Coal power Volt vs. Gas power Prius

The Volt uses quite a bit more than 9.2 kwh/ 46 miles. EPA reports about 350 wh/mile, but remember this is in mild weather. Consumption goes up 50% more when ambient temp is < 30F.

'Brown' coal (lignite) is the major fuel stock of central power plants, and averages 4000 - 8000 btu/pound, equal to about 2 kwh. But combustion efficiency is about 32%, 8% of electricity gets wasted at the plant, and 7% is lost in transmission. All told, a kwh of electricity that moves the volt less than 3 miles required 0.5/(.32*0.9*0.93) = 1.87 pounds of lignite, or about 0.6 pounds of coal per mile. That is for nice weather; consumption is close to one pound of coal a mile in the cold winter.

 

As I have said before, the environmentally friendliness of the Volt is dependent on location. Plugging in a Volt in West Virginia results in a nearly 100% coal powered car. NOT GOOD.

Plugging in A Volt in Vermont and 79% is nuclear, hydro, wind and biomass. 21% is 'imported' from NYC and others and still not all coal. That is a pretty clean place to plug in. Many IFS but if you plug it in daily and drive less then 35 miles daily it beats a Prius.
The Leaf then beats the Volt as it uses less electricity to go the same distance.

 

This is a complicated question. First of all, coal is only ~50% of the mix, according to the page you're citing. In my area (TVA), it's more like 60+%. So, one could argue that the coal number should be divided by 2 or so.

The EPA rated the Volt at 36 kwh per 100 miles in electric mode, which is 16.5 kwh to go 46 miles (this exceeds the EPA electric range of 35 miles, so maybe you stopped to charge in the middle of this drive ).

Wikipedia says coal produces 2.0 kWh/kg of energy and 4.67 kWh/kg of waste heat. Then there's transmission loss, so let's assume another 10% penalty.

That leaves us at 1.8 kWh/kg. For pure coal, that would be a little more than 9 kg to go 46 miles. Assuming only 50% of your electricity is coal, that's more like 4.6 kg.

But then you might live in an area with a different power mix. And you might argue that the power mix is different at night, when you plug in your vehicle. And you might consider this, and you might, and you might...

 

On that note, one can look up their electricity generation mix at EPA - Clean Energy - EE Action Plan.

 

Hampdenwireless refuses to learn. The average fuel mix does not matter, what matters is the fuel stock for demand at the margin. Windmills do not spin faster when the plug is in the socket, nuke plants do not operate faster than capacity, and extra rain does not fall when the Volt faithful sing koombaya.

More coal is mined, and more NG is burned.

 

Even at night, when there's supposedly excess capacity?

And how can you determine which "demand" is "at the margin"? I can't see how it's fair to assign the car pure coal. If my electricity bill is below average, can I add an electric car without logically using pure coal?

The mix calculation seems the fairest and the simplest.

 

Another small thing to consider about the petroleum fuels:

It's IMPORTED. While you burn 'x gallons' of fuel, keep in mind that it took 'y' gallons of petroleum to ship over half of that oil here in a supertanker, halfway around the world, and energy to move it to the refinery, energy to refine it, energy to deliver it to the gas station.

We spend one hell of a large chunk of our military budget 'securing' that petroleum. What do you think we're doing in Iraq? So quite a large hunk of your taxes go to making that oil 'affordable'.

All of those tyrants and terrorists appreciate your business, keeping them in business, too. The U.S. has been in bed with torturers and murderers around the world for decades. It's safe to say every tank of fuel you dump into your car comes with no small amount of human blood in its price.

The coal is at least 'locally produced'. Not produced by slaves for a brutal dictatorship.

And where I am, it's nuclear+wind+solar+NG. In fact, I could put enough solar panels on my roof to EASILY offset watts used to charge an EV or plug-in HEV. Sunny >90% of the time.

So keep all of this in mind while you enjoy paying to put the liquid equivalent of blood diamonds into your fuel tank.

 

You are the one that never learns. You still hate the Volt under all conditions. I have actually changed my view on the Volt. I have learned.

So when you say that how can you ignore the fact that the Volt is charged off peak more often then not? That would make it cleaner then I said (I am quoating the average) not dirtier like you say. Maybe you should try seeing koombaya sometime, really.

For a car charged mostly at night that would be incorrect in most areas. And am not even factoring the less electricity used in fuel refining which is also a factor.

 

Excess capacity just means more use without a blackout, it does not tell you the fuel source. Average mix may be simple, but it is wrong.

Margin is simple, it means additional demand. Consider this example from hydro power in the NW: lets say collected rainfall is X, that produces Y kwh when it flows through the plant. Any demand over Y is not going to be supplied by hydro. If the only other fuel source is coal for our hypothetical region, then 100% of the demand over Y is coal sourced.

It would be unusual across the country for additional demand to be met with pure coal (although the electric companies would *love* that scenario, and are seeking it through night-time charging incentives.) More typical is a mix of coal/NG.

Want an EV that is not coal driven ? Personal PV is the answer for the US.

 

I had a thread on this earlier, in which I got beaten up in a variety of ways. Leaf and Volt get the nearly same electric mileage, so the calculation is the same.

http://priuschat.com/forums/environmental-discussion/87022-leaf-c02-versus-prius-c02.html

You can look up the lbs C02 released per KWH delivered, by state. In Virginia, at 3 miles per KWH, a grid-charged Volt results in about as much C02 release as a Prius. At the national average, it results in more. And as pointed out already, in some areas, less.

I have thought about the photovoltaic issue and decided it is a complete and total red herring, for grid-connected PV at least.

