Why is Energy so Difficult to Store? Why is Stored Energy so Difficult to Use?

By Kevin Kilty

Figure 1. An energy storage scheme with complexities galore. High temperatures, exotic materials, and extreme machine demands. (h/t Chaamjamal)

Air compressed and shoved into old mines and caverns; mass hauled uphill, and let down again; heat stored in mass. New, advanced energy storage schemes? Well, no, these are from the last big energy crisis 1968 to 1982.[1]  However, anyone paying a modicum of attention to either the professional or popular literature must have noticed lately an inordinate number of energy storage schemes being proposed that run the gamut from simple to bizarrely complex (see Figure 1).[2]  I see this as an implicit admission that renewable energy systems cannot work on their own without an array of ancillary services supplied by someone else.

Recently an acquaintance who works for a major U.S. utility sent me brochures describing several schemes, and asked what I thought of them. Two store energy in mechanical ways, and one is a thermal storage system resembling the one profiled on WUWT a few weeks ago. As the time scale to switch to 100% renewables is constantly being advanced on us, even as we only begin to recognize the unsuitability of renewables alone, my acquaintance said, “We are going to waste a lot of money in the next ten years.”

Energy storage

Traditionally we stored energy for our prime movers, lighting, and home heating as agricultural products — hay and grain, candles and oils, and wood respectively. The industrial revolution with its greater scale of energy use continued this same scheme. Instead of feeding old Dobbin (see Figure 2) his hay and grain and putting him into harness, though, we draw upon the stored feed for the thermal plant and have it follow demand for work during the day. If a person only looks backward on the grid as far as the thermal plant, the current electrical grid looks a bit like a just-in-time system, where energy is converted in careful time balance with demand. It is undeniable however, that energy to convert is drawn from stored fuels. Just as grains are a superior source of stored energy for the horse, fuels for combustion are a superior source of stored energy. At large scale energy is surprisingly difficult to store effectively by other means.

Figure 2. Old Dobbin, the prime mover. Give him oats, hay and water. He’ll do 550 foot-pounds of work per second all day. Cecil Aldin circa 1915.

There are four fundamental problems with energy storage schemes; the energy scale, size/material scale, work scale (or how the universe works), and operations. Let’s examine each in the simplest manner possible.

Energy Scale

Nowhere in this section will I worry about how the stored energy can be turned into work in practice — I am just comparing raw calculations of energy. Take a kilogram of diesel fuel and equate its lower heating value to other forms of stored energy.

The lower heating value of one kilogram of diesel fuel is roughly 43,000 KJ. If we try to store the equivalent energy by raising mass, which is what many energy storage schemes attempt, it is the equivalent of one metric ton of mass raised to a height of 4,300 meters. Let’s now compare it to stored rotational energy. One-hundred forty kilograms of diesel, roughly what goes in the tank of an over-the-road semi-tractor, equates to the rotating energy of the turbines and generators of a 3000 MW nuclear plant in operation. Store it in an electrical field? This 43,000kJ is the energy in the electrical field of three and a half million 5 volt, 1 farad super capacitors. Thermal energy? The equivalent is one ton of air or rock at 43C (77F) temperature increase. What comes closest is chemical energy of rechargeable batteries. Our 43,000 kJ  is approximately what energy thirteen good quality automotive batteries or 1,300 3.7 volt lithium cells store. The 50kWhr Tesla battery, composed of Panasonic 4680 cells, is about 4 kg of diesel.[3]

Combustion releases a lot of energy which raised mass, spinning mass, electrical and magnetic fields, or heated mass cannot match. Only chemical energy comes close.

Size/Material Scale

A convenient way to illustrate this is by using the electrical energy destroyed daily by 1000 Americans, or what is equivalent, the daily electrical energy used in about 300 American single family residences. This amounts to 9,000 kWhr of electrical energy[4], which is the equivalent of raising three unit trains with attached locomotives, of 10,000 metric tons each to a height of 100 meters. It is the turbines and generators in six nuclear plants spinning at nominal output.

One of the mechanical schemes I was sent uses 35 metric ton bricks, six at a time and raised nominally 50 meters, and the other uses 357 metric ton railcars loaded with rock moved by cables up and down a steep incline. These systems sized to 9,000kWhr amount to 2,000 bricks, or about 70 railcars, respectively, and either one requires around 2 hectares of land area.[5] While one of the modular systems shown in Figure 3 may be a novelty in some towns, dozens might be considered blight.

Figure 3. The Energy Vault, a European storage system uses 35 metric ton bricks stacked to store energy and unstacked to release it again.

As chemical storage systems seemed to compare most favorably in considerations of energy, we should see how they compare here. To store 9,000 kWhr we need something like 270,000 Panasonic 4680 cells, with a total mass of 35 metric tons; or, 225 metric tons of lead-acid batteries.   

The thermal storage system is the worst of all. From its description of separate hot and cold storage sides, with mass ratios of it requires at least 240 tons of rock, all suitably encased in steel with insulation.

The way the universe works

When I refer to “the way the universe works” I mean obeying the laws of thermodynamics. The systems which suffer most acutely from limitations imposed by thermodynamics are thermal and chemical storage systems. Mechanical systems, aside from friction, represent 100% available energy — that is, all the energy they contain is available for work.

The problems with thermal and chemical systems arise from what we call “irreversibilities” — things that are impossible to undo without expending more work in the process. There are two categories to consider: internal irreversibilities, which are those within the power cycle of the system; and external irreversibilities, which are those arising from the interface between our storage system and that machinery which it serves.

The inefficiency of the compressor and turbine contribute most to internal irreversibilities of the thermal power system. I used an air-refrigeration cycle (see Figure 4 for the ideal) to analyze this proposal with assumed 90% efficiency for both turbines and compressors to find a round trip efficiency of about 68%. At 80% efficiency for both compressor and turbine it drops to about 46%. But this applies only to a short period at turn around of recharge to discharge. As time drags on the efficiency goes down. Thermal systems are notoriously ill-suited to storage and then to recycle energy because of the way the universe works.

Figure 4. An idealized Joule cycle using air as its working fluid. COP is the coefficient of performance of the charging cycle, while epsilon is the efficiency of the reversed cycle providing power. Note that 1.75 times 57% is 1.0, indicating the ideal round trip cycle is 100% efficient. This is nowhere near the cycle efficiency as operated with real equipment on a real schedule.

What contributes most to internal irreversibility in batteries is that they depend on molecular diffusion through an electrolyte. The force that drives diffusion is an internal electrical potential at the electrodes known as an overpotential. It raises the voltage needed to charge batteries, and decreases the voltage available externally upon discharge. It is absolutely necessary to drive diffusion but at the cost of turning available energy into heat rather than work. The overpotential grows with current so that when large amounts of current are called upon to recharge a battery or turn a motor quickly, the overpotential and work wasted both increase too. Also, as temperatures in the battery rise, unwanted side reactions occur. These perpetually degrade the operation of rechargeable chemical storage systems.

The principle issues behind external irreversibilities are the efficiencies of the various ancillary equipment involved — electric motors and generators, and especially heat exchangers, all of which are required to make an energy storage system operate as a useful utility. Advanced batteries also require system monitoring electronics, buck/boost power supplies, control systems both for charging and discharging, and heat exchangers for cooling as well.

Operational Issues

Operational issues means problems like the following: making a storage system serve many purposes which are at odds with one another, or operating a system in a mode where it has to make constant reversals of cycle, or operating at a slew rate it can barely meet.  For example, a need to store energy for a long term power outage which suggests always having a full reserve is incompatible with the need to always have capacity to absorb or supply energy in order to provide ancillary services for grid stability. Mechanical and thermal systems are incapable of quickly supplying energy for sudden grid disturbances and need a grace period of seconds perhaps to respond.[6] Thus using them in a grid bereft of inertia, as we are trending, will require other as yet unspecified systems to supply this inertia.

Cycling power systems quickly can end up stranding stored energy in a way that it has no path except to the dead state. No matter how one may try to limit this problem, heat is going to leak away from any thermal storage system and chemical reactions will occur within the electrolyte of a battery to deplete its charge even as it sits idle. Repeated starting and stopping of thermal systems leaves heat energy stranded in the heat exchangers, turbines, compressors, and this heat ends up in the dead state unavailable for useful work. Think for a moment about turning on a shower at home and waiting for it to heat up sufficiently to be comfortable. We waste warm water while we wait. Then there is shutting down the shower when all the piping is at temperature and leaving it to cool back to home temperature. All this leads to heat being dumped into the dead state that is the house environment.[7] Finally, consider that the thermal system is not attached to reservoirs that can maintain constant temperature, but to finite stores of heat which decline in temperature the moment we begin to use them. Likewise batteries are a finite store of charge where their voltage declines as soon as we begin to demand current.

Then there are practical matters, like how does the stacking of 35 ton bricks work (Figure 3) when covered in ice and snow?


