Air pollution takes a toll on solar energy | Science News for Students

Air pollution takes a toll on solar energy

Haze and pollution can filter out sunlight and cut electricity production
Oct 4, 2017 — 7:32 am EST
polluted Shanghai

By blocking sunlight and dirtying solar panels, air pollution — as seen here, in Shanghai, China in 2015 — can lower the production of electricity.


Air pollution can be a drag for solar energy. That pollution can cut the output of solar panels. And the energy losses from this are quite costly, a new study finds.

Dust and other air pollutants can produce a haze that darkens the sky. That haze then acts as a light filter. It cuts how much sunlight reaches solar-energy panels. Its effect on the electricity production by those solar collectors can be huge, the new study finds. It estimates that across parts of India, China and the Arabian Peninsula alone, pollution can slash electricity from solar energy by 17 to 25 percent.

Andhaze in the air isn’t the only factor that can limit how well solar panels work. If pollutant particles land on a panel’s flat surface, they will further block how much light gets through to the solar cells below. Dust can come from natural sources, such as windswept soils. But human activities produce much of these pollutants. Those activities include driving cars, powering factories and converting coal to electricity.

Michael Bergin works for the Pratt School of Engineering. It’s at Duke University in Durham, N.C. Bergin led a team that collected dust and pollution from solar panels in India. Then his group calculated how much this pollution could cut the solar energy output there, in China and in Mideast nations.

In India, polluted air appears to cut solar electricity by roughly 1 gigawatt (or billion watts). Natural dust and human-generated pollution contribute about equally here.

In eastern China, fossil-fuel use contributes far more than does natural dust. China also generates more solar energy than any other country. So there, air pollution’s toll is much bigger. It likely cuts electricity production by close to 11 gigawatts, the researchers calculate. That’s the full power output of 50.6 million photovoltaic solar panels. It’s also equal to 5,500 large-scale wind turbines or 1,100 coal-fired power plants. And it’s the amount of energy needed to power 1.1 billion LED lightbulbs. Clearly, that’s a lot of energy being lost.

It’s also costly. Making up for that lost energy is costing China the equivalent of about $10 billion per year, Bergin notes. Regular cleaning of solar panels can help. Cleaning the air, he notes, will prove a lot harder.

His team describes how it came to these numbers August 8 in Environmental Science & Technology Letters.

Power Words

(for more about Power Words, click here)

electricity     A flow of charge, usually from the movement of negatively charged particles, called electrons.

engineering     The field of research that uses math and science to solve practical problems.

factor     Something that plays a role in a particular condition or event; a contributor.

filter     (in chemistry and environmental science) A device or system that allows some materials to pass through but not others, based on their size or some other feature. (in physics) A screen, plate or layer of a substance that absorbs light or other radiation or selectively prevents the transmission of some of its components.

fossil fuel     Any fuel — such as coal, petroleum (crude oil) or natural gas — that has developed in the Earth over millions of years from the decayed remains of bacteria, plants or animals.

haze     Fine liquid or solid particles scattered through the atmosphere that make it hard to see. Haze can be caused by harmful substances such as air pollutants or by water vapor.

LED     (short for light emitting diode) Electronic components that, as their name suggests, emit light when electricity flows through them. LEDs are very energy-efficient and often can be very bright. They have lately been replacing conventional lights for home and commercial lamps.

particle     A minute amount of something.

peninsula     A parcel of land that is that is attached to the mainland but surrounded by water on three sides.

photovoltaic     An adjective that describes the ability of certain technologies to convert sunlight into electricity.

pollutant     A substance that taints something — such as the air, water, our bodies or products. Some pollutants are chemicals, such as pesticides. Others may be radiation, including excess heat or light.

renewable energy     Energy from a source that is not depleted by use, such as hydropower (water), wind power or solar power.

solar cell     A device that converts solar energy to electricity.

technology     The application of scientific knowledge for practical purposes, especially in industry — or the devices, processes and systems that result from those efforts.

turbine     A device with extended arm-like blades (often curved) to catch a moving fluid — anything from a gas or steam to water — and then convert the energy in that movement into rotary motion. Often that rotary motion will drive a system to generate electricity.

watt     A measure of the rate of energy use, flux (or flow) or production. It is equivalent to one joule per second. It describes the rate of energy converted from one form to another — or moved — per unit of time. For instance, a kilowatt is 1,000 watts, and household energy use is typically measured and quantified in terms of kilowatt-hours, or the number of kilowatts used per hour.

wind turbine     A wind-powered device — similar to the type used to mill grain (windmills) long ago — used to generate electricity.


Journal:​ M.H. Bergin et al. Large reductions in solar energy production due to dust and particulate air pollution. Environmental Science and Technology Letters. Vol. 4, August 8, 2017, p. 339. doi: 10.1021/acs.estlett.7b00197.