Your gas tank is not an oil well. Your battery will not be a power plant.

Also published on Resilience

My car comes with an amazing energy-storage, demand-management-and-supply system; perhaps you’ve heard of it. It’s called the “gas tank”.

Thanks to this revolutionary feature, if I get home and the electric grid is down, I can siphon gas out of the tank and power up a generator. In a more urgent energy crunch, I can siphon out some gas, throw it on a woodpile, and get a really hot fire going in seconds. If a friend across town has no power, I can even drive over there, siphon out some fuel, and run a generator to provide power in an alternate location. It’s beautiful! I can shift energy provision and consumption both temporally and spatially.

There is one minor drawback, to be sure. If I siphon the fuel out of the tank then I can’t actually drive the car, at least not more than a few kilometers to the nearest fuel station. But let’s not let that limitation cast a shadow over this revolutionary technology. If this flexible load-management system were widely adopted, and there were cars everywhere, think how smoothly our society could run!

These thoughts come to mind when I hear someone rhapsodize about the second coming of the electric car. Recently, for example, a Grist headline proclaimed that “Your Electric Vehicle Could Become a Mini Power Plant. And that could make the electrical grid work better for everyone.” (June 21, 2021)

Stephen Peake, in Renewable Energy: Ten Short Lessons (review here) wrote that “new fleets of electric vehicles parked overnight could become another mass source of electricity storage and supply.” (emphasis mine)

One more example: an Oct 2020 article at World Economic Forum says that “When electric vehicles are integrated into a city’s energy system, the battery can provide power to the grid when the sun is down or the wind isn’t blowing.”

The key to this supply-and-demand magic is “bidirectional charging” – the electric vehicles of the near future will have the equivalent of a gas tank with a built-in siphon. Thus their capacious batteries will not only be able to quickly suck power out of the grid, but also to empty themselves out again to provide juice for other purposes.

But allow me this skeptical observation: electric car batteries do not have huge batteries because the drivers want to offer aid to the “smart grid”. Electric car batteries are huge because cars are huge consumers of energy.

(True, electric cars don’t consume quite as much energy as internal-combustion cars of similar class and weight – but they consume a whole lot more energy per passenger/kilometer than intelligently routed electric buses, trains, or especially, electric-assisted bicycles.)

And let’s be clear: neither an electric car vehicle nor its battery provide any “energy supply”. The car itself is a pure energy suck. The battery is just an energy storage device – it can store a finite capacity of energy from another source, and output that energy as required, but it does not produce energy.

As with internal-combustion powered cars, when the tank/battery is drained for a purpose other than driving, then the car ceases to be a functional car until refueled.

That will leave some niche scenarios where vehicle batteries really might offer a significant advantage to grid supply management. The Grist article begins with one such scenario: three yellow school buses which run on battery power through the school year, and serve as a battery bank while parked for the summer months. If all 8,000 school buses in the local utility service area were EVs, the article notes, their fully-charged batteries “could collectively supply more than 100 megawatts of power to the grid for short periods — or nearly 1 percent of Con Ed’s peak summer power demand.”

When parked for the summer, electric school buses would not need to be charged and ready to drive first thing every weekday morning. So they could indeed be used simply as (terribly expensive) battery cases for two or three months each year.

OK, but … let’s be careful about singing the praises of school buses. This might be a slippery slope. If big buses catch on, soon Americans might start taking their kids to school in giant pick-up trucks!

Of course I jest – that horse has already left the barn. The top three selling vehicles in the US, it may surprise people from elsewhere to learn, are pick-up trucks that dwarf the pick-ups used by farmers and some tradespeople in previous generations. (It will not surprise Canadians, who play second fiddle to no-one in car culture madness. Canadians tend to buy even larger, heavier, more powerful, and more expensive trucks than Americans do.)

The boom in overgrown pick-ups has not come about because North Americans are farming and logging in record numbers, nor even, as one wag put it, that a 4X8 sheet of plywood has gotten so much bigger in recent years. Yet urban streets, parking lots, and suburban driveways are now crowded with hulking four-door, four-wheel-drive, spotlessly clean limousine-trucks. Those vehicles, regardless of their freight-carrying or freight-pulling capacity, are used most to carry one or two people around urbanized areas.

If we are foolish enough to attempt electrification of this fleet, it will take an awesome amount of battery power. And as you might expect, car culture celebrants are already proclaiming what a boon this will be for energy transition.

A pre-production promo video for Ford’s F-150 Lightning electric pick-up truck gets to the critical issue first: the Lightning will accelerate from 0 – 60 mph (0 – 97 km/hr) “in the mid-4-second range”. But wait, there’s more, the ad promises: the battery can “off-board” enough power to run a home “for about three days”.

Keep that in mind when you start seeing big electric pick-up trucks on the road: each one, in just a few hours of highway driving, will use as much power as a typical American home uses in three days.

Keep it in mind, too, when you see a new bank of solar panels going up in a field or on a warehouse roof: the installation might output enough electricity each day to power 100 pickup trucks for a few hours each – or 300 homes for the whole day.

Given that we won’t have enough renewably produced electricity to power existing homes, schools, stores and industries for decades, is it really a good idea to devote a big share of it, right at the outset, to building and charging limousine-trucks? Are the huge batteries required by these vehicles actually features, or are they bugs?

Granted, an electric car battery can provide a modest degree of grid load-levelling capability in some situations. It can be drained back into the grid during some peak-power-demand periods such as early evening in the heat of summer – as long as it can be recharged in time for the morning commute. That’s not nothing. And if we’re determined to keep our society moving by using big cars and trucks, that means we’ll have a huge aggregated battery capacity sitting in parking spots for most of each day. In that scenario, sure, there will be a modest degree of load-levelling capacity in those parked vehicles.

But perhaps there is a better way to add load-levelling capacity to the grid. A better way than producing huge, heavy vehicles, each containing one battery, which suck up that power fast whenever they’re being driven, while also spreading brake dust and worn tire particles through the environment, and which significantly increase the danger to vulnerable road users besides. Not to mention, which result in huge upfront emissions of carbon dioxide during their manufacture.

If it’s really load-levelling we’re after, for the same money and resources we could build a far greater number of batteries, and skip building expensive casings in the form of cars and pick-ups.

Other factors being equal, an electric car is modestly more environmentally friendly than internal-combustion car. (How’s that for damning with faint praise?)  But if we’re ready for a serious response to the climate emergency, we should be rapidly curtailing both the manufacture and use of cars, and making the remaining vehicles only as big and heavy as they actually need to be. The remaining small cars won’t collectively contain such a huge battery capacity, to be sure, but we can then address the difficult problems of grid load management in a more intelligent, efficient and direct fashion.


Illustration at top of post: Energy Utopia, composite by Bart Hawkins Kreps from public domain images.