DAILY SCIENCE

LEDs saved a half billion tons of carbon dioxide emissions last year. Or did They?

A new report shows that LED lighting cut the carbon dioxide emissions by 570 million tons in 2017. But the reality is not that simple.

By Prachi Patel

January 11, 2018

A new report shows that LED lighting kept 570 million tons of carbon dioxide emissions out of the atmosphere in 2017. That’s the equivalent of emissions from 162 coal-burning power plants, according to the report by London-based market analysis firm IHS Markit.

To calculate the carbon savings due to the lower electricity use by LED lights, analyst Jamie Fox and his colleagues looked at historic data on the market share for leading LED component and light manufacturers. They calculated that LED lights used in buildings and outdoor spaces reduced the global carbon footprint by an estimated 1.5 percent in 2017.

Here’s the catch: the analysts assume that every LED lightbulb sold replaces a less efficient older one. In other words, the total amount of lighting in the world stayed constant. But what if the number of lights in the world is increasing?

That is indeed the case, a study published last month in the journal Science Advances showed. In that study, German researchers looked at satellite images between 2012 and 2016 to show that the use of artificial light around the world has gone up by 2.2 percent every year, thanks in good part to efficient, low-cost LEDs. Most of the growth was in Africa, Asia and South America, developing regions where incomes and standards of living are going up.

This is the well-known rebound effect. History shows that as lighting technologies have gotten better, more efficient, and cheaper—from oil lamps to candles to electric lights—the world’s energy use has gone up.

The same goes for LED lightbulbs: as their costs have fallen and their light quality has improved, we are using more of them and finding new uses, such as stuffing them in mason jars to make pretty baubles and embedding them in art.