LEAF creates less CO2 than Prius in W. US and Texas, more in N. Midwest

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GRA

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Researchers find Nissan LEAF creates less CO2 than Toyota Prius hybrid in west US and Texas, but more in N. Midwest
http://www.greencarcongress.com/2015/07/20150701-cmu.html

This joins a long list of studies that show the electricity generation mix is crucial to determining whether or not there's an improvement in GHGs from a PEV. However, this one also concludes that delayed charging overnight is a bad idea in many regions, as much of the baseload is coal-fired and may result in increased GHGs. It also says that the Volt's life cycle GHGs are worse than the Prius in much of the U.S. The study info is here: http://pubs.acs.org/doi/suppl/10.1021/acs.est.5b00815/suppl_file/es5b00815_si_001.pdf
 
I've always struggled with what is the best time to charge.
If you are looking only at the power for the car, charging in the Midwest overnight when coal is being burned is worse that daytime when natural gas peak plans are being used.
However, utilities would love to smooth out demand. Using off peak power rather than peak helps delay the need for new power plants.

Of course, if you are using solar, do you charge while the sun s shining, or do you not, and allow your neighbors to use your excess solar power?

The fact that our cars get cleaner as the grid does s one of the things I love about EVs.
 
Zythryn said:
I've always struggled with what is the best time to charge.
If you are looking only at the power for the car, charging in the Midwest overnight when coal is being burned is worse that daytime when natural gas peak plans are being used.
However, utilities would love to smooth out demand. Using off peak power rather than peak helps delay the need for new power plants.

Of course, if you are using solar, do you charge while the sun s shining, or do you not, and allow your neighbors to use your excess solar power?

The fact that our cars get cleaner as the grid does s one of the things I love about EVs.
Some more info: http://www.cmu.edu/epp/policy-briefs/briefs/Electric-Vehicles-Costs-Benefits.pdf
 
Correct me if I'm wrong, but it seems to me that they are ignoring the fact that currently baseload power plants run overnight, regardless of whether the electricity is used. Whether or not an EV is charged, it is emitting CO2 and other pollutants. Instead of counting that pollution against the EV, they should be looking at incremental pollution due to the EV charging. For the current low take-rates, the incremental pollution is zero. zilch. nada. In fact, studies have shown that we could power something like 70% of light-duty passenger vehicles in the US just on the electricity that is wasted overnight.

Combined with the fact that EVs get cleaner as the grid gets cleaner (and we do need to keep cleaning up our grid), I don't think we'll ever be at a point where a LEAF is dirtier than a Prius.
 
GetOffYourGas said:
Correct me if I'm wrong, but it seems to me that they are ignoring the fact that currently baseload power plants run overnight, regardless of whether the electricity is used. Whether or not an EV is charged, it is emitting CO2 and other pollutants. Instead of counting that pollution against the EV, they should be looking at incremental pollution due to the EV charging. For the current low take-rates, the incremental pollution is zero. zilch. nada. In fact, studies have shown that we could power something like 70% of light-duty passenger vehicles in the US just on the electricity that is wasted overnight.

Combined with the fact that EVs get cleaner as the grid gets cleaner (and we do need to keep cleaning up our grid), I don't think we'll ever be at a point where a LEAF is dirtier than a Prius.
It again depends upon the focus of the study.
You have to remeber they are going off the standard grid.
they are using 2009-2010 grid data.

They do not include any personal electrical generation such as solar panels or purchasing wind credits.

They really can't though, as those are individual decisions. They could report on percentage of EV owners that take such measures.

One of our groups of utility cooperatives just announced that everyone that gets the EV TOU meter and billing will automatically get free wind credits for it. If more companies started doing that you may be able to fold it in to a study like this.
 
GetOffYourGas said:
Correct me if I'm wrong, but it seems to me that they are ignoring the fact that currently baseload power plants run overnight, regardless of whether the electricity is used. Whether or not an EV is charged, it is emitting CO2 and other pollutants. Instead of counting that pollution against the EV, they should be looking at incremental pollution due to the EV charging. For the current low take-rates, the incremental pollution is zero. zilch. nada. In fact, studies have shown that we could power something like 70% of light-duty passenger vehicles in the US just on the electricity that is wasted overnight.

Combined with the fact that EVs get cleaner as the grid gets cleaner (and we do need to keep cleaning up our grid), I don't think we'll ever be at a point where a LEAF is dirtier than a Prius.

Exactly. All these studies just add up the potential GHGs generated per kWh without taking into account how the grid actually works. It's going to be a long time before EVs have a measurable impact on the grid while having real measurable impact on GHGs generated from burning gasoline.

Just consider time of day pricing. My utility offers 20c/4c kwh time of day pricing to encourage people to use more energy at night. They do this because otherwise the utility spends on baseload without use.
 
