EV saves the day? Movie "The Martian"

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zzcoopej
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EV saves the day? Movie "The Martian"

Post by zzcoopej »

Hi, a bit OT, however a friend has recommended I see the current cinema movie "The Martian" so I thought I'd pass on the suggestion to other EV owners.

Apparently issues we iMiEV owners face such as heating an EV and travelling much further than the range of the EV are played out in the movie. I'm sure underneath the Hollywood stretch of the truth, there is a little resemblance to our reality?
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EV saves the day? Movie "The Martian"

Post by Gabz »

at no point have i thought of using nuclear power to heat the cabin of the i-miev. but it doesn't realistic show how many solar pannels are need to recharge an EV, and the amount of time.
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EV saves the day? Movie "The Martian"

Post by bmscott »

The movie is set about 20 years in the future. Given all the battery breakthroughs that are 2-5 years away from the market (which realistically means 5-10...) I'd think they'd have some pretty potent batteries by then.

Unfortunately it's unlikely the solar panels will have improved to match, as there are some fundamental difficulties with going too far over the 33% efficiency mark with them. Especially since you're also nearly twice as far away from the sun!

But let's see - we get about 1kW per square meter here. Divide by 4 to account for distance, then by 3 to account for efficiency. Multiply by say 36 square meters - hard to imagine there being too much more than that which one person could stack on top of a van-shaped EV.

And the day is roughly the same length, and let's say he adjusts their angle manually for maximum efficiency. So that works out to - hey, must be movie magic, it's just enough!
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EV saves the day? Movie "The Martian"

Post by iDaVID »

Don't forget less gravity on Mars which would have an effect on energy usage
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EV saves the day? Movie "The Martian"

Post by Johny »

...and less wind resistance due to lower atmospheric pressure.
(Having not seen the movie yet...)
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EV saves the day? Movie "The Martian"

Post by 4Springs »

Didn't look like he had low rolling resistance tyres though.
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EV saves the day? Movie "The Martian"

Post by bmscott »

But he's also driving something a lot bigger than any normal EV, and towing half of a second one.

I don't think the key is the batteries at all, but how much energy he can collect in a single daytime cycle. Which would depend mainly on how much area he could cover with his panels.

So they'd have to be lightweight, yet strong enough to handle even the implausible windstorms at the start of the film... you could figure a rough maximum # of panels he could carry based on the size of the vehicle, but again, it'd turn out to be "just enough" 'cos it's fiction anyway.

I remember when reading the book wondering why he didn't plug the RTG into the power system. But by the time I saw the movie I owned an EV, and now I realize a few dozen watts from those thermocouples is nothing compared to the kilowatts needed to drive a large vehicle!

Anyhow - driving say 12 hours - even in lower gravity/atomsphere, and let's assume something absurdly lightweight for the vehicle like 2 tonnes. And you're probably only making 30-40kph (did it mention, in the book? Must've, distances and scheduling were explicit)

However you slice it, that's a hell of a lot of solar energy to collect each day!
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