Challenges with energy storage in batteries

Question

Just before saying anything, I just want to warn you that I don't know much about batteries and energy storage, consider that you are talking with a kid of 8 years and a half. Maybe this question is also more suitable for electrical engineering department. I have heard that one of the challenges about energy, is storage(batteries). Maybe I am wrong about this statement.

More specifically, how can we store energy efficiently that is originating from solar/wind source.

Let consider this example : Our Sun produces some X amount of energy that goes through the earth's atmosphere, and when it gets to our solar energy farms, it will all be concentrated and let's say that 100 Joules leaves our solar parks.

It will go through the wires, to our battery packs (e.g Tesla Powerpacks).

Some of that energy will be lost through the wires(AC current), so we will have 98 Joules getting to the powerpacks.

Once the 98 Joules gets to the batteries, it is being converted to DC current and while being stored in the battery, a lot of energy will lost, and the batteries will be heating which causes even bigger losses. Lets say that we end up storing out of 98 Joules, only 70 Joules per hour.

Note that I have chosen Joules just to simplify the problem.

The energy that is being stored in the battery will also be lost over time.

Also, when will want to use that energy from the battery, it will go through the same process and once it reaches our homes, some more energy will be lost.

Now, can someone guide if this all makes some sense, and confirm if the greatest challenges with energy storage is when the energy gets to the battery and is being stored for later re-use.

Thanks

Answer 1

Back to some basics about electricity production first; Energy storage in a generating and distribution system is an attempt to cut off a bit of the peak generating requirement (which is otherwise from the most expensive generators) by using some of the unwanted cheaper generation at times of lower demand. Whether it is a good idea or not is a question of economics. The financial calculation will take account of the physical losses in the system. Currently the only large energy storage systems in use are pumped storage with a water reservoir.

Battery technology has been around for a long time. If you are going to use batteries in the generating/distribution system you can use the cheapest batteries available which would be lead acid. The weight/volume is irrelevant in a central storage system and the technology regarding lead-acid is well developed owing to extensive use in telephone exchanges for example. There are no "large" lead-acid storage system currently in use owing to the fact that it is very uneconomic compared to pumped storage. More modern battery designs (e.g. Lithium Iron Phosphate) are even worse as the lifetime cost of the battery is higher.

Therefore, going back to your question, if you wanted to have a bulk high capacity storage system for solar panels (they are off when it's night !) or wind turbines (might be calm for a week) then surely the only system worth considering is pumped storage on economic grounds.

Of course if you have another reason apart from the normal considerations then batteries might be the best solution (e.g. Back-up UPS systems) but for normal generation/distribution the cost is prohibitively expensive (otherwise we would have done it already with lead acid).

There are a few relatively new battery storage systems grid connected but the storage capacity is tiny compared to, say, daily system demand and they provide, at most, a few hours of power.In addition all these system appear to be "subsidised". This is an indication that you can of course alter the normal scientific calculations and financial equations if you have a source of "free" taxpayers money to throw at something. That's a question of politics, as this is a science forum we like to stick with the facts. The basic fact is that battery storage systems are massively more expensive than pumped storage.