These "studies" all fail to take the energy overhead of the gasoline into account.

It takes between 7.5kWh and 13kWh per gallon of gasoline to produce; depending on the crude you start with. And guess what? That electricity would power an EV between 25-60 miles.

So, the long tailpipe argument against EV's is moot. Every time someone trots out this cliched idea, we need to take it with a very large grain of salt.
 
NeilBlanchard said:
These "studies" all fail to take the energy overhead of the gasoline into account.

It takes between 7.5kWh and 13kWh per gallon of gasoline to produce; depending on the crude you start with. And guess what? That electricity would power an EV between 25-60 miles.

So, the long tailpipe argument against EV's is moot. Every time someone trots out this cliched idea, we need to take it with a very large grain of salt.

Excellent point. Although the numbers you quote are much higher than the 6kW I have seen in studies. Still, 6kW can power an EV 20 miles, more than half what a typical ICEV gets from a gallon, effectively cutting its footprint at least in half (while simultaneously increasing that of the ICEV).
 
NeilBlanchard said:
These "studies" all fail to take the energy overhead of the gasoline into account.

It takes between 7.5kWh and 13kWh per gallon of gasoline to produce; depending on the crude you start with. And guess what? That electricity would power an EV between 25-60 miles.

So, the long tailpipe argument against EV's is moot. Every time someone trots out this cliched idea, we need to take it with a very large grain of salt.
My recollection from when this topic was debated years ago was that it takes a considerable amount of energy to refine gasoline, but that relatively little of it was electricity. Most is natural gas, often used in co-generation, as well as other fuels from the refining process. The result was that the listing of energy use, in refining oil to gasoline, in "kWh" was misleading people into thinking that it was the direct electricity use. It's not that simple.


Edit: Fixed typo by adding missing word.
 
Zythryn said:
...Of course, if you are using solar, do you charge while the sun s shining, or do you not, and allow your neighbors to use your excess solar power?...
I tend to charge my car at midday to use my solar generation directly (if it is a sunny day). Although my car draws a bit more power than my panels can produce, a number of neighbors also have solar that they aren't using at midday, so I am using a slight bit of theirs as well (I have the only BEV in my county, so other EVs aren't a factor).

I suppose the decision is helped by the fact that I'm not on a tiered rate and midday is off-peak in this location anyway.
 
dgpcolorado said:
NeilBlanchard said:
These "studies" all fail to take the energy overhead of the gasoline into account.

It takes between 7.5kWh and 13kWh per gallon of gasoline to produce; depending on the crude you start with. And guess what? That electricity would power an EV between 25-60 miles.

So, the long tailpipe argument against EV's is moot. Every time someone trots out this cliched idea, we need to take it with a very large grain of salt.
My recollection from when this topic was debated years ago was that it takes a considerable amount of energy to refine gasoline, but that relatively little of it was electricity. Most is natural gas, often used in co-generation, as well as other fuels from the refining process. The result was that the listing energy use, in refining oil to gasoline, in "kWh" was misleading people into thinking that it was the direct electricity use. It's not that simple.
Yes, yes, yes. +1+1+1. This is one of those "reverse myths" of why EVs are better than ICEs that (we) advocates need to stop spreading. It only hurts the cause (when it is inevitably called out) and is completely unnecessary for making the case.

An old thread which went into a lot more detail (the chemical engineer who works at a refinery placed the number at less than 1kWh/gallon):


Happy Fourth!
 
How is natural gas any better than electricity of the concern is emissions?
 
Uh, for heating purposes, natural gas is probably at least twice as efficient as electricity, on average. Thus, half the emissions.

And burning the byproduct gases of refining (which the CE says offsets NG) is many times more so.

I imagine that the great majority of the refining process that can only be done using electricity is in pumping.
Alric said:
How is natural gas any better than electricity of the concern is emissions?
 
Alric said:
How is natural gas any better than electricity of the concern is emissions?
That is irrelevant to the point.
If someone says "refining gas takes 6 kWh of electricity", that is easily refuted. The person that stated that then looses credibility, not only on that specific statement, but anything else they say.

There is no need to exaggerate, the truth is plenty.

Most refineries use many kWh worth of energy to refine a gallon of gasoline. F that power were instead used in electric cars...
 
The irony is that people who have no itention of EVER buying a Prius, will use this as an argument against electric vehicles. :roll:
 
You guys are missing the forest for the trees. Why separate electricity use from NG or other forms of energy when discussing gasoline generation? NG could be used to generate kWh which would be more efficient if user to move EVs.

The point is that these lifecycle studies nickel and dime EVs while ignoring huge sources of emissions in gasoline production and ICE manufacturing.

Not to mention the impact of EVs at this point on baseload is nothing. It's going to take a lot more EVs to adjust baseload.
 
Nubo said:
The irony is that people who have no itention of EVER buying a Prius, will use this as an argument against electric vehicles. :roll:
The problem is that you can't really "call them on it" -- i.e., point out the irony or contradiction by observing, 'Oh so you actually do care about emissions and the environment then?' -- since they can always claim that no, they still don't care, but rather are just using the numbers and facts (if they were such) to point out "our" hypocrisy. And that would be a legitimate argument and consistent 'stance' if indeed electricity generation were* as bad as they pretend or hope it were*.

OTOH, I doubt many have thought it through that far, so yes, it is still ironic! ;-)


* 'were', or 'was', or 'is'?? I'm still never fully confident about use of the subjunctive mood in English! :)
 
Alric said:
You guys are missing the forest for the trees. Why separate electricity use from NG or other forms of energy when discussing gasoline generation? NG could be used to generate kWh which would be more efficient if user to move EVs.

The point is that these lifecycle studies nickel and dime EVs while ignoring huge sources of emissions in gasoline production and ICE manufacturing.

Not to mention the impact of EVs at this point on baseload is nothing. It's going to take a lot more EVs to adjust baseload.

I agree with ou for the most part"
All I am saying is that if you use a faulty argument, you weaken, rather than strengthen, your own case.

The tobacco, climate change and anti-EV crowds have gotten very good at picking holes in specific arguements in order to dismiss the larger issue. Don't give them ammo by exaggerations.
 
Alric said:
You guys are missing the forest for the trees. Why separate electricity use from NG or other forms of energy when discussing gasoline generation? NG could be used to generate kWh which would be more efficient if user to move EVs...
Yes, and no. While NG, and other fuels from the refining process, could be used to generate electricity, doing so would be fairly inefficient. You don't get 5 kWh of electricity from 5 kWh of NG, by way of example. Not even close. So, don't assume that the kWh of energy used to refine oil into gasoline is directly comparable to the same amount of electricity. It is not.

While it is fine to point out the inefficiencies of gasoline, as measured from oil well to tailpipe, it isn't helpful to exaggerate the amount of electricity used in the process. As others have pointed out above.
 
There's been a lot of comments that this study ignored upstream GHG and energy costs of gas when making its comparison. This flies in the face of this group's past studies, which all take this into account. It also ignores the statement in this study:

Table S1 summarizes the data sources for
emissions rate used to compute emissions for each life stage. These include vehicle upstream, manufacture, and assembly; battery upstream and manufacturing (Lithium-ion); gasoline upstream and distribution; gasoline combustion; electricity upstream; and electricity production.
It's perhaps more than I should expect, but it would be nice if people read the actual reports, which I always try and provide a link to (as I did in this case), before making uninformed claims. Utopian, I know.

Speaking of past studies by this group at C-M, for those who have never read it or have forgotten about it, I recommend this 2009 report, a sensitivity trade-off analysis:
Impact of battery weight and charging patterns on the economic and environmental benefits of plug-in hybrid vehicles
http://www.cmu.edu/me/ddl/publications/2009-EP-Shiau-Samaras-Hauffe-Michalek-PHEV-Weight-Charging.pdf

From the abstract:
Plug-in hybrid electric vehicle (PHEV) technology is receiving attention as an approach to reducing US
dependency on foreign oil and greenhouse gas (GHG) emissions from the transportation sector. PHEVs
require large batteries for energy storage, which affect vehicle cost, weight, and performance. We
construct PHEV simulation models to account for the effects of additional batteries on fuel
consumption, cost, and GHG emissions over a range of charging frequencies (distance traveled between
charges). We find that when charged frequently, every 20 miles or less, using average US electricity,
small-capacity PHEVs are less expensive and release fewer GHGs than hybrid electric vehicles (HEVs) or
conventional vehicles. For moderate charging intervals of 20–100 miles, PHEVs release fewer GHGs, but
HEVs have lower lifetime costs. High fuel prices, low-cost batteries, or high carbon taxes combined with
low-carbon electricity generation would make small-capacity PHEVs cost competitive for a wide range
of drivers. In contrast, increased battery specific energy or carbon taxes without decarbonization of the
electricity grid would have limited impact. Large-capacity PHEVs sized for 40 or more miles of electric only
travel do not offer the lowest lifetime cost in any scenario, although they could minimize GHG
emissions for some drivers and provide potential to shift air pollutant emissions away from population
centers. The tradeoffs identified in this analysis can provide a space for vehicle manufacturers,
policymakers, and the public to identify optimal decisions for PHEV design, policy and use. Given the
alignment of economic, environmental, and national security objectives, policies aimed at putting
PHEVs on the road will likely be most effective if they focus on adoption of small-capacity PHEVs by
urban drivers who can charge frequently.
This nice thing about it is that it remains valid today, since it takes a base case and also high and low values for a whole range of factors and shows how they affect both life cycle cost and GHGs.
 
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