The United States could reduce greenhouse gas emissions by almost 80 percent from 1990 levels, and do so as soon as 2030, without significantly increasing energy prices, claims a new study by researchers from NOAA and the University of Colorado.
The study, published in the journal Nature Climate Change, says that the reduction can come about entirely from a boost in wind and solar power and that the key to that boost is something as seemingly simple as the establishment of a network of high-voltage power lines.
The argument goes something like this: Even as improvements in wind and solar generation have decreased the cost of producing renewable energy, a significant remaining hurdle has been that that energy is intermittent: The sun is not always shining in any given locale, any more than the wind is always blowing. This matters because the U.S. power grid is divided into several regional grids, each of which contains smaller subdivisions.
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Because of the intermittent nature of renewable energy sources, the theory has been that these regional grids will require significant storage capacities, for cloud-covered or windless days. The problem has been that large-scale storage technologies are not as yet commercially viable.
But what would happen, pondered NOAA researcher Alex MacDonald, if the system were scaled upward, from regional to national? After all, the wind is always blowing somewhere in the country; what if those regional grids were connected in such a way that power could be immediately transported from where it was available to where it was needed?
The key would be the establishment of a high-voltage, direct current (HVDC) transmission grid to supplement the existing grid. HVDC lines, which are in use around he world, are much more efficient than traditional alternating current systems because they lose far less energy over long distances.
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MacDonald and colleagues from NOAA and the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder modeled a range of scenarios to evaluate the cost of integrating different sources of electricity into a national energy system using HVDC lines. Their model estimated 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 held nuclear and hydropower at 2012 levels, included land-use restrictions and demand growth, and projected energy production costs out to 2030, including production and transmission. It sought always to find the lowest-cost energy, and yet under a range of variables it consistently did by including more renewable energy sources on the grid than exist today.
In doing so, it found that a national HVDC grid could lower energy costs while dramatically reducing greenhouse gas emissions.
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The lowest-cost/highest-emissions model scenario produced a system that cut CO2 emissions 33 percent below 1990 levels by 2030, and delivered electricity at about 8.6 cents per kilowatt hour (kWh), 0.8 cents below the cost of electricity in 2012. At the other end of the scale, the modeled system sliced CO2 emissions by 78 percent from 1990 levels, albeit at a marginally higher cost of 10 cents per kWh.
MacDonald likened the creation of such a grid to the building of the 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 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."