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Chevy Volt Concept Car
Electric cars, particularly gas electric hybrid cars, have the potential to lower our gasoline costs. But do they really save us any money?
First, how much does the electricity cost to charge a car? A gallon of gasoline has the equivalent energy content of 37 KWA of electricity. To compare costs, we have to factor for engine efficiency. A gasoline car engine has an efficiency of about 30% converting the gasoline into actual mechanical power. An electric engine has an efficiency of about 95%, so it essentially converts all of the electric power into mechanical energy.
Assuming an average electric cost of 8.7 cents per KWA, the equivalent of a gallon of gasoline would cost $1.02. [(0.087 * 37 / 0.95) * 0.3] If you can get your electric power at off-peak rates available from some utilities, your cost may be half this much.
This, however, is not the whole cost. You also have to count the cost of the battery. Assume an electric car battery will last for 4,000 charge cycles in the car and holds the energy equivalent of one gallon of gasoline (about 12 KWH). Batteries deteriorate with age so the battery will hold less power over time. The distance a car will go on a charge will deteriorate to the point that the battery will need to be replaced. The battery may still be useful to a stationary application like storing energy at a wind farm where charge capacity vs. weight or size is not an issue.
If the battery costs $4,000 dollars then each charge will cost you $1.00 for the electricity and $1.00 for use of the battery; a total fuel cost of $2.00 per gallon. If the battery cost goes up to $12,000 then your fuel cost is actually $4.00 per gallon.
So the battery cost is a big determining factor on how much ‘fuel’ savings you will receive from your electric car. Note that the mpg rating of the car is not a factor in this computation. It only assumes that the battery is replacing one gallon of gasoline.
There are numerous other factors that affect the cost of ownership for a hybrid electric vehicle:
- The car may require much less maintenance.
- The car without the battery may cost less than the equivalent gasoline powered car.
- The battery may have value after the end of its useful life in the car.
- A car may be purchased and the battery leased where you only pay the difference between the value new vs. the residual value plus financing charge.
- The price of gasoline may keep going up.
- The availability of off-peak power pricing.
- The cost of charging a car away from home. Some businesses my offer free or discount charging as a loss leader for shopping at their store. The equivalent of selling milk below cost.
- Government and utility credits.
Comments
Ok... fair enough, but what is the TRUE cost of a gallon of gas if you do the same caluclations for current cars... the cost of the engine and the oil, electricity, metals, plastics, etc that go not only into its construction, but the construction and operation of the plant it was built at... etc. Some would even argue that even the cost of recent wars is a 'hidden' tax on gasoline that we're all paying, though I don't want to appear antagonistic. I just want a fair comparison. Thanks!
I suppose I shouldn't laugh at someone who's trying hard to understand how to compare Evs with gas powered cars, but Ryden obviously is a neophyte when it comes to electric propulsion costs. It is true that battery-only electrics don't make economic sense at the moment, and that that is due to the high cost of bateries, as he says. But his other claims are just plain wrong. Everyone who has been foloowing the Chevy Volt development knows that 1) it is obtaining approximately 6 miles per kilwowatthour 2) it weighs the same as a Honda Accord (around 3100 pounds) 3) the combined or realistic typical MPG for the Honda is 24. The cost of electricity moving the Volt that same 24 miles would be 4 times 8.7 cents, or 34.8 cents, NOT the $1.02 that he claims would be required to buy electricity equivalent to that gallon of gas.
Rydners main errors are that he assumes that the efficiency with which a gas powered car burns gasoline has an exact correlation with EV effiicencies using electricity. It does not, for the simple reason that 1) gas powered cars do not recover kinetic energy ammassed in accelerating the car to speed, which EVs do, and 2) a gas powered engine spends a lot of its time simply idling and doing nothing useful. Also, his efficieny claims are incorrect. However, his main conclusion, that electric propulsion id not economically competitive, is false, because electrical propulsion doesn't just occur in battery-only Evs. It also is present in EVs which take advantage of the very thing that Rydner is
pointing out - that battery costs make EVs non-conmpetitive, which is at least currently true.
But he also apparntly is unaware that there is a capacitor technology being developed by EEStor that reportedly will be commerrcially available
before the end of the year. If that comes to pass, absoluetely nothing that Rydner claims will
still be true. No gas powered vehicle can possible compete economically with an EEStor powered EV. Watch the news for EEStor evelopments - ZENN Motors will get the first
EEStor solid state storage devices that come off the production line.
What an ignorant article...
Are you selling gasoline cars or gasoline
Richard - I appreciate your comment, but nowhere in the article did I make any comments about the mpg or cost per mile to operate an electric car. My only comparison is between the cost of gasoline and the cost of electricity. The viability of an electric car is in large part based on the cost and performance of the battery. This article should be useful to people looking to purchase a plug-in hybrid to understand how much they will actually save in operating costs.
You do point out that an hybrid electric car is more efficient because it can run its gasoline engine more efficiently and can capture some of the energy back from braking. That is very true and will give a hybrid electric vehicle a better mpg rating than a comparable gasoline powered car.
I will be writing some articles on hybrid electric vehicles that use capacitors to store power. There actually is one already on the market.
I admit, I may not be following this, but I think there is a huge mathematical error here.
The $4,000 cost is for the entire battery set for a car. It lasts for 4000 charges. Therefore, if that battery set takes you 40 miles before needing to be re-charged, that means the entire battery set lasts for 160,000 miles. Divide $4,000 by 160,000 miles and you get 2.5 cents a mile. Even if battery costs go up to $12,000, we are still talking about 7.5 cents a mile.
So, take your $1.00 per gallon equivalent for electricity and add, conservatively, $2.00, and you get - even in a crazy world where batteries cost a fortune, vehicles can only go 40 miles with a recharge, and electricity is expensive -- $3.00 per gallon.
Anyone paying $3.00 per gallon right now?
Didn't think so.
We are now paying $3.50/gal in Central Texas. With the crazy arabs and our comparatively low cost of gas here, it's probably going much higher. Don't you have to factor in the amount of CO2 in the environment. Extreme weather must have a cost on some level.
monty0000 - if a car gets 40 mpg then 4000 gallons of gas takes you 160,000 miles. If gas costs $4.00 per gallon, then that is $16,000 or 10 cents per mile. In the battery example, it costs 2.5 cents per mile for the electricity or $4,000. If you get 4000 cycles on a battery that costs $12,000; that equals 7.5 cents per mile. $4,000 for electricity plus $12,000 for battery equals 10 cents per mile or $16,000. Hybrid car costs the same as an equivalent mpg gasoline powered car.
I am not making any value judgement here. Just providing a way of comparing the operating costs of a plug-in hybrid with a conventional gasoline car.
What is the world is a KWA? Did you really mean KW-Hr??
The energy content of a gallon of gas is about 56 kWh, not 37. Big error. However, if the energy storage problem is solved by EEStor (dubious), today's solar cells and an electric car are less expensive to install and operate than gasoline-powered cars. Factor in carbon-composite and carbon nanotubes reaching $10 a pound in 4 years for cars that can weigh as little as 400 pounds and be safer, then there is no energy problem.
Your cost per kwh is about half the actual cost...today!
How much with cap and trade?
The reality is it's like perpetual motion devices...they don't work. You might shift where your money goes but you wont save a dime. That's just what we know, we've yet to discover the unintended costs. Quit the BS.
This is a very intelligent and well written article. It was definitely refreshing to read. I don't typically post on these forums but felt this author deserved kudos. Well thought out, well written, succinct.
Oh, and of course, informative!
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