By the time we consider all the factors I have mentioned most of these storage systems will have to be overbuilt by factors ranging from one and a quarter (1.25) to four (4) or more. Even then they may not supply a full range of ancillary services the grid requires. I did not address the problem of cost, but every problem I did address will eventually impact costs. There are many reasons to believe my acquaintance is correct when he spoke of wasting a lot of money. It took money spent over a century to learn the systems engineering currently built into the grid. It will take a lot of money to duplicate all this for a completely re-imagined grid in a decade. As Petr Beckmann, who was a stout proponent of nuclear energy, said forty years ago, “soft technology will not be America’s energy salvation.”

One more point seems pertinent. A decade ago we were all lectured that the environment would be best served as we de-materialized society. That is, we would reduce our environmental footprint as we used less matter; reducing the energy inputs and associated pollution that processing materials requires. Renewable energy with the low energy density of its sources, and the storage it requires and using many advanced and rare materials, are taking us the other direction. Instead of depending on dispatchable energy sources which can supply a kilowatt per kilogram of material, we are proposing systems which provide a mere watt using tens of kilograms. We will re-materialize society. 


1-As just one example, in the early 1970s one alternative energy wind machine used a “race track” design wherein railcars with airfoils would traverse an elongated track oriented at right angles to the prevailing wind direction. My last senior design class, one group studied and made a preliminary design for a wind energy system that, again, used a “race track” concept, but with even more problematic engineering issues than the original. Compressing air in caverns and mines is straight from the 1970s.  

2-Chaamjamal, a regular commenter here, pointed me to this scheme which contains an element of about every technical problem imaginable.

3-I can find little about the specifications that really matter on this battery. People seem fixated on its dimensions, 46x80mm, rather than C-rating, useful energy stored, and slew rate. Allegedly it involves 960 3.7V cells each with 9Ahr C4 rating. This doesn’t work out to 50kWhr, and the blog-o-sphere is full of impossible recharge rates and other mythology.

4-9,000 kWhr = 300 homes at 30kWhr each per day. The average home uses more energy in natural gas to provide heating and domestic hot water. Here the rate is two Therms per day at 29 kWhr per Therm. Twice the amount of electrical energy used.

5- The GravityLine system which uses rail cars filled with rock is much like pumped hydro storage but solves the problem of not having spare water everywhere. However, it still suffers the problem of there not being suitable terrain in many places.

6-The slew rate and inertia in power systems has to be matched against the time response of the grid to its disturbances in order to keep blackouts at bay. The margin against ungraceful behavior is often measured as the ratio of the amount of rotating kinetic energy (turbines and generators) against the rate they nominally deliver power. So, for example, a nuclear thermal plant, nominally producing 2,500 MW may have rotating energy of 6GW-seconds, making the ratio of the two about 2.5 seconds. This provides adequate time margin for automatic control to maintain frequency and voltage when a generator goes offline, or a sudden load appears.

7-The dead state is an engineering concept. It is a state at ambient temperature, atmospheric pressure, and zero electrical potential where energy finally arrives too depleted to do further work. You have heard of the heat death of the universe? The dead state is the funeral parlor.

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May 29, 2021 6:23 am

High explosives are good stores of energy. What could go wrong?

Reply to  Scissor
May 29, 2021 6:27 am

I can imagine a very large lithium ion battery fire. Any battery with even higher energy density would be not readily distinguishable from high explosives.

Rick C
Reply to  Tom Halla
May 29, 2021 9:08 am

Tom: Good observation. Consider that a “grid scale” LiIon battery system will contain literally millions of individual cells. A defect in a single cell or a short circuit in the connections between cells is enough to start a fire that is nearly impossible to extinguish. I think the idea of using battery storage to make renewables viable will end when the first multi-million dollar back-up battery system fire occurs.

Reply to  Rick C
May 29, 2021 10:19 am

Motive power batteries are switching to the heavier LiFePO4 chemistries or lower mass solid state batteries for good reasons. If you get rid of the flammable electrolyte then you reduce the chance of a fire tremendously.

Gordon A. Dressler
Reply to  Rick C
May 29, 2021 10:20 am

Rick (and Tom),

I do believe the method to address/alleviate the issue that you raise has already been implemented at the Hornsdale Power Reserve in southern Australia. This is a 150MW/194MWh grid-connected energy storage system, with the overall design having hundreds of physically-separated battery units, meaning that a fire in one unit is extremely unlikely to propagate to a neighboring unit, let alone the whole facility.

Last edited 1 year ago by Gordon A. Dressler
Reply to  Gordon A. Dressler
May 29, 2021 11:36 am

That would help to control fires, however it would significantly increase the cost of the structure used to house the batteries.

Reply to  MarkW
May 29, 2021 1:22 pm

This is ironic, notice ‘Greta’ on the wall. This has to be an electric car, no ‘normal’ car that I know of has a petrol tank in the front. Fireman is not particularly concerned with putting fire out or imminent petrol tank explosion. I’m not having one, not now not soon, not ever, rather have a horse.

Reply to  Vuk
May 30, 2021 1:38 am

This fire happened yesterday in the French city of Nice ( https://www.nicematin.com/vie-locale/une-voiture-totalement-detruite-par-un-incendie-a-nice-691774 ), but no mention that vehicle was electric or otherwise. It is away from traffic lane either parked or abandon there by driver escaping the fire. Authorities need to make public properly aware of fire dangers regarding large concentration of lithium batteries.

Gordon A. Dressler
Reply to  MarkW
May 29, 2021 6:11 pm

What??? . . . since when have the AGW/CAGW alarmists—including Joe Biden, his administration and the Democratic political party—ever concerned themselves with cost?

Just look at Biden’s proposed “infrastructure” bill, which is part of his just-proposed $6 trillion (yeah, that’s no typo: USD $6 trillion!) budget for the coming fiscal year.

Reply to  Gordon A. Dressler
May 29, 2021 4:52 pm

Hornsdale may have ameliorated the Li battery fire problem but not eliminated it. In any case, backup batteries cannot make wind and/or solar reliable. Hornsdale was the world’s biggest back-up battery when it was built in 2017. Hornsdale can provide a total of 70 MW for just 10 minutes or 30 MW for 3 hours. That’s TINY. What it does is buffer a wind farm so that when the wind dies off it gives the utility just enough time to bring a fossil fuel fired turbine on line. To store enough energy to prop up a wind or solar farm the size of one nuclear power plant (1000 MWe) for one single night would require a battery about 90 times bigger than Hornsdale but Hornsdale cost over $70 million US dollars. Even a battery 90 times larger than Hornsdale costing $6.0 billion wouldn’t be big enough to buffer the wind or solar farm through a single day of calm or cloudy weather, let alone a week.

Gordon A. Dressler
Reply to  meab
May 29, 2021 6:25 pm

meab posted: “Hornsdale can provide a total of 70 MW for just 10 minutes or 30 MW for 3 hours.”

 Well, that must have been its original design spec, but it has been significantly upgraded since original installation. As I noted above, it is currently rated as a 150MW/194MWh battery storage/delivery system.

That is equivalent to 64.7 MW for 3 hours, or 30 MW for 6.5 hours (no reserves), far greater than the 30 MW for 3 hours that you stated.

It may be relatively tiny . . . but it is a start.

Reply to  Gordon A. Dressler
May 29, 2021 9:01 pm

I must admit to having trouble with this. If providing 1Mw for 1 hour is 1MW/h. How do they achieve 194MW/h?

Gordon A. Dressler
Reply to  lee
May 30, 2021 11:25 am

Ahem . . . the total deliverable energy reserve capacity that I cited for the Hornsdale battery farm is in units of MWh (megawatt-hours), not units of MW/h (megawatts per hour) that you asked about.

Reply to  Gordon A. Dressler
May 31, 2021 3:53 am

Yes, the old W/h problem again. The real unit of energy is the joule (J). One watt is exactly one joule of energy (used or generated) per second. 1W=1J/s. On the other hand, one W/h is 1 J/s/h = 1/3600 J/s/s. Not really a useful unit.

The watt-hour (not watt/h) is probably the most stupid unit of energy ever invented. Just use J for energy. If you want power, just use J/s, or W if you must.

D. J. Hawkins
Reply to  Gordon A. Dressler
May 30, 2021 9:22 am

This is all dependent on the rate of delivery. That 194 MW-hr capacity is the ultimate capacity, at some very low delivery rate. Battery capacity in amp-hrs is listed at some fraction of capacity at a particular delivery rate which is designated as “C”. So a battery rated as 100 amp-hours at C20 is delivering at a rate of 5 amps over 20 hours. At C10, it may have a rating of only 75 amp-hours, and so on.

Gordon A. Dressler
Reply to  D. J. Hawkins
May 30, 2021 11:35 am

As I noted previously, the current rating for the Hornsdale battery farm is cited as “150MW/194MWh”. I take this to mean that this facility can output a maximum electrical power of 150 MW. Of course, it can be tapped, as needed, at lower power draws.

Discounting the minor inefficiency variations that are associated with differing amperage-draw rates (e.g., ohmic losses), a 194 MWh battery farm should be able to provide a constant 150 MW output for about 1.3 hours, or alternatively, say, 50MW constant power output for 3.9 hours.

