Solar and wind power can supply the vast majority of North Carolina's electricity needs, according to a major report released today.
"Even though the wind does not blow nor the sun shine all the time, careful management, readily available storage and other renewable sources, can produce nearly all the electricity North Carolinians consume," explained Dr. John Blackburn, the study's author. Dr. Blackburn is Professor Emeritus of Economics and former Chancellor at Duke University.
"Critics of renewable power point out that solar and wind sources are intermittent," Dr. Blackburn continued. "The truth is that solar and wind energy are complementary in North Carolina. Wind speeds are usually higher at night than in the daytime. They also blow faster in winter than summer. Solar generation, on the other hand, takes place in the daytime. Sunlight is only half as strong in winter as in summertime. Drawing wind power from different areas -- the coast, mountains, the sounds or the ocean -- reduces variations in generation. Using wind and solar in tandem is even more reliable. Together, they can generate three-fourths of the state's electricity. When hydroelectric and other renewable sources are added, the gap to be filled is surprisingly small. Only six percent of North Carolina's electricity would have to come from conventional power plants or from other systems."
Jim Warren, Executive Director of the North Carolina Waste Awareness and Reduction Network (NC WARN), added, "Utilities and their allies are pressing policy-makers to allow construction of expensive and problem-ridden nuclear reactors - with ratepayers and taxpayers absorbing enormous financial risks. Prof. Blackburn's groundbreaking study demonstrates that such risks are not necessary. Solar, wind and other renewable sources can meet nearly all of North Carolina's energy needs."
Dr. Arjun Makhijani, President of the Institute for Energy and Environmental Research (IEER), explained why his center published Dr. Blackburn's report. "This is a landmark case study of how solar and wind generation can be combined to provide round-the-clock electric power throughout the year. North Carolina utilities and regulators and those in other states should take this template, refine it, and make a renewable electricity future a reality." Dr. Makhijani is the author of Carbon-Free and Nuclear-Free: A Roadmap for U.S. Energy Policy.
Dr. Blackburn's report, Matching Utility Loads with Solar and Wind Power in North Carolina: Dealing with Intermittent Electricity Sources, is available online at http://www.ieer.org/reports/NC-Wind-Solar.html along with an Executive Summary.
Those reluctant to endorse a widespread conversion to renewable energy sources in the U.S. frequently argue that the undeniably intermittent nature of solar and wind power make it difficult, if not impossible, to provide reliable power to meet variations in demand without substantial backup generation. Several studies, concentrating on areas with ample sources of both wind turbines and solar power have suggested that a combination of the two, when spread over a sufficiently wide geographic area, could be used to overcome the inherent intermittency of each separately, reducing the need for backup generation. Moreover, since the backup power is required at more or less randomly distributed times, the availability of baseload power, so strongly entrenched in utility circles, becomes more or less irrelevant.
This study examines these ideas with data gathered in the state of North Carolina. Contrary to the idea that such an arrangement will be subject to heavy backup requirements from conventional sources, the clear conclusion of the study is that backup generation requirements are modest and not even necessarily in the form of baseload generation.
In North Carolina the two largest potential renewable electricity sources are solar and wind generation. The former is the case almost everywhere in the U. S., the latter is also the case in North Carolina, given wind resources in the mountains, along the coast, and offshore, both in the Sounds and in the ocean.
Hydroelectricity (now 2,000 megawatts (MW) and potentially 2,500 MW) and biomass combustion represent the other renewable sources available in the State. Solar and wind generation have some obvious complementarities. Wind speeds are usually higher at night than in the daytime, and are higher in winter than in summer. Solar generation, on the other hand, takes place only in the daytime and is only half as strong in winter as in summertime. The study described here used hourly North Carolina wind and solar data for the 123 days of the sample seasonal months of January, July, October, and April. This entailed making 2,952 observations at each of three wind sites and three solar sites or 17,712 entries in all. In the absence of actual kilowatt-hour output data for long periods from functioning installations in widely separated locations, wind speed and solar irradiation were taken at the three sites each and converted to presumed wind and solar power outputs.
Wind data was converted using the specifications of the wind turbines chosen for the study, shown below. Actual power readings for
shorter periods from solar installations at two sites (from readings made in different years), were used to calibrate the presumed solar output at the chosen sites.
The generation patterns given by these sites were, for this initial exploration, taken to be representative of all of the sites in North Carolina. Solar and wind power generation constructed as outlined above were then scaled up to represent 80% (40% each) of average utility loads for the four sample months, with the remainder coming from the hydroelectric system (8%) and assumed biomass cogeneration (12%). The annual utility load was taken to be 90 billion kWh, a somewhat more energy-efficient version of the present 125 billion kWh load. Average hourly loads in each of the four seasons were taken from Duke Energy’s 2006 load profile.
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