Facing South

Challenging conventional wisdom on renewable energy's limits

Offshore_wind.jpgIn making the case for a rapid conversion away from heavily polluting energy sources like coal and nuclear power to cleaner generation, renewable energy advocates often confront the argument that their scheme is impossible due to the intermittent nature of sun and wind.

But a groundbreaking study out of North Carolina challenges that conventional wisdom: It suggests that backup generation requirements would be modest for a system based largely on solar and wind power, combined with efficiency, hydroelectric power, and other renewable sources like landfill gas.

"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," said author John Blackburn, professor emeritus of economics and former chancellor at Duke University in Durham, N.C.. He's also the author of the books "The Renewable Energy Alternative" and "Solar in Florida."

The study was published last week by the Maryland-based Institute for Energy and Environmental Research, whose executive director, Arjun Makhijani, called it landmark research. "North Carolina utilities and regulators and those in other states should take this template, refine it, and make a renewable electricity future a reality," he said.

Blackburn used hourly North Carolina wind and solar data for a total of 123 days in the sample months of January, April, July and October, with samples taken at three wind and three solar sites across the state. Solar and wind power generation were then scaled up to represent 80% -- 40% each -- of average utility loads for the sample months, with the rest coming from the existing hydroelectric system (8%) and assumed biomass co-generation (12%).

The study figured in projected energy efficiency by assuming an annual utility load of 90 billion kilowatt-hours, slightly less than the current 125 billion kWh load, and by calculating average hourly loads from Duke Energy's 2006 load profile with modifications to show some reduction in summer and winter peaks due to more efficient buildings. It also assumed increased storage capacity from a smarter electrical grid.

In the end, with those conditions met, Blackburn calculated that the required auxiliary generation from conventional power plants to fill in the gaps would amount to only 6% of the annual total generation required to meet demand in North Carolina.

"This goes to the heart of the argument by power companies that have long dismissed solar and wind as future technologies," said Jim Warren, executive director of the N.C. Waste Awareness and Reduction Network, a Durham, N.C.-based nonprofit that provided research assistance to Blackburn.

The study was released just days after a new poll from Elon University in Elon, N.C. found overwhelming public support in North Carolina for developing the state's renewable energy capacity. Nearly 80% of the poll's respondents said they favor new wind energy facilities in the mountains or on the coast, while more than 83% favor construction of solar facilities.

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re: Challenging conventional wisdom on renewable energy's limits

Obviously, the study isn't worth much if it used averages to reach its conclusions. Anyone who has done power operations studies understands that averages will not produce any accuracy. Studies of power system operations must be done using hourly demand and available generation to determine the results under study. This study should be viewed with great skepticism.

re: Challenging conventional wisdom on renewable energy's limits

Once again another study timed to gain public support.

Please open you windows, watch the curtains blow. Wind is not reliable and not predictable.

" 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,"

What readily available storage? Please describe this readily available storage.

"It also assumed increased storage capacity from a smarter electrical grid."

Currently this increased storage capactity from a smarter electrical grid does not exist.

"modifications to show some reduction in summer and winter peaks due to more efficient buildings."

And yes, if you turn down the heat and turn up the air condition setting you would also save.

Industrial wind represents high costs and low social benefits. Remove the tax goodies and industrial wind disappears

re: Challenging conventional wisdom on renewable energy's limits

Anonymous asks for a description of the readily available storage. Quoting from the report:

...[T]here is pumped storage capacity in the Duke Energy system amounting to 2,100 MW, of which 1,360 MW has up to 24 hours of storage. In the summer, hourly storage is supplemented by the capacity of some large commercial customers to make ice in off-peak times and then run air conditioning systems without running the chillers at peak times in the afternoon and evening. In addition, the two largest utilities now have some 2,000 MW of load control arrangements.

In case you're not familiar with it, pumped storage capacity involves pumping water from a lower reservoir to an upper reservoir when there's surplus power. Then when power is needed, electricity is generated by letting the water flow to the lower reservoir.

Another significant prospective storage technology discussed in the report are the batteries in plug-in electric and hybrid vehicles. "Compressed air energy storage might also be considered in North Carolina; geological studies show that rock storage is possible in the western half of the State," the study says. However, it does not figure that technology into its calculations.

Regarding Hydroron's comment, I again quote from the study:

The object of this analysis is to examine the hourly matching of available power to hourly loads and to estimate how much backup power, if any, might be needed.

re: Challenging conventional wisdom on renewable energy's limits

When hydroron reads the entire study, he will find that Blackburn uses hourly solar and wind data to match with utility daily load data, the only types of data available. In my opinion, Blackburn's analysis is done correctly and his conclusions are valid.