Variable Resource Working Group

The Variable Resource Working Group (VRWG) reports to the Markets Committee (MC), the Reliability Committee (RC), and the Transmission Committee (TC), providing input on issues related to variable resources in New England.

For more details on the working group, see the VRWG’s charter.

About Variable Resources

Variable resources are electricity producers whose output amount and availability can vary due to the nature of fuel being used—for example, wind, solar, or run-of-river hydro. Wind and solar energy in particular have been expanding dramatically in New England. With zero emissions and no fuel costs, these resources can help achieve federal and state environmental goals.

However, these types of resources have different operating characteristics than traditional power plants. So, the reliable large-scale integration of variable resources presents challenges for grid planning and operation. For example:

• Changing weather conditions can lead to rapid and sizeable swings in electricity output.
• Wind speeds can be at their lowest levels in the summer and during extreme cold snaps—conditions when electricity demand is high.
• Power from solar arrays also tapers off in late afternoon as demand is peaking, particularly in the winter.
• Many solar arrays are installed “behind the meter,” so their generation is not dispatchable by the ISO and is difficult to account for and forecast in system planning and operations.
• Rules for interconnecting wind resources to the grid are not the same as for traditional power plants. Wind farms are also often built in remote areas where the transmission system isn’t designed to carry large amounts of power.

Accommodating a high percentage of variable resources will require wide-ranging changes across the transmission system, grid operations, markets, and system planning. To learn more, see the ISO’s annual report, the Regional Electricity Outlook.