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Severe air pollution in China hampers solar electricity generation

China’s severe air pollution problem is hampering efforts to increase the amount of electricity it generates from solar panels, according to research from Princeton University in the USA.

The country hopes to meet 10 per cent of its electricity needs with solar energy by 2030 but particulates in the air are blocking the light from the sun form reaching the panels.

China’s output of solar energy is particularly reduced in the northern and eastern parts of the country and is worst in the winter when about 20 per cent of sunlight is blocked on average.

That makes air pollution’s wintertime effect on solar energy production as significant as that of clouds, which have long been considered the main impediment to solar energy production.

Aerosol pollution was found to reduce the potential for solar electricity generation by as much as one-and-a-half kilowatt-hours per square metre per day, or up to 35 per cent.

Burning fossil fuels increases aerosol concentrations in the atmosphere. Other researchers have recognised that these aerosols, which include sulphate, nitrate, black carbon particulates and brown organic compounds, are contributing to solar dimming over large parts of China.

But no previous research had calculated just how much aerosols in the atmosphere are reducing China’s solar energy generating efficiency.

“Developing countries with severe air pollution that are rapidly expanding solar power, such as China and India, often neglect the role of aerosols in their planning, but it can be an important factor to consider,” said Xiaoyuan Li, lead author of the study.

To calculate how much of the sun’s radiation is reaching solar arrays on the ground, the scientists used what’s called a solar photovoltaic performance model, combined with satellite data from Nasa instruments that measure irradiance from the sun and analyse aerosol components and clouds in the atmosphere.

They conducted nine separate analyses, which spanned 2003 to 2014 and covered all of China, to compare the impact of aerosols to that of clouds on solar power generation with and without technology that tracks the sun as it moves across the sky.

“Particulate pollution from power plants, vehicles, biomass burning and natural events such as dust storms” can be a major impediment to solar power generation, said Professor Daniel Kammen

He said the study “uses rigorous atmospheric chemistry modelling” to quantify how pollution affects the amount of solar radiation reaching the ground, “which, ironically, also can be used to determine the clean energy benefits” of cutting carbon emissions.

Li said the study’s findings should further spur countries like China and India to cut aerosol emissions so they reduce pollution and thereby increase their solar electricity generation more rapidly, in addition to the already known health benefits.

There is also potential for a virtuous cycle: expanding solar energy production could reduce reliance on fossil fuels, thus cutting down on the very emissions that hamper solar power production, Li said. This would send more solar electricity into the grid—which, in turn, should further cut the need for fossil fuels.

The findings can also help determine where to build new solar arrays. Aerosol pollution in China is heavily concentrated in industrialised, urbanised regions, while remote, thinly populated areas have much cleaner air. If research can quantify how much air pollution is reducing solar power output, policy-makers can weigh the costs of transmitting electricity from cleaner regions to dirtier ones against the benefits of producing more power by building arrays where more sunlight reaches the ground.

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