Electronic – Why don’t we think about battery storage for all sources of electricity on a utility scale instead of just renewables?


One of the repeating solutions that comes up when talking about renewable energy power generation and the intermittency of it is battery power storage.

This has got me thinking, it takes hours or days for gas and coal fire plants (and I assume other fossil fuel options) to fire up and so you essentially have to keep these going as power backups for renewables for when the wind doesn't blow or the sun doesn't shine.

This got me thinking, why isn't anyone talking about using energy storage for all sources? Specifically utility-scale solutions that can hold weeks or months of energy? I would think that such a solution could vastly reduce inefficiencies in all power generation as my understanding our traditional sources are quite wasteful and the energy is use it or lose it.

Maybe my understanding is wrong and quite frankly I am not sure what happens with excess energy that doesn't get used (I assume it is dissipated into the environment in some way).

It just seems to me that we could reduce costs and combine energy generation sources and need less of all sources if we can store all the excess energy we don't immediately use.

Edit (additional info):
There is a lot of confusion about what I mean and intend here. First, the type of battery is not relevant to my thought process here. It could be pumped air/fluid/whatever storage as much as it could be Tesla's utility scale batteries. The point would be to store excess generated and potential energy more readily to reduce raw energy waste throughout the system.

My thought process is that fossil fuel plants don't simply turn it off and on. The oil/gas/coal keeps burning and turning a turbine, whether or not it is connected to a generator at the time or not. It takes time to turn it on and off and thus there is a lot of time that these fuels are burning and generating pollutants when they could just throw that energy that goes to the turbines which goes to the generator (if you let it) into a secondary storage that can be more readily accessible.

As my thinking continues, I suspect there is a ton of potential energy waste throughout our power generation systems. Whether it be those generators that could be generating (but would overload a system that is fully powered) or excess heat not being utilized or electricity that is (I am guessing) somehow dumped and not used.

If I am correct in my thought process then we could be storing that energy in some way, shape, or form instead of losing it. If we can store it and access it readily then we can reduce the need for so much power generation in the first place. I could be totally off base with some or all of my thinking though.

Best Answer

Taking, at random, Overland Park, Kansas, as an example:

  • Population 191,278 (2017).
  • Area 195 km2.
  • Annual energy demand (per capita) 13,500 kWh = 37 kWh/day. World Bank.
  • City demand = 191278 x 37 = 7 x 106 kWh/day = 7 x 109 Wh/day = 3600 x 7 x 109 = 25.5 TJ/day.

For pumped storage the formula for energy stored is \$ E = mg\Delta h \$. Assuming we could create a pair of lakes with a Δh of 100 m somewhere nearby then we would need to move \$ m = \frac{E}{m \Delta h} = \frac {25.5T}{9.81 \times 100} = 25.5 \$ million tonnes of water to the upper lake to store one day's worth of energy. That's 25.5 Mm3 in volume.

Making a lake the size of Overland Park we would fill it to a depth of \$ \frac {25.5M}{195 \times 1000 \times 1000} = 130 \ \text m \$ which is deeper than the 100 m we suggested raising the lake to.

The point is that the energy requirements are huge and any storage system would have to be equally huge. You can find battery energy densities on Wikipedia.

Last time I looked online battery storage was a little below US$200/kWh. That requires an investment of 37 x $200 $7400 just for you and $1,415,457,200 for your city for a one-day battery backup.