Wind power is now as cheap as coal, and in some places, solar is cheaper than natural gas. But there's one thing that most people assume still holds back renewable energy in the U.S.: power plants need a constant source of energy, and there isn't a cheap enough way to store wind or solar at a large scale yet.
But a new study suggests we don't actually need to store that power. Instead—because the wind is always blowing somewhere in the U.S., and a cloudy day in one city will be sunny elsewhere—researchers suggest we just need a bigger grid, and better power lines that could send energy wherever it's needed.
By switching to a national grid and more renewable power, electricity could actually get cheaper by 2030, while cutting emissions 80% compared to 1990 levels.
In the past, most research has gone into trying to make better storage technology, not power lines. "Storage is necessary for other industries, like electric vehicles, and so it makes sense that research dollars would go to using the same technology for the grid," says Christopher Clack, a researcher at NOAA's Earth System Research Laboratory and one of the co-authors of the paper.
When they looked at maps of the weather across the entire country, the researchers noticed that there was a steady supply of wind, just not in one place. They built a detailed computer model that divided the country into 152,000 little squares, linked up regions with new power lines, and then calculated the best places to put new wind or solar plants. Then they told the model to find the cheapest way to cut emissions.
It's a conservative model, so if a similar system was actually built, it might actually cut emissions even more. "The model was deliberately a cost optimized solution," says Clack. "That is, there was no constraint on carbon, and we did not invoke demand management or storage. Technologies will always improve, which will help reduce emissions."
Since the switch to a nationwide grid would save an estimated $47 billion, that money could also be invested in new carbon-free tech. The cost of electricity would stay the same as it is today, but emissions would drop more. If the grid went even further—pulling in hydropower and other renewables from Canada—emissions could go even lower.
Storage technology is getting cheaper, and the World Energy Council predicts that it will drop another 70% in the next 15 years. But the model looked at high-voltage power lines that are available and affordable today.
The technology "is cheaper than storage, it can be produced today in large quantities, and it has a proven track record here in the U.S. and abroad," says Clack. "It also facilitate a much larger market for electricity—unlike storage—so it will enable economies of scale, and access to higher productive resources. Storage, on the other hand, will not give any access to cheap resources—it will simply allow a shift of generation in time."
At the climate talks in Paris, the U.S. pledged to cut total emissions 28% by 2025. A shift in the electric grid, which is responsible for 40% of all emissions, could go even further. But it would be a major political challenge because of the fragmented way electric grids are set up now. The researchers compare it to a project like building the national railroads or the interstate highway system. Doing that would be hugely ambitious at a time when the U.S. Congress has trouble passing an annual federal budget, but Clack remains optimistic that this sort of grid could be built.
"It creates a larger market, and throughout history these have help economies grow, reducing electricity costs. The fact that it lowers the cost of electricity and reduces emissions makes it palatable for everyone," he says.