New England’s grid operator said Monday that the region has enough electricity to meet demand this summer but warned that an extended heat wave with high humidity resulting in the extensive use of air conditioners could force it to ask customers to use less power or impose controlled outages, measures it would take only as a last resort.

Assuming typical weather conditions, ISO-New England said in its summer “grid preparedness” statement that it expects electricity demand will reach 24,553 megawatts. Hotter than average weather, such as an extended heat wave and high humidity, could push demand up to 26,383 MW, a nearly 7.5% increase that would reduce supply margins. The summer period is June 1 to Sept. 1.

About 30,000 MW of capacity are expected to be available to meet consumer demand for electricity and required reserves, the ISO said. The all-time record for electricity demand was set Aug. 2, 2006, when demand reached 28,130 MW after a prolonged heat wave, it said.

The ISO said last year that it expected summer demand to reach 24,605 MW and that it could have increased to 26,421 MW. The peak instead was 22,975 MW, spokeswoman Mary Cate Colapietro said. “Climate change has caused weather to become more volatile and less predictable,” the grid operator said at the time.

Weather is the biggest driver of energy use, said the grid operator, which is based in Holyoke, Massachusetts. Humidity is an important factor, forcing air conditioners to work harder to cool a home or office.

To provide electricity, the ISO uses generators that rely on natural gas, nuclear, oil, coal, hydro, biomass, wind and solar power; customers agreeing to reduce energy use at certain times; and power imported from New York and Canada. To keep the lights on under “abnormal conditions,” the ISO could increase power generation, dispatch standby units, call for voluntary energy reduction or even cut power, it said.


“In worst-case circumstances, ISO-NE could be forced to call for controlled power outages to maintain system reliability and safeguard the infrastructure of the grid,” it said. “With the possibility of more extreme and less predictable weather conditions, there is an increased potential for system operators to activate emergency procedures.”

ISO-NE describes controlled power outages as “intentionally disconnecting electricity customers” to protect the power system when demand outstrips the available supply. The grid operator acts in extreme situations after “exhausting other options” and to prevent a collapse of the power system that could cause damage requiring days or weeks to repair.

Colapietro said the ISO has never called for such outages in its 27-year history. The ISO would initiate controlled power outages only if conservation and other measures fail to bring energy supply and demand into balance, she said.

Dan Dolan, president of the New England Power Generators Association, said the the ISO’s warning is a “standard stance for any grid operator to take to prepare for extreme circumstances during the peak electric demand season.”

“Generators are well-positioned to meet their requirements heading into the warmest stretch of the year,” he said.



Recent problems have occurred because of limited, local troubles such as a downed transmission line or an outage at a power plant, Dolan said. Assessments have determined that the electric grid has enough generation and access to fuel to ensure reliable electricity, he said.

Andrew Price, president and chief executive officer of Competitive Energy Services, a Portland consulting business, said New England has “plenty of generation capacity available this summer” and he’s not “too worried” about power outages.

Some CES clients – colleges and universities, municipalities and businesses – have agreed to to be available to help ISO-New England reduce its electricity load if called on in exchange for payment, he said. And other strategies, such as conservation, solar generation and curtailing operations are available for electricity users to reduce their load on the grid and their costs.

In May, the National Oceanic and Atmospheric Administration predicted a 50% to 60% chance that temperatures in the Northeast will be above normal in July, August and September. The average temperatures in Portland are 64 degrees in June, 70 degrees in July and 69 degrees in August, said Stephen Baron, a meteorologist at the National Weather Service in Gray.

Summer energy forecasts benefit from efficiency measures from appliances, lighting and other equipment that reduce demand by nearly 2,100 MW, the ISO said.

Rising use of solar power also is helping to reduce reliance on New England’s grid. The ISO said its forecasts include a reduction of an estimated 999 MW during the peak hour of energy demand with the use of the region’s solar panels that replace energy from the grid.

The Mystic Generating Station near Boston, which was among the region’s largest power plants that operated since the 1940s, retired Saturday. The ISO said it’s not projecting any capacity problems during the summer based on the closing.

Related Headlines

Comments are no longer available on this story