Economic and Energy Efficiency of Electric Motor Scooters

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PJD
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Joined: 11/22/2006
Points: 1410

The discussion came up on the XM-2000 thread on the costs to operate an electric scooter.

Between June 4 and July 4 I used a kill-a-watt meter to gather a full month of power used to charge my two modified e-max scooters. I did no opportunity charging in the field, so in addition to the total mileage and the total KWH at home, I estimated the consumption from 18 charge cycles at work. This was easy because I know the consumption on the return trip and adjusted the consumption at work down a bit to account for going to work being a net downhill ride. So now, the numbers:

Economic Fuel Efficiency:

Cost per KWH residential (Pittsburgh, PA, USA) = $0.11404
Total consumption over one month = 40.25 kwh
Total distance ridden over one month (two scooters) = 703 km = 435 mi
kwh per km = .0572
kwh per mi = .0925

Cost per km = $0.00653
cost per mi = $.0105

Equivalent required fuel economy for gas scooter = 286 miles per gallon (US$3.00/gal)
Equivalent required fuel economy (European) = 0.824 l/100km ($0.792/l)

ENERGY Fuel Efficiency:
(forgive the mixed units...)

Energy content of gasoline = 131 megajoules per gallon or 34.9 MJ per liter
1 kw = 1000 J/sec, so 1KWH = 1000 J/sec * 3600 sec = 3.6 x10^6 J

so, KWH pr gallon = 131 MJ per Gal/3.6MJ per kwh = 36.4 kwh per gallon

scooter uses 0.925 kwh per mi, so:

equiv required energy efficiency (mi per gallon) = 36.4 kwh/gal /0.092 kwh/mi
= 394 miles per gallon = 0.597 l/100 km

Now, some will argue: "but the important thing is CO2 emissions, and the power plant and transmission to the outlet is 25-30% thermally efficient at best, plus about 70% of it (average for US) is generated with coal, which produces somewhat more C02 than gasoline". So, are we back to being no more "clean" than a typical 150 cc scooter? One answer is that this viewpoint is neglecting the energy and CO2 emissions to pump, transport (from the ME), and refine the gasoline - compared to the relatively short train or barge trip from the mine tipple to the power plant, so we may be ahead, even when using the normal coal-rich mix, after all.

Can anyone give a shot at this calculation?

I try to assuage my uncertainty about this situation by buying new-wind-energy offsets - more than enough to cover my total household electric consumption, plus a good bit of what I use at work. Go here:
http://www.newwindenergy.com/

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andrew
andrew's picture
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Joined: 11/28/2006
Points: 1361
Re: Economic and Energy Efficiency of Electric Motor Scooters

Wikipedia gives an estimate of the US national average 1.28 lbs CO2/kWh for electricity generation: http://en.wikipedia.org/wiki/Battery_electric_vehicle

Quote:

Generating electricity and providing liquid fuels for vehicles are different categories of the energy economy, with different inefficiencies and environmental harms. A 55 % to 99.9 % improvement in CO2 emissions takes place when driving an EV over an ICE (gasoline, diesel) vehicle depending on the source of electricity.[12] Comparing CO2 emissions can be done by using the US national average of 1.28 lbs CO2/kWh for electricity generation, giving a range for BEVs from zero up to 0.2 to 0.5 lbs CO2/mi (0.06 kg/km to 0.13 kg/km). Since 1 gal of gasoline produces 19 lbs CO2 the average US fleet produces 0.83 lbs/mi (0.23 kg/km) and the Insight 0.27 lbs/mi (0.08 kg/km).[13] CO2 and other greenhouse gases emissions do not exist for BEVs powered from sustainable electricity sources (e.g. solar energy), but are constant per gallon (or litre) for gasoline vehicles.

This would mean 14.84 kwhrs of generated electricity release as much CO2 as a gallon of gasoline which can produce 36.4 kwhr. Applying this modifier you are still getting equivalent to 160 mpg in terms of CO2.

But the real kicker is you can invest in renewables or generate your own to power your scooter. Try powering an ICE from renewables, it just ain't going to work! This effectively reduces your CO2 output to nothing or 1,000,000,000,000,000... mpg. It kind of gives a different perspective when you look at it in terms of infinity. A hybrid car can't do that, and neither can a plug in hybrid, but when you take gasoline out of the equation you open up new possibilities.

