i have no eletricity cost which mining coin will be good ?
Good, step one is done!
Now, the other variables!
How much electricity can you get at no cost, is there a capped consumption? Because if it's a 100kwh per household it's nothing.
How much can your powerlines sustain without having to bribe somebody? If it's a college campus room you're going to trigger the breakers with just two Asics.
How much money do you have to spend on mining equipment?
There are different ways to mine different coins, someones like Monero can only be mined with GPUs,
Randomx has killed GPU mining for monero, of course, you can still mine it but it's a waste of power, you're far better of mining other coins with your videocard.
Mining is a science related to the study of the amount of energy and effort in producing a currency and the return from that currency.
Electricity is one of the main parts of this investing but it is not the only one.
There is the cost of purchasing mining tools, maintenance, cooling, mining location, noise control, customs and legal restrictions and the rate of depreciation. If you do not manage all these risks, free electricity will not make you profit from mining.
Common, it's not nuclear science, it's a pretty simple thing, you have costs and you have revenues.
Cooling, noise control is of little impact unless you mine in a dorm or in Sahara, customs are already priced at the gear price, the factor that makes the difference between profit and bankruptcy will always be electricity costs.
I can't picture even one single scenario that is so fucked up in which you will make no money with zero electricity costs right now unless you buy gear at an overpriced factor of x10.