ISO-NE EPCET report projects future power supply and demand

New England's electric grid must overcome operational, engineering, and economic challenges to support state decarbonization commitments, according to a recently released draft report by grid operator ISO New England. ISO-NE's Economic Planning for the Clean Energy Transition (EPCET) study report concludes that a "vast renewable build-out may be required" to support wide swings in demand for electricity across days and seasons.

Today, peak demand for electricity occurs during the summer for reasons including air conditioning demand. But ISO-NE projects that peak demand for electricity will shift from summer to winter by the mid-2030s, as heat pumps are increasingly used to decarbonize building heating. 

As this new form of heating load becomes dominant, the weather will increasingly affect the level of peak demand, with a severe winter calling for up to 20 gigawatts more power than a mild winter. Increased variability in power system demand will require "vastly different supply levels from year to year", according to ISO-NE. The grid operator expects that this variability will mean that some dispatchable capacity is needed for reliability but might operate infrequently: "Some resources needed to maintain reliability during the harshest conditions may only run for a few days once every few years."

Another consequence of this variability is that emissions reductions will vary seasonally. Relatively high power production by wind and solar resources in spring and fall could combine with relatively lower levels of electricity demand in those seasons to yield substantial decarbonization in spring and fall, many years before summer or winter achieve that level of decarbonization. "Modeling shows spring will be mostly decarbonized by 2040, but a small portion of winter days will still produce significant emissions in 2050."

To meet these projected levels of demand solely with renewable resources, ISO-NE projects that the scale of development needed is vast. "If the future resource build-out is almost entirely wind, solar, and batteries, the region will need to add roughly 18 times its current combined capacity of these resources to achieve state emissions goals and maintain reliability." Revenue structures for generators might also need to change, to accommodate expected surplus generation from wind and solar resources in spring and fall. 

ISO-NE thinks that long-duration storage can help during shorter cold snaps but not over more extended periods of severe winter weather. To ensure reliability during prolonged severe winter conditions, ISO-NE suggests firm, dispatchable, zero-carbon generation, such as the use of synthetic natural gas (SNG) and small modular nuclear reactors (SMRs) as possible resources. The EPCET report concludes that SNG and SMRs may reduce overall system costs, by reducing the need for new renewable capacity.