Electrical energy is useful by definition. As indicated in the article, you have to essentially do arbitrage by using “excess” generation to do something that produces value ($), like storing the energy in a battery for later when the grid is more expensive, or to do useful work like make fertilizer, capture carbon, condense water, run your AC extra hard , etc.
Batteries have a 50% efficiency cut on storage and recall... it is unlikely that cutting the spot price in half will make this profitable.
"Although battery storage has slightly higher round-trip efficiency than pumped storage, pumped-storage facilities typically operate at utilization factors that are currently twice as high as batteries." [1]
Also very limited run times on the grid: "For example, in 2015, the weighted average battery duration was a little more than 46 minutes, but by 2019, weighted average battery durations had doubled to 1.5 hours."
Imagine the battery was your only source of power, the EIA is saying that 50% of the time you could discharge / recharge those batteries - at grid scale. Capacity factors are huge for total efficiencies because it measures the time your system is operating...
After a heavy charge / discharge cycle temperatures in batteries might be high enough that you have to allow them to cool or recharge at lower rates.
Under normal circumstances batteries do _not_ heat up during charge/discharge, both the BMS and their internal electrical design (most of the cells are connected in parallel) are intended to prevent that. And you connect the batteries in parallel too. The current in individual cells
is not significant enough to cause any visible temperature changes even when the whole pack makes hundreds of amps @48v.
According to data from the U.S. Energy Information Administration (EIA), in 2019, the U.S. utility-scale battery fleet operated with an average monthly round-trip efficiency of 82%,
First, batteries aren't only available "50% of the time", where does that come from?
Second, that isn't how 'efficiency' works, it is the percentage you get back from what you put in and your own link says 82%. Where are you getting these ideas?
efficiency is lower. This is what is meant by capacity.
Capacity or efficiency? You're getting your terms mixed up.
Math is hard. Understanding efficiencies via words is harder :)
It isn't that hard if you're talking about things that are true and make sense.
What? Round-trip efficiency already means in-to-out. Even if it meant in->stored and stored->in, that would be 0.8 * 0.8 = 64%. Your numbers make no sense.
:( Capacity factor 50% means you only have batteries at half the availability... ie the batteries need to cool or recharge at fixed rates and you can't use them as energy storage buffers in a continuous manner... as one would need for grid batteries to work effectively.
Also you're mixing up 'efficiency' which is what you said at first now with 'capacity factor' which is completely different.
ie the batteries need to cool
Where are you getting that from?
or recharge at fixed rates
Everything recharges at a 'fixed rate'. Lithium titanate batteries and some LiFe batteries like the Headway 38120 HP can charge at 10C, which means they can charge in around 6 minutes if you have the amps to put through them.
as one would need for grid batteries to work effectively.
Then how are people already using them as grid batteries?
"Also you're mixing up 'efficiency' which is what you said at first now with 'capacity factor' which is completely different.
"
Effective utilization on the grid is affected by efficiency and capacity factor. One is "when the system is operable, how well does it perform". The other is "how often is the system operable".
People generally colloquially use efficiency as effectiveness. However in real systems, that power peoples lives & livelihoods, effective systems are both efficient and available.
People generally colloquially use efficiency as effectiveness
Not if they are talking about specific technical definitions. You should ask these hypothetical people if they know anything about batteries.
However in real systems, that power peoples lives & livelihoods, effective systems are both efficient and available.
I don't know what point this vague abstract description is supposed to make, but battery systems are literally working right now and making people money.
