GPowers
Well-known member
The Best Buy here in town also offer special parking spots for "Clean air Vehicles".
Wow, can we drop this yet? Yes, if you assume a 100% coal-powered EV, and compare it against the most efficient ICE vehicle in production, and ignore various externalities of gasoline production, and are only concerned with CO2/mile, the ICE wins. You win. Happy now?JRP3 said:Using his numbers, a Prius at 50mpg uses 2 gallons of gas for 100 miles...
:shock: Gary! Did you get shocked playing with the CHAdeMO port?!? =)garygid said:Oh, isn't that der kar one ov dem High-Bred v-hick "L"s?
But, I tink it don't uze no gaz a-tall, u-bet-cha!
Heh. Okay, then, JRP3: I have updated the information using data from the EPA, and the actual percentages of greenhouse gas emissions from the various types of power plants that make up our electric grid nationwide. Maybe you'll deem the results a bit more acceptable...?JRP3 said:The link was posted as a reference, I think it has some seriously flawed data and should not be used as a reference. To be clear I think his numbers come off much worse for EV's than they should, even though he mistakenly used 6kwh's of equivalent energy as coal powered electricity, which should have skewed things more in favor of EV's. I'll "win" when studies and comparisons use more accurate data.
One incorrect assumption about the LEAF numbers is the battery capacity of 24 kWh. Since only ~21 kWh is usable the kWh for full charge, using the listed efficiencies, would be 24/.87/.93 = 25.95 kWh for a full charge. The lbs. CO2 for a full charge would be 25.95*1.2283 = 31.87 lbs. CO2. Working though the rest of the steps gives 43.66 lbs. CO2 per 100 miles using a grid average CO2 output.Yanquetino said:
True! But the grid mix I cited is *not* specified for only daytime hours. So while there might be more coal at night, there might be less coal in the day. I can only assume that the percentages listed represent a 24-hour "average." Do you have data showing different percentages for day and night?JRP3 said:Yes that seems more in line, and puts a Prius only slightly below a grid mix charged LEAF for CO2 emissions.
http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=31715&id=31767&id=32154&#tab2" onclick="window.open(this.href);return false;
The only caveat of course is if you assume night time charging which is not the same as grid mix and skews more heavily towards coal and higher CO2 emissions.
I don't think that's correct. I have already included the "useable" charge in my figures, but it is not readily apparent on the surface. You see, I am basing my calculations on the EPA's 73 mile range for the Leaf, which already depends upon it "useable" charge --not the full 24 kWh. Moreover, even though only the useable 21 kWh achieves that range, the EVSE is putting 24 kWh into the pack. Hence, backing up the lines to the power plant, the amount of CO2 it produces is still based on 29.66 kWh.dgpcolorado said:One incorrect assumption about the LEAF numbers is the battery capacity of 24 kWh. Since only ~21 kWh is usable the kWh for full charge, using the listed efficiencies, would be 24/.87/.93 = 25.95 kWh for a full charge. The lbs. CO2 for a full charge would be 25.95*1.2283 = 31.87 lbs. CO2. Working though the rest of the steps gives 43.66 lbs. CO2 per 100 miles using a grid average CO2 output.
Not true I think. If 3 kWh of the pack is not accessible you don't have to replace it when charging*. The 73 miles of range comes from, at most, ~21 kWh of energy added to the battery pack after being fully depleted to turtle (not including efficiency losses that you calculate separately).Yanquetino said:I don't think that's correct. I have already included the "useable" charge in my figures, but it is not readily apparent on the surface. You see, I am basing my calculations on the EPA's 73 mile range for the Leaf, which already depends upon it "useable" charge --not the full 24 kWh. Moreover, even though only the useable 21 kWh achieves that range, the EVSE is putting 24 kWh into the pack. Hence, backing up the lines to the power plant, the amount of CO2 it produces is still based on 29.66 kWh.dgpcolorado said:One incorrect assumption about the LEAF numbers is the battery capacity of 24 kWh. Since only ~21 kWh is usable the kWh for full charge, using the listed efficiencies, would be 24/.87/.93 = 25.95 kWh for a full charge. The lbs. CO2 for a full charge would be 25.95*1.2283 = 31.87 lbs. CO2. Working though the rest of the steps gives 43.66 lbs. CO2 per 100 miles using a grid average CO2 output.
