Most Comprehensive Study Yet On Environmental Impact of Electric Vehicles

An anonymous reader writes: A few articles came out Thursday talking about the recently released report from the National Bureau of Economic Research on the environmental benefits of electric cars. The general consensus is kind of obvious -- that it depends on the ratio of coal vs. clean electrical generation that is used to charge your car. What is interesting is the extent to which it makes a difference, and that when viewed on a regional basis, there are cases where the EV doesn't do so well. And when it comes to policy decisions, it seems the central focus needs to be on the replacement of large-scale coal generation, and the rest will fall in to place. Here is one cover story from Ars Technica. Google others for varying perspectives.

Comments

Re:I see theyre using the Step 2 profit model

[michelcolman]

Yes, just a few weeks ago an article was posted here on Slashdot saying that the amount of electricity needed to pump up, refine and transport gasoline is about the same as that consumed by an electric vehicle for the same distance. So when you have finished filling up your gas tank, you have already used the same amount of electricity as the electric car and you haven't even started burning the fuel yet. Did this "study" take that into account?

Add to that the fact that pollution for electricity generation normally happens outside population centers. You should see the smog produced by cars in front of my kids' school on a foggy morning. I can't wait for all cars to be electric.

Solar rocks

[fyngyrz]

The sun is always shining. What you mean to say is that the sun is not always visible due to clouds or fog, or on the side of the planet that would be optimum for power generation when the sky is clear. I'm not just being pedantic. Because:

Although that is all factual, the idea that solar does not generate power when when not in direct sunlight (cloudy, foggy, shaded, etc.) is wholly incorrect.

Solar works all day, every day, no exceptions. Rather than "not work", it varies in efficiency, and not so much that it doesn't remain useful when it is cloudy; efficiency of a well aimed system on cloudy days varies from about 20% to 50%, depending on the tech in the panel and just how dense the occlusion is. Here's a back-yard demonstration of exactly that. (TL;DW -- he gets about .6 amps out of his 4-amp panel on a cloudy day, without aiming: about 15 % efficiency.)

The more exposure and better angle you have, of course, the better it all works. But clouds and fog... facts of life. Yet you can still get all the energy you need from a solar system on days that aren't perfectly clear. You can even plan for it, and build in enough overcapacity (with full sunlight in mind) so that you always have enough power.

Concrete example: I have a small trailer that I have some 12 vdc ham gear in. It has lights, a refrigerator, and a 100-watt HF transmitter that pulls about 200 watts, worst-case. On the 10x6 roof, I have 6, (nominally) 100 watt solar panels. Minimum I've *ever* seen out of them at midday, on a cloudy winter day, is about 6 amperes. That's about 90 watts of continuous charge. I never, ever run out of power. Sunny days I have ridiculous amounts of excess power available, and I run an air conditioner or a heater with it.

I have an (unfortunately large, this tech isn't really where it needs to be yet) bank of ultracaps in the trailer. No batteries. I also run LED lighting and a very efficient small refrigerator. Surge power to start the compressor is no problem - the ultracaps can deliver far more than is required. Once running, the fridge's power draw is negligible. The charge and supply electronics are of my own design (ultracap discharge slopes aren't like batteries, so you need something significantly more complex than a wire and a fuse) and no doubt they could be improved, but I have never run out of power and I transmit quite a bit at times.

I've also gone out at night and done many hours of shortwave dx'ing (in the country, away from the town's copious RFI), lights on, opening the frig once about every half hour, and not run out of power.

My home's main roof area is 60x45. That's room for about 360, 100-watt panels, or about 36,000 watts of peak capacity. At 80% derating -- what we can anticipate on a really, really overcast day -- peak output is still about 7,000 watts. Quite usable for lighting and light duty loads. the pacemaker will get charged. :)

My house is very well insulated, too, so that's a bonus, heating- and cooling-wise.

Solar is the way to go. Period. All those rooftops, all those square miles of empty space, just waiting for us to get in gear.

Currently, individual ready-to-mount 100-watt solar panels are about $135 on Ebay, with a 25-year warranty. less in quantity. The math is quite compelling, even with the major shortcomings of battery lifetime. Set up a small system to run something. Learn the basics and work through it so you understand it. Batteries, charge controllers, panels, aiming and auto-aiming and either low voltage client devices like my trailer system, or an inverter and the usual type of 120 vac power clients. If you do, I suspect your enthusiasm level will change dramatically for the positive. There's something ultimately satisfying about spending money on YOUR infrastructure and giving the bird, even if it's a very small bird, to the power company.