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boringgtoday at 5:27 PM5 repliesview on HN

True but having capacity allows for generation - doesn't work the other way around.

AKA the forward march of progress.


Replies

AnthonyMousetoday at 6:27 PM

> True but having capacity allows for generation - doesn't work the other way around.

The issue is that comparing "capacity" as a percentage is misleading. A baseload generation source can have average generation above 90% of its rated capacity, solar at something like 25%, wind something like 25-40%. Which means that saying "nearly 50%" of capacity can imply something closer to 15% of generation, and potentially even less if the amount of local capacity is high, because then you get periods when renewable generation exceeds demand and the additional generation has nowhere to go, which effectively reduces the capacity factor even more.

And on the other side, natural gas peaker plants can have a capacity factor even lower than solar and wind because their explicit purpose is to only be used when demand exceeds supply from other sources, so that "nearly 50%" in a grid which is entirely renewables and peaker plants could actually imply more than 50% of total generation. This is much less common in existing grids but it makes looking at the nameplate capacity even more worthless because you can't just multiply it by a fixed factor to get the real number.

Whereas if they would just publish the percentage of actual generation, that's what people actually want to know. But then you'd have to say "13%" or "24%" or whatever the real number is, instead of "nearly 50%".

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rembaltoday at 6:00 PM

I'm too lazy to double check the numbers, but as far as I remember, Germany in order to increase it's average generation by 10% had to expand capacity by 70% in solar plus wind. With stats like this, there's a thin line between progress and waste. And all this while we have nuclear. (How the world really works, Vaclav smil if anybody is less lazy than me)

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Manuel_Dtoday at 6:59 PM

A lot of renewables have intermittent generation. If daytime electricity demand is already saturated, adding more solar panels increases capacity but doesn't increase generation (or to be more specific, it doesn't increase generation that actually fulfills demand).

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butvacuumtoday at 5:29 PM

We can also time shift many of the things we do. Does your fridge need to run between 3-5pm in the heat of summer? or can it make sure its a little cooler to avoid running then? (trivial example, probably not a good one)

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mhh__today at 6:23 PM

You have to massively overprovision some renewables

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