The U.S. Could Switch to Mostly Renewable Energy, No Batteries Needed

Better electricity sharing across states would dampen the effects of variable weather on wind and solar power

Solar panels and wind turbines could help the U.S. reduce carbon emissions for cheaper than you think. gong hangxu/iStock

The United States could lower carbon emissions from electricity generation by as much as 78 percent without having to develop any new technologies or use costly batteries, a new study suggests. There’s a catch, though. The country would have to build a new national transmission network so that states could share energy.

“Our idea was if we had a national ‘interstate highway for electrons’ we could move the power around as it was needed, and we could put the wind and solar plants in the very best places,” says study co-author Alexander MacDonald, who recently retired as director of NOAA’s Earth System Research Laboratory in Boulder, Colorado.

Several years ago, MacDonald was curious about claims that there was no technology available that could mitigate carbon dioxide emissions without doubling or tripling the cost of electricity. When he investigated the issue, he discovered that the studies behind the claims did not incorporate the country’s variable weather very well.

One of the big issues with wind and solar power is that their availability is dependent upon the weather. Solar is only available on sunny days, not during storms or at night. Wind turbines don’t work when the wind doesn’t blow enough—or when it blows too much. Because of this, some studies have argued that these technologies are only viable if large-capacity batteries are available to store energy from these sources to use when they aren’t working. That would raise the cost of electricity well beyond today’s prices.

But “there’s always wind and solar power available somewhere,” MacDonald notes. So he and his colleagues set out to design a low-carbon electricity-generation system that better incorporated—and even took advantage of—the nation’s weather. Their study appears today in Nature Climate Change.

Their computer model showed that by switching to mostly wind and solar power sources—with a little help from natural gas, hydroelectric and nuclear power when the weather doesn’t cooperate—the United States could reduce carbon emissions by 33 to 78 percent from 1990 levels, depending on the exact cost of renewable energy and natural gas. (The lower the cost of renewable energy and the higher the cost of natural gas, the more carbon savings.) Adding coal into the mix did not make electricity any cheaper, but it did result in a 37 percent increase in carbon emissions.

Wind potential

The key to this future would be the development of a system for transferring electricity across the country, so that a windy day in North Dakota could power a cloudy, calm day in New York. This would not only require new agreements between states—Texas, for instance, has its own separate power grid—but also an upgrade to the transmission lines that move electrons from one place to another.

In most areas, energy moves over high-voltage alternating current lines, but there are limitations in how far these lines can transmit energy. Switching to high-voltage direct current would let energy producers transmit more electricity a longer distance. That means new wind turbines and solar energy plants could be built in the places that have the most potential for wind and solar energy, because the distance from where energy is needed wouldn’t matter.

Building a new network for transmitting electricity would be a big job. But the computer model showed that it can be cost effective, because in the long run it would allow cheap power to be available, notes study co-author Christopher Clack, a mathematician at the Cooperative Institute for Research in Environmental Sciences at Colorado University-Boulder.

“By building these transmission facilities, we reduce the costs to remove the carbon rather than increasing it,” he says.

Some states, such as California and New York, are already on the path to this lower-carbon future, and Vermont just approved plans for a high-voltage direct current line from Canada, notes Mark Jacobson, an atmospheric scientist at Stanford University. Last year, he headed a study published in the Proceedings of the National Academy of Sciences that showed how the United States could achieve an all-renewable energy electric grid, with some help from storage technology.

“We can use existing transmission pathways,” Jacobson says, and just improve the lines that run across them. “You don’t need as many new pathways as you think.”

Increasing renewable energy would have benefits in addition to lower carbon emissions, such as reductions in air pollution and lower costs. “There’s little downside to transitioning,” he says.

Plus, MacDonald notes, moving to low-carbon electricity generation could serve as a catalyst for lower carbon emissions in sectors such as home heating and transportation. “No matter what, you have to do electricity first,” he says, and the rest will follow.

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