Connecticut trails only Hawaii for the highest electricity bills in the country, according to a new study, as state legislators undertake a fresh analysis of system costs while factoring in the need for reliability.

Connecticut's average household shelled out $2,077 to cover the power bill over 12 months through last September, according to estimates by Ownerly analyzing data from the Energy Information Administration. No other Northeast state cracked the 10 with the highest annual bills.

While Connecticut ranked fourth for electric costs as calculated by the price per kilowatt hour, Massachusetts and California have lighter monthly electric consumption on average, resulting in lower bills on average than in Connecticut. And Rhode Island electric customers saw among the smallest increases in the nation last year on their electric bills on average.

Connecticut and Massachusetts have launched a joint initiative to find ways to reduce power costs. ISO New England runs the market for the wider region that sets prices for electricity produced by power plants.

In 2019, Connecticut approved new power purchase agreements with Dominion's Millstone Power Station in Waterford, whose two nuclear reactors supply more than a fifth of New England's electricity.

But roughly half of New England's power is generated through the burning of natural gas to fire turbines. With the cost of natural gas increasing last year, higher bills are hitting Connecticut households that purchase electricity through Eversource and United Illuminating due to increased costs for power plants that burn natural gas to power turbines.

During an online forum this week convened by the Connecticut Public Utilities Authority, Sen. Bob Duff, D-Norwalk, questioned why a utility the size of Eversource does not wield more pricing leverage in procuring the power that goes over its lines. Duff contrasted Eversource's costs with those of Avangrid subsidiary United Illuminating and members of the Connecticut Municipal Electric Energy Cooperative, which includes South Norwalk Electric and Water and the Norwalk Third Taxing District.

"Connecticut, Massachusetts and New Hampshire all have different kilowatt-hour charges — but the facts remain, these high costs will be difficult for many to bear," Duff said. "What is the process by which Eversource procures energy, and can it be improved? How do they forecast natural gas and their fuel sources, and are they providing their ratepayers sufficient protections from increases like we have just seen?"

In advance of the hearing, an Eversource spokesperson told CTInsider the company does not control the cost of natural gas and makes no profit on power generation. The spokesperson described as "fully transparent" the procurement of power supplies for customers that pay for power delivered over its lines.

New England achieved an all-time low for grid electricity consumption across multiple days last spring, with an increasing prevalence of solar panels thought to be a contributing factor. But ISO New England warned last year that any prolonged cold snap could force rolling blackouts, given the competing demands for natural gas to fire home furnaces in addition to power turbines.

Only on Wednesday, ISO New England detailed steps it had taken on Christmas Eve to avoid rolling blackouts, after some 2,150 megawatts of unspecified power generation capacity was no longer available for roughly an hour and a half, including during the 5 p.m. hour when demand peaked on the day. That resulted in an electricity supply "insufficient to meet required operating reserves in addition to satisfying consumer demand," in the words of ISO New England.

ISO New England levied $39 million in penalties on unspecified power generation companies under rules allowing it to do so, with power generators that took up some of the slack to get reimbursed.

Includes prior reporting by Luther Turmelle and Abigail Brone.