Dispelling the Myths About Renewable Energy Intermittency

If you’ve done much work on energy and emissions issues, chances are you’ve run into questions about the intermittency of renewable energy. They come up all the time—both in interpersonal interactions, and even more in online forums. After you’ve sung the praises of renewable energy and made your point about how much potential there is to develop renewable power, someone asks a question that goes something like this: “What are we going to do when the wind’s not blowing and the sun isn’t out? Won’t all the lights go off?”

This is one of the most common and pernicious myths in the world of renewable energy and low-emissions technology, and the act of asking the question displays a certain naïveté about how the electricity grid works. The truth is energy grids are incredibly complex systems that usually draw from several different power sources, and normally experience a wide amount of variability anyway in terms of both demand and supply.

Energy demand peaks around the middle of the day and falls to low levels at night. In places where hydropower is used to generate electricity, the ups and downs of rivers must be taken into account. And even the most reliable power plants must sometimes be taken off-grid for repairs or routine maintenance. Keeping the correct amount of energy flowing through power lines twenty-four hours a day is a complicated business. Fortunately, power companies are well equipped to handle it.

The fact that energy demand varies from hour to hour and day to day means utilities have a certain amount of flexibility built into the grid already. Retiring fossil fuel plants and replacing them with more intermittently powered wind turbines and solar panels does provide a bit of an extra challenge, but the idea that the lights will suddenly go out when the wind stops blowing is vastly over-simplistic. Energy grids are not built to work that way.

Even if you assume renewable intermittency will cause problems the current grid isn’t built to address, technologies that can store wind or solar power for later use are becoming more and more feasible. Just last week the state legislature of California passed a bill that requires utilities to invest in infrastructure for storing renewable energy. Lawmakers hope this will help California make the transition to a grid that no longer relies on large power plants, with their copious carbon emissions, to function. California utility PG&E plans to experiment with storage methods including use of wind power to pump water into an uphill reservoir during peak wind conditions, so water can later be released to power another turbine when the wind lags.

Also promising is the idea of using electric cars to store energy. Another myth born on the waves of the Internet is that growing demand for electric cars will strain the grid and make it more difficult to replace fossil fuel plants. In fact the reverse is the case: electric cars can help solve the challenge of intermittency. Most cars will do the bulk of their charging at night, when energy use is at its lowest and the added demand is easy to meet. However there will always be a certain number of cars parked during daytime—and with the right technology, they can feed some of their stored energy back into the grid during hours when demand peaks. Electric cars can essentially serve as ready-made energy storage units, and their widespread adoption will make renewables easier to integrate into the grid.

So next time you hear someone make the claim that renewable intermittency is an insurmountable problem, don’t be fooled. Finding the best way to integrate wind and solar power into the grid does present some challenges, and will involve a certain amount of trial and error. But energy entrepreneurs are fully capable of taking on a challenge. That’s what human beings are good at.

Photo credit: Nick Engelfried

Nick Engelfried is a freelance writer on climate and energy issues, and works with campuses and communities in the Pacific Northwest to reduce the causes of climate change.