Why don't we think about battery storage for all sources of electricity on a utility scale instead of just renewables? [duplicate]

Question

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.

Answer 1

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.

Answer 2

I am not sure exactly what you are expecting as an answer, but storage has already started to be used to supplement all energy sources. Utility-connected battery banks have already proved superior to any alternative peaker plant.

This report on the Australian 129MWh Tesla battery installation's first year of operation could shed some light on it. In just one year it has pretty much recouped more than 75% of its costs (33% to the owner and the rest in savings due to its reducing FCAS market pricing by nearly 90%).

Conclusions from the report include that the battery system has contributed to the withdraw of the requirement for a 35 MW local Frequency Control Ancillary Service (FCAS), decreased the South Australian regulation FCAS price by 75%, helped connect South Australia to the National Electricity Market, among various other contributions.

That means that 35MW of fossil-fuel-powered peaker plants can be removed from the market. Given its near instantaneous response to demand, it also means that utility energy markets might start pricing speed of response differently, which will further benefit these types of storage.

Just adding enough storage capacity to sustain the grid while a fossil-fuel plant is being wound-up, is enough to provide some CO2 savings. Extrapolating from the Australia installation, savings could be at the very least on the order of 30% of the installed battery generating capacity.

Replacing peaker plants is an explicit market focus for Tesla, which as of this writing has installed more than 1GWh of utility-connected battery banks worldwide.

Answer 3

Part of your basic premise is false: gas turbines can go from zero to full power in a matter of minutes. They've been used to provide peaking power for decades, since it's rare for power demand to vary so rapidly that they can't handle it. Because traditional generation capacity can be changed so quickly, there's no need to store electricity on more than a trivial scale.

The reason we're looking at battery storage (and flywheel storage, and pumped-hydropower storage, and a whole lot of other things) for renewables is that they can't be used to generate power on demand. If the grid operator sees that the Superbowl halftime show is coming up, they can instruct a gas turbine or two to start up to deal with everyone microwaving their snacks at the same time. But they can't turn the Sun on at night, or order the winds to blow harder. Hence the need for large-scale storage of renewable power.

Answer 4

One thing about batteries is that they cost energy and materials to build them. The more storage capacity you need, the more it costs.

As things are now, energy is stored in the fuel - huge oil tanks, train wagons full of coal. The fuel consumption rate is matched to the output power.

The coal and the oil come from the ground though. The ground is like a huge storage bin for all the fuel, and we extract the fuel as we need it.

So, we already have massive scale, high energy density, storage of energy in the form of the raw fuels.

Even the sun can be viewed as a gigantic storage of energy.

Solar/wind power is commonly paired with batteries because of the intermittent source of energy. Night, clouds/weather can reduce the amount of available power. But if we had a worldwide network of solar panels/wind turbines, we wouldn't necessarily need those batteries - it's gotta be sunny/windy somewhere.

One advantage of battery storage is the capability of having a higher power output than from the generator charging the batteries. For example, a generator which can produce 1 kW charges a 1kW*hr battery. If that is all the generator is doing, it takes 1 hour to charge the battery, or maybe it takes several hours and the generator powers a few other things. Once the battery is charged though, it can provide more than 1kW of power. It could provide 2kW for half an hour, or 4kW for 15 min. Or maybe it powers a laser for a brief moment.

Grid scale storage is done with dams and hydroelectric. If more power is needed, generators come online. Are batteries necessary? Are they the best form of storage? It's debatable - are they the most cost efficient? what is their max power output? how long do they last? how much additional infrastructure would be necessary to incorporate battery facilities into the grid?

We are doing what works, and will continue to do that because it works. Having fuel as energy storage is more energy efficient than making the electricity and storing it in batteries and then inverting it when it's needed. And because the fuel already exists deep in the ground, we don't have to build storage facilities for it, we just have to extract and transport it.

Answer 5

Because it's terribly expensive. The idea is there. Many ideas to store energy are in the cartons (spinning wheels, artificial lakes, weight lifts...) but none are commercially viable or enough efficient. Or as Tesla's pilot project in Australia (see answer from Edgar Brown), it's not realistic on a global scale. Batteries don't work eternally. After a few years you have to replace them. Raw material are scarce. Environment hazards. etc.

That being said, laboratories search for more efficient batteries. Fluoride batteries look promising. Unfortunately as always, these marvellous discoveries don't go beyond the newspaper report. 10 years later we are still with Li-ion. Let's hope one day we get them.

Answer 6

Co-generation and large UPS people have worked through most of the available alternatives. Batteries are the second worst way to store excess electrical energy (only capacitors are worse). In round numbers, the batteries to power the Empire State Building for one week would be the size of Central Park (all of Central Park) and 50 feet high.