This is from a discussion I had on the power-assist Yahoo Group.
It basically says that an electrically power-assisted bicycle gets the equivalent of about 300 miles per gallon of gas.
-----Original Message----- From: MH [mailto:hoagy-don't-spam-him@nelson-tel.net] Sent: Tuesday, May 06, 2003 3:49 PM To: power-assist-and-don't-spam-the-group@yahoogroups.com Subject: Re: [power-assist] Re: Electric MPG
Lee wrote: > > Another stab at this. This is more of a sanity-check since I'm doing a > little guessing. > > A portable gasoline powered electric generator > (http://www.southwestfastener.com/productsMQgeneratorport.htm) > has published specs of: > > 2000 continuous watts > 3.6 gallon fuel tank > running time 7.25 hrs Let's compare. The above -- Multiquip GA-2.3R2 Robin Gasoline Engine Portable Generator $999 Below -- portable Robin diesel generator RGD2500 $1299 Rated Output [AC (W)] 2200W 2.06 gallon fuel tank running time 7.1 hours at full load http://www.southwestfastener.com/productsRobinGenerator.htm I've read when comparing a air cooled hydrocarbon fueled ICE with diesel fuel will out last a gasoline version 3-6 times longer. > That's 2000 * 7.25 = 14.5 kilowatt / hours out of 3.6 gallons > 14.5 / 3.6 = 4,000 watt hrs / gallon of gasoline 2200 x 7.1 = 15.6 kW 15.6 / 2.06 = 7,580 watts/US gallon of diesel fuel > It has been said on the list "1 gallon of gasoline = 36.6 KwH"... assuming > 100% conversion of power. NOTE: Gasoline -- HHV = 125,000 Btu/US gallon [125,000/3412=36.6kW] LHV = 115,000 Btu/US gallon [115,000/3412=33.7kW] DinoDiesel Fuel -- HHV(?) = 130,500 Btu/US gallon [130,500/3412=38.2kW] Biodiesel -- HHV (?) = 123,800 Btu/US gallon [123,800/3412=36.3kW] The appropriateness of using LHV (Lower Heating Value) or HHV (Higher Heating Value) when comparing fuels, calculating thermal efficiencies, etc. really depends upon the application. For stationary combustion where exhaust gases are cooled before discharging (e.g. power stations), HHV is more appropriate. Where no attempt is made to extract useful work from hot exhaust gases (e.g. motor vehicles), the LHV is more suitable. In practice, many European publications report LHV, whereas North American publications use HHV. http://bioenergy.ornl.gov/papers/misc/energy_conv.html > It's also been said that gasoline engines are 10-20% efficient in converting > gas into motion. By my rough calculations (and also realizing that, in a > generator, some more energy is lost by converting that motion into > electricity) the calculations of the list members are correct. Therefore: Again I've read, about -- 25-30% Gasoline ICE efficiency for Light Duty Vehicles (cars, Pkups, Suv, vans) 35-40% Diesel ICE efficiency for Light Duty Vehicles (cars, Pkups, Suv, vans) say in a hybrid vehicle when the ICE is run at peak torque/rpm which is usually the optimum hydrocarbon fuel combustion efficiency.... Non hybrid vehicles then drop when adding a transmission, air conditioning, power steering, alternator, tire rolling resistance, airodrag, city driving, etc. > --------- > 1 gallon of gasoline can be converted into (throwing in a guessed-at 10% > loss) roughly 5 kilowatt/hrs of motion, or 4 kilowatt/hrs of electricity. > ---------- > > A power-assist bike might have 2 12 v 12 amp/hr batteries. 2 * 12 * 12 = > 288 watt/hrs > and it'll go 15 miles on that charge. 288/15 = 19.2watt/hrs / mile (call > it 20 watt/hrs / mile) > > So, to make the equivalence that we've been looking for, an electric power > assisted bike would go > 4000 watt/hrs/gallon / 20 watt/hrs/mile = 200 miles per gallon of > gasoline. This is a rough estimate but it's in the right ballpark. 7,580 watts/US gallon of diesel fuel / 20W/mi = 379 MPG using the above dinodiesel fuel genset. > Now, the only big thing that everyone has forgotten here (and it's a huge > thing!) is that this comparison assumes that the electricity coming out of > the wall socket is a "power source". Gasoline is (arguably) a power source > because it gets pumped out of the ground and then burned, essentially for > free. But electriciy isn't a power source, it is generated at a power > station and then transmitted to us. Free ?? Another genset comparison -- $1.50 per US gallon of Gasoline & Diesel Fuel $0.65 per US gallon of DIY Biodiesel $1.50 / 4.00kW/US gallon = $0.38 kW [gasoline genset] $1.50 / 7.58kW/US gallon = $0.20 kW [dinodiesel fuel genset] $0.65 / 7.20kW/US gallon = $0.09 kW [DIY biodiesel fuel genset] NOTE: Biodiesel kW/US gallon has been reduced because of the 5 percent reducation in Btu output compared to DinoDiesel Fuel Btu/US gallon. http://bioenergy.ornl.gov/papers/misc/energy_conv.html ________________________________ Yahoo! Groups Sponsor ________________________________________________________________ To unsubscribe, mailto: power-assist-unsubscribe@yahoogroups.com To get e-mail help, mailto: power-assist-help@yahoogroups.com Power-Assist on the web at http://www.power-assist.org/