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By Robert Rapier on Jan 20, 2008 with 2 responses

Electric Cars versus the ICE

Someone asked today at The Oil Drum about the primary reasons one would favor electric cars over the internal combustion engine (ICE). I responded

Yes. To me there are two big incentives. One is that electric motors are much more efficient than the ICE. Second is that electricity can come from such a large diversity of sources. Yes, it’s coal now. It can increasingly be solar, biomass gasification, nuclear, wind, geothermal, etc. There just aren’t too many liquid options, and different liquid fuels may require different engines.

But I decided to double-check the efficiency numbers, and came across the following link:

Debunking the Myth of EVs and Smokestacks

Now you know a love a good debunking, so I had a read. It’s a bit dated, but the information was still worthwhile. I ran across Table 4, shown below, which I thought was quite interesting:

EVs & Power Plants ICE & Fuel Refining
Processing 39% (Electricity Generation) 92% (Refining)
Transmission Lines 95% -
Charging 88% -
Vehicle Efficiency 88% 15%
Overall Efficiency 28% 14%

Table 4. Operating Efficiency Comparison Between EVs and ICE Vehicles

The bottom line is more or less what I expected, but the vehicle efficiency at 88% is higher than I would have guessed. Anyone with experience in that area? If the efficiency is correct (also note Tables 3 and 5), that provides a compelling argument for electric transport. Now we just need to get those darn batteries sorted. (The plug-in Prius is only going to be able to go 7 miles on battery power).

  1. By Allan Martin on September 6, 2015 at 7:01 pm

    Siemens has a natural gas fired H-class combined cycle turbine that is 61% thermally efficient making the net efficiency of an electric car up to 44% efficient using the rest of the numbers in the chart. That’s reaching 3.14 times the net efficiency of an ICE. I do question the 15% number on the ICE as being a little low however it may be true if the vehicle efficiency numbers take into account all losses through transmission and friction. I know that Gasoline engines can reach about 28% efficiency without transmission and other losses. But even at a nominal number of 20% vehicle efficiency, to give modern vehicles the benefit of the doubt, or 18% net overall. That still makes the electric vehicle 2.44 times more efficient than the best gas powered ICE car. Food for thought.

    Allan

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  2. By Forrest on September 8, 2015 at 7:16 am

    The tabulated efficiency looks good to me. Steam turbine generators run lower, but gas combined cycle may bring the average up for electricity. Not much value in calculating wind turbine or solar efficiency. This is not a well to wheels analysis, just a quick comparison. I would think the battery car would make a nice 2rd car for short trip metro zones if the cost would be about half. A small passenger car with support of traditional auto for long trips, heavy loads, pulling trailers, and emergency. I just read Henry Ford II interview. He said unless some unforeseeable battery breakthrough, the battery car will have very low sales volume. The mainstay of automobile industry will be the low cost “mild” hybrid that offers the max benefit of cost to consumer. I would say this guy has the best view of the crystal ball upon reality. So, per reality the best environmentalist can do and hope for would be to promote higher ethanol fuel blends. This is a powerful environmental improvement as the additive cleans up the most harmful elements of gasoline and will promote more efficient ICEs. Ethanol carbon rating continues to improve, latest -40% of gasoline. New technology, processes, and agronomics put the fuel on steep improvement trajectory, as well. Engine technology continues to find better more efficient technology to maximize the fuel’s character. The latest is port injection upon typical diesel engine wherein the diesel emission drop and torque of engine increase.
    Consider the forgotten zone of maximum return on alternative energy. I guess it’s not sexy enough for public, but the environmental benefits are huge. We need to refocus battery power to terrible polluters of small engines. Look up the data on these little monsters to quickly determine battery power would hit the ball of of park and provide tangible benefits to consumer. This sector needs to be reinvented to maximize battery power conversion. The higher horsepower applications whereupon battery power fails should be converted to E85 class of engines. Our transportation sector is very refined and engineered to maximum benefit with minimum pollution. Just the opposite in small engine devices.

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