Battery fundamentals for local weather warriors


From Rud Istvan

I had to think about WUWT 2.0, and some of the fact that munitions climate skeptics might need something here if Kerry Biden becomes climate guru. So here is a little more WUWT factual ammunition for what might be another climate war.

One of the big problems with renewable energy is its disruption. Another reason is the lack of net inertia. (More information can be found in my last guest post on grid stability.) Countless numbers like Kerry still claim that both problems can / will be overcome by more grid connection or better storage of the grid batteries. These hopes / beliefs are almost certainly false. My last post, referenced above, challenged belief in interconnectivity. This hopefully not too technical additional contribution explains why their hopes for rechargeable mains batteries are also wrong. This is done in a simplified yet easily researchable way. It provides all of the key words for anyone looking for a deeper understanding of network battery storage.

Basically there are only three non-kinetic electrical storage mechanisms: electrochemical, pseudocapacitive and capacitive. We are deliberately excluding indirectly kinetically pumped hydropower plants for which there are two major expansion problems: insufficient remaining suitable terrain and California, which has refused.

Electrochemical batteries involve some chemical species changes (lead acid, also known as PbA, is discussed below, chemically simplified, the lead anode goes to lead sulfate and then back to lead thanks to the sulfuric acid electrolyte). The general nature of such reactions is that they are faradic (including electron exchange, named in honor of Michael Faraday, also honored by the farad of capacitive charge). The original discovery of the Faradic battery was made centuries ago by Volta (the volt, unit of direct current electromotive force – EMF, is named in his honor). He used zinc, copper, a paper separator, and salt water electrolytes to power the frogs' legs out of his “battery pack”. The same principle of “electrochemical erosion” is used today by sacrificial zinc anodes to prevent corrosion of the hull in salt water.

You can build a modern "Volta Pile" replica, enough to light a single mini Christmas pear (for a while) with just two US pennies and a lemon. Grind one of the pennies to remove the copper plating (copper is so valuable now, pennies are just copper-clad zinc, but the US Treasury Department is still losing money for each minted). This will give you the zinc and copper electrodes from Volta. Usually insert both into deeply peeled knife slots at a distance of approx. 1 cm into an unpeeled lemon (the pulp is a separator, acidic juice is an electrolyte). Attach two wire clips to the protruding penny edges and then to each mini-bulb cord (completing a DC circuit where polarity doesn't matter). A low voltage direct current flows enough to illuminate the resistively heated mini-bulb until the copper coating on the unsanded penny has been electrochemically eroded. Makes a great experiment for an entry-level high school science fair. This simple experiment at home also shows one of the many ways that all rechargeable or non-rechargeable batteries (like this one) have a finite life that is much shorter than the life of the mains.

Pseudocapacitance is rare and complicated. We mostly skip it. A decade ago there were several DARPA-funded efforts based on ruthenium hydroxide, all of which failed. Evans Capacitor has a type that is based on tantalum, but Dave's expensive, high-powered military unilateral band fighter jet radar power pulse is actually an electrolyte cap (defined below) with pseudocapacitive "overtones".

There are two types of capacitive storage: all "solid bodies" or with a "Helmholtz" layer. Nowadays, all "solid bodies" are most of the billions of small "chip caps" in electronics, just two metallic conductors separated by a ceramic dielectric. The Leyden glass was their ancestor. Even "wet" aluminum electrolytic capacitors, which are prone to failure of the electrolyte drying, are technically still in this "solid state" taste. Very fast, almost infinite life (except for wet dielectrics), but very faradic storage with low charge. Dave Evans & # 39; brilliant tantalum military material is still just a version of the wet form of the "solid" with very high power density. All caps of this "taste" have insufficient energy storage to supplement the renewable energies of the grid.

The other aroma uses the Helmholtz capacitance effect "electrolytic double layer". The best-known example is the thunderstorm lightning that Helmholtz first explained (the “electrodes” can be steam to water or water to ice – probably both in every large storm cloud). The commercial example is a super capacitor (also known as EDLC). The service life is several million full discharges. Used in high power density applications (think Navy Rail Guns) but only about 1/10 the energy density of a high capacity LiIon battery at best. They are used in networks as "Statcoms" with a power of up to 4 MW, mainly for power factor correction and the associated support of the network frequency. Not nearly enough EDLC energy density to support renewable intermittency grids.

