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Electric vehicles & Renewable energy

July 12, 2017

Lovely summer so far. I want to address a subject that is important and also full of some hype: electric vehicles (especially plug-in electrics), and the energy sources which are to power them. Not sure how deep to go here – there is a lot of arithmetic that was rewarding for me to follow in detail but will probably put most people to sleep.

But it has a political dimension, especially with Trump’s overtly anti-environmental bias. The political dimension is that opponents of Trump’s regressive environmental policies frame the issues in exactly the right way to alienate swing-state voters. So I’m hoping to reach maybe one or two such readers here.

Start with some principles – i’ll grossly oversimplify.

  1. If you want environmentally friendly energy policy, you can’t afford to lose elections in all branches of government.
  2. In US politics, you can’t afford to lose the support of everyone who drives pick-up trucks.
  3. When trying to reach an audience who is skeptical of you, you can’t afford to make exaggerated claims that are easily falsified

Ok great. So obviously I’m implying that there is some of #3 going on.

Technology that is available today makes it possible to drive a fully electric plug-in car for hundreds of miles. They’re pretty sweet, I drove a Nissan Leaf around for a little while. However, widespread adoption of plug-in electrics brings several serious challenges, but before I get to those, lets start with the basics.

Per person, the US burns far more than our fair share of the fuel consumed on planet earth. A little under a quarter of our energy is consumed by transportation (US EIA 2017). That is, motor fuels. Half of that is burned by vehicles classified as “light duty, short wheel base” (meaning any thing the size of a Ford Explorer and smaller) (US DOT 2010). It is this class of vehicle, which has potential to have its energy consumption and carbon consumption greatly reduced by EV or hybrid technology.

Further, within that class of “light duty, short wheel base”, 70% of the miles driven, representing something like 35% of national motor fuel consumption, are classified as “urban” (same source).

So in other words, the use case for EV’s is urban and suburban commuter transport. A simpler solution, mass transit, has existed all along but was not adopted. Person-miles traveled by buses for example, is 10% that of small vehicles. Trains? Forget it. Keep this in mind when making appeals to common sense.

But certainly there is incredible room for improvement there — we burn roughly 35% of our motor fuels on commuter transport, and do it in nearly the most inefficient way possible. Why not plug-in EV’s running on clean carbon-free solar?

First of all, at scale – meaning if you tried to upgraded the bulk of the passenger vehicle fleet – you would have some energy transfer problems. This means EV’s used for commuting get charged at home – other options are not realistic, I’ll skip the math here but the energy transfer rates of an EV gas station are large, and consequently fill times are slow, there would be lines at such a gas station, you wouldn’t be able to leave (unless your car drives itself up the line), and it would take long enough to be a major inconvenience. You would charge your EV at home. That’s fine.

If you have a job you would charge it at night. That is a difficulty for the solar power case. Wind power is possible, however. It is also something that is favored in the center states of the US – an important marketing point.

But the more insidious technical-political difficulty is where the energy comes from, and how you market that. Say half the families in your neighborhood change one of their vehicles to a plug-in EV. Therefore, Evening/Nighttime electric use goes up noticeably. (We’re talking like 10-20% overall increase in electric use if you switched out most of the small-vehicle fleet, depending on the size of the EV’s (are we including midsize SUV’s and small pickups?, and depending on the recharge rates). So we’re talking about adding electric generation and transmission capacity. (while at the same time retiring coal and probably Nuclear due to cost if nothing else). Guess what that means? More natgas. A lot more natgas. This is something we should be upfront about.

Why natgas? Why not solar or wind? Because NG is cheap in the US and at this particular time is plentiful. The shales in PA and OH are limited by pipeline capacity and are thought to be able to supply the entire country for a few decades. Thus far, producers are able to dump the wastewater free of charge (Thanks, NY state highways /sarc).

