7 kW/100 km and similar number are, of course, nonsense. In other words, power/distance is nonsense. Maybe if we were SI than the mistake would be obvious. You might have seen the article I wrote and published several years ago. Here it is again should anyone be interested i learning how difficult such comparisons are even with the correct (and SI) units.
*Comparing Electric and Gasoline Cars* *By: Stanislav Jakuba* *This article is about the pros and cons of ownership an electric Nissan Leaf and a gasoline Honda Civic. It addresses the respective energy and “fuel” expenses, the amount of pollution generated in manufacturing and use of either car, the grid demand for charging vehicle batteries and the availability of electricity from renewable sources. Data are based on a real-life usage and include the effects of variables such as local climate and the cost of electricity vs. gasoline. Although the numbers are not applicable universally (driving conditions and prices change from region to region and from time to time) the method presented here enables evaluating numerically the impact of those changes.* *Let’s start the comparison by investigating the driving distance on “full” battery or tank. As with all vehicles, that distance is influenced by drivers’ skill, but with electric cars there is, in addition, the ambient temperature dependence; it impacts their driving range far more than cars with internal combustion engines. Concerning the Nissan Leaf, the Society of Automotive Engineers (SAE) published the average driving range of the Leaf models vs. ambient temperature as shown next. [1[* *The chart illustrates the variability often overlooked in judging the achievable battery range in, say, Texas vs. Wisconsin. Other conditions being equal, ambient temperature decrease alone can cut the range from the best 122 km to 75 km. Already at the beginning of this treatise we can see that comparisons will be tricky and not easily generalized.* *The Environmental Protection Agency (EPA) determined in its tests that the average Nissan Leaf consumed 19 kWh/100 km which is 0.68 megajoules per kilometre (MJ/km). That is the record of several drivers, an important consideration. Other variables, however, such as the battery draining when not in use, when heating the passenger compartment in cold weather, and the speed of charging play were not included. For the latter, fast-charging consumes up to 50 % more electricity than in slow charging.[5] The car electricity consumption reflects the electricity flow from the “wall” outlet to the charger, not just from the battery to the motor and auxiliaries. And while it is straight forward to determine the distance at the point of “running out of gas” it is not so straight forward with electric vehicles.* *Expecting that most car owners will be quick charging only rarely, we estimate a 20 % penalty for all the above three loses which then changes the “mileage” number to 0.85 MJ/km. When considering the normal 33 % efficiency in electricity generation from fossil fuels, the major source of electricity, the overall number triples to 2.5 MJ/km. * *My Honda Civic, a bigger but lighter car than the Leaf, and not designed for the extra low friction of electric or hybrid cars, has been getting 39 mls/gal which is 2.0 MJ/km. Gasoline refining and its distribution burn about 15 % of the energy in the fossil fuel, a consideration that raises the number to 2.3 MJ/km. But since I drive in the style of a driver who “does not need brakes,” I looked up the dealer advertised number as being more “average” and found 36 mpg. That mileage brings the number to 2.5 MJ/km.* *By coincidence those final numbers for both cars are the same. This closeness confirms the obvious: If the origin of the energy for powering either car is based on fossil fuels burning, the energy consumed per distance cannot differ much if the cars are similar. And while the above numbers can be taken broadly applicable for gasoline cars, for the electrical cars the numbers vary according just the speed of charging as said.* *The Leaf is heavier than the Civic by about 450 lb due to, mainly, the battery. The difference is equivalent to carrying extra two or three husky men vs. the average 40 lb (1/2 tank) of gasoline in the Civic. Measurements by SAE, charted below, show the percentage increase in energy consumption due to the increased weight of road vehicles.[2] The percentage disadvantage of the extra 200 kg for the Leaf is apparent.* *Accepting the energy consumption similarity, let’s now focus on how costly one unit of energy is in electricity vs. one in gasoline. An overall comparison here is more complicated because the cost of electrical energy varies from region to region, more than gasoline prices do. * *Focusing on my region, the northeastern U.S., the residential rate is 0.1 $/kWh for generation and the same for “delivery”, or 0.2 $/kWh total. Thus that electricity costs 0.055 $/MJ. The cost per road distance is then 0.055 x 0.85 = 0.047 $/km. (Those analysts that account for just the generation cost rather than the whole bill miss a half of the cost.)* *Now to the Civic: At 3.50 $/gal price of gasoline (10 % alcohol), and at the above listed dealer mileage, the cost is 0.050 $/km. * *The conclusion: Again, both cars’ “mileage” cost is close in this specific case. Should, however, gasoline prices keep dropping as seems to be the case in the later part of 2014, the Civic will be proportionally cheaper to operate. At 1.75 $/gal price, for example, the Civic would travel at half the energy cost of the Leaf. Or twice as far. But there is more to this.