The environmental benefits of renewable energy depend on when and where electricity is generated, a new study by researchers at the University of Colorado Boulder has suggested.
According to the study, which was published in The Energy Journal, the environmental value of renewable energy depends on what type of power it displaces on the grid.
For example, if a wind turbine replaces a coal-fired power plant, this has clear environmental benefits. If it is competing with another clean energy source, the environmental benefit ‘effectively disappears’, the researchers note.
“You can have a technically identical megawatt-hour of energy from a wind farm or a solar plant,” commented Daniel Kaffine, University of Colorado at Boulder. “But the value to society of that megawatt-hour, from an environmental standpoint, can be very different.”
Environmental value
In addition, factors such as the time of day, transmission constraints and energy policy can influence the environmental value of renewable energy generation.
The researchers use the example of carpooling, noting that taking a car off the road ‘does a lot more good during a gridlocked rush hour’ than it does taking it off an empty highway at 3am.
‘In many cases, renewable energy works the same way,’ they note. ‘A wind turbine spinning at 3am in Indiana is like carpooling during rush hour. It is likely pushing a coal plant offline, cutting real emissions. That same turbine spinning at 3pm in California, when the grid is already flush with solar-generated electricity, is more like carpooling on an empty road; the energy is clean, but it is not actually reducing emissions.’
Location, location, location
Geography also plays an important role. Using the United States as an example, the researchers note that wind generation in coal-dependent regions, such as the upper Midwest, can have a more significant impact than new renewable generation in areas with high renewable capacity, such as California.
“You don’t want to be subsidising a wind generator that is just bumping off solar in the middle of the day,” Kaffine adds.
Yet at the same time, policies tend to treat all renewable energy equally, regardless of location, with production tax credits, renewable portfolio standards and Renewable Energy Credits (RECs), showing little variation depending on when or where the renewable energy is generated.
The researchers argue that future policy should instead account for the environmental value of renewable generation by considering the emissions reductions achieved by individual projects.
“We know clean air is valuable to people. We know that the environment is valuable to people,” says Kaffine, “But there’s no market for it, so we don’t have a price for it. How do you put a number on that?” Read more here.
