kwh @ wall, vs reported

[bronco7TX]

Is that true when longer distances are included, considering the breadth of your coverage area? And what about losses at less than 30kV before the power reaches the high voltage transmission system. I'm obviously in favor of using electricity for propulsion, but I would like very much to work on not having my bias lead to putting out false information.

The 8% figure is a generic assumption used in our electricty capacity markets and in transmission planning. Losses can vary either direction by a couple of % depending on the generation dispatch across a control area. Generally the farther the generation is away from the load centers, the higher the losses and vice versa.

Most large generating stations connect directly to the high voltage network, typically a unit >50 MW will connect directly from the generator voltage of around 13.8kV - 25kV through a step-up transformer to 115kV - 345kV (or even 500, 765kV, 345 is the highest in New England). Losses at the plant itself are usually as small as possible since a generator is only paid for the electrons produced at the high voltage level. The 2.5% high voltage loss figure includes the losses at the generating step-up substation. Internal losses at the plant are not in that figure.

[gbergman]

If you have a Solar PV system - you're in perfect shape to "fuel at home".

My friend who has a Solar PV system, similar to my own, said the same thing until I pointed out that,
although we have lower overall costs because of what we sell back, the actual cost of what we use
beyond what we can sell, is the same as anyone who does not have solar. The only way I can
charge my car cheaper, is if I use less electricity than my solar system generates.

Dopeler effect: The tendency of dumb ideas to seem smarter when they come at you rapidly.

[Jeff N]

The cited article is not quite correct in its interpretation of the numbers. (The quoted letter is better) The 6kwh is the difference in energy input verses the energy in the gallon of gas. It includes input electricity but also includes losses from uncaptured hydrocarbons (e.g. gases that are burned off during cracking), and uses of other sources of energy (e.g. natural gas is commonly used as is steam ). Of the 6-8kw per gallon only about 10% of that is actually electricity. See
http://www1.eere.energy.gov/industry...ng_roadmap.pdf
for a discussion of the energy used in refining.

The latest national numbers show about 4% of the energy used in refining is from grid electricity (see table 3 in the link below). When estimated in a couple of different ways it ends up working out to roughly around 0.2 kWh of grid electricity per gallon of gasoline. In other words, 3.5% (another recent study) or 4% of 6 kWh is 0.21-0.24 kWh.

http://www.transportation.anl.gov/pdfs/TA/635.PDF

The myth of "6 kWh electricity to refine a gallon of gas" is completely wrong but this meme is going to be hard to kill.

It also makes no sense to correctly say "6 kWh of energy" and then assume you can somehow use that to directly power an electric car for 20+ miles since the energy used during refining is almost entirely from fossil fuels (it would take a large hit from further conversion losses to generate electricity from it). And, most of that fossil fuel is derived from the crude oil being processed so it would not be available in a futuristic world without gasoline refineries anyway. Only 20% of the energy used in refining is from purchased natural gas, on average.

So, 20% of 6 kWh is 1.2 kWh of energy and converting and distributing that at 40% efficiency results in about 0.5 kWh of electricity. Now add the 0.2 kWh of purchased grid electricity and you could reasonably claim that 0.75 kWh of electricity from refining a gallon of gasoline "could have been used" instead to power your electric car for 2-3 miles if the gasoline hadn't been refined.

[Jeff N]

Thanks, that 13.3 is on 110 I assume. What is the cost on 220? Obviously it may vary depending on the 220 interface I select

The official EPA wall socket charge is 12.9 kWh. I've seen people say that 12.5 is typical at 240 V. That's roughly a 5-7% difference at least for mild climate conditions. A Tesla owner measured his charging efficiency using various rates from 120 V at 12A all the way up to 240V at 70 A. He found that 240 V at 30-40 A was 10-20% more efficient than lower rates and higher amps didn't improve things further.

This may mean that cars which support charging at 30 A may show EPA kWh/100 mile efficiency ratings that are better than the LEAF and Volt largely due to just supporting a faster charging rate.