The U.S. could slash greenhouse-gas emissions from power production by up to 78% below 1990 levels within 15 years while meeting increased energy demand, according to a new study from the National Oceanic and Atmospheric Administration (NOAA) and the University of Colorado Boulder.
According to the researchers, the study used a sophisticated 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’s. The paper was published online in the journal Nature Climate Change.
“Our research shows a transition to a reliable, low-carbon, electrical generation and transmission system can be accomplished with commercially available technology and within 15 years,” explains Alexander MacDonald, co-lead author and the recently retired director of NOAA’s Earth System Research Laboratory in Boulder.
Although improvements in wind and solar generation have continued to ratchet down the cost of producing renewable energy, the study says, these energy resources are inherently intermittent. As a result, utilities have invested in surplus generation capacity to back up renewable energy generation with natural-gas-fired generators and other reserves.
“In the future, they may not need to,” adds co-lead author Christopher Clack, a physicist and mathematician with the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder.
Because the sun is shining or winds are blowing somewhere across the U.S. at all times, MacDonald theorizes that the key to resolving the dilemma of intermittent renewable generation might be to scale up the renewable energy generation system to match the scale of weather systems.
So, MacDonald, who has studied weather and worked to improve forecasts for more than 40 years, assembled a team of four other NOAA scientists to explore the idea. Using NOAA’s high-resolution meteorological data, they built a model to evaluate the cost of integrating different sources of electricity into a national energy system. The model estimates renewable resource potential, energy demand, emissions of carbon dioxide (CO2), and the costs of expanding and operating electricity generation and transmission systems to meet future needs.
The model allowed them to evaluate the affordability, reliability and greenhouse-gas emissions of various energy mixes, including coal. According to the researchers, it showed that low cost and low emissions are not mutually exclusive.
“The model relentlessly seeks the lowest-cost energy, whatever constraints are applied,” Clack says. “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 kWh. By comparison, electricity cost 9.4 cents per kWh in 2012.
According to the study, if renewable energy costs were lower and natural gas costs were higher, as is expected in the future, the modeled system sliced CO2 emissions by 78% 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 costs (8.5 cents per kWh) but also the highest emissions.
At the recent Paris climate summit, the U.S. pledged to cut greenhouse emissions from all sectors up to 28% below 2005 levels by 2025. The new paper 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 the electrical sector represents just 38% of the national CO2 budget. These changes would include rapidly expanding renewable energy generation and improving transmission infrastructure, the study says.
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 an HVDC grid with the interstate highway system that 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.”
According to the researchers, the new model is drawing interest from other experts in the field.
“This study pushes the envelope,” says Stanford University’s Mark Jacobson, who wrote an editorial praising 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.”
More on the study can be found here.