Is High-Voltage DC the Best Way to Modernize the Grid and Reduce Emissions?
Recently released study finds a mix of renewables and new transmission can do the job.
Wind and solar power coursing across a national system of high-voltage direct current transmission lines could significantly cut power sector carbon dioxide emissions without increasing the cost of energy in the U.S., according to a new study published in Nature Climate Change.
Researchers at NOAA’s Earth System Research Laboratory and the University of Colorado, Boulder looked at three scenarios in which wind, solar, hydropower and nuclear were paired with natural gas at different cost points. They also included the cost of building a national high-voltage direct current (HVDC) transmission system on top of the existing power system.
“The average variability of weather decreases as size increases; if wind or solar power are not available in a small area, they are more likely to be available somewhere in a larger area,” wrote lead author Alexander MacDonald, director of NOAA’s Earth System Research Laboratory. Although energy storage can also provide stability to the grid, HVDC can do it at a lower cost, the study contends.
The results showed that with mid-cost renewables and mid-cost natural gas, electric power CO2 emissions could be cut by about 60 percent by 2030, a figure that rises to nearly 80 percent if natural gas costs rise while renewables decline by 2030.
In all scenarios, the cost of power in 2030 would be cheaper than the International Energy Agency’s estimate of an average $0.115 per kilowatt-hour for the levelized cost of electricity in the U.S. in 2030.
The model used weather data with high temporal and spatial resolution and assumed co-optimized dispatch of renewables across the modern HVDC grid. “We integrate complex weather data over continental-scale geography while still handling the salient features of an electrical power system,” the authors wrote in the paper.
The authors modeled 3 gigawatts of HVDC transmission to carry 523 gigawatts of wind power, 371 gigawatts of solar PV, 471 gigawatts of natural gas, 100 gigawatts of nuclear and 74 gigawatts of hydroelectricity, an increase of 30 percent over 2012 installed capacity.