* *About one third of the price for gasoline at the pump is attributed to the federal, state and other taxes (the exact amount again differs from one location to another). That tax is near zero for electricity. Should electric cars become ubiquitous with time, electricity will then be taxed to yield equal revenue resulting in a unit of electricity costing a third more. Similarly, at present, 95 % of electricity is generated by the cheapest methods in the U.S. – by burning fossil fuels, hydro, and nuclear reaction. Should it originate from renewables such as wind, solar, and geothermal, it would cost three to eight times more. * *To finish the cost comparison, the dealer price for the Leaf is 20 % higher than for the Civic, similar models. The present-day federal and state subsidies, credits, etc. for el. cars reverse the percentage in favor of the Leaf by about equal percentage. Finally, el. cars buyers may accrue the cost of the charging station in one’s garage that, however, should last for several generations of Nissan Leafs, so we omit that cost here.* *As to the maintenance cost of el. cars, with the exception of the engine oil and filter changes, it is the same as with most cars: new fluids such as A/C and brakes, filters, tires, battery, pads and rotors, the latter less frequently with regeneration. As to batteries, the lead-acid ones are commonly recycled and sold repeatedly. Contrasting, refurbished Li batteries are more expensive than new ones, and the disposal of Li batteries risks environmental contamination. * *After all this information, it is, unfortunately, still up to the reader to decide which car type is better under his/her circumstances while also considering that conditions and costs are changing with time. No universally applicable numbers exist; the author hopes that this is apparent from the above, and that published comparisons will thus be viewed with suspicion unless they are accompanied by considerations for all the above-listed variables, such as the impact of local climate, electricity cost, purchasing price, subsidies, credits, etc., and also the driver’s driving style such as the proverbial “pedal to the metal” style. El. cars, similar to the old steam-powered ones, are known to rocket off from the start while their poor acceleration at high speeds is of little concern when observing the speed limits on public roads.* *Emissions:* *Generally speaking, el. cars relocate emissions from the exhaust pipes to the stacks of fossil fuel burning power-plants (for the “green” energy option read on). A **British study (unverified) found that a mid-size electric car would produce 23 Mg of CO2 over its lifetime, compared with 24* *Mg for a similar petrol car. Emissions from manufacturing electric cars, however, are some 50 % higher for their light metal contents and for the batteries being made from materials such as lithium, copper and refined silicon, which require more energy for processing.* *Similar to gas cars, electric cars are expected to need a replacement battery eventually. Once the emissions from producing the second battery are added in, the total CO2 from producing an electric car rises to 12.6 Mg, compared with 5.6 Mg for a petrol car. Disposal doubles the emissions for the energy consumed in recovering and recycling metals in the Li battery. Recycled Li batteries are more expensive to produce that new ones.* *Grid electricity demand* *As a side issue, let’s examine how much more electricity would be needed in the U.S. should all cars (200 million of them) be the electric Leafs and driven as today for 15 000 km annually. Charging them would draw the average of 80 GW based on the earlier MJ/km number. But not everybody will be satisfied driving a small car so the overall consumption will be higher, say 110 GW. (This number excludes busses, trucks, delivery vehicles, etc.)* *To put that number into perspective, the present (2015) average electricity draw of the whole country amounts to 450 GW.[3] This four times higher wattage powers everything: from ranges and air conditioners to trains, factories, hospitals and cities. It is uncertain what new sources would generate the extra 25 %. Or perhaps only ~20 % if charging only during the off-peak time to take advantage of the spare capacity of existing power plants.* *As for the charging from “green” sources of electricity, as is the goal, the three sources that have a growth potential (wind, geothermal and solar) reached 22 GW after 40 years of subsidized construction (see the graph below). The two other renewables, hydro and wood, had been generating more power than the former three combined but their yield has been stagnant or declining as a decades-long trend and there is no appreciable new domestic capacity to develop. The other renewables, those not-listed here, contribute insignificant net amounts with no prospect for a worthwhile gain in the future. Viewing the mentioned graph, the time needed for adding the above gigawatt from renewable sources extends past several generations by which time the needed amount will be higher yet.