Electric Cars - Won't we still need a lot of oil?

[Kel_Varnsen_Latex_Division]

If every person in America had an electric would it really lower our dependence on oil?

[Askance]

Depends what you used to generate the required electricity. Coal, solar, hydro, geothermal, natural gas, and nuclear would all play their parts I suspect. Probably the last option would be to import oil to do it.

[Malodorous]

Presuming we would still generate electricity in the same ways we do now and not using, say, all wind power (in which case the answer would be obvious).

My first thought was that of course the switch would save oil. Essentially all cars run on oil derived gasoline now, if we switched to all electric cars then at least some precentage of that electricity would be nuclear/hydro/bio/coal/etc.

But then I thinks, I’m pretty sure burning gasoline in an internal combustion engine on site is much more efficent then doing it at a central power plant and then transfering it through power lines. So even though some precentage of our cars would be run on power from, say, hydro, the difference might be made up for by the fact that it takes more oil to generate power for those cars that use electricity from a oil burning electric plant.

So final answer: I don’t know.

[Roches]

In the US, a relatively small amount of electricity is generated from oil (a few percent). Coal is a the most important source of electricity (more than half), followed by nuclear power at around 20%. Oil is mostly used for transportation. Thus, if a large proportion of cars were powered by electricity or electrically-generated hydrogen (as opposed to hydrogen from natural gas), the amount of oil required would be substantially decreased.

Some oil would still be necessary for the remaining gas/diesel vehicles, aircraft, and as a starting materal for petrochemicals, but the demand for imported oil would be much lower. Of course, electrical generation would need to be increased, possibly by building coal or nuclear plants. Coal reserves (in the US and worldwide) are far larger than oil or natural gas reserves and coal-burning power plants can be made fairly clean.

So, electric or hydrogen cars would create increased demand for electricity, which would probably be provided largely from coal and natural gas. (Natural gas reserves are quite limited and there is increasing demand for imported natural gas, so this might trade one problem for another.) Nuclear power is currently too unpopular in the US to allow building more plants, but this could change in the future.

Efficiency is also a factor. Fossil fuels are used most efficiently when they are burned for heat, rather than for mechanical energy. A large amount of energy is lost in distributing electricity and the generation process is not entirely efficient; some energy would also be wasted as heat by the car’s motor. But internal-combustion engines are not terribly efficient, and I think electric cars would still be more efficient than gasoline-powered cars.

[Derleth]

What about oil for lubracation? Do electric cars not have metal-on-metal contact that needs some form of lube like petroleum-based oils?

I know it’s probably epsilon compared to what gas-powered cars need by way of oil, but it’s something.

[Shalmanese]

Lubrication oil is typically longer carbon chains than fuel oil. Although higher chained carbons can be cracked into lower ones, i suspect that lubrication simply is just not a big enough deal.

[Diceman]

We would certainly need a shitload more electricity. Sources like geothermal energy, hydroelectric power, and wind power are only feasible in limited areas. Most of the new power plants would be either coal-fired or nuclear.

[zut]

@Malodorous

But then I thinks, I’m pretty sure burning gasoline in an internal combustion engine on site is much more efficent then doing it at a central power plant and then transfering it through power lines. So even though some precentage of our cars would be run on power from, say, hydro, the difference might be made up for by the fact that it takes more oil to generate power for those cars that use electricity from a oil burning electric plant.

My impression was that electric cars would come out ahead after considering all the sources of loss. I scrounged around for some supporting documentation with numbers, and found this site, which compares battery-electric vehicles (BEVs), hybrid-electric vehicles (HEVs), and conventional vehicles (CVs) for overall efficiency.

Considering only the vehicle itself, EVs are far more energy efficient than CVs. A BEV operates at roughly 46% efficiency, whereas a CV operates at about 18% efficiency. In other words, approximately 46% of the electrical energy taken from the wall plug to charge EV propulsion batteries is delivered to the drive wheels as useful work. In contrast, only about 18% of the energy dispensed into the fuel tank as liquid motor fuel ends up at the drive wheels of a CV. In order to determine systemwide energy efficiency (from source fuel to drive wheels), the upstream losses of refining and delivering motor fuel and the losses of generating and delivering electricity must be factored in.

The losses of converting source fuels into electrical energy (conversion losses) and delivering the energy to a local electrical outlet are far greater than the losses of extracting, refining, and delivering petroleum motor fuel. However, petroleum fuel chain efficiency does not include conversion losses, as does the electrical energy chain. Conversion of liquid motor fuel into useable power takes place in the vehicle and is therefore considered a component of CV energy efficiency. Specifically, about 83% of the energy contained in crude oil arrives at the service station as gasoline, whereas only 20% to 27% of the primary energy used to generate electricity (depending on the source fuel and conversion efficiency) arrives at the electrical outlet ready to charge EV batteries. When the entire energy chain is considered, studies generally conclude that battery-electric cars are roughly 10% - 30% more energy efficient than conventional gasoline cars, depending on the particular assumptions of vehicle energy use and energy chain efficiency. [my bold – this is a small part of a much longer article]

For comparison, this site uses less conservative numbers, showing a much larger advantage to the electric vehicle:

In a recent test at the American Tour de Sol, an energy efficiency event held annually in New England, it was established that an electric Geo Metro could go about twice as far on the same amount of oil (converted to electricity) as a conventional gas Geo Metro. Complete “well-to-wheel” efficiency was measured, taking into account generating, transmission, and charging losses, on the electric side–and refining, distributing, and the inherent wastefulness of incomplete combustion, on the gasoline side.

   An EV is **70% efficient** at converting the energy stored in its batteries to motion at the wheels.  Compare that to **20%** (at best, when running hottest) for a conventional IC engine, trying to do the same with the potential energy in its gas tank.  

For what it’s worth, I’d tend to lean toward the first cite as more accurate, but (as the first cite notes), since you’re inevitably comparing system with inherent differences, there’s no objective apples-to-apples comparison metric.