Is Detroit rethinking green autos?

[TennTradition]

Good post. This was what I was alluding to earlier. If that Prius was in a region with a coal power plant, it would be even worse on the environment. It quite funny that more people don't see this hypocrisy.

I know that CO2 isn't the only "pollutant" (with respect to all views on the matter) of concern with regard to coal - but if I just use it as one metric, here is what I come up with.

Chevy Volt: 2.78 miles/kwh (reported mileage)
Coal: 2.0 kWh/kg coal (average Coal plant)
2.93 kg CO2/kg coal
Chevy Volt in all coal region: 0.53 kg CO2/mile

*Note: I don't know what the battery charge efficiency of a Volt is or what line losses are. If you assume a total efficiency of 90%, that would make this number more like 0.59 kg CO2/mile. Also not included here is the CO2 "cost" of mining the coal or delivering it to the plant.

Gas Auto: Let's just use an average of 20 mpg
Gasoline: 8.92 kg CO2/gal gas
Gas Automobile Emissions: 0.45 kg CO2/mile

Note: This doesn't account for the CO2 cost of drilling the oil, refining the oil, or delivering the gasoline to the gas station.

So, based on these numbers, you are somewhat better off to drive a gasoline automobile if all of your power comes from coal.

However, with something like CO2, local emissions don't really matter. What really matters is total emissions. So, it is appropriate to look at average CO2 emissions per kWH across the US rather than just coal emissions when looking at this problem.

Avg CO2 / kWh in US: 0.69 kg CO2/kWh

Avg Emissions of Electric Car in US: 0.25 kg CO2/mile

Again, assuming some transfer inefficiency, this number might look more like 0.30.

So, on average, a gas-powered car will emit about 50% more CO2 than an electric-powered car in the US under the assumptions of these calculations.

 

[milohimself]

Decent calculations, but probably short given that you're not including the production of gasoline itself, while you are for coal power. I'm not familiar with the production line for the Volt battery, though.

 

[TennTradition]

Decent calculations, but probably short given that you're not including the production of gasoline itself, while you are for coal power. I'm not familiar with the production line for the Volt battery, though.

It's absolutely short, milo. No-where close to a life-cycle analysis...just a 15 minute data lookup and calculation.

I looked at it as ignoring the gasoline production cost (drilling oil, transporting oil, and refining gasoline) AND ignoring the coal production cost (mining coal, transporting coal). Gasoline has a higher energy density, so its transportation costs per kWh energy content are somewhat reduced - but it has a lot further to go and refining isn't cheap.

What I did try to include what the "combustion costs" of both. The coal plant kWh/kg coal and the gasoline mpg from the car's engine are both included.

If we want to throw in refining costs, then:

Assuming 85% refining efficiency, the cost of refining is 1.1 kg CO2 / gallon gas. Assuming 20 mpg, this is an additional 0.06 kgCO2 / mile for a gas-powered car. The effect on the above calculation is then:

CO2 Cost of a Gasoline-Powered Car: 0.51 kg CO2/mile.

 

[PKT_VOL]

I know that CO2 isn't the only "pollutant" (with respect to all views on the matter) of concern with regard to coal - but if I just use it as one metric, here is what I come up with.

Chevy Volt: 2.78 miles/kwh (reported mileage)
Coal: 2.0 kWh/kg coal (average Coal plant)
2.93 kg CO2/kg coal
Chevy Volt in all coal region: 0.53 kg CO2/mile

*Note: I don't know what the battery charge efficiency of a Volt is or what line losses are. If you assume a total efficiency of 90%, that would make this number more like 0.59 kg CO2/mile. Also not included here is the CO2 "cost" of mining the coal or delivering it to the plant.

Gas Auto: Let's just use an average of 20 mpg
Gasoline: 8.92 kg CO2/gal gas
Gas Automobile Emissions: 0.45 kg CO2/mile

However, with something like CO2, local emissions don't really matter. What really matters is total emissions. So, it is appropriate to look at average CO2 emissions per kWH across the US rather than just coal emissions when looking at this problem.

1) The last highlighted part was the crux of my point. I was only referring to coal power plants. Other types of power plants are definitely better for the environment.

2) As your opening statement alluded to, carbon dioxide is not the only pollutant produced as a by product of burning coal. It is actually pretty harmless compared to the other pollutants. I know we are making headway on developing technologies to clean up the "toxic" vapor/steam before it is released into the environment. And that was a couple years ago when I was studying coal power plants.

Overall, I think those calculations are reasonable. I am sure the extremists on both sides would say that your assumed conversions are faulty. Just about every conversion I have ever seen is different.

 

[volinbham]

I assume you're talking about plug-ins, hybrids are already very mainstream

I guess it depends on the definition of mainstream. Hybrids as a group represent less than 2% of vehicle sales.

 

[milohimself]

I guess it depends on the definition of mainstream. Hybrids as a group represent less than 2% of vehicle sales.

Or regionally, I see priuses and civic hybrids all the damn time