But, you might say, even if the fuel cost of NG is just a couple cents per kWh, solar is free and wind is free? That’s where it gets interesting. Once the plant is built, yes- wind and solar win every time. But to make the decision to build the plant in the first place, you also have to count interest payments and amortization. Compared to solar, NG has lower upfront costs by 2.5x, lower maintenance costs (EIA 2016 , EIA 2017), and after factoring in NG’s higher capacity utilization due to it always being available, its fuel cost is not much more than just the interest payments on the difference that remain! (And an interesting sideshow to this all is how the fate of renewables in the US is closely tied to interest rates!)

Thus, for renewables, the federal government gives loan guarantees to get the rates down. The amortization of the extra upfront cost for renewables then requires federal and state tax credits to cancel out. Then the renewable plant gets built – and it will then always be used since the incremental cost of operating it is very low.

BUT, even if solar and wind can deliver a lower per-kWh cost than natgas, the NG plant will still get built to exactly match the capacity of the renewable plants! That’s because the renewables are not available 100% of the time, but electricity must always be delivered. Thus renewables will ALWAYS have competition, and it will be super cheap, thus federal government help will ALWAYS be needed. Thus you will need to make a political (i.e., rhetorical) case for why the federal government should do this. And because of swing states, you need to appeal to the pickup-truck drivers of America.

Remember this when when making comparisons to the situation in the EU (or select parts of the US where conditions favor renewables). Don’t Bullshit. The majority of US population is not going to be driving plug-in electric cars powered by solar until major breakthroughs happen in both energy transmission and energy storage.

A more realistic thing to promote are hybrid vehicles, plug-in hybrids as an added bonus. When plugged in, half the electricity may someday come from wind (higher availability than solar, better use of limited resources). Can use regular fuels, don’t inconvenience the drivers. Are able to provide the wishes of US car buyers — namely, a vehicle that can transport a bunch of stuff, produce 200-300 hp to accelerate and climb hills at 70mph (electrics peak at low speeds), and has okay mileage.

All this is possible more or less right now with a turbocharged hybrid, with the electric systems set up primarily to harvest energy for regenerative braking – to boost the mpg but generally consume a liquid fuel at a steady pace with optimal engine conditions, rather than to be used in pure battery-powered mode. It can be made affordable. It can be used for vehicles the size of a midsize family SUV:  2 ton vehicle powered by 2.0L turbo in the 200hp range at full speed, 40mpg, could be 50 mpg if fuels were high octane or diesel (at scale, may incur cost penalty in refineries due to to domestic oil production becoming lighter grade from shale). Anyway… family SUV with 50-100% increase in gas mileage. Get that image in your head. I’m pretty sure the arithmetic says changing all the 20 mpg cars to 40 mpg would be more helpful than changing the 40mpg cars to 100mpg.

Not a good enough solution for suburban cummuters (representing the vast majority of person-miles in the US)? Ok, here’s one that is effectively 300 mpg:

A park-and ride and light rail. Beats EV’s and hybrids every time.


From → Uncategorized

  1. An excellent reality check.

  2. I am not very well read in this topic but isn’t Tesla countering and fixing all these issues with their current models?

    • Their first 2 models were luxury sedans with 1000 lb of batteries in them. The model 3 looks more or less like the Chevy Bolt to me – a mid-price sedan with excellent mileage. With the federal subsidy, it beats the existing 35-40 mpg sedans as a commuter vehicle.

      My objections are that (1) that’s attacking a small chunk of the fuel consumption, vs making a push to upgrade mileage on midsize SUV’s and pickups (2) the marketing appeals to solar electricity, which is nowhere near viable at this time for a bunch of reasons, and in doing so, alienates voters who are in a position to obstruct energy efficiency efforts in general, even though they could be won over with more a intelligent political strategy – and (3) if we accept that federal subsidies are a necessity to become energy efficient, there are much, much more effective ways to use those financial resources. By the way, when Tesla got all sorts of help from the federal government when they were selling $100k luxury cars. They are liable to become an easy target for cheap shots during the 2020 elections.

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