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Comment by DanielHB | Hacker News Reader

When I worked with medium-sized scale batteries one of the most surprising use-cases was to use them _together_ with diesel generators. Diesel generators are incredibly wasteful because they don't vary the power output / fuel-consumption very well based on demand.

When you couple a large battery with a diesel generator the generator turns off when the battery is full so the generator always run at optimal efficiency.

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I feel like this is one of those things that isn’t surprising to Factorio players

Factorio power generators always run at 100% efficiency, so it is not really the same thing, you still consume the same amount of coal if you have batteries or not.

I guess it applies for nuclear power if you do that jank thing to not put fuel cells unless you need power. But then it is a thermal battery...

Or S-R latched heat tower with accumulator, though it's more of a hassle than it's worth.

I don't think that's true for steam engines - they produce only what is demanded and scale their steam (and hence fuel) consumption accordingly. This is what makes steam an effective backup & load smoothing source, you can load up a bunch of coal in the boilers for when your laser turrets start going, but it won't get consumed as long as your nuclear/solar power is running. One of my strategies when I run out of coal is to cut the power to everything but the coal mining patch (by deleting power poles), and then let it mine enough to fill up the boiler belt.

It's nuclear that continues to burn regardless of demand. The extra energy will heat your heat pipes up to 1000C but any heat beyond that is wasted.

Also, if you play Space Age you're well accustomed to using batteries (accumulators) to smooth out power spikes. Fulgora power generation through lightning rods is incredibly bursty, and if you don't drop about 20-30 accumulators per lightning rod you will waste power and not make it through the day.

That’s what they mean by 100% efficiency, whereas real generators can’t perfectly scale their fuel use with electricity usage.

100% efficiency is impossible.

Yep, this is the fully hybrid electric path. Generators work much more efficiently when ran at a fixed RPM.

Unless its a Chevy Volt. That was a really interesting car in many ways, but they kneecapped fuel efficiency by eating transformer losses twice instead of licensing Toyota patents.

Not just fixed but most engineers design with UL standards so while they advertise maximum output they're all most efficient somewhere around 80% their maximum.

The batteries help the grid because they can maintain a minimum demand the power plants need and compensate for any excess demand that would tax the grid infrastructure.

I've never tested a generator, are they all producing pure sine waves?

We did this many years ago for remote First Nations sites with an energy monitoring startup I worked for - saving them enormous sums of money (and carbon!) in the process. It's actually quite amazing how low some of the low hanging fruit is once you start looking.

That is really cool, our use case was powering an off-grid festival in a remote location. Our battery fit in a semi-truck (so it was fairly big, but not grid-scale). I don't remember the exact savings on fuel but it was ridiculous, like truly non-sense why doesn't everyone do it like that. I think the generator was on only about 40% of the time.

Even as backup power it still makes sense to have a battery attached because it extends the capacity of the system so much. The main problem is that you need some BMS software to coordinate the generator and the battery, but there aren't self contained solutions like this widely available (at least last I worked with it).

That's literally how hybrid cars work, yeah.

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