Quote:
Originally Posted by RobertSmalls
Per the metrics derived in the first post, the two methods of travel have a CO2 footprint that is equal. Looks like Dr. Samaras knew what he was talking about.
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His work you linked two actually makes a different claim.
Quote:
Results
Under the U.S. average GHG intensity of electricity, PHEVs
were found to reduce use phase GHG emissions by 38–41%
compared to CVs, and by 7–12% compared to HEVs
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He was using 2004 grid emmisions numbers ... the grid gets cleaner over time ... electrification of the transportation PHEVs and BEVs automatically benefit from.
Last ~10 years of Grid numbers are here:
Electric Power Annual - Summary Statistics for the United States
In the last ~10 years
CO2 / kwh has decreased ~11%
SO2 / kwh has decreased ~59%
NOx / kwh has decreased ~66%
The national U.S. fleet MPG went up ~6% in the last ~18 years.
BTS | Table 4-23: Average Fuel Efficiency of U.S. Passenger Cars and Light Trucks
The Grid kwh / mile is getting cleaner significantly faster... ~3.3x faster... than the MPG increases.
So not only is it already ahead today ... it is getting better faster for the future.
Quote:
Originally Posted by RobertSmalls
If you have a certain number of dollars to spend on environmental concerns, you'd be wrong to spend them on vehicle electrification before you first work on reducing the carbon intensity of your electric supply. The same goes for time you spend advocating for environmental causes.
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I am not putting up my own power plant any time soon... few people who live in apartments do.
So I do not have the option of choosing between PHEV and a RE power plant.
But when I get my next vehicle , I will have the choice between PHEV or spending 7% to 12% more GHG for a HEV ... or 38% to 41% more GHG for a CV.
His work also does not look at BEVs at all ... which would do better than the PHEVs in terms of kwh / mile ... and CO2 / mile ... the last metric of $ / mile , is still a bit up in the air for BEVs as the initial cost is still significantly higher, which might counter act allot of the $ / mile savings in fuel and operating costs.
But I do 100% agree with you , in that there is significant benefits to be had from 'greening up' ones electric supply ... but I disagree with saying that someone would be 'wrong' for choosing an option that is 7% to 12% GHG better from the grid , and can benefit later from greener electric supply.
I also personally put energy efficiency above GHG emissions ... they sometimes are one and the same ... but when they differ I usually side with energy efficiency.