Reply to  Tom Halla
May 29, 2021 2:31 pm

“Any battery with even higher energy density would be not readily distinguishable from high explosives.”

You’d think so. But maybe not. For example, an Aluminum-air battery might have an energy density around 8kwh/kg. At least on paper. Way higher than Li-ion. It can start a fire of course. Your car battery can do that. But it probably won’t burn or explode. (I think). The Li-ion problem isn’t just energy density. It’s also subject to thermal run away. OTOH, people have been trying to build a practical Aluminum-air battery for many decades with not much to show for it.

And big batteries don’t have to be Li-ion. That just happens to be what Elon Musk sells. The 32mwh battery at Presidio, TX is Sodium-Sulfur. Not that I’d want a NaS battery next door. But there’s not much availability problem with the raw materials.

Reply to  DonK
May 29, 2021 2:47 pm

I was thinking of conventional batteries, which contain both the “fuel” and “oxidizer”, that is, both parts of a chemical reaction just like conventional explosives. Fuel-air explosives can be quite effective, but are not subject to that problem.

Walter Sobchak
Reply to  Tom Halla
May 29, 2021 8:03 pm

Cool. I would pay to watch that.

Clyde Spencer
Reply to  Scissor
May 29, 2021 12:21 pm

High explosives are like trying to put a saddle on a wild horse.

Intelligent Dasein
Reply to  Scissor
May 29, 2021 3:10 pm

High explosives are an energy sink when you account for the enormous costs of their manufacture. The process as a whole is highly endothermic.

May 29, 2021 6:31 am

This is at the heart of the physical absolute reality of energy density and delivery physics. Primary energy density needs to be high to minimise the resources required for its extraction – and transmission if electricity, mechanical work if an engine, heat if used in that way. (The best way ti use gas at 90% efficiency now).

Electricity once created must be used in real time or converted to another form of energy, rather inefficiently, and can only be stored in a diffuse form, such as hydro or chemical energy.. Hence the mass of material required to store the converted electrical energy and regenerate it. I did write my own paper on this. There is no way around the natural properties of materials and the laws of physics. Most of the delusional hype is propaganda from ignorant activists that is either plain wrong or pointless and undeliverable at scale. They have simply not done the maths. As I explain and quantify in my own way here.


Nothing wrong with the well made points above, but here is another complementay way to tell them with simple energy facts and figures and a scalable cost impact for the UK system. How does it affect the people it supposedly serves?

Scaleable to other countries. There are only the facts and the physics. Belief powers nothing except fear and ignorance, and enables extortion and tyranny of the believers by their deceivers.MBA,. CPhys, CEng.

John Dawson
Reply to  Brian R Catt
May 29, 2021 7:51 am

Great paper Brian – thanks. I heard David Mackay lecture on renewable energy several times – his early death was a serious blow to the proper engineering evaluation of renewables.

How on earth do we convince our government of the monumental folly of its current approach to energy provision?

Reply to  John Dawson
May 29, 2021 8:50 am

Remove their and their friends ability to profit by their schemes.

Kevin kilty
Reply to  Brian R Catt
May 29, 2021 7:57 am

All great points. As you know, to keep a message in someone’s mind until they can absorb its lessons you often have to repeat it over and over. Doing so in different ways, especially if you can tie the different approaches together will help.

Kevin kilty
Reply to  Brian R Catt
May 29, 2021 8:26 am

One more point, the cross reference to this

Biofuels: Efficiency, Ethics, and Limits to Human Appropriation of Ecosystem Services

is some of what I worry about when I mention going the wrong was and re-maertializing our society.

alastair gray
Reply to  Kevin kilty
May 29, 2021 12:39 pm

Biofuels. Someone ( an ecoloon) tried to sell me a home heating stove that runs on bio-ethanol made from corn. I asked if we could redesign it to run on popcorn instead. Same CO2 emissions but much more efficient. He is not talking to me now, but am I right in thinking the popcorn stove would be better?

Reply to  alastair gray
May 29, 2021 5:01 pm

It would save the tremendous amount of time fermenting corn into ethanol, and some of the heat could be used to continually pop the raw kernels to feed the stove ☺

Reply to  alastair gray
May 29, 2021 5:52 pm

They already have stoves that burn corn directly.

Reply to  MAL
May 29, 2021 10:43 pm

But you can do that with oil and gas already. And you can’t eat oil or gas, so burning corn is a lose- lose idea.

Reply to  Brian R Catt
May 29, 2021 5:38 pm

Very good paper, Brian, hopefully many more than just WUWT community will be able to read it.
As I read into section 1.4, knowing the purpose of the paper is energy storage, still the spectre of last winter’s Texas catastrophe came immediately to mind. The chaos caused by a nearly perfect storm of storms brought the literal heart of the American energy region to a freezing standstill for nearly a week in the midst of the coldest winter weather in nearly a half century.
I hold that the renewable / sustainable sources have a part in a complementary way within a properly planned diverse array of energy generation; they should not supplant all other technology in some emotional display of penance to Gaia.

Reply to  Rhee
May 30, 2021 3:10 am

“I hold that the renewable / sustainable sources have a part in a complementary way within a properly planned diverse array of energy generation;”

Why use them at all for a grid?

David Dibbell
May 29, 2021 6:36 am

Kevin, thank you for this article. Hopefully more and more engineers and analysts will speak up.

And for comparison to the concepts you have described, nature shows best how to store energy as photosynthesis converts CO2 and H2O to future food and fuel at low temperatures. CO2 is not a pollutant. It is a starting material.

Last edited 1 year ago by David Dibbell
Kevin kilty
Reply to  David Dibbell
May 29, 2021 8:20 am

Great points and why I included Old Dobbin in the conversation. My grandfather had a first-grade education, but learned civil engineering under fire, so to speak, at the front in France in WWI. He mustered out and started a construction/demolition company and gravel pit run mainly on the power of as many as 20 Percherons in harness at one time. There were no hydraulics yet for construction machinery at that time. Everything involved horses and inclined planes. Give those horses proper feed, let them digest for an hour, and they were incredible prime movers.

Rick C
Reply to  Kevin kilty
May 29, 2021 9:35 am

Kevin: Great essay, I enjoyed your energy comparisons. I’ve found that very few people have any real concept of energy quantities. Being an old US engineer I think in Inch-Pound units. Here’s a way to get an idea of the British Thermal Unit (BTU).

One BTU is the amount of energy required to raise the temperature of one pound (or pint) of water 1 degree F. One BTU is equivalent to dropping a 4 pound brick from the roof of a 19 story building (778 ft-pounds). One cubic foot of natural gas contains 1000 BTUs. If you could convert the kinetic energy of a falling brick directly to heat, you’d need to drop 300 bricks from the top of a 19 story building to boil a quart of water – or you could burn about 1/3 cubic foot of natural gas. That’s energy density.

Gunga Din
Reply to  Rick C
May 29, 2021 3:37 pm

But would 300 bricks dropped from a 19 story building be enough to penetrate the “Green-Energy” dense?

Reply to  Gunga Din
May 29, 2021 5:57 pm

No! Not even if you hit them squarely on the head each time. Do I really need a sarc tag for this. I would assume there a some people that would think I actually would propose dropping bricks on people. That the intellect level of a lot of people who support green energy.

Danley Wolfe
May 29, 2021 7:29 am

Not being and electrical engineer, I got stuck on “slew rate”… what is it?

See https://www.electrical4u.com/slew-rate/

(Quote) In electronics, the slew rate is defined as the maximum rate of output voltage change per unit time. It is denoted by the letter S. The slew rate helps us to identify the amplitude and maximum input frequency suitable to an operational amplifier (OP amp) such that the output is not significantly distorted. The slew rate should be as high as possible to ensure the maximum undistorted output voltage swing. Slew rate is a critical factor in ensuring that an OP amp can deliver an output that is reliable to the input. Slew rate changes with the change in voltage gain. Therefore, it is generally specified at unity (+1) gain condition.

Kevin kilty
Reply to  Danley Wolfe
May 29, 2021 7:58 am

It is how fast you can ramp up a source of energy, or a machine in more general terms, and have it perform as needed.

May 29, 2021 7:30 am

If energy storage improves, then it is going to cause importation of cheap energy from cheap-energy coutries to high-priced energy countries via battery ships. And this energy won’t be needed to be bought from the grid. This will not help “renewables” but rather make them completly useless.

Reply to  TomR
May 29, 2021 8:44 am

How can anything make something that is already completely useless even more completely useless?

Just sayn.

Loren C. Wilson
Reply to  TomR
May 29, 2021 8:15 pm

LNG ships and oil tankers are already battery ships, as are the coal carriers going from the US, Canada, and Australia to China.

May 29, 2021 7:43 am

“It is the turbines and generators in six nuclear plants spinning at nominal output.“

Micro reactors?
Typical thermal steam nuclear reactors are in the 0.8 GW to 1.1 GW output range. So 1,000 MW. Run over 1 hr they produce 1,000 MWh.

1 MW will typically supply about 400-900 homes. So 1 GW will supply about 400,000 to 900,000 homes.

I think you’re off by 3 orders of magnitude.

