ISO New England analysis made public Wednesday estimated about 10% of the total 2030 offshore wind power portfolio connected into southeast Massachusetts and Rhode Island would be “spilled,” or curtailed, under certain assumptions due to transmission constraints and a glut of supply.
Transmission developer Anbaric requested ISO-NE perform a study reviewing the impact on energy market prices, air emissions and regional fuel security of three offshore wind power scenarios for target year 2030: 8,000 MW, 10,000 MW and 12,000 MW.
An ISO-NE presentation during an earlier Planning Committee meeting discussed the Anbaric economic study for scenarios with 8,000 MW to 12,000 MW of offshore wind additions in southern New England.
The addition of 8,000 MW to 12,000 MW of offshore wind plus assumed resource retirements of nearly 4,500 MW result in southeast Massachusetts and Rhode Island (SEMA/RI) export interface transmission congestion, according to the presentation.
Other key points include a finding that connecting more offshore wind close to load centers outside of southeast Massachusetts and Rhode Island, especially the Mystic and Millstone substations, would reduce the congestion hours of the southeast Massachusetts/Rhode Island export interface.
Additionally, demand from heat pumps and electric vehicles, depending on their alignment with offshore wind production, may cause more southeast Massachusetts/Rhode Island export interface congestion, according to the presentation.
The “location of battery storage matters” and installing more storage in areas with large amounts of offshore wind development, such as southeast Massachusetts, Rhode Island and Boston, would reduce congestion at the southeast Massachusetts/Rhode Island export interface compared with installing storage resources elsewhere, ISO-NE said.
During a Wednesday Planning Committee meeting, ISO-NE provided further information specifically addressing how much offshore wind energy might be spilled behind the constrained export interface.
Offshore win spilled due to the constrained interface was quantified for two scenarios: the Anbaric 10000 and 10000_Sen. Offshore wind was also spilled due to energy oversupply, the presentation said.
The difference between the two is the volume of electrification in the heating and transportation sectors, as well as the prevalence of storage devices.
The Anbaric_10000 scenario does not include power demand from heat pumps or electric vehicles and assumes 2,000 MW of battery storage additions. The Anbaric_10000_Sen, or electrification scenario, assumes 2,050 MW of demand from heat pumps and that 550,000 EVs are in use by 2030, along with 4,000 MW of battery storage.
The ISO-NE study found about 90% of the energy produced by offshore wind in southeast Massachusetts and Rhode Island served loads in both scenarios.
“Electrification lowered the [offshore wind] spillage by 0.53 TWh, which is 1.8% of the total [offshore wind] available and about 18% of the 2.97 TWh of spilled [offshore wind] observed in the Anbaric 10000 Scenario,” according to the presentation.
Around 10.1% of the total offshore wind connected into southeast Massachusetts and Rhode Island areas was spilled in the Anbaric 10000 Scenario, ISO-NE said. Of that total, 5.7% was spilled when the export interface was constrained.
The higher electrification scenario showed that electrification demand increased about 1.8% of the offshore wind energy usage on the basis of the total energy available from offshore wind modeled within the export interface, the grid operator said.
The volume of offshore wind spilled due to constrained transmission decreased from 5.7% in the 10000 Scenario to 5.1% in the 10000_Sen scenario. And the volume of offshore wind spilled due to energy oversupply fell from 4.4% to 3.1% between the two scenarios, according to the presentation.
About 8.2% of the total offshore wind connected into the areas was spilled in the 10000_Sen scenario.