Rapid, affordable energy transformation in U.S. possible

Even in a scenario where renewable energy costs more than experts predict, the model produced a system that cuts CO₂ emissions 33 percent below 1990 levels by 2030, and delivered electricity at about 8.6 cents per kilowatt hour. By comparison, electricity cost 9.4 cents per kWh in 2012.

If renewable energy costs were lower and natural gas costs higher, as is expected in the future, the modeled system sliced CO₂ emissions by 78 percent from 1990 levels and delivered electricity at 10 cents per kWh. The year 1990 is a standard scientific benchmark for greenhouse gas analysis.

A scenario that included coal yielded lower cost (8.5 cents per kWh), but the highest emissions.

At the recent Paris climate summit, the United States pledged to cut greenhouse emissions from all sectors up to 28 percent below 2005 levels by 2025. The new paper suggests the United States could cut total CO₂ emissions 31 percent below 2005 levels by 2030 by making changes only within the electric sector, even though the electrical sector represents just 38 percent of the national CO₂ budget. These changes would include rapidly expanding renewable energy generation and improving transmission infrastructure.

In identifying low-cost solutions, researchers enabled the model to build and pay for transmission infrastructure improvements — specifically a new, high-voltage direct-current transmission grid (HVDC) to supplement the current electrical grid. HVDC lines, which are in use around the world, reduce energy losses during long-distance transmission. The model did choose to use those lines extensively, and the study found that investing in efficient, long-distance transmission was key to keeping costs low.

MacDonald compared the idea of a HVDC grid with the interstate highway system which transformed the U.S. economy in the 1950s. “With an ‘interstate for electrons’, renewable energy could be delivered anywhere in the country while emissions plummet,” he said. “An HVDC grid would create a national electricity market in which all types of generation, including low-carbon sources, compete on a cost basis. The surprise was how dominant wind and solar could be.”

The new model is drawing interest from other experts in the field.

“This study pushes the envelope,” said Stanford University’s Mark Jacobson, who commented on the findings in an editorial he wrote for the journal Nature Climate Change. “It shows that intermittent renewables plus transmission can eliminate most fossil-fuel electricity while matching power demand at lower cost than a fossil fuel-based grid - even before storage is considered.”

— Read more in Alexander E. MacDonald et al., “Future cost-competitive electricity systems and their impact on US CO2 emissions,” Nature Climate Change (25 January 2016) (DOI: 10.1038/NCLIMATE2921)