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Excluding storage facilities from the definition of an energy production facility?

EITAN PELED's picture

Education: Industrial Engineering and Management, MBA, LLB. Initiation and development of energy management systems in complexes and high-rise buildings. Establishment of a system for energy-zero...

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  • Apr 16, 2021

How do you set up a storage facility? Is it part of production or part of demand? Does the location of the storage facility affect its definition? A storage facility can regulate production and on the other hand can regulate demand. what do you think?

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Is this a question related to the natural gas industry or electric utility industry?

This issue involves a myriad of considerations.  When I put gasoline in my fuel tank for my car, I am transferring energy from one storage tank (at the gas station) to another (the tank in my car).  Natural gas is stored in the pipeline system in the US (3 million miles worth), as well as underground storage facilities.  When I charge an alkaline rechargeable battery, I take grid energy and store it in the battery (to be used at another time).  When a university energy system has an 8 Mw solar installation (along with other power generation equipment), a passing cloud can drop the output faster than the local equipment can ramp up.  In that case, the power grid becomes the "battery".  If a nuclear plant trips, a battery immediately takes over key equipment because it takes 20 - 30 seconds for an emergency generator to come online to power the plant to a safe shut down.  These are all energy storage issues.

The problem for electricity is that, for the most part, it is used as it is generated.  Storage has been considered the "holy grail" for the power industry for decades, regardless of whether we are talking about renewables, or nuclear, or other power sources.  As pointed out in some of the responses, the current niche market for battery storage has been ancillary services (frequency control, voltage support, etc.).  These services are profitable at current power prices.  A number of studies have been done looking at operating costs only.  These have typically concluded the same thing.  For the most part, ancillary services can be profitable, while large scale power shifting has not appeared to be so.  Some peak shaving can be profitable where power prices are high.  Recent MIT studies on energy storage have indicated that batteries will be useful for shorter term energy storage, while some kind of fuel will be necessary for longer term storage.  Thus, day to night variations in solar output can likely be handled by batteries.  Longer term shortages will need to be addressed by fuel storage.  I like to cite my example of traveling to Pittsburgh early last year to teach a course.  I flew out of Connecticut on a Monday morning and arrived in Pittsburgh in the early afternoon.  It was already cloudy.  The next day was cloudy, turning to rain in the evening.  The following day, it rained.  The next day, it snowed.  By the time I left Pittsburgh on Friday, it was just starting to clear up.  Thus, for the better part of 4 days, wind and solar would not have been available.  A 1 Mw, 4 hour battery would not have been sufficient to power the greater Pittsburgh area for 4 full days.  While solar has every day variability, it is not too often that the sun doesn't shine for a week.  Wind, on the other hand, can be too low to generate power for over 2 weeks at a time.  There are also seasonal variations (i.e. winter to summer).  These situations will require a much broader consideration for energy storage.

The most common suggestions for fuel storage are hydrogen, ammonia, and biofuels.  These fuels can be made from renewable energy sources.  The question becomes at what cost.  Each of these systems requires additional generation capacity to produce the fuel, as well as a storage system, and a transportation and distribution system.  In most cases, there will also be a storage system at the end user location.  None of this is trivial.  The current natural gas pipeline system is generally not suitable for moving pure hydrogen around.  Further, the heating value of natural gas is 1000 BTU/ft3, while the heating value of pure hydrogen is only 325 BTU/ft3.  On a volume basis alone, the current natural gas pipeline system would have to be more than tripled (that means 9 million miles). That doesn't account for losses, as hydrogen is a very small molecule and will penetrate most metal pipes while under pressure.  Ammonia and biofuels each have their own issues. Then there is the issue of getting approval to actually build a pipeline (Keystone, Dakota Access, Algonquin, others).

The simplest solution would be to use natural gas as the storage fuel and use CCS to capture and store (or utilize) the CO2 that is produced.  That is not a zero cost solution either, but it is likely to be cheaper when the cost of extra generation capacity, additional storage requirements, additional transportation and distribution requirements, and additional end storage requirements are figured in.  Now this amount of gas use with CCS may only be needed for the last 10 - 20% of total generation.  That appears to be when the alternative costs start to sky rocket.  Even that estimate may be off.  The Carbon XPRIZE just announced the winners for their competition to capture CO2 from power plant flue gas and make a useful product (one for coal and one for gas).  As it turns out, both teams came up with methods to improve the production and strength of cement by incorporating CO2 into the final product.  I was one of the judges for that prize.  Cement happens to be the largest material that we use, outside of energy.  Even so, that will only account for a portion of the overall CO2 emissions.  Underground storage will likely be needed to close the gap.

