A scientist with the U.S. National Oceanic and Atmospheric Administration (NOAA) has produced a detailed explanation of the modelling methodology behind the agency’s recent finding that 78% of U.S. electricity could be supplied by renewable energy by 2030, without resorting to battery storage.

The findings were published late last month in the journal Nature Climate Change. Now, Christopher Clack writes about how NOAA reached its conclusions. “If the U.S. were to move to a national 48-state electric system, rather than the regional one in place now, the country would be able to transport more renewable energy around the country,” he writes.

(Editor’s note: The full read is worth the time for anyone who’s wondering how renewables can supply a large share of North America’s grid electricity.)

“Using a computer model, we found that this larger electric system would utilize power more efficiently, regardless of the generators within it,” Clack explains. “The cost reduction between the national-style system we modeled and the current one, which is divided into about 130 regions, is US$47 billion per year. That translates into an electricity cost of between 8.5 and 10.2¢ per kilowatt-hour (kWh), compared to the current national average of 12.7¢/kWh.”

This isn’t the first time a U.S. agency has modelled the potential to decarbonize most of the grid using a wider mix of distributed energy supplies. NOAA’s model is a bit different, since it builds on the agency’s knowledge of weather and land use.

NOAA’s National Energy with Weather System (NEWS) simulator “includes features of the electric grid, such as transmission, generators, electric demand, land use constraints, generator behaviour, weather data, and cost data for generators,” Clack writes. “To figure out how to minimize costs, the NEWS model will calculate how to supply power every single hour for an entire year, based on the available generators and transmission lines that transport power long distances.”

The model also builds in an overlay of the high-voltage direct current (HVDC) lines across the country. “In concept, this is very similar to the interstate highway system overlaid upon the road network,” Clack explains. “HVDC technology has one big advantage over traditional power lines: there is less energy lost in transporting power from one point to another.”