Consider a grid-connected PV setup in West Virginia. Every KWH you put into the grid displaces a coal-fired KWH. Every KWH you put into your car displaces the C02 emissions of a Prius. If you live in WVa, you avoid more C02 emissions by driving a Prius and using your PV to reduce coal-fired electrical generation, than you would by using your PV to fill your Volt.

In short, if you are grid-connected, your production of electricity and your consumption of electricity are separate decisions.

I've also heard the argument that the grid is getting cleaner, so this is an investment in the future, but I have not seen hard data on how fast that is occurring, so that I could judge whether the Volt might in fact end up cleaner, on average, than a Prius, in Virginia, over some reasonable expected vehicle lifetime. Wish I could find hard data on that.

One final thought: Is it possible that the EPA test is harder on EVs than on gas-powered cars? I note that both the Leaf and the Volt came in at 3 miles per KWH. Yet the Hymotion Prius conversion is said to get (and as far as I can tell, gets) about 4 miles per KWH. But that's mainly for low-speed driving. Electrical losses go up as the square of the current draw, so I wonder if the extreme driving that's now part of the EPA test (hard accelerations, 80-mph stretches of highway driving) depresses the mileage of these cars moreso than it would the equivalent gas cars? So, maybe its vastly easier to beat the EPA mileage in an EV than a gas car. At 3 miles per KWH, I'm disappointed in both the Leaf and the Volt, and I'm not in the market. At 4, that's a modestly different story. Any engineers want to chime in on that? Anybody see any real-life mileage data on these cars yet?

Didn't the RAV4 EV get mileage like that? OK, I bothered to find the actual RAV4-EV data. Five trucks, driven as work trucks by Cal Ed workers, averaged 0.40 KWH/mile over more than 100,000 miles of travel.

www.evchargernews.com/miscfiles/sce-rav4ev-100k.pdf

That vehicle weighed about 3500 lbs and, per the above, got about 2.5 miles per KWH. The Leaf weighs in at about 3000, and gets 3 miles per KWH. So I guess the Leaf mileage is consistent with the actual observed mileage of the RAV4-EV.

 

Ahh ... another person gets it.

You are of course right, except in those cases where people put up PV *because* they bought an EV. If EV only increases consumption it is silly from an environmental standpoint; it has to increase clean energy production. I used to think it was illogical to link the two but a reality of what people do, but then I thought about myself. My home energy consumption is much smarter to cover with solar heating than PV, and once that is done my residual electric consumption is way under 200 kwh a month -- not enough to bother with PV. However, if I have an EV then my electric consumption jumps to 400 kwh a month, and investing in home PV is a great idea.

 

OK, but taking that and applying it to your own personal electricity usage seems harder. I could look at ALL of my electricity demand, from the lights to the computer, as "additional" to the total demand, and therefore ultimately fueled by coal/NG/whatever. This approach seems overly pessimistic. However, such pessimism would certainly encourage conservation!

With some research and math, I guess you could appropriate the kwh produced by hydro/nuclear/etc to each electricity consumer and come up with your own personal allocation for those resources. By not exceeding those levels, you could argue that you're not using energy from "bad" sources.

TVA offers a "green power switch" program, where you pay more for your electricity and the extra money funds "green" sourcing of energy. I guess you could then argue that you're not using coal at all, despite the overall mix.

Anyway, there are many different ways of looking at this. Dang fungibility.

 

Unfortunately people here are still comparing actual Prius PHEV consumption VS EPA tagged Volt and Leaf consumption. The EPA test has a negative 30% factor in it. Most of the Volt user data is also winter milage. I am looking forward to see what spring brings.

That being said it looks like the Prius PHEV will be one of the most efficient in terms of miles per kwh. In terms of production vehicles so far, only the Tesla roadster uses less juice per mile. That also brings great hope for low power use per mile on the Tesla/Toyota partner electrics.

 

Absolutely. And the grid (in the USA) is only getting greener. More wind power keeps coming online, plants are being upgraded as fuel cost goes up and new better plants are coming online.

 

So a Volt driven on personal EV is not evil?

 

HW: A Volt bought without taxpayer subsidy, run on PV put up for that purpose, is a *very* green consumer I salute. Ditto for the LEAF, and future EVs.

Krelborne: Energy and pollution accounting is not 'pessimistic,' it is physics. The basic idea we should all accept is that electrical energy use greater than our clean production is 100% from dirty sources. If you add even more demand, it is all covered by dirty fuel.

So what is a green consumer to do ? Only a couple of things matter:

• Use less energy
  Produce clean energy.
  Produce energy efficiently.
  Use energy efficiently

Examples that should jump out as obvious:
1. A power plant that produces energy less efficiently than the Prius ICE is not progress
2. 360 wh/mile Volt battery to wheels is not progress compared to say, a Prius
3. Burning dirty fuel (coal) no more efficiently than cleaner oil is not progress

 

I have yet to come across a program that was not a scam. The problem when you look into the details is that clean energy *already* on the grid is being bought, and not ADDITIONAL clean energy added to the grid.

 

So how do you feel about all of the Prius's that have government money towards their purchase?

 

Much the same way, although I recognize that at least theoretically the Prius is an energy conservation device. The Volt is an energy hog.

I will argue against government subsidy all day long. If however you frame the question as "what is better to subsidize: Prius, Volt, or home insulation?" then I'll say insulation, then Prius, and dead last the Volt.

And if the question was "we are going to subsidize cars. Which ones should it be?" I would say use a sliding scale based on fuel economy and pollution without regard to size or technology.