Analysts have long argued that nations aiming to use wind and solar power to curb emissions from fossil fuel burning would first have to invest heavily in new technologies to store electricity produced by these intermittent sources—after all, the sun isn’t always shining and the wind isn’t always blowing. But a study out today suggests that the United States could, at least in theory, use new high-voltage power lines to move renewable power across the nation, and essentially eliminate the need to add new storage capacity.

This improved national grid, based on existing technologies, could enable utilities to cut power-sector carbon dioxide emissions 80% from 1990 levels by 2030 without boosting power prices, researchers report today in Nature Climate Change.

The findings come on the heels of the Paris climate agreement, in which the United States pledged to cut its national emissions by up to 28% from 2005 levels by 2025. About 40% of U.S. emissions come from the power sector, and the U.S. Environmental Protection Agency (EPA) recently released rules that task states with reducing power-sector emissions. States can choose from a menu of strategies, EPA says, such as boosting renewable energy use.

But some observers wonder whether the U.S. power grid can rise to the renewables challenge. The grid is divided into several regional grids or “interconnections,” which contain smaller subdivisions. Because regions experience both sunless and windless periods, energy planners and experts have long believed that a wind- and solar-dominated grid would need to store some power for later use. The problem is that large-scale storage technologies haven’t been commercially realistic.

Alex MacDonald, a National Oceanic and Atmospheric Administration (NOAA) in Washington, D.C., researcher, was familiar with that problem. But he realized that researchers hadn’t explored all the potential solutions. For instance, meteorological data suggest that wind is always blowing somewhere in the United States, MacDonald says. So, although renewable energy output might be intermittent on a regional scale, it would have a more constant flow at a national scale. MacDonald wondered whether the U.S. grid might be able to overcome intermittency problems if it added high-voltage, direct-current (HVDC) transmission lines—which suffer less energy loss than do traditional alternating-current transmission lines—to connect regional grids, so that power could be moved to where it was needed.

The study also suggests the U.S. may make the transition without heavy investment in energy-storage technologies, which are seen by some as essential for helping to smooth out the intermittent flows from wind and solar farms.

Instead, the Nature research, using a computer model to simulate the U.S. electric system in 2030, found a reliable grid can be built using existing technology — if the country also invests in better transmission lines and other technology to carry power long distances.

Key to the transition would be a national network of high-voltage, direct-current power lines, capable of connecting power supplies in areas with favorable weather to regions with the most demand, according to the study by scientists with the university and the U.S. National Oceanic and Atmospheric Administration.

“It looks a lot like an interstate highway system for electrons,” said co-author Alexander MacDonald, a recently retired NOAA scientist. “You can pipe the power around in real-time and essentially have electricity that’s the same cost as today.”
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The research “provides confidence” that nations can make the pollution cuts they promised last year at an international climate summit in Paris, Stanford University’s Mark Jacobson said in an commentary accompanying the study.

“The study pushes the envelope to show that intermittent renewables plus transmission can eliminate most fossil fuel electricity while matching power demand at lower cost,” said Jacobson, a professor of civil and environmental engineering. “The goals of the Paris agreement are within reach.”