GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Electrical grid fuel mix & Pilgrim Nuclear

forcedexposure | Posted in General Questions on

Good morning folks,


The EPA has not updated their data on the fuel mix of New England’s electric supply since before the Pilgrim Nuclear plant shuttered last year.

How can we know, then, that the electricity that we’re using is getting greener? 

Is it normal for the data on here to be so old?

thanks, Kris

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. maine_tyler | | #1

    Does that help at all?
    There's quite a few links from there with more detailed and current data as well.

    1. forcedexposure | | #5

      this is excellent, thank you

  2. jwasilko | | #2 shows current fuel mix

    1. forcedexposure | | #4

      this is for all of New England and includes quite a lot of nuclear power. Is it correct for Massachusetts, though, that the electrical fuel mix includes only 40% natural gas? I can't see how to drill down to the state level.

      1. maine_tyler | | #6


        It is my understanding that it would be difficult, and perhaps irrelevant, to 'drill down' to the state level. The grid does not care about political boundaries so much as the physical infrastructure (generation, transmission, distribution, and use).

        You will note that in the table on the first link I provided, there is a difference between regional generation and regional Net Energy for Load (NEL). This is because there are imports and exports from/to other grid operators. Take your pick which you find most relevant.

        Note also that the real-time charts/graphs Jeff links to are for regional generation, not NEL.

        I find the real-time fuel mix graph to be really fascinating. You can see which fuel sources are used to match demand and which are used for base-load (or have their own generation output limits as with solar and wind). Nuclear is like freight train. Gas scrambles all over the place to match demand. Hydro to some degree also.

        You can also set that graph (setting upper right corner) to show just renewables, and you will see the expected climb in solar with the daylight and the variance in wind output.

        edit: this is a good illustration of the challenges we will face if/when we fill closer to 100% with renewables, and why dispatchable storage is such a big deal.

  3. Expert Member
    BILL WICHERS | | #3

    The ISOs (independent system operators) will usually have the most current data for generation in their regions. Many of the ISOs actually show a real-time fuel mix as a pie chart which is nifty. In the case of ERCOT, the Texas region, wind power is specifically itemized out and is often a BIG chunk of their overall system capacity. It’s interesting to see the variation throughout the day.

    Most of the time nuclear plant capacity is replaced with new natural gas generation. I’d consider that to be “less green” since nuclear is the cleanest of the conventional generation types (along with hydroelectric).


  4. maine_tyler | | #7

    It's also interesting to note that if the proposed NECEC goes online, it will add roughly the same energy to the mix as our current domestic hydro production (up to 8,600 Gwh).

    According to the linked table, we currently import 14,010 gwh from Quebec; I'm not sure what percentage of this is hydro, but point is we wouldn't be doubling our USE of hydro, I'm simply relating the scale of the project to our domestic hydro production.

    Also note that NE-ISO doesn't (likely can't) classify hydro as renewable for reasons that would likely be too wandering here.
    Not that anything became any clearer for me from it, but you might be interested in this thread on the NECEC:

    1. Expert Member
      BILL WICHERS | | #8

      Hydro Quebec is currently pretty much 100% hydroelectric. They may have some small gas peakers around, but they have closed or mothballed all of their conventionally fueled plants.


  5. Expert Member
    NICK KEENAN | | #9

    I do know that one of the dirtiest coal-fired plants in New England, the Brayton Point plant in Somerset, Ma, closed recently. The owners claimed it was no longer competitive with solar and wind. The distribution network for the plant is being repurposed to be a hub for an offshore wind farm in the Narragansett Bay.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |