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Vermont replacing power plants with home batteries

389 points · 304 comments · devonnull

  1. snickerbockers · · focus · HN ↗
    >The US now has over 40GW of virtual power plant capacity, according to internal analysis by Wood Mackenzie. It's still relatively small compared to the roughly 600GW of natural gas and 200GW of coal, but a total of 160GW of capacity could be unlocked by 2030, according to a 2025 US Department of Energy report – equal to some 20% of the country's expected peak energy demand.

    >Through GMP's programme, its virtual power plant has quietly become Vermont's biggest source of power. Now, the state is testing how far this "hidden" form of power can go.

    Does anybody at the BBC actually understand what batteries are, and why they cannot possibly compete with power plants!?!?

    1. epistasis · · focus · HN ↗
      What do you mean? These numbers provide great guidance so that people can understand the size of the battery discharge, and what they could replace.

      Batteries do indeed compete with power plants, every day of every moment they are on the grid. They are also consumers from power plants, they go both ways.

      1. snickerbockers · · focus · HN ↗
        Power isn't a particularly helpful metric here, energy is. Power doesn't tell you anything about how long the batteries will last, it only tells you how quickly they can drain. Also there's a limit to how much power you can draw through residential lines so regardless of whether or not batteries can deliver power on the same order of magnitude as a coal-fired plant, it's highly dubious that these specific batteries can do that.

        >Batteries do indeed compete with power plants, every day of every moment they are on the grid. They are also consumers from power plants, they go both ways.

        Hey don't tell me that, tell the BBC. They're the ones who wrote an entire article about "replacing power plants with home batteries".

        1. medler · · focus · HN ↗
          They literally did replace power plants with these batteries though. From the article: “ GMP similarly used to rely on oil, diesel and natural gas peaker plants to meet peak demand. Now the company's virtual power plant has effectively replaced them, says McClure. "We've been slowly able to decommission those as they've become end-of-life," she says.”
        2. Dylan16807 · · focus · HN ↗
          I agree with how power is a bad way to measure batteries a lot of the time (though if you assume they last 4 hours you shouldn't be too far off).

          But I don't think the residential line limits are too bad. A house that's sending out power takes its load off the grid and can also power multiple other houses without any lines being overloaded. And if an area has a high enough battery:house ratio, the full megawatt capacity of powering those houses but flowing the other way is a ton of power. (If the equipment can handle power flowing both ways.)

        3. epistasis · · focus · HN ↗
          I don't think the BBC is confused here at all. Batteries do indeed replace power plants. They are already actively replacing gas peaker plants all over. In California, batteries they are dramatically reducing regular, non-peaker, gas turbine generation, by outcompeting them on the grid.

          > Also there's a limit to how much power you can draw through residential lines so regardless of whether or not batteries can deliver power on the same order of magnitude as a coal-fired plant, it's highly dubious that these specific batteries can do that.

          These specific batteries, on the other ends of residential lines, indeed do push power back on the grid in aggregate enough to replace coal power plants. There's nothing special about a point generator on the grid versus the aggregate action of thousands of batteries on the other side of the distribution stations. In fact that's what's so amazing about batteries versus large thermal generators: thermal generators are large because if they get super inefficient when they're not large. Nobody is installing a small coal generator at their home to run daily, and even small diesel generators are hugely inefficient. But batteries are so useful that even accounting for the extra expense of large numbers of custom installs, they reduce grid demand enough to make a ton of financial.

          And power is indeed the most important metric when it comes to the grid. It's how everything is run, how individual grid assets are dispatched, because power needs to be balanced at every moment. Somebody could throw an asset on the grid that only dispatched for 15 minutes (or whatever the minimum bid time is), and it would still be described primarily by power. Capacity decisions may be made in kW-month or whatever unit, but you can run a grid on a pure energy market without any capacity market at all, as ERCOT shows.

    2. murkt · · focus · HN ↗
      Batteries compete with peaker power plants, though.
      1. red75prime · · focus · HN ↗
        Batteries compete with peaker plants for diurnal variance, but they can't replace peaker plants for seasonal variance. It's an interesting dynamic.
        1. hamandcheese · · focus · HN ↗
          Are there peaker plants that come online for seasonal variance?
          1. mono442 · · focus · HN ↗
            There is a coal power plant near me which in recent years I saw it running only during winter.
          2. entech · · focus · HN ↗
            I think what he was saying is that with a peaker plant you have an extra source of power. So if you have a low wind/low irradiance period - you can rely on peaker to provide more power, but by this stage batteries are long gone.
          3. belorn · · focus · HN ↗
            Is that a local question for Vermont, a nation question for the US, or a global question?

            If the question is global, then yes, there are, although as renewable energy has increased globally so has the need for peaker plants to handle the variance in the grid, thus plants that historically has only been used for seasonal variance are now used all year round to handle weather variance. An example of that is the oil power plant in south of Sweden.

      2. snickerbockers · · focus · HN ↗
        Well you're probably right that this could reduce the amount of load coming from power plants during brownouts, but the article presents it as something that is going to protect against blackouts and I really can't imagine that working as a replacement for peaker plants. If you're in silicon valley or NYC you probably think of a blackout as something that happens once or twice a year for about 15 minutes but in a lot of the country blackouts are several hours or even days long and happen fairly frequently.
    3. loeg · · focus · HN ↗
      > Does anybody at the BBC actually understand what batteries are, and why they cannot possibly compete with power plants!?!?

      VPPs displace more expensive generation capacity at the margin. Because your marginal loads are for relatively short durations. It's actually quite smart, especially if you can get end consumers to subsidize it.

      1. snickerbockers · · focus · HN ↗
        Well that's fine if the goal is to use it to protect against brownouts like a large-scale UPS but the article discusses it in terms of a protection against blackouts which often are not relatively short durations.
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