This is true, but it only makes sense if you are talking about generation sources that can’t be controlled (e.g. solar, wind). It’s a complete waste if you’re just storing energy from something like natural gas plants, coal, etc. In the latter cases you are better off deferring generation of electricity you don’t need.
Gas turbines can start quickly but its said to be very expensive to do the startup. Its better to run them idle than have to cold start.
If the goal is to remove steam energy sources from coal and gas and oil, I get this. But if you have them, and you have efficiency from constant operating load, then rather than incurr start and stop cost, its better to store, even with wastage.
Back when I was a trainspotter, I used to hang at loco sheds and I asked a driver once why so many diesel locos ran idle doing nothing. he said that starting from cold was a pain. They costed it, and it worked out ok to run idle at their fuel cost, rather than have to restart. I think this is a similar moment.
So basically, I think you may have inverted the thing a bit. You can ignore free-energy inputs like wind and solar, but its wasteful so if you can't shed load in coal, its worth storing energy from solar and wind, meantime. If you have total excess energy from all sources, its worth storing it from anything which it is costly to stop-start, and you might as well store everything you can, to the capacity of storage.
Because wind and solar cannot guarantee supply in specific situations, storage can turn them into reliable power (albiet at lower intensity than the wallplate, because the storage either runs down too soon, or can't deliver as much peak)
Thats what I am reading anyway. This all feels like a classic complex linear programming optimisation problem for wiser people in power engineering economics.
The additional wear is not on the engine itself but on the starter components and those are simply designed for the additional load so that they can deal with the starts and stops.
I think it's going to be hard to pick winners, even if you do some of the math.
The idea would be (for me at least, I am not neutral in this) to marginalise the coal and oil and gas generation to make it the most expensive form.
If you live in Poland, or Victoria (Australia) you have unlimited brown coal, which burns sulphurously filthy bad smoke, its the worst possible energy source we have right now but its the cheapest. It has already been seen to displace high quality low-ash black coal, because thats worth money in China and India for export. So I get your message: cheap beats clean.
If you legislate for the cost of dirty cheap power, then storage losses are a lot more tenable, compared to the remediation cost. BTW economists actually do cost the deaths per gigawatt. Dirty Coal has a really high death rate both mining it, and burning it. Kids die of Asthma at far higher rates, in economies which burn coal for power. The economic costs of killing children, quite apart from the social costs, are huge. Actuarially speaking, you don't want to do this because you alienate future income from those kids grown up, earning money. Its a third-party damage problem which makes it easy for the brown coal generator to ignore, but when the kids of the coal miners and power station workers die, (and that happens) it gets a bit more direct.
Victoria had underground brown coal fires burning for YEARS.
Citation needed. Considering the economic side only, most places I've seen this cited around $3 - $30 Million per person killed, and compared to many emissions reduction tech, killing people is cheap.
For instance, "the hump" which was the US air shipment of materiel to China, in order to bomb Japanese forces was obviously a major loss maker in energy terms. Some huge multiplier of fuel spent to send fuel, worse than 5:1. Was it "worth" it? Yes! the war effort demanded the loss be borne.
So with this energy storage. Energy in the form of electricity is fleeting. If you don't convert it to a persisting potential energy form, it isn't there when you want it. Loss in the system is well understood by the engineers, financiers, planners.
Pumped Hydro has losses. Compressed Air has losses. Conversion to Ammonia or Hydrogen has losses. Winching concrete uphill in trains has losses.
Of all of these, thermal storage of energy in molten salt is perhaps the best understood. Its not unusual.
TL;DR short statements like "buuut the losses" are silly. This is not an absolute deal killer, it's an understood problem.