• antimongo@lemmy.world
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    2 months ago

    Piggybacking on your grid stability point, another issue I don’t see getting addressed here is ramp rate.

    If we install enough solar where 100% of our daytime load is served by solar, that’s great. But what about when the solar starts to drop off later in the day?

    A/Cs are still running while the sun is setting, the outside air is still hot. People are also getting home from work, and turning on their A/Cs to cool off the house, flipping on their lights, turning on the oven, etc.

    Most grids have their peak power usage after solar has completely dropped off.

    The issue then becomes: how can we serve that load? And you could say “just turn on some gas-fired units, at least most of the day was 100% renewable.”

    But some gas units take literal hours to turn on. And if you’re 100% renewable during the day, you can’t have those gas units already online.

    Grid operators have to leave their gas units online, running as low as they can, while the sun is out. So that when the peak hits, they can ramp up their grid to peak output, without any help from solar.

    There are definitely some interesting solutions to this problem, energy storage, load shifting, and energy efficiency, but these are still in development.

    People expect the lights to turn on when they flip the switch, and wouldn’t be very happy if that wasn’t the case. Grid operators are unable to provide that currently without dispatchable units.

    • Vilian@lemmy.ca
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      2 months ago

      If we install enough solar where 100% of our daytime load is served by solar, that’s great. But what about when the solar starts to drop off later in the day?

      Store the surprus of energy from the solar panels and use that as a buffer with batteries or gravity

      But some gas units take literal hours to turn on. And if you’re 100% renewable during the day, you can’t have those gas units already online.

      Why not? Just time it and start it hours before, wind energy could help in that too

    • Resonosity@lemmy.world
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      2 months ago

      One solution to what you’re describing is to expand the grid. If your grid stretches half the planet, when the East starts to experience night, the West still experiences day and can ship electricity from renewables to the East to make up for their self curtailment. The same goes for wind where if one location on the planet doesn’t experience wind, odds are another location does and the power can be shuffled around.

      Another option is to build out more battery storage such that any clipped energy from solar or wind - that is, the energy that can be generated from your solar or wind resource but that can’t be exported because it would overload your inverters or transformers or exceed your PPA agreement with your utility - is stored and can be exported for 2-4 hours as the sun goes down or wind dies out.

      Not a lot of renewables sites are colocated with battery storage, but more and more are.