Green sparked Formula 1 racing and then tried both high-performance LiIon and EDLC hybrid designs. Too many car battery fires due to insufficient LiIon power density, while EDLC (prior to my issued patents on carbon materials) was physically too large to easily mount the F1 horsepower car racing chassis. F1 has finally stopped its alert green hybrid racing attempt – bad for business. The real world invaded. Below is a hybrid Mercedes F1 in Singapore after a training lap after its high-performance LiIon was blown up with the driver sitting on it.

As a potentially complicating (and hopeful) side note, a speculative position at Judith Currys Climate Etc a few years ago concerned Henrik Fisker's second electric car company. There is a hybrid variant with half a battery / half an EDLC device (one electrode of each type), which combines the attractive properties of both (high energy and power density, service life of 20,000 cycles). It's available in limited numbers for things like correcting large inductive motor power factors. Invented and then sold by Subaru when it is not good enough for hybrid electric vehicles. Not yet commercialized for EVs, except for Fisker, and even he deferred LiIon for his first "Fisker2" vehicles.

Battery restrictions

All energy storage systems are characterized by three basic physical parameters that ignore cost: (1) energy density (how much charge they contain, also known as the duration of discharge in Wh), more is better, (2) power density (how many ) Charge / discharge amps per second), higher is better and (3) battery life, where higher is always better.

It's pretty easy to get 2 out of 3 of these in a commercially available rechargeable battery system. It's REALLY difficult to have all three in one device.

For example, PbA (2 + 3) are car starter batteries. PbA (1 + 3) are golf cart batteries. Unfortunately, they are NOT interchangeable. The former uses thin electrodes for power supply. The latter uses thick electrodes to generate energy. The cycle life of the former is roughly 2x longer than that of the latter, since the former (by definition) normally do NOT discharge nearly as deeply as the latter. A deep discharge deforms the PbA electrodes chemically faster and faster through (large crystals) sulfation and thus shortens the life of the cycle. A starter battery is empty after about four full discharges due to sulfation. Is also the reason older starter batteries usually die in winter.

The degree and speed of discharge / recharge have a profound effect on the service life of the battery for several reasons. Simply put, "full" charge / discharge EV batteries with the same chemistry will last much less than hybrid EV batteries as in my Ford Hybrid Escape, MY 2007, NiMH chemistry that is now 13 years old and still is mostly strong (exception is when the engine starts afterwards) sit down for a week due to the slowly increasing leakage current that Ford anticipated by providing a "jump start" button (not really) that can be used when the battery ages and that Car sits more), as the hybrid traction battery charge only ever floats between about 45% and 55% of the full charge.

By the way, my hybrid escape made direct economic “green” sense. It is a small but robust I-Beam SUV with all-wheel drive and class 1 trailer hitch, total HP ~ 210 (comparable to the 3-liter V6 variant). The HP comes from a scaled-down 1.4-liter Atkinson cycle I4 with 140 hp and about 70 hp equivalent from the electric machine. (The Atkinson cycle sacrifices torque for about 15% fuel efficiency during the Otto cycle – this doesn't matter, however, as the electric machine more than makes up for a torque deficit.) The MY2007 V6 has about 22mpg highway and about 18mpg city. Our hybrid version still hits 32 cities and 28 highways (27 at our usual 75 mph with summer AC turned on). The hybrid premium over the V6 was almost exactly $ 3,000. In 2007, the federal hybrid tax credit was around $ 3,000 (no coincidence, a Ford pricing strategy). The day we drove the car home from the dealer, we made money off of fuel savings. The best part is that our I4 Atkinson uses regular gas. The corresponding Otto V6 required Premium. Where we are, the octane difference is over a dollar a gallon. Fewer even cheaper gallons.