Kevin kilty
Reply to  Joel O’Bryan
May 29, 2021 8:00 am

Joel, I am talking about the rotational KE in the turbomachinery. The ratio between the KE of the turbomachinery and the power output of the plant differs by, yes, three orders of magnitude, but amounts to the few seconds needed to respond gracefully to grid disturbances.

The ratio is in units of seconds. Wind turbines alone, on the other hand provide essentially nothing in this regard.

Last edited 1 year ago by Kevin kilty
Reply to  Kevin kilty
May 29, 2021 9:02 am

That’s a little bit absurd, Kevin. Nobody considers the rotational energy of an ICE to be an energy source, except maybe the engineer that designs the flywheel.

Kevin kilty
Reply to  DMacKenzie,
May 29, 2021 9:39 am

What you are saying no engineer will consider, is known to American engineeers as “Beta” and British engineers as “H”. In order to help stabilize the grid against disturbances people are now speaking of using “Synchronous Condensers” — these are a conventional power-plant with everything except nominal power output.

Leo Smith
Reply to  DMacKenzie,
May 29, 2021 11:52 pm

Oh dear. Most of the battery plant that is being attached to the UK grid is to compensate for the loss of KE due to shutting down of conventional thermal plant.

If any generator goes off line suddnely, the grid frequency without that KE drops dramatically and all the renewable energy plant trips and disconnects itself.

Of course no one shouts thus from the rooftops. So the public believe that batteries will actually solve the real problem of intermittency instead.

Reply to  DMacKenzie,
May 30, 2021 6:12 pm

Rotating inertia. Or grid inertia. It smoothes out spikes and drops. It’s needed. You can have a grid without it. Planning Engineer wrote about it at Curry’s. Wind and solar do not have inertia in 99% of cases. Another strike against them.

Reply to  Kevin kilty
May 29, 2021 10:52 am

Then it has nothing to do with “nuclear power.”

Kevin kilty
Reply to  Joel O'Bryan
May 29, 2021 10:58 am

Actually not, but it was a measure I happened to have in my mind at the time. There are proposals galore to store energy in rotating mass, and I just needed a scale size to compare. A big thermal plant of any design and equivalent output would serve as an example as well.

Reply to  Kevin kilty
May 31, 2021 9:25 am

You made it sound as if that was all the energy that a nuclear plant could provide. Really threw me off, made me wonder what other numbers were wrong. Doesn’t help for getting your point across.

Reply to  Kevin kilty
May 29, 2021 11:30 am

You should go read up on the spinning mass -steam reserve scenario the Chernobyl engineering shift B-team was trying to test when they blew up their reactor in a massive fission power surge. The B-team was tasked with running the test when the A-team was gone and put the reator in an unstable low power state to test how long the residual thermal steam could keep the turbines spinning. The team panicked and due to a very poor control rod design, they scrammed the reactor which caused a massive runaway fission burst as the control rods descended into the reactor mass.

Michael S. Kelly
Reply to  Joel O'Bryan
May 29, 2021 8:43 pm

The Chernobyl team was inexplicably unschooled in the role of xenon 135, a fission product with a half-life of 9.2 hours, and having the highest known neutron absorption cross-section of any isotope of any element (up to 3 million barns under reactor conditions). After having shut down the reactor and having the steam plant inertia experiment fail (yet again), they tried an immediate restart. When the reactor failed to ramp up, they withdrew the control rods completely, not knowing that the xenon 135 that was stopping the reactor was decaying. Only when enough of the 135Xe had decayed (or been burned by neutron absorption) did the reactor start to come to life. When they went to insert the control rods, the unfortunate fact that those rods had graphite tips inserted more reactivity into the reactor, and caused it to go from a design 3,000 MW thermal to 30,000 MW thermal in a fraction of a second – a prompt criticality accident on a huge scale.

How Soviet reactor operators were not schooled in this subject is a mystery. Enrico Fermi guessed (correctly) that the problem was responsible for the behavior of the Hanford B Reactor during the Manhattan Project, and it was widely known and integrated into American nuclear reactor operations ever since.

Molten salt reactors, BTW, allow for 135Xe to be continuously removed in a distillation tank, a demonstrated technology. This does away with one of the barriers to varying fission plant output to meet demand.

Last edited 1 year ago by Michael S. Kelly
John Dawson
Reply to  Joel O’Bryan
May 29, 2021 8:07 am

I think he is referring to the rotational energy stored in the moving mass of the machinery, not the long term output of the system. Thinking of it in electronic terms (my speciality), it’s the reservoir capacitor in a DC power supply, that can keep it running for a few seconds when the mains power is removed.

So, if I’ve understood it correctly, this inertia will keep the generators running for a few seconds if there’s a sudden loss of input power, enabling systems elsewhere enough time to respond and maintain the grid output.

But I agree, it’s clumsily put.

Reply to  John Dawson
May 29, 2021 11:00 am

The problem with capacitors is that the current they can supply to correct a reactive power imbalance in power factor drops as the voltage drops. A synchronous condenser, as a spinning mass, can supply current to offset reactive power regardless of how the voltage fluctutates on a tiume scale of milliseconds.

The control systems on modern super critical steam generators can easily monitor and detect everything (torque on the generator shaft, frequency output i.e. rotational speeds, voltages) to adjust the amount of steam being fed into the turbines several dozen times per second to keep the frequency and output voltages stable regardless of how the demand changes – this is basic, load-following feedback control stuff engineering.

Reply to  John Dawson
May 31, 2021 7:37 am

I have a question for you or anyone. We have rotating inertia as from a generator spinning while weighing tons. Planning Engineer also talked about sync. They rotate in sync. 98% of them. Does a battery provide in sync power or does it provide garbage power like solar that is not in sync? PE never got around to answering this question for me. Thank you.

Reply to  Joel O’Bryan
May 29, 2021 10:31 am

If you factor in charging EV’S then a lot less homes.

Last edited 1 year ago by nickc
May 29, 2021 7:44 am

Good, clear review.
How can one present paractical engineering to impractical people?
Who, sadly, can’t tell the difference.

Kevin kilty
Reply to  Bob Hoye
May 29, 2021 8:10 am

Thanks, I struggled with this review for a couple of weeks because, as you imply, the story always became too complex and a bit dull as a result. It is a challenge to explain to people that what they believe we should be doing, which seems simple to them, doesn’t work as they believe and has the potential to make a huge mess.

Operational details, which are in that complex world between how things must work because of universal laws and what a working system can do and can supply — systems engineering — is remarkably obscure to most people.

Michael S. Kelly
Reply to  Kevin kilty
May 29, 2021 9:05 pm

Excellent post, and very accessible in my estimate. I’m a (sort of) retired engineer, and in my field (rocket propulsion and space launch system engineering) we deal with energy and power on a scale no one else even approaches (except for explosively, which we avoid). Your assessment of the various storage problems is dead on, and I’ve looked at all of them myself.

Komerade Cube
Reply to  Bob Hoye
May 30, 2021 7:44 pm

>>impractical people<< these people are emotional, not analytical. Facts that don’t satisfy their emotional need / fit their emotional world view cannot be internalized – they just bounce off.

Carlo, Monte
May 29, 2021 7:50 am

If I’m interpreting Fig. 1 correctly, it is an example of what is usually called thermophotovoltaics (TPV). It needs PV diodes made from III-V semiconductors with low-energy bandgaps.

Kevin kilty
Reply to  Carlo, Monte
May 29, 2021 8:06 am

Yes, and look at what else it requires…the machinery demands, pumping liquid silicon at near the melting point of wolfram.

When I see complex schemes like this I am reminded of what I call “German Engineering”. German engineers seem to enjoy the task of taking an unnecessarily complex scheme and making it work, when many proven and simpler schemes will do the same. I learned this from working on my two volkwagen beetles, the post 1999 variety of beetles.

Carlo, Monte
Reply to  Kevin kilty
May 29, 2021 9:39 pm

I remember trying to remove the drive shaft from a 1970s era Mercedes, it was nearly impossible without torching all six (yes, SIX) of the flange bolts.

Reply to  Kevin kilty
June 1, 2021 8:34 am

VW engineers worked their “magic” on my 1973 Westfalia camper van. In many areas the build quality was wonderful but overall it was Entropy on wheels and helped push me into nothing but Hondas and Toyotas for many years. Also living in Canada and trying to endure our winters with the -20 or -30C temperatures with the VW heater that was basically useless sealed the deal.

Reply to  Carlo, Monte
May 29, 2021 8:06 am

A liquid silicon pump operating at ~2,000 deg C.
Cells filled with pressurized krypton gas.

Now that thar’ is funny.

When the pump fails, and it will, all that will be left is destroyed pipe system filled with solid glass. And Where does one get krypton gas at industrial quantity?

Burgher King
Reply to  Joel O’Bryan
May 29, 2021 10:27 am

“Where does one get krypton gas at industrial quantity?”

