

"Please Don't Buy an Electric Car" - danpalmer
http://danpalmer.me/blog/articles/2013-04-16-please-dont-buy-an-electric-car.html

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jfim
You can't really have an international grid on the scale you describe, due to
transmission losses. If you take a conductor, even though for short distances
the material it has negligible resistance, it comes out to be a limiting
factor for long lengths (thousands of kilometres).

If you look at Joule's first law, which says that the heat produced by a piece
of wire is proportional to the square of the current times the electrical
resistance of the wire (ie. I^2*R), you'll notice it doesn't say anything
about voltage. This is why power transmission lines for long distances usually
have high voltages (~100kV) or even higher ones(the transmission lines where I
live are 735kV). Unfortunately, there is a limit as to how much voltage that
can be put, due to other problems caused by the high voltage itself (coronal
discharge, arcing, etc.).

This is why electricity (per kilowatt, retail) costs me one third of what it
costs my friend in Los Angeles; it's not technically feasible to send our low
cost electricity all the way to there while still turning a profit. Note that
this completely changes if there is high temperature[1] superconductivity, but
at this point, it's not exactly doable[2].

[1] High temperature, in this case, essentially means without liquid nitrogen
and other relatively exotic cooling methods. Your living room would be
considered high temperature, for example. [2] The current superconductor with
the highest transition temperature is HgBa2Ca2Cu3O8, at 133K (-140C).

~~~
maxerickson
You are a little pessimistic:

<http://en.wikipedia.org/wiki/Pacific_DC_Intertie>

[http://www.abb.com/cawp/seitp202/25b65cc026636ebfc1257574004...](http://www.abb.com/cawp/seitp202/25b65cc026636ebfc1257574004f0232.aspx)

(The first link describes the system that reduces energy costs in LA by
carrying it in from the Columbia river system, the second one is from the
company behind the technology and discusses their plan to send 6 Gigawatts
over 2,000 km in China)

The economics are certainly less favorable as distance increases.

~~~
jfim
Not really. Current residential electric rate here is 0.0541$/kWh, compared to
0.232$/kWh in LA. I am sure they would enjoy having this cheap electricity,
but they're too far from here.

Furthermore, to take his example of solar electricity from the Sahara to the
UK, the line of sight distance between both is over 3000km[1], includes
underwater segments and is more than 25% longer than the longest HVDC link(the
Rio Madeira, at 2375km).

Can electricity be sent over long distances? Sure, but not intercontinentally,
or even intracontinentally if you're looking at, say, New York to Los Angeles.

[1]
[http://www.wolframalpha.com/input/?i=distance+between+the+sa...](http://www.wolframalpha.com/input/?i=distance+between+the+sahara+desert+and+london%2C+uk)

~~~
maxerickson
I take the existence of the interlink as evidence that it lowers prices (this
seems like a reasonable definition of profit here). Maybe it only works due to
the regulatory situation in California. It would take some more information to
decide how much of the price difference is due to the interlink.

I don't particularly think intercontinental systems are in the near future,
but I don't think "a little pessimistic" was outlandish. What if ABB can push
their tech 50% further?

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ggchappell
An interesting discussion.

I'm wondering about some of the reasoning, though. For example:

> On top of all this extra power being used, we have targets to meet on
> reducing emissions. That means shutting down coal fired power plants,
> reducing our gas usage, and moving to cleaner sources such as wind, solar,
> wave, geothermal, and dare I say it, nuclear. How are we going to meet
> demand?

Are we actually trying to reduce emissions here, or just meeting someone's
target for shutting down coal-fired plants? It's my understanding that a
typical coal-fired plant produces around 500 megawatts. That's 12 million kWh
each day. You quote a figure of 8kWh to charge an electric car. If that 8kWh
is needed every day, then your coal plant gives you the ability to keep 1.5
million cars charged. If that 8kWh is _not_ needed every day, then you get
even more cars for the deal.

Now, shut down that coal-fired plant and replace 1.5 million (or more!)
electric cars with fuel-burning cars. Have you reduced overall emissions? I'm
not sure; but I think it is likely you haven't.

> Maybe we should all go out and buy electric cars. We will experience
> brownouts, electricity prices will soar, and it will be difficult. But
> hopefully it will start some change.

Or perhaps _some_ of us should buy electric cars. As the number of such cars
grows, electricity prices start rising. and then two things happen: (1) demand
for electric cars drops, and (2) pressure from the public makes it likely that
power-generation capacity increases. And then prices drop, and more people buy
electric cars .... So I don't really see the need for a gloom-and-doom
forecast.

In any case, as I said, an interesting piece. Please do more of them.

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danpalmer
Your second point is essentially what was being said. We probably don't want
everyone to buy an electric car right now, but we need enough that it forces
the changes to be made.

As for the car charging, I'm not exactly sure on the figures for a typical
coal-fired power station, but the UK has capacity for about 3 million electric
cars right now, although that would be pushing it, bringing us right up to the
maximum power generation we can handle. And remember, that's falling at the
moment as a few plants are being turned off.

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danpalmer
I don't do a lot of long form writing like this, and I feel I could improve
quite a bit, so if you have any comments about how I could improve this piece,
please let me know. Thanks.

~~~
mikeyouse
You could make mention of the efficiency of load balancing on the grid since
electric vehicles are almost exclusively charged at night during off-peak
usage.

Also, the entire essay is predicated on that first scary stat of people using
between 5-20kwh of electricity per day and the average car requiring 8kwh to
charge. It would be useful to note how many days that 8kwh charge are good
for, how many people does each car serve, etc. I.E. if that's a weekly charge
with 2 people per car, the incremental electricity usage would be 8khw / 2
people / 5 days -- pretty much noise at that point.

~~~
danpalmer
I don't have the references for the first statistic, but I trust that the
speakers know what they are talking about with it. And it seems a reasonable
statistic. Even if it's off by 20% or something though, the issue still
remains. I think you may be right in pointing out that some cars won't need
charging that much each day, but remember that the spare capacity in our grid
is very small, and 40% of energy (not electricity, just in general) usage goes
on transport. We can't just move that 40% to electricity.