By far the most commonly used battery is Lithium Ion (LiIon), also known as the lithium rocking chair invented more than 30 years ago. In a way, it's partly pseudocapacitive about its "rocking chair". When charging, lithium ions migrate from their chemical home metal cathode through a lithium ion electrolyte to intercalate into the carbon anode (the rocking chair). The intercalation does not involve any chemical change in the anode, only lithium ions that "cuddle" to their "rocking chair electrons" in the carbon anode. Only the metal cathode (where the cobalt is located) changes chemically as it charges / discharges.

The LiIon energy / power limitations are similar to those of PbA. By making everything thinner, you get more surface area per battery volume for maximum energy density. A Tesla EV battery is big enough for the range so that the power density is only in the foreground when charging. The cycle life limitations vary, but are still limiting. F1 LiIon made the power density thick – just not enough.

There is a secondary consequence of a relatively low power density for Tesla. Fast charging generates more heat than can easily be dissipated. The Nernst equation states that heat affects the life of the cycle (above ~ 40 ° C, about 2x per 10 ° C). Something Tesla does NOT say about its fast charging stations. You can often quickly charge for convenience, but this also causes your car's Tesla battery to run out pretty early. Maybe an undisclosed financial warranty from Tesla?

Of course, installing the Tesla mains battery “Stunt” in South Australia (more on this to come) is NOT economical and cannot last very long. And since Tesla launched its “Powerwall” network a few years ago, the price has increased by about 35% (not decreased as promised by Gigafactory) while the warranty has been reduced by about 1/3. Not a good business deal.

Future battery options

These usually come in three hopium flavors.

First, nanotechnology will come to the rescue. With the exception of all previous examples, it was either fraud (Silurgy, NanoOne) or errors such as A123 systems or speculations without laboratory evidence such as in a recently published WUWT article on lithium sulfur.

Second, batteries flow for the grid (where the charge is stored in the liquid electrolyte rather than in the electrodes, so that with sufficiently large electrolyte tanks the energy density is theoretically unlimited). Other than that, despite the encouragement from California and many VC investments, all of these various flow chemicals have so far failed commercially. Short lifespan and / or high cost (vanadium in large quantities is not cheap and cheaper rhubarb does not have a lifespan). See the California Dreaming essay in the Blowing Smoke eBook for some (now somewhat dated) specific illustrated examples.

Third, exotic chemicals like sodium sulfur work but are expensive and very high in temperature. Lithium sulfur (a recently published WUWT paper on new theories to solve the two remaining problems) has not even been proven in the laboratory due to the inherent technical difficulties in creating such a problem.

Two final definitive Climate Warrior ammunition memories

First, batteries live in a DC world. Networks live in an AC world. There is always the significant added cost and limited reliability of the high voltage, high performance DC / AC interfaces required. Quoting the battery cost without the inevitable interface cost is intellectually dishonest. Tesla Powerwall 2 was either integrated in DC only or in DC / AC. The price difference in 2017 was about $ 1500 for a 14 kWh base DC battery, then about $ 5500. So about plus 30% for the costs of the network interface.

Second, the use of batteries to solve the renewable grid disruption is touted by Elon Musk and "given" to South Australia by him after the 2016 renewable energy catastrophic blackout. But Elon used a simple marketing con, just like the California Flow batteries featured in the California Dreaming essay.

It is quite possible to truthfully state a mains battery system in MW. After all, it has. BUT the relevant value for the grid interruption is MWh (how long the battery delivers this vital MW of emergency power). If the MWh answer is minutes while the grid's MWh demand is hours, the joke about the grid's installed MWh battery capacity is yours while your grid goes dark.

Elon "cheated" South Australia (IMHO to get free "publicity"), and Australia's MSM never caught on. Tesla's Hornsdale, SA facility (below, now expanded by 50%) delivered 150 MW! But only 189 MWh. It can hold the SA network for a little longer than an hour. The length of the blackout in South Australia depended on where you were. The metropolis of Adelaide was first restored. Central Adelaide was dark for at least three hours. More symbolic hopium that doesn't work in the real world.

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