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What’s So Fun About Batteries?!

Chapter IV. One must imagine Sisyphus happy.

“The energy storage revolution will finally enable the transition to a majority-renewables grid.”


“…Sisyphus teaches the higher fidelity that negates the gods and raises rocks. He too concludes that all is well. This universe henceforth without a master seems to him neither sterile nor futile. Each atom of that stone, each mineral flake of that night filled mountain, in itself forms a world. The struggle itself toward the
heights is enough to fill a man’s heart.
One must imagine Sisyphus happy.”

– Albert Camus, The Myth of Sisyphus


Myth is right! Imagine me happy? Indeed, that requires some imagination, Albert.

How could I find joy in fruitless labor? I imagine you writing your essay, Albert, if each sentence were to fade from the page the moment you came to a full stop. You would never complete a work, let alone a word. You would create nothing, contribute nothing. Yet you expect you would find joy in this arrangement?! I have my doubts, Al.

But fret not, dear reader! This Corinthian King’s labors have, at long last, borne sweet fruit. I have found rapture in my repetition, transcendence in my trudgery. No longer do I serve a démodé deity; today, I serve The Grid.

Things seem to have changed a bit since I began my ascent several millennia ago.

Among these things:

        1. Nobody worships Zeus and his ilk any more (HA!)
        2. Monarchy is pretty passé now 😢
        3. Sometimes, people brush their teeth
        4. Regenerative braking is a thing

…and that about covers it!
Today, I would like to focus on by far the most thrilling of these developments. If you drive a Prius, you probably know about regenerative braking (“regen”); if you don’t, then you probably don’t. But it’s not just for Prii – regen was first patented in 1907, if not earlier. But what is it?



First, consider a traditional, non-regen vehicle. When you pump the brakes, friction is applied to the wheels, converting their kinetic energy into thermal energy. In this process, none of that kinetic energy is destroyed – you and your vehicle just cannot harness it in its new state as “waste heat.”

Instead of applying friction to the wheels (as in traditional braking), regen slows the vehicle simply by cutting power to the motors that turn the wheels. The wheels’ kinetic energy then flows back to the motors, using them as electrical generators to recharge the battery. In other words – when accelerating, the battery powers the motors, which turn the wheels; when regenerative braking, the process is reversed, as the wheels power the motors, which charge the battery. Regen cannot slow a car as rapidly as traditional braking can, so at greater speeds, the vehicle must supplement regen with friction, causing the loss of some kinetic energy as waste heat. But in a modern regen car, about 70%-80% of the wheels’ kinetic energy can be captured and used to recharge the battery. The other 20-30% is lost to standard inefficiencies in the lithium-ion battery charge/discharge process.

You’re probably wondering, “Who cares? What, does Sisyphus have a Prius?!”

Of course I don’t! Even the unusually spacious Prius hatchback can’t accommodate this (literally) damned rock.[note]That said… Toyota, feel free to reach out re: licensing opportunities for the Limited Edition SisyPrius, the first car powered entirely by the curse of a jealous god![/note] No – I am the founder and CEO of Sisyphus Storage, the world’s finest boulder-based energy storage firm. As ever, I shoulder my boulder, but now the ignominious ingot sits in a railcar outfitted with regenerative brakes. When grid operators need electricity stored, I mainline the stuff, supercharging my ascent.[note]I understand that this is an unusual arrangement – at most similar energy storage installations, electricity powers a traditional engine which drives the weighted railcar uphill. Boring![/note] As I near the summit, I lock the car to the tracks. Thus, the electricity fed into the motor (my body) has been converted into gravitational potential energy. When grid operators need to draw power from this “battery,” I unlock the car from the tracks, hop atop my boulder, and speed downhill.

Choo choo! What now?

        1. Gravitational potential energy is converted into kinetic energy, driving the wheels downhill;
        2. Regenerative braking is applied, feeding kinetic energy into motors that convert it into electricity;
        3. Electricity is sent back to the grid;
        4. We slow to a gentle stop at the bottom of the decline. The battery has been fully discharged.



But… why do any of this? It’s not like you’re actually generating any new electricity, right?

That’s right – I just take electricity from the grid and hold onto it for safekeeping. But this is an extremely valuable service! Grid operators call on me to charge and discharge electricity for all sorts of reasons. Most of the time, they ask me to store excess electricity from wind and solar farms. Since these energy sources aren’t “dispatchable,”[note]A diesel generator is “dispatchable” because, well, it can be dispatched to generate power at any time, as long as you have fuel. Wind and sunlight can’t be stored for future use in the same way… or can they? Such intermittent sources of energy can be made dispatchable if you pair them with energy storage. [/note] they’ll often produce more (or less) power than what customers need at a given moment. Any electricity beyond what’s being demanded by customers has to be safely sent somewhere – this is so vital that sometimes a utility will actually pay a neighboring utility to take its excess power! You won’t be surprised to learn that for-profit corporations don’t particularly relish this scenario.

That’s where I come in. The utility instead pays me to take its excess power, which I use to hustle up my hill. Then, the next time their renewable power plants are under- instead of over-generating, I send my stored energy back to the grid. Voila – we’ve turned the wind and solar farms into dispatchable resources, like traditional natural gas power plants. Of course, my battery is slower-moving than the lithium-ion ones that rule the market – those nimble little guys are great at responding to second-by-second fluctuations in electricity demand and supply. However, I can hold a charge a whole lot longer than they can. Once I’m charged, I can sit on my hilltop perch indefinitely. I can even hold excess solar power from the summer and save it for the shorter, dimmer winter days. Such “seasonal storage” is going to be absolutely vital if we’re ever going to build a majority-renewables grid.

This is all to say – you don’t need a chemical battery to store energy. In fact, depending on your needs, you might prefer to pay a damned, immortal monarch to shove a boulder up a hill. I’m just happy to d-


Ah, a demand peak! My apologies, but I’ve got to shove off – duty calls.



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