Possibly from ancient deposits of meteoric green kryptonite left over from the destruction of the planet Krypton 1 which once occupied the space inside what is now an asteroid belt. Just dissolve the green kryptonite in acid to produce the needed gas.

Obtaining the needed quantities of krypton gas may sound like a superhuman task. But with enough commitment in time and money, it’s perfectly feasible, at least according to the green energy technologists, anyway.

Kevin kilty
Reply to  Burgher King
May 29, 2021 10:58 am

Lux Luther, Inc.

Reply to  Burgher King
May 29, 2021 4:04 pm

I should add that I did a little research… and found that CERN’s big LHC uses krypton gas, a lot of it but it is extremely expensive. It takes a lot of cryogenic disstilation to get much Kr gas as it exists at ~1 ppm in normal air.

Ron Long
May 29, 2021 8:03 am

Good report, but there is a simple solution: it is easy to store energy in nuclear fuel rods.

Reply to  Ron Long
May 29, 2021 8:57 am

Or in big piles of coal, or big tanks of oil, or underground in caverns filled with large amounts of natural gas, or large tanks of LPG, or??

Again, as is the point of this piece, we don’t need to store “energy” for electrical generation if we have a grid supplied by DISPATCHABLE generation sources..

Wind powers is good for pumping water or grinding grain.

Solar for remote areas where the cost of running to the grid is too great and the demand is small enough NOT to need prime mover generation.

Otherwise “renewables are not only useless, but are actually detrimental to the grid.

All of which anyone reading this already knows. Even griff and Simon and Loydo.

Kevin kilty
Reply to  Ron Long
May 29, 2021 9:32 am

Now that we are being allowed by our betters to discuss the origins of SARS-Cov-2, soon we may be able to clearly discuss nuclear again. Other rational discussions may take longer.

Matthew Schilling
Reply to  Kevin kilty
May 29, 2021 10:49 am

We live in the Soviet Union. We thought we beat them, but they absorbed us.

Reply to  Kevin kilty
May 30, 2021 9:59 am


Your comments about the use of horses are well appreciated by me. In the high mountain park areas in Colorado many of the old ranchers kept teams of horses on hand as it was not only an effiecient way, but sometimes the only way, to get hay out to cattle in deep snow. Not sure if that is still going on, tho.

In Hamilton, Mt there is a local museum that has a small treadmill on display that appears suitable for dogs, goats, sheep, and I guess children. Not sure just what it was used for. Butter churn, water pump, etc.?

Just north of there are several miles long railroad car storage tracks. Mostly gondola’s if I remember correctly. Many, many cars. I understand there are also several other areas that grain boxcars are waylaid when not in use. Seems to me that they could all hold coal and maybe represent a “just in case” energy storage scheme.

Having spent several childhood years in South Dakota where the winters can only be described as “brutal” at times I don’t ever recall sleeping in a cold house. We always had the coal bin topped up in the fall. Messy but worked well.

I spent several months in Wichita Falls, Tx in the early 70’s. I remember one of the locals telling me there was nothing bteween the panhandle and the North Pole in the winter but a barb wire fence.

The concept of designing large utility systems that fundamentally accept that “tolerating” the 50 yr or 100 yr event is no problem seems too much like the “gamblers fallacy” that keeps Vegas in business. Eventually you will tap out.

Orienting your thinking along “just in time” vs “just in case” seems to have it’s limitations. May work well in some cases but not suitable for all.

Totally enjoyed this post and the comments Thanks to all.

May 29, 2021 8:08 am

There is another simple way to show that ANY energy storage system isn’t a technically or economically viable solution for renewable intermittency by simply considering capacity factors.

According to EIA, the US actual annual onshore wind capacity factor is about 31%. This also considers that wind is mainly now installed in favorable locations like north Texas. If you expand wind, its capacity factor will drop.

According to EIA, the southern California annual solar capacity factor is about 29%. As with wind, expanding to less favorable locations must drop the current EIA value.

For sake of argument, assume a renewable system average capacity factor of 30%, and that the whatever storage system is 100% efficient. (In reality none can be. The round trip efficiency of lithium ion is about 80%, which is why Tesla batteries have a liquid cooling system.)

Now the storage system must provide grid electricity (1-0.3) 70% of the time. It has to be charged by renewables, and those are available only 30% of the time. So the effective renewable grid available output is only (0.3*(1-0.7)) 9% of rated capacity. Put differently, to combine renewables with storage on a closed ‘green’ system you need about 11 times as much renewables. Which drops their capacity factors significantly, which makes the problem much worse… You cannot get there from here. Ever. No matter the storage system.

Kevin kilty
Reply to  Rud Istvan
May 29, 2021 8:45 am

Thanks for suggesting an interesting way to analyze the problem. Among the things I thought about in struggling with the message here was to build an imagined model “system” with necessary feedbacks and show no steady solution.

Mentioning the Tesla battery, I found discussions on-line about eventually recharging one of these batteries in 15 minutes. Can you imagine that? Assuming an impossible 100% efficiency, 250V one-phase at 750 amperes!

Reply to  Kevin kilty
May 29, 2021 9:17 am

YW. I spend a lot of time thinking about how to simplify complex climate issues to their essence, for better communication to lay individuals. David MacKay’s ebook was the original inspiration.
Another oft commented example is Crockford on polar bears. Alarmists: polar bears will die because of loss of summer Arctic ice.
Simplest response: they don’t depend on summer ice; 80% of their annual caloric intake is during the spring seal welping season when sea ice will always be abundant.

Reply to  Kevin kilty
May 29, 2021 6:08 pm

They do have chargers that can do about 80% in fifteen minutes, the working input voltage is 850 volts, it has to be that way to have a manageable power cable. As far as I am concern the pure insanity the slightest amount of corrosion is going to cause a lot of heat. Nothing like roasting marshmallows while you charge up you car.

Reply to  Rud Istvan
May 29, 2021 9:04 am


Showing my ignorance, but is that Cali 29% solar capacity factor for while the sun is shining, (daytime) not averaged over a 24 hour day?

If so, what is the capacity factor for 24 hours a day? That should be the # used.

Just asking.

Reply to  Drake
May 29, 2021 10:12 am

EIA solar CF is 24/7. The reason it is significanly lower than ~0.5 is mainly two things. Less efficient at ‘dawn and dusk’, and in winter. Has to do in both cases with angle of incidence. Best is perpendicular, because anything else will partly reflect.

Reply to  Rud Istvan
May 29, 2021 3:44 pm

Thank you for the reply. So actually BETTER than I thought but still not dispatchable without storage.

And again, as noted by Leonard below, this is for Cali, a good area for solar, not in Sara’s Wisconsin or north to Canada and Alaska, or the rainy Pacific NW or UK.

Leonard Weinstein
Reply to  Drake
May 29, 2021 1:29 pm

An untracked solar cell in an average location at 20% conversion (level of good present cells), produces an average of 1 kWh per m2 per day. Note this is an average, and frequent periods of several days are cloudy, so no energy. If power required for a home averages 2kW (48kWh/day), then at least 48 m2 of cells are needed, and about 80% (about 38 kWh) has to be stored for use much of the 24 hours (low Sun angles, clouds, and night). However, since the clouds may lat several days, you need several time the storage, and increase in cells to charge them in reasonable time. A realistic PV system should have a peak output (so called rated output) of about 25 kW and storage of 100 kWh batteries to operate at near full average capacity, and still may run out on occasions. This is very expensive.

Reply to  Leonard Weinstein
May 29, 2021 3:46 pm

Thank you for your reply. Helpful and knowledgeable people here at WUWT.

I WAS ignorant of what you and Rud responded to.

Thank you both again.

Kevin kilty
Reply to  Leonard Weinstein
May 29, 2021 4:37 pm

Indeed, since most homes have at least a 200 amp panel then 25kW is just about exactly what they need as a maximum power capability no matter what storage system they rely upon. Getting 25kW out of thermal storage especially requires heat exchangers with a large surface area.

Reply to  Leonard Weinstein
May 29, 2021 5:00 pm

I can buy a lot of grid electricity at $0.12/KWh retail consumer for the $75K – $80K that system would cost. And it still would be far short of peak demand I’d need as the Sun was setting on a hot summer day.
That system would just cover my pool pump and nothing for my home. I run a pool pump that pulls a 2KW (240 V @ 0.8 amp running) for 10 hours/day right now. The economics of solar PV is beyond dumb, far worse than even wind turbine stupidity.

AC Osborn
Reply to  Rud Istvan
May 29, 2021 12:16 pm

Rud, I have been trying to explain this to “Renewable believers” for months and you just can’t get through to them.
They are positive that new technology, that is just around the corner will allow it.

Reply to  AC Osborn
May 29, 2021 12:41 pm

AC, with respect to batteries I did a fairly comprehensive, albeit now a bit dated, overview in essay California Dreaming in ebook Blowing Smoke. Nothing works gridscale.

Reply to  Rud Istvan
May 29, 2021 4:15 pm

California legislature in its virtue signaling stupidity has mandated that all fossil fuel power plants integrate batteries by 2025 or 2026 as I recall.