It should also be recognized that we don't want the atmospheric concentration of CO2 to get much below 200 ppm, as photosynthesis will shut down.  That is a much more dangerous situation than having CO2 at 600 or 800 ppm.  Every carbon atom in our bodies came from CO2.  Every oxygen molecule that we breathe came from CO2.  Plants undergo photosynthesis and absorb CO2 from the atmosphere to make the oxygen we breathe and the carbohydrates and proteins that we eat.  The fact of the matter is that we don't really know how much CO2 in the atmosphere we can tolerate.  We do know that around 4000 ppm, people that are trained (submariners, astronauts, fighter pilots, stc.) start to make mistakes in carrying out relatively simpler tasks.  Without training, that tends to occur at around 2500 ppm.  These conditions are known.  The level that is "dangerous" for the atmosphere is much less well known.  We do know that in prehistoric times, the CO2 levels were in the 1000 - 4000 pm range.  However, since no humans were alive at that time, we don't really know a "precise" number today.  That doesn't mean that we should do nothing.  Exponential growth would eventually make the CO2 concentration in the atmosphere too high, whatever the "correct" number is.  The point is not to go to extremes.  There will be a place for renewables, battery storage, fuel storage, pumped hydro, and many other technologies, including CCS and CCUS.  There is no silver bullet.

That is a rather long winded response.  The problem is very complex and simple answers are not going to resolve the problem.  We are still in the midst of a pandemic which did substantial damage to our economy, including job losses, business closings, bankruptcies, etc.  The toll in human lives and health has yet to be fully determined.  For all that, we recorded a 6.4% reduction in CO2 emissions.  For better or worse, fossil fuels still contribute to the bulk of our energy needs.  The US consumes roughly 100 quadrillion BTU/yr.  Over 80% comes from fossil fuels and another 8+% comes from nuclear power.  A little over 11% comes from renewables.  While that number will increase, we will still need to use fossil fuels to maintain the health of our economy and our people.

Storage can be part of supply, demand or even transmission and this matters greatly because where you put the storage also determines the regulations you have to follow.

If you develop storage as supply you may end up in the regulatory regime for qualify facilities (Order 872)

MISO, CAISO, & SPP are discussing "storage as transmission" - think of it like one of those zipper machines that move lanes during rush hours.  In this case the ISO/RTO rules will apply.

And if a private entity wanted to use storage solely to manage their own supply needs they might avoid regulation, but also avoid the benefit of selling into the grid.

The rules are being written before our eyes at the federal, state and intrastate level.

I'd be happy to show anyone on this forum how EnerKnol can monitor the development storage regulatory rules in all jurisdictions. 


Energy storage is pure energy conversion process. In one phase it is a demand, while in another it is production. Multi benefits have been provided through the process , the main is the storage of excess cheep energy , to utilized when it will be needed badly. Other byproducts are increasing resilience and robustness of the power systems. 

Hi Eitan:  My answer is that a definition does not really matter,  Fundamentally, if we are going to put fossil fuels as an energy source to bed for good, there needs to be a massive amount of energy storage available.  The solar and wind power options presently available are at best intermittent.  To create a landscape of baseline dispatchable renewable energy, we are going to need to see energy storage everywhere. From the utility perspective energy storage will allow them to offer electricity as they have always done. Energy storage will appear at solar panel locations, at wind power locations, at utility substations, and at separate locations devoted wholly to energy storage. From the customer perspective, having energy storage behind their meter will allow the customer to self-generate with whatever technology works at their location, and become less reliant on the grid.  In fact, adequate energy storage at each residential, commercial, government and industrial property will allow the property owner to worry less about grid disruption.

Just as we are seeing in the solar panel market with efficiency on a steady climb upwards and price on a steady path downwards, energy storage will experience the same. There are some great energy storage technologies in the lab that will change everything, allowing the vision I describe to become reality.

One last philosophical point, as some of my esteemed colleagues have noted, energy storage is somewhat expensive. Our choice is pretty straightforward. Either the world makes the societal investment to create a 100% clean energy future, or the last person left alive when climate change has had its way with us can turn off the last light, which will likely be a bonfire.


Hi Eitan:

Utilities can potentially use large battery energy storage installations for the following functions:

  • Voltage regulation for distribution substations with a high concentration of intermittent self-generation/renewables
  • Converting intermittent renewable generation to firm, dispatchable resources
  • Mitigating transmission constraints
  • Providing fast-reacting regulation services
  • Providing reactive power support
  • Some combination of the above

The largest BESS generally provide services that are most profitable, unless they a dedicated to a specific role (like combined photovoltaic plus BESS, second bullet above).