* *The chart[4] bellow illustrates electricity generated from all the significant non-carbon sources since 1890. * *As seen, the energy contributions of geothermal and solar (both PV & CSP) are nearly invisible on the scale of the two predominating sources, hydro and nuclear. The improvement in the existing nuclear plants operation alone yielded thousands times more electricity than geo and solar combined. That improvement also just about equals the output from the wind turbine gene* On Sun, May 17, 2020 at 6:14 PM Brian White <[email protected]> wrote: > I have ten cars, not one of them electric. :) > One 1.5 liter 4 cylinder > One 1.6 liter 4 cylinder > Two 2 liter 4 cylinders > One 2 liter 4 cylinder 16v turbo > One supercharged 3 liter V6 > One 3.4 liter V8 > One 4.2 liter V8 > One 4.4 liter V8 > One 4.8 liter V12 (18.5 liters of oil and 120 liters of fuel) > > > On May 17, 2020, at 14:59, John Nichols <[email protected]> wrote: > > > > Entropy is a wonderful thing > > > > > > *From:* USMA <[email protected]> *On Behalf Of *Martin > Vlietstra > *Sent:* Sunday, 17 May 2020 3:08 PM > *To:* 'Michael Payne' <[email protected]>; 'USMA List Server' < > [email protected]> > *Subject:* [USMA 1402] Re: Talking to people about metric > > > > One other advantage, particularly in city traffic is regenerative braking. > When you apply brakes in a petrol-powered car, the energy that you used to > get up to speed is thrown away, in a vehicle with regenerative braking, it > is “pumped” back into the battery. > > > > *From:* USMA [mailto:[email protected] > <[email protected]>] *On Behalf Of *Michael Payne > *Sent:* 17 May 2020 12:08 > *To:* USMA List Server > *Subject:* [USMA 1401] Re: Talking to people about metric > > > > Yes, my error, consumption is in kWh and power consumed in Kw. The car has > a 66 kW motor. Low cost of operation is one of the advantages of electric > vehicles, apart from no maintenance (oil, filters, plugs, etc.) the cost of > operation is very low and even cheaper in traffic where the consumption is > the inverse of internal combustion engines. I’ll attach a couple of > pictures, as you can see I’ve only done 65 km this month with the lockdown. > We can do more traveling now we’ve opened up a bit from the 11th May. I > reset the data the 1st of every month. > > > > <image001.jpg> > > > <image002.jpg> > > > On 15 May 2020, at 17:59, Martin Vlietstra <[email protected]> > wrote: > > > > Mike, > > Surely you mean 7 kWh/100 km? (Also 12,5 to 16 kWh/100 km). > > Your running costs show one of the advantages of using metric units. A > petrol-powered small car uses about 4 L/100 km (larger cars typically 7 or > 8 L/100 km). (I will not quote the mpg as that would means specifying > whether I am talking about US or Imperial gallons). A litre of petrol is > typically €1,40 so the running cost of your electric car is one quarter > that of a petrol-powered car. > > Martin Vlietstra > > -----Original Message----- > From: USMA [mailto:[email protected] > <[email protected]>] On Behalf Of Michael Payne > Sent: 15 May 2020 09:21 > To: USMA List Server > Subject: [USMA 1397] Re: Talking to people about metric > > I have an electric car as well. The numbers you give show a consumption of > just over 7 kW/100 km, this is very low compared to my Renault Zoe (the > same platform as the Nissan Leaf) which averages about 12,5 to16 kW/100 km > which give me a cost per 100 km of about €1,30. Also charging on the cheap > rate which the car does automatically. > > Mike Payne > > On 14 May 2020, at 02:35, Harry Wyeth <[email protected]> wrote: > > I haven't written anything here for a long time, but what Al wrote a > couple of days ago is really right on. What he says about > liberal-right-wing-left -wing-fake news-etc is absolutely correct. The > best way to convince someone about the usefulness of the metric system is > to gently point out how simple and easy to use it is, and mention that it > is used without a second thought everywhere else on our planet. > Unfortunately, with our miserable political divisions and now the virus, we > on the metric cutting edge are pretty much way out on the back burner for a > while. But it would sure be nice to hear about 2m social distancing for a > change! > > On another point, Tesla vehicles have a computer readout showing kWh used > since the last charge, per trip, or overall. There is also a Wh/km rate > display for the same periods. One vehicle I have information on shows 2200 > kWh used for about 15500 km traveled overall. At a $ 0.12 /kWh rate for > home electric vehicle charging in northern California (starts at midnight), > the electricity cost is $264 or just $ 0.017/km. > > All the driver has to do is select metric instead of miles on a > preferences screen. > > HARRY WYETH > > > _______________________________________________ > USMA mailing list > [email protected] > https://lists.colostate.edu/cgi-bin/mailman/listinfo/usma > <https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Furldefense.proofpoint.com%2Fv2%2Furl%3Fu%3Dhttps-3A__lists.colostate.edu_cgi-2Dbin_mailman_listinfo_usma%26d%3DDwMFaQ%26c%3Du6LDEWzohnDQ01ySGnxMzg%26r%3D2z9QGiy5Dxy8_0qMMqfA98Bie-nGD-VfgJgfw4byoU4%26m%3D7yDbupnCtIHh7lNeXj0RGqWuqko7QYfbTd5y2JZheCs%26s%3D8iE8rKryIt1Z-HHkGHouwn9iRfM9docTipvzMCnmKP0%26e%3D&data=02%7C01%7Cusma%40lists.colostate.edu%7Cebb18856044549a16a5e08d7fab3485c%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C637253520244629134&sdata=wNjqpJh%2FbjO0jTD5Kc9NUK30Z9SXnFOfKxq%2Bw1x5k3s%3D&reserved=0> > > > _______________________________________________ > USMA mailing list > [email protected] > https://lists.colostate.edu/cgi-bin/mailman/listinfo/usma > > _______________________________________________ > USMA mailing list > [email protected] > https://lists.colostate.edu/cgi-bin/mailman/listinfo/usma >
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