Power transmission systems in 25 states plus the District of Columbia saw record-high electricity demand during last week’s heat wave while demand in New England hit its second-highest level ever, regional transmission organizations said.

The record demand surge was reported by PJM Interconnection, serving 13 mid-Atlantic and southern states, and by MISO, which covers 12 Midwestern states plus the Canadian province of Manitoba.

PJM said demand peaked at 158,450 MW at 5 PM Eastern Time on July 21, just ahead of the previous record of 158,258 MW on Aug. 2, 2006. MISO reported record demand of 103,975 MW on July 20, outstripping the 103,246 MW record on July 31, 2006.

In New England, ISO said power demand on July 22 rose to 27,762 MW, exceeded only by 28,130 MW on Aug. 2, 2006.

And the New York transmission organization NYISO reported 33,939 MW, missing its all-time record by only 74 MW.

For more on the challenges New York transmission operators faced, and overcame, during the recent spike in usage see: New York Survives 4PM.

Surviving The Surge

Despite the demand surge, the RTOs said they were able to maintain supplies to all customers.

The demand “was met without problems, and generation supplies were adequate,” PJM said in a statement. The operator said it did not call on demand response to reduce load.

MISO said it set a succession of demand records earlier in the week as the summer heat increased demand for air conditioning. On July 19, demand rose to 102,306 MW, the highest for the year-to-date, surpassing the previous record of 99,409 MW set only the day before.

No blackouts or brownouts were reported, but the system operator in New England activated backup systems designed to both cut power use and add power to the grid at short notice.

ISO called on 640 MW of consumption to be reduced by participating businesses, which receive monthly payments in return for agreeing to cut power use. Power cutting measures include turning up air-conditioning thermostats or timing production for non-peak periods.

To read more on how utilities get creative during heat waves and other spikes in usage, read: Looking To Past, Future For Heat Beating Methods.

The New England regional transmission organization also called on its network of backup regional generators to increase power output with either 10 minutes’ or 30 minutes’ notice.

The network does not anticipate comparable demand in the coming weekend despite renewed forecasts of triple-digit temperatures in some areas of the East Coast, Marcia Blomberg, a spokeswoman for ISO, said.

Price Peaks

Across the three regions experiencing the peak demand, wholesale day-ahead power prices for the mid- to late-afternoon peak hours rose from about $100 per megawatt-hour during the early part of the week to almost $350 by the end of the week when the heat wave peaked in the east, the Energy Information Administration said.

It noted that day-ahead power prices were higher in the PJM region than in New York City where prices are usually higher.

Nick Braden, a spokesman for the American Public Power Association, representing around 2,000 municipally owned utilities, said its members had met surging demand without interruption but may have benefited from declining demand from businesses at the end of the work week when temperatures were at their highest.

“We’ve had no indication from any of our members that a blackout or brownout is looming,” Braden said.