As far the implementation details, I would expect most large battery energy storage system (BESS) controllers use programmable logic controllers with custom software for each project.. Smaller BESS (like Tesla Powerwall) use custom hardware and standard (for the manufacturer) software that is has modules "activated" to perform specific functions for a given project. 


Bob Meinetz's picture
Bob Meinetz on Apr 20, 2021

John, do you have evidence a single BESS, anywhere in the world, is actually "converting intermittent renewable generation to firm dispatchable resources"?

In a May 2020 article, Large Battery Storage Systems Are Often Paired With Renewable Energy Power Plants, the author writes

"The U.S. Energy Information Administration’s (EIA) latest inventory of electric generators shows that the number of solar and wind generation sites co-located with batteries has grown from 19 paired sites in 2016 to 53 paired sites in 2019. This trend is expected to continue..."

Several times in the article he describes storage as being "paired with" or "co-located with" renewable energy power plants. But what does that mean? Can we assume the batteries are actually converting intermittent renewable generation to firm dispatchable resources, as you suggest?

"Energy storage (batteries and other ways of storing electricity, like pumped water, compressed air, or molten salt) has generally been hailed as a “green” technology, key to enabling more renewable energy and reducing greenhouse gas emissions. 

But energy storage has a dirty secret. The way it’s typically used in the US today, it enables more fossil-fueled energy and higher carbon emissions. Emissions are higher today than they would have been if no storage had ever been deployed in the US."

Batteries Have a Dirty Secret

No, in fact, we can't. We can safely assume storage is being used as a tool to arbitrage energy whenever profitable, that nowhere is it "dedicated to a specific combined photovoltaic plus BESS", as you suggest. We can safely assume grid-scale storage is designed to capitalize on blind, irrational acceptance of renewable energy, and that it is increasing CO2 emissions - a step backward in the fight against climate change.

Eitan, FERC Order 2222 and 2222-A provides some insights that may help answer your questions. A lot depends on whether the storage is in front of or behind the meter. It's interconnection point (transmission or distribution) level is also a factor in determining how it's treated. You may also find this NERC document helpful.

EITAN PELED's picture
EITAN PELED on Apr 20, 2021

Thanks for the reference but I am in Israel and with us the regulation is different of course

Eitan - very good question.  In my opinion, energy storage can be either and one way to define it would be by its scale and what market the owners are focused on.  Historically this could be done by reviewing the interconnection voltage and whether it was co-located with a significant, non-supporting load, certainly would be the case if it was integrated with an electricity generation source like solar or wind.  So if the facility was dedicated to storage only and connected at 1000's of voltages - it would be generation.  If it was integrated with a site load at an traditional usage voltage of 480/4160V - it would be load or load support.   Certainly from an electricity user basis, the ability to control their grid demand for price/tariff and even reliability issues - energy storage would operate very differently than for a generation asset.   Another key metric would be whether the connecting utility allowed the system to back feed to grid, for safety reasons, it is critical to make this information available to the utility.  

Eitan, because its definition is only important from a policy/economics perspective, we can use whatever terminology to describe storage that best serves our interests.

Energy storage can be useful for correcting minor inefficiencies in electricity transmission, among them frequency synchronization problems, and irregularities in line voltage. That it's found these niche applications is an accidental consequence of the one it's being disingenuously marketed to represent, however: a means to mitigate the problem posed by the intermittent availability of solar and wind energy.

The premise, roughly, is as follows: the physics of grid electricity require supply must align precisely with demand. Thus, if electricity from solar panels or wind turbines is only available on an intermittent, unpredictable basis, we might store energy when nature provides a surplus, then dispense it when nature's supply is deficient. That the notion has gained a popular (and lucrative) following ignores several basic limitations:

  1. Storage is wasteful. Storing electricity requires two conversions: from electromagnetic energy to potential energyand back again. During these conversions 40% of it or more is lost as heat to its surroundings.
  2. Storage is expensive. It requires an entirely separate infrastructure involving transmission, monitoring, and maintenance. Electrochemical batteries need to be replaced every 7-10 years.

Despite the quasi-religious public attachment to "renewable" sources of energy, storing energy is wasteful, expensive, and unnecessary, and deserves few of the scant financial and natural resources at our disposal if we're honestly committed to restraining the inexorable progression of climate change.

EITAN PELED's picture
EITAN PELED on Apr 20, 2021

I have a number of quotes in which the efficiency of a complete cycle (loading and unloading) is around 95% - 93%. You should keep up to date. Thanks for the reference.

Bob Meinetz's picture
Bob Meinetz on Apr 21, 2021

Eitan,  I'd like to see the details of your quotes. Do they include bi-directional inversion losses - AC to DC, and back again?

Figues like that are available under idealized test circumstances. Though they're often quoted by battery salesmen, they occur nowhere in practice.

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