I have posted this picture before, but it is merits reminding people that plugging batteries into fossil fuel power plants to charge them incurs significant storage losses in charging charging and discharging cycles that generate heat, and in the whole scheme does not reduce CO2 emissions one bit. Better just to take the electricity used to charge the batteries and send it to the grid rather than waste a significant portion on battery cycling. And then when the demand is high fire up the quick start gas turbine peaking plants. That is what Arizona’s APS and Tucson Electric is doing in the So Arizona, using GT’s for peaking when the sun starts to do down and solar poser drops dramatically.

Moss Point NG (2 x 500 MW CCGT) Power plant on Monterey Bay, Cal with the world’s largest (400 MW/1200MWhr) BESS plugged directly into it.

Last edited 1 year ago by joelobryan
Reply to  Joel O'Bryan
May 29, 2021 5:04 pm

Errata: The Moss Point BESS is currently at 300MW/1200 MWhr. By August 2021, an additional 100 MW battery installation is supposedly going to take it to 400MW/1600MWhr capacity.

Reply to  Joel O'Bryan
May 29, 2021 11:28 pm

Errata 2: Moss Landing is the correct name of the town where the power plant is located and how the plant got it’s name.

As an aside, no one can purchase retail electricity from them at $0.12 /KWh. The cheapest rate is double that and tier pricing kicks in after “conservation” levels are exceeded tripling and quadrupling the rates for higher KWh usage.

And that’s not even counting “peak” and “partial peak” time of day usage adjustments. I dry my laundry at midnight.

Reply to  Joel O'Bryan
May 30, 2021 9:33 am

I guess you are right if you want very expensive virtue signaled electricity

Reply to  AC Osborn
May 29, 2021 3:51 pm

I had an ENGINEER tell me that wind bird choppers had inertia for the grid, like real generators. I tried to explain that that was not the case, and sent him to THIS site. He was a WAY lefty and would not even look.

BTW: He worked in the swamp of DC for the defense department on weapons systems for 30 years. That scared the heck out of me.

Reply to  Drake
May 29, 2021 5:08 pm

He doesn’t understand AC electrics and what happens in the AC-DC-AC conversion-inversion process to combine the many small wind turbine ACs outputs into one synchronized HVAC output to the grid. The power inversion process decouples the turbine spinning mass instabilities (by design) from the very stable AC grid frequency (mandatory), the result being no grid inertia from the wind turbines.

Reply to  Joel O'Bryan
May 31, 2021 2:53 pm

Good explication of the situation RE inertia, however he had no intention of understanding wind power. He stated that bird choppers had such inertia from pure ignorance, just like MANY leftist are ignorant of economics and math of any kind.

He probably read it on some far leftist blog. You know the types, those, unlike WUWT, where ignorance runs wild and any factual dissenting viewpoints are wiped off the comments immediately.

Lawrence Sellin
Reply to  Rud Istvan
May 29, 2021 1:48 pm

[User permanently banned for impersonation]

Reply to  Lawrence Sellin
May 29, 2021 4:36 pm

No, sorry. It doesn’t matter how many GW of capacity you install: As soon as the wind isn’t blowing, you need 100% storage or you won’t be able to deliver electricity continuously. The size of your storage only determines how long the lack of wind may last before your system breaks down. And don’t forget that, once your storage is depleted, you will not be able to deliver full capacity even when perfect operating conditions return, as you then have to use part of the generated energy to replete your storage. The larger the storage, the larger the overhead capacity has to be, to fill up the large storage during the limited available time of surplus energy generation. Or you will end up with just charging and discharging your storage in cycles, with very little deliverable energy left.

Reply to  Lawrence Sellin
May 29, 2021 4:47 pm

What happens when it needs to be recharged and the wind still isn’t sufficient?
Low wind conditions happen often enough that even a day-long blackout every few months or a few times a year would be completely intolerable to a First World technological country. Blackouts like that happens all the time now in oil rich Venezuela and the 3rd World. I guess you like living in a 3rd World country Lawrence.

Last edited 1 year ago by joelobryan
Reply to  Joel O'Bryan
May 29, 2021 11:46 pm

Socially woke people like promoting middle class misery in order to save the world. But they are doing it “for the children” so that’s OK in their minds. Of course, most of them do not have children and the end result is always feudalism, but they skipped that part of medieval history in school because it was so boring.

May 29, 2021 8:18 am

On the heat pump diagram, where does one find 127 K ( -146 degC) cold side on Earth?

Kevin kilty
Reply to  Joel O’Bryan
May 29, 2021 8:32 am

Once the hot air has passed through the hot-side heat exchanger it is now at 300K, but is at high pressure; so, it has available work left in it, and passing it through a let-down turbine to recover this work will cause it to cool further. The ideal 20:1 pressure ratio takes it to 127K.

Last edited 1 year ago by Kevin kilty
Reply to  Kevin kilty
May 29, 2021 9:12 am

In a real world air cycle heat pump, you wouldn’t pump it up to a 20:1 ratio to start with.

Kevin kilty
Reply to  DMacKenzie,
May 29, 2021 9:47 am

I am just analyzing the scheme as stated.

H. D. Hoese
May 29, 2021 8:30 am

“…..straight from the 1970s.” We went through much of this then resulting in many “fossil” wind turbine parts and structures in the 80s. Probably torn down by now. Other ideas of energy capture, like waves and algae, are currently being recycled without homework. 

Kevin kilty
Reply to  H. D. Hoese
May 29, 2021 8:52 am

There was a 12MW wind turbine at Medicine Bow, Wyoming, built in the late 1970s by the Boeing Company which stood until a decade or so ago. Some fellow purchased it for pennies on the dollar and was making a living of sorts selling the power.

Why it was finally abandoned once and for all I don’t know.

AC Osborn
Reply to  H. D. Hoese
May 29, 2021 12:53 pm

Plus the joke of Hydrogen, with all it’s costs and efficiency losses.

John Adams
Reply to  AC Osborn
May 31, 2021 1:21 pm

As an aside, any thoughts on why Toyota who certainly has competent engineers, is promoting a hydrogen fueled car?

alastair gray
May 29, 2021 8:30 am

How dare you bring Physics-think to the climate Love-in.. This is
doubleplusungood brainthink and Greta will scold you you dangerous person you. Apart fpom taht A nice wodge.
Big Oil Cheque is in the post too.

alastair gray
Reply to  alastair gray
May 29, 2021 8:32 am

sorry meant to say a nice wodge of common sense

Kevin kilty
Reply to  alastair gray
May 29, 2021 8:52 am

I learn a new expression.

Abolition Man
May 29, 2021 8:40 am

Nice, simple overview of the problems of energy density and conversion!
Unfortunately, the level of scientific illiteracy and innumeracy of the Climastrolgical sheep is only matched by the corruption and greed of their cult leaders! “Modern” education has dumbed down enough people that most cannot see the futility of unreliable energy systems or the fallacies of the underlying hoax; CAGW!
We, the members of the rebel alliance against human stupidity, have our work cut out for us in trying to stop the colossal waste of blood and treasure that GangGreen is trying to foist on humanity! The battle for the future is long and the enemy is taking NO prisoners! We should, perhaps, being living the motto of Cmdr. Peter Taggart: “Never give up, never surrender!”

Matthew Schilling
Reply to  Abolition Man
May 29, 2021 10:54 am

GangGreen! I love it! I plan on using it – sorry, not sorry!

Abolition Man
Reply to  Matthew Schilling
May 29, 2021 2:54 pm

No apology necessary! I don’t remember exactly where I stole it; but I asked politely and it’s still one of the best descriptors of the cult!

May 29, 2021 8:47 am

“Then there are practical matters, like how does the stacking of 35 ton bricks work (Figure 3) when covered in ice and snow?”

Taking the word “brick” literally, that is a baked clay fired brick, they are quite porous. Meaning they will likely hold water when down on the ground and leach/evaporate water while elevated.
That is, the brick returning stored energy will be lighter than the brick lifting that consumes energy. For a more substantial loss.

“Integrated Ag/Au back reflector”

Described in Figure 1.
Ag/Au, that is, silver-gold alloy is called Electrum. Sounds like the, ahem, system designers, are grasping for the most expensive outré technology they could dream/dredge up.

Last edited 1 year ago by ATheoK
Jim Gorman
May 29, 2021 8:59 am

5- The GravityLine system which uses rail cars filled with rock is much like pumped hydro storage but solves the problem of not having spare water everywhere. However, it still suffers the problem of there not being suitable terrain in many places.

Looking at the size of some big city trash dumps, let’s make mountains out of them and run trains up and down them. Quit using ravines and canyons as starting points. With all the windmill blades and ICE autos that will need to be trashed we should be able to create some really large mountains pretty quickly!

Dave Andrews
Reply to  Jim Gorman
May 30, 2021 8:27 am

Yes. Wind Europe the trade body for wind in Europe estimate some 14,000 turbine blades could be decommissioned in Europe by 2023.

