States could drastically reduce their greenhouse gas emissions from the power sector in the next 15 years, if they ramped up their investment in renewables such as wind and solar, according to a study released Monday.

The findings, by scientists at the University of Colorado Boulder and National Oceanic and Atmospheric Administration, found that reductions could be as much as 78 percent below 1990 levels by 2030 while keeping cost in check and meeting expected demand increases.

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The study could be used by the Obama Administration to counter concerns about the cost of its Clean Power Plan, which requires states to cut their carbon emissions mostly from coal-fired power plants 32 percent from 2005 levels by 2030.

“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,” Alexander MacDonald, co-lead author of the study in the journal Nature Climate Change and recently retired director of NOAA’s Earth System Research Laboratory (ESRL) in Boulder, said in a statement.

While the costs of wind and solar have become increasingly competitive, they remain dogged by fears that they cannot consistently supply power.

Utilities have responded by investing in surplus generation capacity – fueled by natural gas – to ensure a steady power supply. But the researchers found that may not be necessary in the future, if  states would only invest more heavily in renewables and make improvements in the transmission infrastructure.

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Using NOAA’s high-resolution meteorological data, the researchers 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 researchers to evaluate the affordability, reliability, and greenhouse gas emissions of various energy mixes, including coal.

“The model relentlessly seeks the lowest-cost energy, whatever constraints are applied,”  Christopher Clack, a physicist and mathematician with the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder and a co-author of the study. “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 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.

As part of the U.S. commitment to an international climate deal agreed in Paris last year, Obama has pledged to reduce American emissions 26-28 percent below 2005 levels by 2025. A key component of that commitment is the Clean Power Plan, which is being challenged in court by 24 states. They claim it amounts to an unlawful power grab that will drive up electricity prices and eliminate coal mining jobs.

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The researchers, for their part, said the objective of their study was simply to find out the most cost-effective way to reduce those emissions.  Somewhat surprisingly, it was by greater investment in renewables - rather than fossil fuels like coal.

But those emission cuts, the researchers said, will only come if states build and pay for transmission infrastructure improvements – especially 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 and help keep costs down.

Think of it as the 21st century version of the interstate highway system.

 “With an ‘interstate for electrons’, renewable energy could be delivered anywhere in the country while emissions plummet,” MacDonald 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.”

Stanford University’s Mark Jacobson, who wrote an article accompanying the study, praised the authors for pushing “the envelope.”

 “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," he wrote.

“This finding — alongside previous modeling that suggests the electrification of all sectors combined with the use of low-cost electricity and heat/cold storage, hydrogen and demand response can result in 100% decarbonization of all US energy sectors — provides confidence that the goals of the Paris Agreement are within reach if high percentages of clean, renewable energy can be integrated worldwide,” he added.