Electricity supplies should be sufficient to meet New England’s demand during winter 2017/2018, but possible natural gas pipeline constraints could limit electricity production from natural-gas-fired power plants. The final Winter Reliability Program has been implemented to incentivize gas- and oil-fired power plants to procure sufficient fuel before winter begins. Maintaining reliability could require the use of emergency procedures if the region experiences any combination of the following: extreme cold for an extended time, power plant outages, or limitations on natural gas delivery.
See more details in the press release, “Reliable Power Grid Operations Expected This Winter,” and in Winter Generator Readiness 2017/2018, a presentation from the ISO’s winter preparedness seminar for power resource operators.
ISO New England issues forecasts for electricity supplies and power system conditions ahead of summer, when New Englanders use the most electricity, and winter, when fuel for generators can be constrained. The outlooks take into account many factors that could be boons or challenges to the reliable supply and delivery of electricity, such as weather forecasts, available generation capacity, and possible resource scenarios.
Because of relatively low demand for electricity during these times of the year, the ISO does not release specific seasonal forecasts ahead of spring and fall. Electricity supplies are generally more than sufficient to meet demand, barring extraordinary circumstances. Typical peak demand ranges from 15,000 to 16,900 MW for spring and 15,900 to 17,300 MW for fall, though peaks can be much higher if summer-like weather edges into these seasons.
During periods of mild weather when there’s little need for climate control, the amount of electricity being generated can at times exceed demand, particularly on weekends and during early morning hours. These situations can be dangerous if too much supply leads to excessively high system voltages and frequencies and unscheduled flows of power into neighboring regions.
When generation and external transactions are anticipated to exceed system demand, the ISO first asks generators to voluntarily lower output and then if necessary may order some generators to reduce output or shut down. This process is carefully executed because:
See details on the ISO’s protocol for managing these situations in FAQs: Minimum Generation Emergency.