US electric grid isn’t ready to handle our future climate

The future grid will see big spikes in use, driven by demand for air conditioning.

Climate change is driven in part by our production of electricity. And there's a chance for feedback here, as the warming will significantly impact our overall consumption of electricity. In fact, it has been suggested that the majority of costs of climate change will likely come from the additional expense of indoor cooling. This will come through both a steady background of warmer temperatures and periods of high demand during extreme heat events.

As it stands, the electricity grid is designed to withstand days of high usage, which typically fall on the hottest days of the year. Right now, US grid operators are typically capable of supplying 15 to 20 percent above the forecasted peak electricity load. If the intensity or frequency of these extreme heat days increases, our current grid may not be able to meet the demand.

If it won't, then we need to evaluate the electricity supply infrastructure and provide additional investments in peak generation capacity, transmission, and storage. Recently, a team of scientists analyzed the impacts of climate change on the US grid to get some answers.

Influence of daily temperatures

The scientists created a dataset that combined electricity-load data with daily weather patterns with a fine enough resolution to capture changes in temperature and load throughout the day. The team used this to evaluate the influence of daily temperatures on daily electricity consumption and peak load across the 166 distinct load zones within the US.

Electric use responds to temperature as people opt for more heating or cooling. As the temperatures increase, both average and peak load numbers will follow in nearly all of the regions tracked in this study.

The researchers combined their understanding of how peak load responds to daily temperature and combined it with projections of future temperature derived from climate models. This produced estimates of the changes we'll see in average load and daily peak load through the end of the century. As a direct result of climate change, they predict a 2.8 percent increase in average hourly load and a 3.5 percent increase in daily peak electricity demand.

Peak loads would get peakier. The top 5 percent of daily peak load events would see usage up by anywhere from 6 to 21 percent, depending on the details of the model used. We'd also see more peaks. The number of days where the load was projected to be above the current top 5 percent went up significantly, doubling on the low range of estimates and going up by four times the current levels at the high end. The number of days above the current top 1 percent of days could be up to 1,500 percent more frequent.

All of which tells us that increases in electricity generation or storage should be planned to overcome future climate change-induced temperature increases.

Why peak load matters

The scientists then looked more closely at why peak load increases more than average load. They found that most of the high peak load days occur due to warmer temperatures. Since climate change predicts increasing temperatures, this results in an increasing upward shift of peak load to compensate as electricity consumption spikes due to air conditioning.

The team also evaluated how the intensity of peak loads changes by county across many regions of the US. Areas in the South experience the highest load increases. By contrast, the Northwest actually sees decreases in load. So, planning to adapt the grid will obviously need to take regional differences into account.

There are lots of potential ways of making the grid more robust to spikes in demand. These can range from increased generating capacity and storage to the use of more efficient appliances that adjust their behavior in response to the supply of electricity. Whatever we choose to do, getting started now can help keep the changes from being rushed into place in response to a crisis.