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comment by WanderingEng
WanderingEng  ·  2660 days ago  ·  link  ·    ·  parent  ·  post: Coal is dead, because nobody wants to build coal-fired power plants.

    Shouldn't we take power when we can get it (solar, wind) and then store it for when we need it?

Having more flexible load has been talked about for years, but nobody has made much progress on it. Little load is flexible. Around a home, refrigerators have to run regularly to keep food safe. Businesses have to keep running to sell their goods. Industry needs to keep running because while they may have high energy bills, if they aren't running they can't pay for their capital needs.

Storage is definitely a big deal. Today, energy is stored in piles of coal and gas pipeline pressure. Doing a little math, this link says a 500 MW coal plant burns about 1.4 million tons of coal per year. I think coal plants usually store about two weeks worth of coal, so let's say they have 50,000 tons on hand.

Wolfram Alpha says coal has about 7000 kWh/ton, so that coal plant has about 350 million kWh worth of energy sitting in a big pile outside. Only about 35% of that will go out the wires; the rest will go up the stack or into the lake or river. But that's still 120 million kWh of usable energy.

As far as I know, this 120 thousand kWh battery is still the largest single battery out there. It would take a thousand of these just to equal the storage capacity of a coal plant's backyard, and you still haven't produced a single watt.

The problem isn't impossible, but we're still so far away from the solutions being easy.





goobster  ·  2660 days ago  ·  link  ·  

Thanks for engaging with me on this.

I really think that our power grid needs to be way more like plumbing: a base level of water is always available, and then if Nevada needs to water their lawn tonight, there is additional capacity in store to draw on.

A radical rethinking of where we get power, how we store it, and how we make it available to the places that need it, especially when that need spikes...

It's a Big Problem, but one I can't imagine we aren't going to have to solve in the next 20 years.

WanderingEng  ·  2658 days ago  ·  link  ·  

It's definitely a Big Problem. The challenge with flexible load is finding load that's flexible and manipulating it to the advantage of the system. Some load can be shifted pretty simply. My refrigerator is currently running. If it had waited five more minutes to run, my food would still be cold and safe. But it will need to run eventually.

Storage is the potential miracle here. Despite press to the contrary, batteries aren't economical today to store energy for any significant length of time. They've been deployed economically for extremely short duration energy shifting, seconds to maybe a minute. I think they need to come down in price by an order of magnitude to really change anything. Maybe they will; it'd be great if they did.