(Inside Science) -- Climate change discussions tend to focus on how electricity is produced. But much of the world's electricity is lost before it ever reaches people's homes or businesses, according to researchers Sarah Jordaan and Kavita Surana.
In a new study, Jordaan and Surana estimate that energy lost in the grid results in the release of nearly a billion tons of extra carbon dioxide equivalents into Earth's atmosphere each year. That number, they say, could potentially be cut in half -- a reduction that's roughly the equivalent of eliminating all greenhouse gas production from the United Kingdom.
"Ensuring that we have a more efficient grid is extremely important," said Jordaan, an energy systems scientist at Johns Hopkins University's Washington, D.C. campus. "It's something that all countries should really be thinking through more seriously in moving towards a lower carbon future."
The researchers analyzed 142 countries, representing the vast majority of electricity produced in the world. For each country, they had data from the International Energy Agency on the total amount of electricity lost in the power grid in 2016, plus a breakdown of the sources such as coal and solar that had produced each country's power. They also used published data on how much greenhouse gas is typically produced by each type of power generation.
Combining these data to come up with estimates of potential greenhouse gas savings was no easy task. For one thing, the available data lumps together two very different ways in which electricity can be "lost" in the grid. One way is through mechanical inefficiencies, also known as technical losses -- for example, when the resistance of wires causes electricity to escape as heat. The other way is when electricity is used but not paid for.
From a greenhouse gas perspective, technical losses are a bigger problem, because every kilowatt-hour that's wasted as heat must be made up for through increased production. Any effects from pilfering would be smaller and less direct, since the stolen electricity is still being used and thus reducing overall demand. Still, the researchers argue that pilfering can also result in excess greenhouse gas emissions, since people are less likely to conserve power when they are not paying for it. For example, in the African island country of Comoros, past research suggests that the use of formerly pilfered power drops by one-third once people are forced to pay.
Pilferage doesn't necessarily mean that people are surreptitiously stealing power by tampering with machinery, noted Robert Stoner, the deputy director for science and technology at the MIT Energy Initiative. In developing nations, it's not uncommon for people and even government agencies to refuse to pay their bills, often in protest over unreliable service.
To separate the technical losses from pilfering, the researchers extrapolated from the few locations where past research has examined grid losses in more detail. Most developed countries lose about 5% to 6% of the electricity they produce, primarily from technical losses, although Singapore has achieved the most efficient grid in the world with losses of just 2%. In developing nations, the losses are often much higher, and they are dominated by pilferage, according to the researchers. The highest losses are seen in countries suffering from conflict or natural disasters -- for example, Haiti and Iraq both lost more than half their power in 2016.
The new analysis suggests that technical losses and pilferage together result in an additional 949 million metric tons of C02 equivalents being released into the atmosphere each year. That number could potentially be reduced by about 411 million tons per year by improving grid infrastructure to reduce technical losses. For example, utility companies could replace old transformers with more efficient models, and they could work to create more distributed power systems so the electricity doesn't have to travel as far, said Surana, a public policy researcher at the University of Maryland in College Park.
If power companies manage to prevent pilfering in addition to reducing technical losses, the researchers estimate that emissions could be reduced by an additional 133 million metric tons of C02 equivalents per year, for a total savings of 544 metric tons.
It may seem that developing nations are the place to focus grid improvement efforts, since they lose a greater fraction of their power. But developed nations like the U.S. and China produce far more greenhouse gas emissions overall, so relatively minor improvements to their grids can make a big difference to the climate. For example, the U.S. lost about 6% of its power in 2016. The study suggests that by reducing those losses to 3.2%, Americans could cut their greenhouse gas emissions by about 29 million metric tons per year -- more than the total yearly emissions of Lebanon.
The authors believe their estimates are conservative, and the true global savings could be even larger. But MIT's Stoner, who was not involved in the research, said he thought they were more likely to be overestimates.
"These are sort of very broad-strokes estimates based on some very simple assumptions, which I would characterize as back of the envelope almost, and certainly likely to be on the upper end of what is really realizable," said Stoner.
Despite the uncertainties, Anders Arvesen, a researcher who conducts life cycle assessments of electrical systems at the Norwegian University of Science and Technology, called the study a "timely contribution." He was one of the independent peer reviewers for the study, which was published last month in the journal Nature Climate Change.
"It is a crude estimate, but it is the first estimate of this kind," said Arvesen. "I think [the study] shows that the electricity grid losses are important on a scale that is relevant for global climate assessments and discussions."
There are already efforts underway to improve grid infrastructure. For example, the U.S. Department of Energy is working on an ambitious Grid Modernization Initiative, and India has been working on its own initiative, called the National Smart Grid Mission, since 2016.
Nevertheless, the study authors don't think policymakers fully appreciate the potential of power grids to combat climate change. In the greenhouse gas mitigation strategies submitted as part of the Paris Agreement, only 32 countries mentioned electrical grid efficiency, while 110 countries mentioned renewable energy.
"When we started, we thought this would be an obvious thing to do. But we were surprised that it wasn't," said Surana. "I think it's largely overlooked."
Of course, noted Jordaan, the most important thing is still to move away from fossil fuels and toward renewable energy sources. But in the fight to avert climate change, grid improvements may be another weapon in the arsenal -- one we can't afford to ignore.