>One Reason Electric Cars Won’t Be as Good

>Consider how long it takes you to fuel up.

Gasoline contains 115,000 BTU per gallon (32 MJ/L).*/** Costs me $4.10 and takes about 15 seconds to transfer by fuel hose. For the couple minutes it takes to transfer fuel, I transfer 10 gallons (38L), at an energy transfer rate of about 8 megawatts. In all, my 10 gallon tank stores about 330 kWh of liquid fuel, on which I can drive about 330 miles (530 km). Now, because I’m using a heat engine, not all of the heat energy is usable, but I can still get between a fifth and a quarter of the energy (between 65 and 80 kWh) out as useful work.

Compare to a reasonable electric car that has a 60 mile (100 km) range. A typical electric car travels a mile on about 200 Wh (watt-hours), and for that range, you would need to store 12 kWh. Think about charging 12 kWh of batteries with a normal plug-in connection. Instead of being able to refuel in about two minutes, I’m now limited by my 1.8kW house wiring (120V at 15A). I’m going to need about 7 hours to fuel up instead of two or three minutes.

Even if battery technology improves significantly such that a reasonable battery can store 20 or 30 kWh, unless I upgrade my outdoor electric connection to more than a 120V, 15A circuit (by installing a 240V, 20A circuit, for example) I’m not going to be able to use that extra capacity except by charging the car all day in addition to all night.

I’m not saying electric cars are unreasonable in and of themselves, or that they’re not going to be part of the solution to expensive liquid fuel, I’m saying that it will be hard to expect the same type of performance we’ve been accustomed to with liquid fuel.

That’s why a large part of adapting to expensive fuel is going to have to be designing our cities and living arrangements so that the trip lengths are shorter and more pleasant by walking or cycling, or at least manageable by electric car. Transit will be a big part of it too.

*Apologies to any non-US readers for the ancient units. I just took the mechanical PE exam which is in US customary units so I find it impossible to think in anything else. I converted everything thanks to Google.

**That’s about the energy needed (per gallon) to lift my civic (2500 pounds/ 1100 kg) up to airline cruising altitude (about 36,000 feet/10,900 meters). The amount of energy in a shot of fuel (2 oz./ 60 mL) is enough to lift the car to the top of the Washington Monument (555 feet/170m) and only costs 6 cents.


About perkinsms

I'm an engineer and father interested in transit, parking and economics.
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2 Responses to >One Reason Electric Cars Won’t Be as Good

  1. Anonymous says:

    >Who Killed the Electric Car? Info Snack Headquarters, apparently.

  2. Mark says:

    >>I’m saying that it will be hard to expect the same type of performance we’ve been accustomed to with liquid fuel.I continue to support the idea that two-car families would be well off with one conventional car and one electric commuter car.The electric car needn’t go faster than 60mph top speed. It needn’t have a range greater than 100 miles. Even if it takes hours to ‘refuel’, that’s fine, because it sits at home every night anyway.Of course, the same way that Joe Lunchpail needs to buy a Ford F-150 even though he doesn’t actually haul a half ton of stuff more than once a year, I’m sure it would be seen as unmasculine to have a wussy car. But, no problem, the wife can drive that one for her little shopping trips to the supermarket.

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