News and analysis about energy in California with an eye toward renewables.

Renewables Easier to Manage Than Expected for Grid Operators

Wind turbines dominate the landscape -- and the grid -- in Texas | Photo: fieldsbh/Flickr/Creative Commons License

Fossil fuel interests routinely criticize renewable energy as being too unpredictable to meet the demands of a large power grid. But as it turns out, even a resource as unpredictable as wind power -- which can fluctuate statewide by hundreds of megawatts in the course of an hour or two -- isn't that hard to incorporate into a grid the size of California's.

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Opponents of renewable energy have long capitalized on fears over intermittency, saying that grid managers like California's Independent System Operator (CaISO) will have to resort to expensive measures to integrate fluctuating renewable power sources like solar and wind, making the overall grid more fragile. But according to a recent piece by Herman Trabish in Greentech Media, such fears are -- to risk a wind-related pun -- overblown.

According to Trabish, the total cost of integrating wind power into the grid operated by The Electric Reliability Council of Texas (ERCOT), the Lone Star State's equivalent of CaISO, run around fifty cents per megawatt hour. And that's in a state with ten gigawatts of wind generating capacity, almost twice California's.

The key is to take advantage of new ways to monitor and predict weather a few days -- or a few hours -- in advance, so that grid operators can anticipate the wind dying down, or a cloud passing over a solar facility.

That's got to be bad news for fossil fuel friendly groups like the Koch Brothers-backed American Legislative Exchange Council (ALEC), which has attacked renewables development to the point where solar and wind trade groups are dropping their ALEC memberships. Grid fragility due to intermittency is a key criticism ALEC's made of renewables development, but sadly for ALEC, and happily for renewables backers, that fragility seems to be a non-issue.

That ease with which renewables can be incorporated into the grid offers some good news even for those who have concerns over the environmental and social impacts of Big Renewables. The easier it is to make the grid flexible, the easier it will be to manage renewable development that doesn't cram thousands of turbines into raptor migration corridors so that their power output can be aggregated. Having thousands of individual farm families own their own turbine or two, rather than designating wind sacrifice areas across California, might ease both the environmental and quality-of-life downsides to wind power development, and a more responsive grid could make that possible.


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About the Author

Chris Clarke is a natural history writer and environmental journalist currently at work on a book about the Joshua tree. He lives in Joshua Tree.
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This article gets the main point right: significant amounts of renewable energy can be integrated into the utility grid without concern of reliability. However, there is some room for further explanation.

First, as alluded to, dozens of wind integration studies, including many conducted in California, have confirmed that adding wind and solar to the grid only results in modest increases in total system variability. This is partly because changes in wind and solar output occur slowly, as it takes hours for a weather system to move the hundreds of miles necessary to affect a large share of a region’s renewable energy capacity. In addition, changes in wind or solar output are often canceled out by opposite changes at other wind or solar plants, or by opposite changes in other sources of electricity supply or demand. Moreover, changes in wind and solar output can be forecast by using advanced weather models, allowing grid operators to plan ahead and even more readily accommodate their output. Any incremental variability that is not accommodated through these factors can then be addressed by using slightly more of the same type of reserves that are already used to accommodate the variability and uncertainty that has always been on the power system.

Second, the California Public Utility Commission's Energy Division has been working on a five-year rate forecasting project and found that, overall, utility rates are expected to increase by just 2 to 3 percent a year over the next five years. "This tracks inflation," said Terrie Prosper, a spokesperson for the PUC. "The drivers of the rate increase are the general need for infrastructure improvements, most of which would be needed even if there was not a (renewable energy) mandate."

Finally, the CAISO February 2012 analysis compared the reserve needs and challenges associated with reliably accommodating two different generation mixes for the state. In one scenario, all of the state’s electricity needs were met from natural gas, while the other scenario 33% of California’s electricity was obtained from renewables plus shutting down many of the state’s conventional power plants with once-through cooling systems.

Analysis of data in the report indicates that moving to a 33% renewable system from an all-gas system causes a 3-4% increase in total system reserve costs. In 2010, all of these reserve costs accounted for less than 1% of the total cost of energy in the California electricity market. Therefore, on an average household’s monthly electric bill of $100, the increase in reserve costs in the renewables case would work out to an increase of around 3-4 cents!

In short, based on in-state government analysis, renewable energy does not add significant variability to the utility grid, nor will it drive cost increases that should worry the California homeowner.

For more information on these studies and the integration of renewables into California's utility grid, please visit: