EV's: They're Only as Green as Your Grid's Fuel

This is like saying anyone wanting to drive a Prius should
- Make sure the oil comes only from sweet crude with a very high EROI
- Make sure the oil comes from non-conflict regions where they do not rape/kill the environment (and/or the people as well) for oil
- Make sure the oil money does not go to a middle east government / royal family whose corrupt members are known to pay off terrorists to keep peace or worse actually fund them

I'm sure I missed quite a few others.

Oh, BTW, did you know the energy used to refine a gallon of oil can drive your EV a good 20 miles ?

 

I have to love the double and triple standards. For me green house gas way down on the list when it comes to energy comparisons. Ignoring the economic, political, and health reasons for ev's lets look at one small other thing. With or without ev cars coal power contributes 40% of greenhouse gases in the US. Making the grid cleaner is a different environmental fight. Putting ev and phev cars on the grid frees us from dependence on foreign oil and reduces pollution in our congested cities.

And how much GHG is produced from canadian shale? When an ev or phev is charged at night with excess power needed to keep the plants running for the next day, hydro, and wind they produce 0% of the co2 of a prius. But let's look at your city. If charged during the day the marginal load for ev vehicles is NG. When charged at night you likely are using slack capacity. NM is not building any new coal plants to cover excess demand for ev. The NM is planning to add renewable energy to make it 20% of the grid in 2020. There may be a place where coal will be added for increased ev or phev use, but I don't know of it. Your constant use of tailpipe for power plant emissions is more troubling. According to the EPA ev and phev would reduce air pollution for 80 people for every 3 people affected by increased power plant pollution. This research was assuming that new power plant emissions standards did not increase. By 2020 their may be sequestration for these coal and gas power plants. With sequestration GHG levels drop 90%. If you are driving a gasoline powered car enhancements to the grid do nothing to reduce your pollution. The average car before cash for clunkers was held for 16 years. Doesn't making a phev prius available make sense from a pollution point of view?

I was looking at their data not their pov. Given current laws and trends ev and phevs are cleaner than gasoline powered cars. Cleaning the grid is its own reward, but not doing one because you are not doing the other makes no sense.

 

Running a coal plant at night with excess capacity is not equivalent to free energy.

We have discussed NIMBY'sm before. You think it has merit, I do not.

 

You know I had to look up NIMBY, as I didn't know what it was. I did quote the epa, but I'm sure that labeling me is more important than looking at information, reading it, or comprehending it.

You could read darelldd or evnow's coments as you might allow some of the thoughts to sink in.

Please call pnm and ask them how much co2 would be created if 800,000 kwh a day of demand were added at night during low demand hours. That is enough power to drive 100,000 ev and phev more than an average of 30 miles a day. If they give you the information you will find it is much lower than your predicted coal rate.

 

Dogmatic and not relevant to the effciency/pollution issue with EVs and grid power source.

 

this wouldn't apply to me since half of arizona gets its power from a nuclear power plant. no greenhouse gases there =)

 

Why do I have to do this in some sequence? Everyone that I know on Prius Chat that drives an electric car also conserves and makes purchases based on long term effects......all at the same time. Seems like a very good example to follow now, not tomorrow.

 

Prius is a better buy than other ICE cars because of the efficiency improvement, not because it runs on cleaner fuel.

Because their well-to-wheel efficiency on a mixture of coal and NG is not better than a Prius well-to-wheel running on petrol; and in fact, the tailpipe/smokestack emissions are worse. Much worse.

I want your set-up, an EV and the home PV to run it. But here is the point where we differ: I do it for my own ethos, so that I can say I am handling my own use cleanly. But I am aware that the only good I did on a public scale was the PV; my EV car use rather than Prius is a net zero (or less) improvement on environmental grounds. This is apparently a subtle point, and lost on people with a rigid ideological viewpoint.

As an aside, I find your conservation tactics vastly more compelling than the EV demagoguery. And of course I salute your PV, like any greenie.

 

I have not understood your point yet. However, bear with me because I like to stay respectful even if I don't understand.

EV's can be part of a sustainable transportation solution. Fossil Fuel vehicles cannot be part of a sustainable transportation solution. I fully understand that EV power that comes from an unsustainable fossil fuel power plant is....unsustainable. But that is not the fault of the EV, its totally an issue with the power station. So why is it that you call someone supporting one of the elements of a sustainable future (the EV) as having a "rigid ideological viewpoint"?

 

This really doesn't make any sense. You basically have to have all coal fired power for an EV to compare to a hybrid and does that argument taking into account the fact that you're comparing inputs to outputs? If you consider the entire fuel chain of each type of vehicle I'd be willing to bet that the EV still comes out ahead because the vehicle itself has no emissions. So you're really comparing the all coal fired supply chain to the well to wheels emissions of the HV. Like FL Prius mentions, the EV can run on electricity and it's fuel source agnostic. If we green up the electricity infrastructure, the EV emissions drop.

 

Sage -

I have to admit that I'm pretty confused about some of your comments - and that means my responses may not be on point. I'm just aiming at the target I see - Might not be the right one!

OK. So does it then follow that an EV is a better buy than a Prius becasue the efficiency improvement is from cleaner fuel? My Prius runs on gasoline. My EV runs on sunshine. Now that my system is paid off, and the energy input of my PV system is repaid - my fuel costs nothing, and pollutes not at all. For me, the EV is a "better buy" because of the cleaner fuel.

So why don't we compare the tailpipe/smokestack emissions for EVs that run on solar power - as half of the currently-owned production EVs do? Which is "much worse" in that secenario?

As others have pointed out, and EV can be fueled from almost any feedstock. It could be wind, tidal, solar, hydro, nuke... even gasoline if we wanted to be silly. A gasoline car doesn't have this choice. Gasoline cars *always* pollute. EVs don't. And mine doesn't.

Thanks! Conservation is always job #1 around here. And while I talk up hybrids to the Joe Sixpack crowd, I tend to talk up EVs to he Prius crowd, and I tend to talk up bicycles to the EV crowd. My audience definitely changes my message because nobody wants to take anything beyond baby steps.

If I were Supreme Ruler of All, we wouldn't even be talking about the best personal automobile technology for the planet. We'd be discussing the best personal transportation options - and that does not typically include the personal automobile - no matter how it is fueled.

 

Can you post your numbers?

At least on a national scale, looking at CO2/NOx emissions - EVs appear to be much cleaner than the Prius.

Data on this page is for NEVs, but NEV efficiency isn't much different than the reported EV efficiency of ~4mi/kWh.

http://www.lincolnev.com/nevcleaner.html

 

Darrell, Tripp, and FL_Prius_Driver,

Thanks for the question. Since the three of you raise a similar question I'll try to answer in one go, first with argument about relative wtw efficiency of petrol, NG, and coal, and then present my reasoning why the respective efficiencies make EV as attractive an alternative as Prius, but not more than Prius.

First then, Well-to-wheel(wtw) efficiency: Petrol has about a 20-30% energy loss from ground to tank, and then TD of the Prius powerplant is about 27-33%, for a wtw efficiency of 26-19%. Coal varies in its end combustion CO2/btu density, but on average it is about 100% higher than NG, while petrol is 47% higher**. TD combustion of coal is about 33% efficient, but does not include powerplant power use of 11%, tank to wheel about 90%, transmission to local utility about 92%, home to car about 95%, as well as mining and transport to plant energy costs. I do not know details of the NG line, except to say that powerplant efficiency tends to be higher. *
I think it fair to say that wtw EV-coal GHG is higher than petrol-Prius, while NG is lower. Note that although petrol starts out with a 50% GHG excess over NG in powerplant combustion, by the time wtw is calculated, the excess from petrol has dropped to 15%.

From here it stands to reason that an EV that runs only on coal is inferior to a Prius, than an EV that runs only on NG 13% better in GHG than Prius (and much better 'tailpipe' emissions). So the question left to answer is: what is the source fuel ? I argue that it is at best NG, at worse coal, and as a matter of daily use, somewhere in the middle. No way, I can here you saying: part of the grid is clean! Consider this example:

1)I run a home that consumes 600 kwh a month, on a grid that is 90% coal and 10% clean; and in addition run a Prius that consumes 200 kwh a month at the wheels.
If I equate petrol with coal, I consume 60 kwh of clean energy and 740 kwh dirty.
---
2)I now set up PV that produces 300 kwh a month. Notice, this is more than my Prius uses.
Now my home uses 360 kwh of clean energy, 240 kwh or dirty energy, and
my car continues to consume 200 kwh of dirty energy at the wheel. Cool, I have displaced 200 kwh of dirty energy, and now consume 440 kwh of dirty energy.
---
3)Now I choose to park the Prius, and run an EV that consumes 200 kwh at the wheel.
The EV runs off my PV -- no problem. But only 100 kwh are left to use on my house, so it is back up to 440 kwh of dirty energy.

Going from 1) to 2) was great; 2) to 3) didn't decrease emissions at all, it just changes where my clean energy is consumed. Extrapolating out, this means that until the grid is 100% clean AND can supply additional demand with clean energy, EV will not decrease emissions as Prius replacements.

There you have my argument. I would actually like to be wrong but each time I think about it I come to the same conclusion. This week I was a bad host and forced my Physics prof buddy (and greenie) to listen to my argument. He could not immediately see an error, but has requested time to mull it over. I give him that time

Darrell, I smiled when I read that you encourage your EV buddies to bicycle. That is brilliant! It also happens to match exactly my perspective that conservation and clean energy production that displaces fossil fuel consumption are the only two things that make a real difference today, and for quite a few years into the future.

Cheers, looking forward to reading your comments.



* I have posted in another thread links to petrol refinery energy costs, and I think a very well researched report from CA that concludes that the wtw GHG of NG is 13% less than wtw Prius.
** Wikipedia: Electricity generation using carbon based fuels is responsible for a large fraction of carbon dioxide (CO2) emissions worldwide and for 41% of U.S. man-made carbon dioxide emissions.[14]. Of fossil fuels, coal combustion in thermal power stations result in greater amounts of carbon dioxide emissions per unit of electricity generated (2249 lbs/MWh[15]) while oil produces less (1672 lb/(MW·h)[16] or 211 kg/GJ) and natural gas produces the least 1135 lb/(MW·h) (143 kg/GJ).US EPA Clean Energy—Gas</ref>)

 

Just to follow up with some numbers of my own. Numbers don't include the EROI of the fuel involved - just the burning of it. Shouldn't matter much since most EROI numbers seem to be similar in most cases:

Prius CO2 emissions: 200g/mi
Coal plant CO2 emissions: 1000g/kWh
Gas plant CO2 emissions: 400g/kWh

So an EV which travels 4 mi / kWh
Coal: 250 g/kWh
Gas: 100 g/kWh

So comparing a Leaf to a Prius - the Leaf can have up to 25% higher CO2 emissions if 100% if your electricity comes from coal or 50% lower CO2 emissions if your electricity comes from gas.

So unless your electricity company generates 75% or more of it's marginal electricity using coal, your CO2 emissions are lower with the Leaf (assuming that the other 25% is gas or other low CO2 generating sources).

Claiming that having to wait until 100% of the grid is "clean" to make it worth while (from an emissions standpoint) to move to EVs is a fallacy.

I would argue that any area which has a CO2 / kWh less than 800 g / kWh (1.76 lbs) would very likely benefit from a Leaf compared to a Prius.

Here's a list of state's CO2 emissions / kWh: http://www.eia.doe.gov/oiaf/1605/ee-factors.html

Not many above 1.76 lbs/kWh and many are substantially lower - see Pacific Coast who's CO2 emissions are 0.45 lbs/kWh - coincidentally where the primary launch areas for EVs happen to be.

 

Really interesting stuff this - even if I'm struggling to keep up. I have a couple questions though;

What about other countries where their mix of electricity generation differs? Canada where hydro is prevalent or France where nuclear is top? Also, not sure if you have a similar system to the one in the UK, but here you can choose your supplier with an option of how the supplier generates their electricity. So say I choose a supplier that provides only wind electricity, will that be a clean option to power a Leaf? Presently my home electric provider guarantee 80% wind power.

 

Then you're even better off, emissions wise. Enjoy your clean EV driving.

 

Sagebrush-Thanks for your clear response. I can see where my viewpoint diverges completely. All of your analysis is based on the here and now. My viewpoint is based completely on decades from now. Some specifics-

1-The present power plant mix determines your calculation baseline. The new power plant construction mix determines mine. Today your calculations hold water. 20 years from now, they will not.

2-The energy consumption of EVs on the road now is a trivial percentage of transportation gas energy consumption. If they are not developed and sold now, when your scale is tipped to the EV's favor, they will not be there in the numbers needed for a significant gas use reduction. Note that it was over 10 years ago that the Prius was introduced, so 20 years is rather little time to get significant EV production in place.

3-You completely leave out the economic pressure of gas and coal price increases and lower prices from solar/wind/battery technology development. The future numbers can only change in one direction. Also left out is the significant work on energy storage technologies to change wind and solar into 24/7 economically reliable sources.

4-You leave out the social/educated driver aspect. For quite some time (10 years?), EV drivers will be limited to mostly those that practice a total conservation lifestyle.

So for me, all factors....personal economics, reduced exposure to harsh pollution/chemicals, lower maintenance time, independence from outside regulations, etc. support my getting an EV as soon as viable....and the major limit on viability has been lack of a family sized EV.

 

Welcome to the conversation Drees. I will comment on the 'fallacy' question later, but for the moment just numbers clarification:

By my arithmetic 200 gram/mi = 43 US miles/gallon for the Prius. Too low, no ?
2)Your ratio of coal/NG GHG is 2.5:1, while I found 2:1. This ends up being a big difference when applied to the Prius comparison, and is worth sorting out. Where are the numbers from ?

I agree with your approach until you list the energy mix of each state. As you noted one sentence earlier, the important datum is what energy source is added to cover the additional EV demand. E.g., if a water rich area supplies 75% of its present energy mix with hydro and 25% with coal, but no hydro is in reserve, then additional demand is 100% coal. This example is contrived and not representative of what happens on the ground, because NG is a common energy spike source, not coal. OTOH, coal is a preferred baseload source for much of the US. So in a bit of irony, e.g. in southern California, additional demand that cannot be consistently anticipated is 88% NG sources; but if EV demand was incorporated into baseload, coal would be the source. It is my understanding that nuclear, like hydro, runs at full capacity -- or at least utility tries to set it up that way, because they bring on-line the the cheapest plants first.

I think if we could show that hydro or nuclear capacity is underutilized at night -- and is the source that the utility local to an EV would bring on-line when the increased demand is met as baseload, then a strong case for EV low GHG is made. At least for that case.

 

FPd, I think a fair characterization of my position is this: how is additional demand dealt with by utilities now, and in the future until some point where clean energy is the go to fuel. That latter happenstance will happen when clean reserve is available and the cost is right. Well, at least in a non-regulatory market. One (of the many) ironies of clean energy is that by virtue of the cost being all capitalization and maintenance, it makes little sense to hold the fuel in reserve. The emerging exception to this rule is replacing NG with stored heat during marginal demand spikes , but I think this is something of a contrived situation driven by regulation, because it would be much cheaper today to store heat from coal combustion as opposed to a solar farm, but to my knowledge this is not done.

2)Honestly, I think EV will become mainstream when it saves Joe Consumer money each month. This will be calculated as Fuel_savings - Car_payment_delta. I am not saying this is right or makes sense, just that it is mainstream.

I hope I summarize the remainder of your post reasonably well by saying EV meets a personal choice desire now, and you think EV now may have a positive multiplied effect later. Well, to be frank, I share your personal choice preferences but do not think they dissuade me from my argument; and as for EV now being a butterfly for the future -- I have no idea.

Cheers, Eric

 

SageBrush, please forgive me if you have answered this, where do you find the information about what source a utility uses when increasing its baseline or marginal energy needs?