As renewable energy sources, the sun and wind emit no greenhouse gases and help to wean the U.S. off of its dependence on costly foreign oil, but they are too unreliable and costly to ever become a significant contributor to national energy supply – right?
Well, not necessarily. According to a just-released University of Delaware/Delaware Tech study, solar and wind power can be just as reliable as fossil fuels when applied over a large electrical grid, and are no more costly than coal, oil and natural gas when the pollution costs of those traditional fuels are taken into account.
After two years’ work and a computer model that considered 28 billion combinations of energy sources and storage mechanisms, a team of researchers from UD’s College of Earth, Ocean and Environment and Delaware Tech’s Energy Management Department concluded that renewable energy could fully power a large electrical grid 99.9 percent of the time by 2030 at costs comparable to current electricity rates.
The study claims to be the first to consider the viability of renewable fuels across a large electrical grid, and based its conclusions on four years’ worth of meteorological and electricity-demand data from PJM, the nation’s largest electrical grid covering 13 mid-Atlantic and Midwestern states from Delaware to Illinois, representing some 20 percent of the U.S. power system.
While critics of wind and solar argue that these forms of energy can’t be a major contributor to the national power supply because the wind doesn’t always drive wind turbines, and the sun doesn’t always shine on solar panels, the study concluded that those sources can in fact be reliable when considered on a grid-wide basis.
If the sun isn’t shining in Delaware, it may be in Ohio or Kentucky. If the wind isn’t blowing in Illinois, it’s likely to be doing so in Pennsylvania or off the coast of New Jersey, the study found. Adding inland and offshore wind to solar power in many different locations across the grid, and creating storage for the power generated would allow a large grid such as Pennsylvania-based PJM to meet electric customers’ demands almost entirely from renewable sources, it concluded.
“The real grid-management problem is not to simulate a single baseload plant by creating constant output; rather, the problem is to meet fluctuating load reliably with fluctuating generation, for an entire grid,” the six-person team wrote in a paper first published in the Journal of Power Sciences in November, and publicly announced on Dec. 10.
If neither wind nor sun is generating enough power to meet grid demand, the balance would be met from storage, and on the “rare” occasions when demand is too great for all three sources, fossil fuels would be used as a backup, the study argued.
If the renewable sources generate more power than needed, it would first fill storage, then substitute for natural gas as a heating fuel. Only as a last resort would it be allowed to go to waste, according to the group’s model.
“These results break the conventional wisdom that renewable energy is too unreliable and expensive,” said Willett Kempton, a co-author of the study, and a professor in UD’s School of Marine Science and Policy. “The key is to get the right combination of electric sources and storage … and to calculate costs correctly.”
To compare the costs of grid-wide renewables with those of fossil fuels, the team eliminated current state and federal subsidies for wind and solar, and added in “external” costs of burning fossil fuels such as health insurance to cover medical treatment for pollution-related illnesses, which are not included in the market price.
After projecting that the capital cost of wind and solar in 2030 would be about half of its current level because of increased volume, the team concluded that the grid could run almost entirely on renewables by that time at about the same cost as it does from mostly fossil fuels today.
But David Stevenson, Director of the Center for Energy Competitiveness at Delaware’s Caesar Rodney Institute, a free-market policy group, said the study uses inaccurate assumptions about the amount of time that wind farms and natural gas power plants are working; ignores international evidence that widespread use of renewables can be unreliable in some weather conditions, and overstates the external cost of burning fossil fuels.
“This whole argument is flawed,” Stevenson told DFM News. “If I was a professor and this paper was turned in to me, I wouldn’t even give it an F; I would give it an ‘incomplete.’ This study is pathetic.”
He said episodes of extreme heat or cold in Britain, Australia and Texas in recent years have resulted in sharp reductions in wind power to the grid, leading in some cases to “brownouts” for electric customers, and undermining the study’s conclusions that renewables can be reliable on a grid-wide basis.
Stevenson also dismissed the notion that solar could substitute for wind, arguing that solar is a daytime power source while wind power is generated mostly at night.
He said the UD/Del Tech team had assumed a wind farm capacity factor – the proportion of time a farm is generating power – of 40 percent, or more than twice the 19.6 percent reported globally by the International Energy Agency. That means wind farms would generate half as much energy as the report claims, resulting in a doubling of their costs, Stevenson argued.
The study exaggerates the external costs of fossil fuels, Stevenson said. He cited the latest Integrated Resource Plan, published by Delmarva Power on Dec. 3, anticipating reductions in power-plant emissions, leading to improvements in human health, as a result of more generation from natural gas plants; retirement of coal plants and cleaner operations by remaining coal generators.