posted on Jan, 25 2013 @ 05:39 AM
Yet another "electric cars are not as green as gas" thread!
Let's put this in perspective:
In any complex system there are losses, the same goes for transmitting and using electricity. I don't know the exact figure but let's assume that
the 7% transmission loss stated in this thread is correct.
The charger for a modern electric car is not the simple, inefficient device you have for your AA batteries. Losing a few Watts there is not worth
bothering about as you save much more by not having to buy throw-away cells.
A well designed high power charger should be better than 90% efficient, it is possible to get up to 98% efficiency with current devices. The internal
losses are really very small.
The losses in the battery may well be 90%, and the motor/inverter system may also be only (ONLY!!!) 90% efficient. But that still gives a Power Plant
to Wheel efficiency of some 67% (multiply them together and include the transmission loss).
I think that you'll find that a modern power plant is in the region of 40 - 60% efficient, which drops the fuel to wheel efficiency to only 33%
(sorry I don't have the numbers handy as I'm on vacation - but I thought I'd put my comments in anyway. Anybody with real numbers please correct me
Compare that with the efficiency of a petrol or diesel car. You'll be lucky to hit 15% for petrol and 20% for diesel. And that is with the engine
running at optimum revs.
That's why a gas car needs a gearbox. You have to try to match the speed of the car with the most efficient speed of the engine. At all other engine
speeds you are running at less than optimum efficiency.
Reciprocating engines are horrendously inefficient! So Power Stations use the more efficient turbines to provide rotary motion. And these turbines are
designed to run at their optimum speed (maximum efficiency) all the time.
Producing Megawatts of power in one place means that it is much easier to scrub any resulting pollutants from the Power Station "exhaust" as well.
Everything can be optimised as you don't have a tiny mobile system to cope with.
Yes, cars have to be manufactured and that causes pollution as well. But an electric car, by its very nature, has far fewer parts in its construction.
The body panels will be very similar to those in an ICE car but the frame and support structure can be much simpler with fewer things to "bolt on".
Look at the "skateboard" chassis of Tesla's Model S, designed from the ground up as a pure electric car.
The batteries certainly contain some nasty materials but these are almost 100% recyclable at the end of the battery's life. They don't leave a trail
of pollutants behind them like a gas car!
So much for at least some of the "hidden environmental costs" of electric cars. What about the "hidden environmental costs" of oil?
It is very dishonest to talk about the pollution produced from a gas car by considering only the exhaust system. If you want to do a "Well to Wheel"
comparison then think about the hidden costs of oil.
It has to be mined (drilled), transported, refined and stored. Yes, these things apply to an oil powered power station and, in a similar way, to a
coal powered station. But electricity can be produced in many ways, and as the nation moves to more sustainable means of power production SO DOES THE
ELECTRIC CAR! You can't say that for the gas car.
Every nation has its own way to subsidise gas. If they didn't you would be paying many times the current pump price. But things like armies in
certain countries (to protect our interests, i.e. oil) and the occasional unfortunate oil spill (shame about the wildlife), not to mention the loss
and destruction of wildlife habitat are absorbed by other fundings or simply ignored.
Toyota estimated that it takes about 7.5kW of electricity to refine one gallon of petrol. Interesting - that same 7.5kW could take most electric cars
20 miles or more! Without any petrol!
Even if you look at the most pessimistic figures it's still far more efficient and environmentally friendly to produce power (electricity) in a small
number of relatively efficient large power stations than in millions of tiny very inefficient ones.
Then think of the "hidden cost" of health care that YOU pay for if you suffer from a health problem caused by those small power plants (gas cars)
driving past you every day!
And don't get me talking about the even worse fracking that Big Oil wants to use to get us tied to the Hydrogen pump! That's for another thread.