. “This allows us to explicitly resolve the complex regional-scale surface-vegetation-atmosphere feedback in the Tarim Basin that accompanies massive PV deployment.”
“The most striking finding is that large-scale, highly efficient PV deployment in the Taklamakan Desert could intensify regional water stress, especially in the populated areas along the desert edges,” the researcher added. “We are currently working on a new paper that focuses on the interactions between wind and solar energy deployment via local climate-ecosystem feedback in the same study region.”
Image: Tarim University, Science Bulletin, CC BY 4.0
For their assessment, the research group used four climate datasets and one vegetation dataset for the period 2016-2020: CN05.1 and CRU TS4.05 (Climatic Research Unit Time-Series version 4.05) for temperature and precipitation; the Global Precipitation Climatology Center (GPCC) dataset to evaluate precipitation patterns; the European Center for Medium-Range Weather Forecasts (ECMWF) ERA5 reanalysis to provide the primary atmospheric forcing data; and the Global Land Surface Satellite (GLASS) Leaf Area Index (LAI) product to characterize vegetation cover and plant dynamics.
They also used two main numerical models: the Weather Research and Forecasting (WRF) model to simulate regional climate processes, and the Lund-Potsdam-Jena General Ecosystem Simulator (LPJ-GUESS) to represent vegetation dynamics and ecosystem responses.
Within this framework, WRF simulated key climate variables in the Tarim Basin, including temperature, precipitation, wind fields, runoff and soil moisture. These results were then used to drive LPJ-GUESS, which simulated vegetation cover, LAI and ecosystem responses to changing environmental conditions. The resulting vegetation changes were then fed back to WRF, allowing the model to capture how shifts in plant cover further influence local climate and hydrological processes.
This coupled modeling approach allowed the researchers to assess both the direct climate impacts of PV installations and the additional indirect impacts mediated by vegetation-climate feedback.
Image: Tarim University, Science Bulletin, CC BY 4.0
The simulations assumed that the entire Tarim Basin was covered with PV panels, excluding legally protected areas, forested areas and terrain with slopes steeper than 30 degrees. To evaluate the climatic consequences of large-scale solar energy, the researchers defined six effective albedo scenarios representing different levels of sunlight reflection and energy conversion by PV installations.
These scenarios include a control case without PV implementation (Ctrl); a current PV case with an effective albedo of 0.1925 and an estimated conversion efficiency of about 15% (S19); a future high-efficiency scenario with an effective albedo of 0.335 and roughly 30% efficiency (S335); two extremely high efficiency cases with effective albedos of 0.62 and 0.905, corresponding to conversion efficiencies of about 60% (S62) and 90% (S905); and an extremely low albedo “black panel” scenario with an effective albedo of 0.05 and an efficiency of about 5% (S05).
The researchers found that the higher efficiency PV scenarios, including the more realistic future case S335 and the extreme S62 and S905 scenarios, reflected more incoming solar radiation and reduced surface heating in the basin. According to the simulations, this caused a surface cooling of up to 1.5 degrees Celsius across the entire desert area.
The cooling effect weakened the moisture transport into the basin, enhanced the downward air movement and stabilized the lower atmosphere, ultimately suppressing the formation of rain. The reduced precipitation subsequently led to a decrease in vegetation cover and Leaf Area Index (LAI), especially around the edges of the basin. As vegetation cover decreased, evaporation and low-level cloud formation also weakened, further reducing the availability of moisture in the atmosphere and amplifying the decline in rainfall.
“We find that large-scale PV installations can significantly reduce water resources in populated areas, with a reduction of more than 30% in runoff, precipitation and drought indices, in addition to an 8.5% drop in soil moisture,” the academics said. “These results highlight the critical need to include vegetation feedback in future studies to fully evaluate the hydrological impact of PV and emphasize the importance of careful planning to mitigate the environmental risks associated with large-scale solar projects in Northwest China.”
They added that future studies should further investigate the hydrological impacts of large-scale PV deployment and emphasized the need for careful project planning to minimize the potential environmental impacts associated with utility-scale solar energy development in Northwest China.
Their findings are published in “Large-scale photovoltaic deployment in the Taklamakan Desert could intensify regional water stress” in Science Bulletin. Researchers from China’s Tarim University, Xiamen University, Beijing Normal University, Tsinghua University, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Sweden’s Lund University, University of Gothenburg and Denmark’s University of Copenhagen participated in the study.
Another recent study from China assessed the impact of using up to 50% of the Sahara Desert to deploy large-scale solar power plants and found that these could affect global cloud cover through disrupted atmospheric teleconnections. This in turn would impact solar energy generation itself in North Africa, Southern Europe, the South Arabian Peninsula, India, Northern Asia and even Eastern Australia.
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