Heat wave pushes New England electricity use to highest peak this year

Sweltering temperatures and high humidity from July 14 through July 20 sent electricity demand soaring and set some new records for power use. At the onset of the week, ISO system operators forecasted very high demand for electricity—the highest of the season—and tight power system conditions were expected throughout the week.

To have as many resources available as possible, on Monday, July 15, the ISO issued an alert to all market participants to cancel or postpone nonessential maintenance or repair work on generation and transmission equipment. As an additional precaution, on Tuesday, July 16, and again on Thursday, July 18, ISO New England asked consumers to voluntarily conserve electricity to help manage system conditions.

As is typical during heat wave conditions, demand for electricity increased steadily throughout the week.

Note: the following peak demand figures have been updated to reflect settlement values; they are still subject to the 90-day resettlement period.

Operational procedures to maintain reliability

On Friday, July 19, as demand climbed above 27,000 MW, ISO New England implemented several steps of its operating procedure to manage a capacity deficiency and keep the power system operating reliably. For example, at 1:05 p.m., ISO New England dispatched approximately 200 MW of demand-response resources (DR)—companies that agree to reduce their power use when called on by the ISO—in all of New England, with the exception of Maine.

The DR performed as it was designed to do, providing a quick reduction in demand when it was dispatched. Pictured below is the system load graph from July 19, 2013, which depicts the forecasted consumer demand (in blue), and the actual demand (in yellow).

Records set:

New England didn’t exceed the all-time peak demand of 28,130 MW set on August 2, 2006; however, several days did make it into the record books:

• Two weekdays made the top-10 peak demand day list:

• Thursday, July 18: peak demand was 26,867 MW (ninth highest)
• Friday, July 19: peak demand was 27,360 MW (fourth highest)

• The ISO also tracks a separate list of top 10 weekend demand days because demand for electricity is lower on the weekends:

• Saturday, July 20, landed at the top spot: peak demand was 24,649 MW

• The average weekday weekly temperature from Monday, July 15, through Friday, July 19, in New England was 82.8 degrees °F, which, according to ISO weather records dating back to 1960, is the hottest on record.

• From July 1, 2013 through July 21, 2013, preliminary data indicates that approximately 9,674 gigawatt-hours (GWh) of electricity was used, which ranks as the highest energy consumption when compared to the same time period in other years. July 2013 is on track to break the record for the highest energy use month; the current record is from July 2010, where 13,384 GWh were used.