---
Avatar taken from http://www.electricmotorbike.org/
Anyone got one they want to sell?
My KZ750 Project: here

PJD
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Joined: 11/22/2006
Points: 1410
Re: Economic and Energy Efficiency of Electric Motor Scooters

"11 and half cent a kw, what the heck is up in PA"

It's called "deregulated markets" or more to the point "deregulated monopolies"

- 6.303 cents per kwh generator fee, .87 cents transmission fee, and 4.231 cents distribution = 11.404 cents per kwh

We were supposed to be able to shop and choose our power generator, but in reality, all the generators pulled out of the residential market, so, unless you are a big corporate industrial user, you now must simply buy the generation portion from Duquesne light's power-broking division at whatever rate they want to charge us. Actually it was even higher, we were paying a separate "stranded costs" fee to Duquesne light for a few years after deregulation.

I presume in Virginia you still do it the old fashioned way - Virginia Power (or PEPCO?) generates, transmits, distributes, and all prices are regulated under the State PUC. You should keep it that way.

At least high costs encourage conservation.

PJD
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Joined: 11/22/2006
Points: 1410
Re: Economic and Energy Efficiency of Electric Motor Scooters

And, back to the topic, thanks for the info!

I knew coal - almost 100% carbon - produces a whole lot more CO2 per unit of energy than gasoline, which is eight parts carbon and eighteen parts hydrogen. But thankfully, it looks like the e-scooter is still about twice as CO2 efficient as a gas scooter - and we still haven't considered the energy usage and and CO2 emitted transporting and refining the oil into gasoline.

Like I wrote, I buy new-wind energy "offsets" from Community Energy located near Philly. They're now a subsidiary of Iberdrola, S.A. a big Spanish wind energy developer (sounds like they might be a nice outfit to work for). Basically, for a "promise" to add 100 kwh of wind energy to the grid, you send then 2 dollars per 100 kwh per month. This is reportedly to offset the higher cost of this new energy source compared to the going market price. I buy 6 shares, so potentially, my carbon emissions from my scooter usage is zero.

Now, if we can get more that one household in the in the entire western two-thirds of Pennsylvania to start doing this, and we might get somewhere.

andreas
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Joined: 08/04/2007
Points: 4
Re: Economic and Energy Efficiency of Electric Motor Scooters

Please don't forget the battery costs. I have heard that a new set of batteries for the XM-2000 cost about $645 + tax. Let's say that the batteries can be charged 400 times and the average range per charge would be 25 miles. The depreciation costs are roughly $.06/ mile, thus one charge depreciates the scooter by about $ 1.50 . Is this correct ?
Andreas

goodnslo
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Joined: 01/08/2007
Points: 67
Re: Economic and Energy Efficiency of Electric Motor Scooters

Here is where I disagree with many naysayers of electric propulsion when they compare ICE maintenance to Battery maintenance. Replacing batts should be part of the maintenance costs, not part of the fuel costs. Just like replacing oil and antifreeze on an engine (or failing to) to preserve the life of the engine, batts have to be maintained within their tolerance levels to get effective and longer lasting charge/recharge cycles for the life of the batts. I.e. if you over rev and overheat an engine while failing to change the fluids you shorten its life dramatically. While failing to maintain batts by over draining and overheating the batteries between charging, shortens the life.

For batts, the disparity can best be seen in the forklift and golfcart industry with ppl claiming replacing batteries after 5 or more years while others are replacing after one.

Brock
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Joined: 08/16/2007
Points: 87
Re: Economic and Energy Efficiency of Electric Motor Scooters

If you want to add in the CO2 from burning coal to produce electricity that’s fine, but don't forget that the petroleum industry is the single largest consumer of energy in the United States. Mostly natural gas, but they are way up there for electricity as well. So the pollution from refining a gallon of gas, before it is burned to move you X miles, is already more then pollution from driving an EV what would be that same distance.

smace
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Joined: 03/05/2008
Points: 78
Re: Economic and Energy Efficiency of Electric Motor Scooters

I found this article while looking for something else
http://www.templetons.com/brad/transit-myth.html
For tihs discussion, it is interesting because it compares,amoung others, electric scooters to ICE cars, electric cars, ICE motorcycles and othes.

While this is not a total zero based cost, by that I mean whole cost from build to operations, it is interesting.

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