Solution to Renewable Energy's Intermittency Problem: More Renewable Energy

A mix of offshore and onshore wind, along with contributions from solar power, could provide reliable and cost-effective power flow during all but a handful of days in a hypothetical four-year period under study

By Nathanael Massey and ClimateWire

 

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Middelgrunden Offshore Wind Farm, Copenhagen, DenmarkImage: Flickr/PEBondestad

By 2030, scaled-up green power could meet the demands of a large grid 99.9 percent of the time, according to new research from the University of Delaware.

A mix of offshore and onshore wind, along with contributions from solar power, could provide reliable power flow during all but a handful of days in the hypothetical four-year period under study.

Moreover, researchers found that scaling up renewable generation capacity to seemingly excessive levels -- more than three times the needed load, in some instances -- proved more cost-effective than scaling up storage capacity, due to the high systems costs associated with storage technology.

"That's a lot of overbuilding," said Willett Kempton, a professor in the School of Marine Science and Policy at the University of Delaware and a co-author of the study. Much of that excess capacity would be underused during all but a few days a year, he said.

At the same time, thermal power plants face a similar problem today through inefficiency, he added.

"If you think about it, power plants burn three times the amount of fuel energy needed to produce their energy output," he said. "You burn three units of coal to get one unit of electricity."

Overgeneration would be cost effective even if all excess energy were simply dumped, according to the study. If that excess energy were harnessed -- to offset the costs of heating fuels, for example -- costs could be lowered even further.

Diversity of supply
Reliability has long been the Achilles' heel of renewable energy, which depends on intermittent weather conditions like wind and sun to generate power. However, by extending enough wind turbines and solar panels over a wide enough area, it is possible to achieve approximate reliability by shifting power from active to passive regions.

The study did not assume the introduction of new, more efficient technologies, although it did form its calculations based on 2030 technology costs and energy prices. Its models incorporated four years of energy use and weather data from within PJM Interconnection, a regional transmission organization covering about one-fifth of the United States' total electrical system.