May 29, 2021 9:02 am

Thanks, I appreciate your holistic approach to assessment of energy storage. Early on you point out that the energy stored in grain provides energy for the horse which can then do useful work. Of course, we need not feed the horse because we know how to convert stored biomass energy to other forms which are more useful. For instance, 40% of the US corn crop is used to make fuel ethanol. I used to work for an oil company that converted soybean oil to renewable diesel, which can directly replace diesel fuel produced from petroleum. Power plants can burn biomass rather than coal or natural gas. I think you should expand your analysis to calculate how much farmland and at what expense it would take to generate sufficient fuel to replace all our current consumption of fossil fuels. After all, it is energy that comes from the sun; what’s not to like.

Kevin kilty
Reply to  Tom
May 29, 2021 9:45 am

Agttempting to supply one-half of US transportation fuels with biomass would take farmland about equal to the area of two Western states, and along with all the inputs of energy, fertilizers, water, and labor would be environmentally and economically ruinous. I gave a talk at a college about 14 years ago on this point, but no one there seemed to grasp the issue.

Matthew Schilling
Reply to  Kevin kilty
May 29, 2021 10:59 am

It will probably take an economic collapse, more than partly blamed on GangGreen (excellent term gotten from Abolition Man above), for people to wake up.
Of course, it will also involve forcefully ejecting the professional propagandists who will work feverishly to deflect the blame for the collapse from the culprits to innocent parties.

Reply to  Kevin kilty
May 29, 2021 11:33 am

I think the alternate agendas get in the way of people being able to objectively evaluate energy options. The first agenda is just to kill fossil fuels; people (activists) just hate it. Close behind is the fight for social and economic justice and the establishment of dirigisme.

May 29, 2021 9:20 am

Most of the greens writing on energy storage assume a battery with the energy density of Heinlein’s Shipstones. If they ever actually read the novel, “Friday”, the organization owning the trade secrets essentially runs the world. It is, of course, fiction.

Kevin kilty
Reply to  Tom Halla
May 29, 2021 10:07 am

One of the things I like about WUWT is the thread following each article where people make interesting references to literature and show equally interesting analyses. “Friday” is unknown to me.

Reply to  Kevin kilty
May 29, 2021 10:16 am

It is one of Heinlein’s more approachable novels, as it is a stand alone (mostly).

Robert A. Taylor
Reply to  Tom Halla
May 29, 2021 3:32 pm

Mostly: Don’t forget Kettle Belly.

May 29, 2021 9:26 am

very interesting, thank you

Dan Thomas
May 29, 2021 9:39 am

Hoisting weights to altitude as a mechanical storage is near 100% efficient? Don’t think so. Those weights must be hoisted by some motor, typically electric, which has efficiency losses. Then the weight drops, driving a generator (perhaps the same motor that hoisted it) and there are more losses. Add the losses in the hoisting mechanisms. It gets ugly.

Compressing air is about the worst possible way to store energy. The air gets hot, and the compressed air loses its heat while stored, lowering the pressure somewhat. As it’s used its temperature drops a big bunch, contracting it further. I have a one-HP air compressor that I use to drive air tools. It can’t keep up with a simple quarter-inch die grinder. If I had an electric die grinder with about the same power (torque and RPM) as this air-driven one, it would use much less current than the one-hp compressor and I wouldn’t have to wait for the compressor to catch up. Air tools are used in places where sparks from electric tools are a risk. They’re not used because they’re efficient.

Abolition Man
Reply to  Dan Thomas
May 29, 2021 10:15 am

Most auto tire and repair shops be to differ! Of course, using a 1hp compressor is inefficient for running a die grinder and other pneumatic tools; most shop compressors should be at least 4-5hp with a 50gal or larger storage tank! That 1hp compressor is great for finish nail and staple guns, and you might be able to run a framing gun with it!
Of my several compressors the one I use the most is rated at about 6-7amps; I can easily carry it from room to room and use a 15amp circuit to install trim or paneling all day long! Sounds like you need another compressor or an electric grinder.

Leo Smith
Reply to  Dan Thomas
May 30, 2021 12:02 am

Generators and electric motors can be – if you are prepared to spend enough on materials – over 90% efficient – that puts the turnround efficiency of a mechanical store possibly sowmehere in the 80% level.

Pumped water has a similarly high efficiency – with turbine losses it comes out at IIRC about 75%.

Anything involving heat is going to be inefficient. But mechanical and electrical storage is really quite effcient,

It just has very low energy density – you need an awful lot of it.

May 29, 2021 10:00 am

Yes the history of mankind’s ability to store energy is rather pitiful apart from in the form of calories or pumping water uphill. We’re experts at the former and with hydro power we’ve largely grabbed all the low hanging fruit. Which leaves the dreamers and dilettantes and smokers of illicit substances to ponder the capacity of diverse elements on the periodic table with electrochemical storage vs oxidation reactions-
Why Gas Engines Are Far From Dead – Biggest EV Problems – YouTube

Gordon A. Dressler
May 29, 2021 10:06 am

I consider the above article to be a good read and science-based, but was surprised to find no mention of hydrostorage as a good, relatively simple and very reliable method of storing energy for mankind’s future use. It’s application dates back to the earliest times of humans forming dams for storage and using waterwheels to extract energy. And even today, hydropower plants provide about 7% of total U.S. electricity generation.

And yes, please, I am fully aware of all of the environmental, social and political problems of expanding hydrostorage/hydropower within the US.

Kevin kilty
Reply to  Gordon A. Dressler
May 29, 2021 10:29 am

As you imply, just speak of building reservoirs and detaining anyone else’s water and the politics turn vicious. I left it out as it is a well known technology with weaknesses covered by the GravityLine system. It would be interesting to know what potential is still left for pumped hydro storage.

Jon Z
Reply to  Kevin kilty
June 3, 2021 11:46 pm

I think water storage is sorely underrated in the west. We need as many reservoirs as is possible. With the increased populations, the predictable droughts and the increasing demand for power, I would think it would be a regional effort to store more water and electricity without the expense of developing battery storage that the current technologies fall way short, for any meaningful storage.

I would love to see an overlay of the future US landscape when fossil fuels are no more and we are relying on renewables exclusively. If anyone has a link please send. How many solar farms and wind farms will it take, and what is its collective impact on our environments on these farms? I suspect it’s going to look like a blight on the continent. Where are we going to put the expired panels and windmills? What about all the rare earth metals that are currently not able to be recycled from the solar panels? These are water soluble compounds that leach into the ground if a panel breaks and gets wet. Oh my!

Beta Blocker
Reply to  Gordon A. Dressler
May 29, 2021 2:04 pm

Mark Jacobson’s paper on reaching 100% renewables depends heavily on pumped hydro storage to make it all work, even after cutting per capita demand for electricity in the US in half.

The permitting process for one of these hydro projects might take a decade or more, from beginning to end, by the time all the court challenges were resolved. The only way of overcoming the NEPA hurdle is to bypass that hurdle altogether by exempting pumped hydro from the government’s environmental review processes, and by giving the president the power to override any regulatory review decision which stands in the way of building a proposed pumped hydro facility.

It remains my opinion that the president can grant himself the authority to bypass NEPA — and also any other regulatory review process which might stand in the way of granting a permit for a green energy project — simply by declaring a carbon pollution emergency in an executive order.

Gordon A. Dressler
Reply to  Beta Blocker
May 30, 2021 11:46 am

BB, you posted: “It remains my opinion that the president can grant himself the authority to bypass NEPA . . .”

My understanding is that the National Environmental Policy Act (NEPA) is an existing United States environmental law. Per the US Constitution, the President does not have the power to bypass existing laws/statutes, that power is reserved to Congress (via overriding such with new laws) or the Supreme Court (by declaring such a law to be unconstitutional).

Beta Blocker
Reply to  Gordon A. Dressler
May 30, 2021 1:35 pm

The overall strategy Biden could use to effectively bypass NEPA would be to integrate environmental law with national security law in ways which use each body of law to supercharge the other.

It is national security law which gives power to the president to push the constitution to its limits and beyond, depending upon how serious any given ‘crisis’ is judged to be.

The approach President Biden could use to effectively bypass the current version of NEPA — the one that is the ponderously slow incarnation of the law we have been using for the last three decades — would be to declare a carbon pollution emergency under powers granted to his office by national security law.

Using those powers, Biden could implement a fast track version of the process which has the look and feel of NEPA but which uses the dangers of climate change as a justification for concentrating the review authorities among a very small number of people which report directly to the office of the president.

Assuming Biden chooses people who will do his bidding, the fast-track review process will approve every green energy project which comes before it.

Such an approach will generate many lawsuits. Sure, there is some risk an unfriendly lower tier court might put a stop to the fast track process for a particular project.

But if that happens, Biden has the option, and probably the inclination, to simply ignore whatever decision a lower-tier court hands down, thus allowing a green energy project’s work to go forward while the litigation is being fought out in the courts.

Gordon A. Dressler
Reply to  Beta Blocker
May 30, 2021 6:29 pm

You may well be right on Biden performing such shenanigans, but remember that Congress, and only Congress, controls the “purse strings” (i.e., allocates funding so that a particular action can go forward to actually do something). In the process you describe, one would hope Congress would say, basically, “WTF?” and refuse to fund such Presidential antics.

