Coal vs. Gas (Electric Cars vs. Internal Combustion Engine)?

The efficiency of coal fired power plants is about 30%, 2.1 lbs of CO2 is generated from every kwh being produced. In charging a battery and energy transfer, the loss is 90%, when the power from the battery is being used, there is only 72% efficiency. So for that single kwh produced, we also produce 2.1 lbs of CO2. But that 1kwh only reaches the battery at .9kwh, then when it is converted into motion we have .65kwh remaining.

Assuming that a gasoline car is able to get 25 miles per gallon.

One gallon of gasoline is able to produce 36.6 kWh/US gallon.

That when converted into motion in cars, there is only 20% efficency. So that results in a transfer of only 7.32kwh for one gallon. The carbon dioxide output for the combustion of one gallon of gasoline is 2421grams (2.421 kg -> 5.34 lbs carbon per gallon) 5.34 lbs of carbon has not been converted into CO2 yet, so the conversion results in 19.5lbs of CO2 per gallon of gasoline.

19.3lbs*.65kwh/2.1lbs = 6.03kwh electricity

6.03kwh of electricity will produce the same amount of carbon dioxide emissions as does gasoline.

6.03kwh/7.32kwh*100 = 82.4% as carbon efficient as gasoline. assuming that all of the energy used to power the electric car comes from coal.

That calculation shows that electric generation by coal is not as efficient as using gasoline, but we need to take into account one more factor.

The United States uses 21.2% of the world's oil, in order to get this oil, we ship it all across the world. We produce about 5% of the world's supply, so in order to get 75% of the oil that we do use, we import it. In order to import it, ships travel across the oceans to deliver our oil. After it arrives, large portions are considered waste when it comes to gasoline refining. During the process, electricity, and fuel are consumed, putting even more carbon emissions into the sky. So at the end of the day, burning that coal is actually more carbon efficient than that gasoline that we are putting into our tanks. Further compounding this is the fact that not all of our electricity is being produced by coal. Some is being produced by oil, some is produced by nuclear. 30.8% of our electricity is being produced by coal, 6% by petroleum, 40.8% by natural gas, 10% nuclear, 7.5% hydro electric, the remaining is other renewables/gasses. If you take into account all combusting methods of electricity generation, the efficiency rating rises from 30% for coal to an over all efficiency rating of 40%. With this kind of efficiency rise, and after adding nuclear power, hydroelectric, and other renewables, it becomes clear that electricity will beat out gasoline in carbon efficiency.

The average price of electricity in the United States is $0.09 per kwh. if you make the calculation, thats about $1.01 to travel the 25 miles that one gallon of gasoline can travel. With gasoline prices at $3.50 a gallon, electricity begins to make allot more sense.

Depending on where you are, an electric car might be powered by nuclear, wind, hydro (water), or natural gas -- but coal is a definite possibility.

Efficiency is about the same either way, being determined by Carnot's law, and about 30%. Weight of batteries will lower efficiency for an electric, but regenerative braking will make some up.

Greenhouse emissions depend some on how you count water vapor. Gas will have more water vapor, since it has more hydrogen.

Coal cost much less than gas, so if efficiency is considered in dollars (or other currency) per mile, electric costs less -- at least after the car itself is paid for.

Well, electric cars are more efficient than gas cars, but they have a lot of downfalls. (which is why we don't all just drive electric cars and not gas) Electric cars generally get shorter ranges. You can travel maybe 30 miles with an electric car (not saying all, but giving an example) and several hundred on a tank of gas. Electric cars are generally much less powerful. Many are too slow to keep up on say, a highway. It might work if u only have to make very short trips. Also, electric cars have to recharge. This can take many hours, as opposed to a couple minutes to fill a tank of gas. The other thing is price. Sure some electric cars coming out today have/will have more batteries or better batteries, and be able to travel farther, but look at the price tag. Electric is more efficient, but has its downfalls. (which is why we don't only drive electric cars)

Coal can be converted to methane + CO2, and the methane converted to electricity + CO2, to power a fuel cell with greater overall efficiency for fuel consumed over energy delivered.

The route from coal to methane and into an ICE would not give the same efficiency,

coal fired plants can be 40% efficient and they cosume less than 10% of teir energy in transportation, so a net 36%. Add in trasport and battery so a net 30% from mine to wheels. Gasoline engines can be 30% with 10% in refining and 10% in transport so net 24% from wellhead to wheels.

As for CO2 who cares, its the energy we need to worry about, but if you want to go down that road, It doesn't matte where you live, you share power with everyone, so that electric car uses 50% coal. You have links above to that. The net is a gasoline car makes less net CO2 than electrict.