Hmmm. The more I thought about this, the more I think you're right, dgpcolorado. I was stuck on thinking of the Leaf's battery pack as fresh from the assembly line, totally empty --which would take the full 24 kWh to fill it for the first time. Yet it is true that, after being driven for its full 73 mile range, there would still be 3 "unuseable" kWh in that pack. So charging it with the EVSE would only put 21 kWh back into it.Yanquetino said:I don't think that's correct. I have already included the "useable" charge in my figures, but it is not readily apparent on the surface. You see, I am basing my calculations on the EPA's 73 mile range for the Leaf, which already depends upon it "useable" charge --not the full 24 kWh. Moreover, even though only the useable 21 kWh achieves that range, the EVSE is putting 24 kWh into the pack. Hence, backing up the lines to the power plant, the amount of CO2 it produces is still based on 29.66 kWh.dgpcolorado said:One incorrect assumption about the LEAF numbers is the battery capacity of 24 kWh. Since only ~21 kWh is usable the kWh for full charge, using the listed efficiencies, would be 24/.87/.93 = 25.95 kWh for a full charge. The lbs. CO2 for a full charge would be 25.95*1.2283 = 31.87 lbs. CO2. Working though the rest of the steps gives 43.66 lbs. CO2 per 100 miles using a grid average CO2 output.
We don't know if the EPA's "upstream" emissions for gas cars include everything that should be included (drilling, extracting, pumping, etc.), although one response to my web page claimed that its information comes from the GREET model --which supposedly is pretty comprehensive.garygid said:Beats the Prius a lot on what is added to the local pollution.
Did the gas "long" tailpipe count all the evaporation and spillage along the way?
How about the gas/oil used in "oil" wars and the production of war materials for those wars?
How about the training and maintaining of forces anticipating those wars?
How about the energy and pollution "costs" of building and maintaining the oil/gas supply line, storage, and delivery: in ships, tanks, pipes, trucks, and their support and supply?
Without the "black opium" industry to support, a HUGE section of the world's economy could be devoted to better things: perhaps building and maintaining parks!
Yanquetino said:Whoa...! Here is a widget from SMUD to compare CO2 lbs. between EVs and ICEs:
http://c03.apogee.net/contentplayer/?utilityid=smud&coursetype=misc&id=18862" onclick="window.open(this.href);return false;
The differences between my software's results and what this widget tallies are enormous! They can't be right, can they? Am I missing something here?
I can't find solid data, but "grid mix" uses available generating capacity, much of which is shut down, or turned down at night.Yanquetino said:True! But the grid mix I cited is *not* specified for only daytime hours. So while there might be more coal at night, there might be less coal in the day. I can only assume that the percentages listed represent a 24-hour "average." Do you have data showing different percentages for day and night?
My understanding of the grid does not support that assumption. NG plants do not keep "smokin' away at night", they throttle way back or shut down. Coal plants also throttle down some. Nuclear is baseload and keeps putting out close to rated power I think. Hydroelectric is tricky, as it's both baseload and peak load. Hydro can be throttled back at night to bank up capacity for peak use during the day, that way peak hydro, which is cheap, can be used instead of peak NG, which is more expensive. So while hydro might be able to throttle back up in some areas at night to fill in the extra load of a fleet of EV's plugging in, it's more likely that coal will be kept up higher at night to allow the hydro to be banked for daytime peak loads. Bottom line is it appears that most additional night time marginal load will be provided by coal in many areas, pushing the over all CO2 mix for night charged EV's higher than the overall grid mix.And my point down below on the page still stands: those "long tailpipes" are still smokin' away at night anyway, whether not EV owners are charging their vehicles. Consequently, they're not "adding" to the amount of CO2 produced: they're merely putting the excess energy to good use rather than wasting it.
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