Praise God for giving the founding fathers of the USA the foresight to enact the checks-and-balances afforded by our Constitutionally-enacted, tripartite form of government.

Last edited 1 year ago by Gordon A. Dressler
Beta Blocker
Reply to  Gordon A. Dressler
May 30, 2021 7:11 pm

The approach of merging environmental law with national security law as a means of enabling the president to basically dictate that America must reduce its carbon emissions has been around for a long time.

It’s been long recognized by those who specialize in environmental law that the president’s power to declare a state of emergency could be employed as a means of bypassing many of the checks and balances that would prevent a climate activist president from employing the Clean Air Act to its maximum possible effectiveness.

I’ve demonstrated just how far a president could go legally, constitutionally — and unilaterally without additional legislation from the Congress — in pursuing an aggressive GHG reduction scheme here.

You might be familiar with the term lawfare — the weaponization of the law, and the processes which administer the law, for pursuing social justice objectives — environmental justice being one of those objectives. The Section 202 endangerment finding for carbon published in 2009 was one of the tools the activists were planning on using to enable the president to use the Clean Air Act to its maximum effectiveness.

But after their victories in the courts in 2011 and 2012 when the endangerment finding was upheld, the climate activists then abandoned their Clean Air Act approach, even though they knew full well that by having Barack Obama declare a carbon pollution emergency under national security law, they could have had everything they said they wanted in terms of forcing America to begin the process of drastically reducing our GHG emissions.

AGW is Not Science
May 29, 2021 10:25 am

IOW, there’s no such thing as free lunch. Trying to make intermittent energy sources supply modern energy needs is a fool’s errand.

Stop trying to fix a non-existent “crisis,” and you need not waste the time and resources to do something so monumentally stupid.

Matthew Schilling
Reply to  AGW is Not Science
May 29, 2021 11:14 am

Exactly. Virtually every single premise of the Left is invalid.

Atmospheric CO2 is an unmitigated blessing – what we have is great and more would be better. Every facet of that statement will still be true even if we ever see atmospheric CO2 levels double.

Reply to  Matthew Schilling
May 29, 2021 12:54 pm

I’m trying to decide if “Virtually” in your response in superfluous. I think it is.

Bruce Cobb
May 29, 2021 11:18 am

I daresay you haven’t mastered the power of magical thinking. You’d be amazed what it can do. Think Peter Pan could fly with your negativity?
C’mon, man!

Reply to  Bruce Cobb
May 29, 2021 11:55 pm

But if you wish hard enough, Tinkerbell will come back. Everyone knows that.

Peta of Newark
May 29, 2021 11:44 am

Epic Point 7
If only a few (more) folks could get their magically fixated heads around that within the notion of the Green Gas Gas Effect, progress might be made
Quote:”It is a state at ambient temperature, atmospheric pressure, and zero electrical potential where energy finally arrives too depleted to do further work

i.e. Once heat energy has left the surface dirt and gone into the atmosphere, it is in that Dead State.
It cannot do any more heating – except to things colder and Carnot’s Law (an expression of Entropy) says it can not return to the surface dirt.
Well it can try, but it will be reflected, bounced, scattered and sent even further down the thermal gradient
The energy is still conserved, being in the Dead State does not mean it has been ‘destroyed’

May 29, 2021 12:15 pm

I think your diesel truck example is even more dramatic than the figures you used. 140 kg of diesel is less than 40 gallons, and many trucks have two 150 gallon tanks.

Kevin kilty
Reply to  Randy
May 29, 2021 4:43 pm

I knew it was a bit short, but still in the same realm of magnitude. Thanks.

May 29, 2021 12:33 pm

Concentration of energy will always bring danger

Reply to  Hatter Eggburn
May 29, 2021 12:57 pm


Thomas Gasloli
May 29, 2021 1:59 pm

What today’s brilliant minds don’t seem to understand is we use fossil fuel boilers, simple & combined cycle natural gas turbines, nuclear power, and hydroelectric dams because all the other bad ideas were rejected.

Expensive bad ideas will not replace what we have now without deindustrialization and a dramatic reduction in the standard of living.

Expensive bad ideas sound good to our “elites” because they just don’t know anything ( for example the current Energy & Transportation Sec.) And sadly they do not have a learning curve so no matter how many times it is explained to them they will still go for the expensive bad ideas.

Robert A. Taylor
Reply to  Thomas Gasloli
May 29, 2021 3:38 pm

But, remember deindustrialization, dramatically reduced living standards, and fewer people are the stated goals of the greenies, therefore successes.

Reply to  Thomas Gasloli
May 30, 2021 9:10 am

This is the first time I have come across “do not have a learning curve”. Well said!

Jon Z
Reply to  Thomas Gasloli
June 3, 2021 11:19 pm

Yes, everything you say is valid. They want less people, and throwing our country back to the 19th century seems fine to those worshiping the creation. I’m glad I’m old and my heart goes out to the young and yet born. We are capable of such great things, but I haven’t seen any in the energy sector for decades. They can’t even get the Grid Hardening complete. With all the money they throw at solar and wind they still haven’t done it. Instead, they continue to destabilize the entire grid for their crack pipe dreams and subsidies.

May 29, 2021 8:00 pm

Does anything beat the energy density of radioactive isotopes? Storage isn’t even needed, you can waste it without shame if you must and it doesn’t increase cost significantly. Best grid storage battery you can build.

Leo Smith
Reply to  markl
May 30, 2021 12:09 am

Glad you said it first. In practical terms, no, nothing does. Good ole E=mc² etc, but it does suggest a mechanism that is worth research. If a battery of the future does in the end work, it will be some sort of nuclear or quantum battery.

May 30, 2021 12:17 am

The biggest problem with so called (Weather Dependent) “Renewables” is the storage of energy; but also the fact that the sources of Sun & Wind are renewables for billions of years but not the extraction apparatus which needs Fossil Fuels from: Design, Mining/muster materials, Land-Clearance, Commission, Maintenance/Fault-Finding, Repairs/Spares provisioning, to Decommissioning (if possible) & LandFill and are not anything like the answer & can’t be manufactured w/o FF’s (we don’t see them providing the energy to make themselves!); and are very heavily subsidised. Solar & Wind have their place, such as in remote areas away from a grid, but not as the only methods to generate a reliable stable National Grid(s).

Jon Z
Reply to  stargrazzer
June 3, 2021 11:07 pm

You said it. We need reliability and clean. That would be reservoirs with hydro and Nuclear power. Reservoirs are the best storage of power and water available, and we need the water everywhere. The new modular nuclear plants look promising too. We just need to wait until it’s a full blown crisis before we change course. It’s that “Hit the ice berg and then realize there aren’t enough life boats” moment, that will force change, I hope.

May 30, 2021 1:15 am

I think this kind of paper is exactly what we need to make the layperson wake up to the realities of energy use and distribution

However – I think the Nuclear analogy doesn’t work

A convenient way to illustrate this is by using the electrical energy destroyed daily by 1000 Americans, or what is equivalent, the daily electrical energy used in about 300 American single family residences. This amounts to 9,000 kWhr of electrical energy[4], which is the equivalent of raising three unit trains with attached locomotives, of 10,000 metric tons each to a height of 100 meters. It is the turbines and generators in six nuclear plants spinning at nominal output.

My reading of this is that you need 6 nuclear plants to power 300 homes …..

Can’t be right…..

May 30, 2021 9:14 am

I really like the competent technology analysis you have done. It’s a shame that people like you aren’t listened to more than the psycho control freaks.

May 30, 2021 12:08 pm

Energy is very easy to store in the form of a Hydrogen and carbon molecular compound.

Williaml Gray
May 31, 2021 7:53 pm

One wind turbine can supply Base and load power simply by raising 1/5/10/200 tonne weights. storing energy… It then is commissioned.

June 1, 2021 7:29 am

Thanks for this. It was on my backlist, having come up in an internet “coverage gap” that I had expected to last much longer. Good read and excellent summary.

Jon Z
June 3, 2021 10:49 pm

I’m no scientist but I did listen to a few documentaries about global warming. Storing electricity is something that is easily accomplished with a hydro electric generator in dams and on rivers. It’s clean, it’s able to store more power than any dirty battery will ever store, and it offers the benefit of water stored at a time of year things go dry in the desert, that is two thirds of the west coast. It also supports eco systems that benefit from the lakes made to store the power and waster.

All the greenies want to talk about is solar and wind. Both have proven to be dirty, poisonous, Un recyclable, very inefficient and unreliable for a modern society. It’s time to stop the madness and get serious about the best alternatives. We don’t talk about modular nuclear power, why not? And even though we have the best technologies for clean coal and gas it’s not good enough for them. The US is one of the cleanest country’s on the planet and the innovator of many clean technologies to help clean up gas and coal around the globe. If the US wants to help clean up the planet, then put the money and restrictions on the biggest polluters, China and India. Otherwise, shut up! I’m so sick of these illogical constructs. Common sense scares most people these days.

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