The United States could slash greenhouse gas (GHG) emissions from power production by up to 78% according to a new study by the National Oceanic and Atmospheric Administration (NOAA) and University of Colorado Boulder researchers. This would bring them below the 1990 level and continue to meet increased demand, all within 15 years.

The study used a mathematical model to evaluate future cost, demand, generation and transmission scenarios. It found that with improvements in transmission infrastructure, weather-driven renewable resources could supply most of the nation’s electricity at costs similar to today.

Wind and solar energy can be a big part of an economical, low-emission electricity generation. Image credit: Pixabay. The model allowed researchers to evaluate the affordability, reliability and GHG emissions of various energy mixes, including coal. It showed that low cost and low emissions are not mutually exclusive.

“The model relentlessly seeks the lowest-cost energy, whatever constraints are applied,” says co-lead author Christopher Clack, a physicist and mathematician with the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder. “And it always installs more renewable energy on the grid than exists today.”

Even in a scenario where renewable energy costs more than experts predict, the model produced a system that cuts CO2 emissions 33% below 1990 levels by 2030 and delivers electricity at about 8.6 cents per kilowatt hour (kWh). 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 slices CO2 emissions by 78% from 1990 levels and delivers electricity at 10 cents per kWh.

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

At the recent Paris climate summit, the U.S. pledged to cut GHG emissions from all sectors up to 28% below 2005 levels by 2025. The new study suggests the U.S. could cut total CO2 emissions 31% below 2005 levels by 2030 by making changes only within the electric sector, even though it represents just 38% of the national CO2 budget.

In identifying low-cost solutions, the 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 reduce energy losses during long-distance transmission. The model chose to use those lines extensively, and the study found that investing in efficient, long-distance transmission was key to keeping costs low.

Alexander MacDonald, co-lead author and recently retired director of NOAA’s Earth System Research Laboratory, compares the idea of an 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 says. “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.”

"This study pushes the envelope,” says Mark Jacobson, professor of civil and environmental engineering at Stanford University, who was not part of the study. “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."