That would be 20 J/m. --- On Fri, 9/18/09, lps <[email protected]> wrote:
From: lps <[email protected]> Subject: [USMA:45837] Re: Fuel efficiency – joules per metre To: "U.S. Metric Association" <[email protected]> Cc: "U.S. Metric Association" <[email protected]> Date: Friday, September 18, 2009, 8:15 PM My bicycle expends an average of 20 kJ/km or 0.02 J/m (best for comparison with cars) or (Help me here) 20 mJ/m (yes miliJoules) My battery is a 20 A*h 36 volt battery (LiFeO2). Pat Naughtin wrote: > On 2009/09/19, at 08:36 , lps wrote: > >> You can use J/m with electric cars too. I use the figure with my electric >> bicycle. I convert w*h/ km to J/km. You can convert that to J/m if desired. > > Dear Linus, > > Thanks for your email. I would like to make two points: > > 1 Could you share with us some of your data in joules per metre for your > electric bicycle so that we can make comparisons with other vehicles. Where > does your electric bicycle fit on this scale? > > Car 3 200 J/m > Boeing 747 5 440 J/m > School bus 13 510 J/m > Truck 15 440 J/m > > 2 I think that it is preferred practice in SI to have the denominator in a > unit without a prefix and to apply any prefix to the numerator. In this case, > kilojoule per metre (kJ/m) would be preferred to joules per kilometre (J/km). > However, that said, I believe that the simplest SI unit applied with whole > numbers is the best possible solution. > > Cheers, > Pat Naughtin > Author of the ebook, /Metrication Leaders Guide,/ that you can obtain from > http://metricationmatters.com/MetricationLeadersGuideInfo.html PO Box 305 > Belmont 3216, > Geelong, Australia > Phone: 61 3 5241 2008 > > Metric system consultant, writer, and speaker, Pat Naughtin, has helped > thousands of people and hundreds of companies upgrade to the modern metric > system smoothly, quickly, and so economically that they now save thousands > each year when buying, processing, or selling for their businesses. Pat > provides services and resources for many different trades, crafts, and > professions for commercial, industrial and government metrication leaders in > Asia, Europe, and in the USA. Pat's clients include the Australian > Government, Google, NASA, NIST, and the metric associations of Canada, the > UK, and the USA. See http://www.metricationmatters.com > <http://www.metricationmatters.com/>for more metrication information, contact > Pat at [email protected] > <mailto:[email protected]> or to get the free '/Metrication > matters/' newsletter go to: http://www.metricationmatters.com/newsletter to > subscribe. > >> Pat Naughtin wrote: >>> Dear All, >>> >>> I have just read the article at >>> http://www.metrication.us/content/demise-mpg where I was struck by the >>> first paragraph. >>> >>> /Even before the advent of partially- or fully-electric cars, it was >>> becoming increasingly apparent that the old fuel economy metric of miles >>> per gallon isn't as useful for measuring energy consumption in vehicles as >>> when it was first codified in the original Corporate Average Fuel Economy >>> standard in the 1970s. That is due in part to the proliferation of new >>> fuels--E85, LPG, LNG, CNG, methanol, and hydrogen--but also because >>> expressing the relationship between distance and volume in this way >>> obscured the diminishing returns to higher levels of fuel economy. As a >>> Wall St. Journal column earlier this week put it, adding electricity into >>> the mpg mix, "risks giving consumers inaccurate information about the >>> financial and environmental costs of driving." But if we need a new metric, >>> what should it measure?/ >>> >>> I think that the time is rapidly approaching for energy to be measured in >>> the only SI energy unit – joule – and that old pre-metric measuring words >>> for fuel efficiency should be converted to the only SI unit available for >>> energy efficiency for road transport – joules per metre. >>> >>> As a starting reference, here are some examples: >>> >>> *Average car* >>> 32 megajoules per litre (32 MJ/L) for lead free car fuel, and >>> 10 litres per 100 kilometres (10 L/100 km) fuel consumption, then >>> an average car consumes 3 200 joules of energy for each metre it travels (3 >>> 200 J/m). >>> >>> *Average truck* >>> 38.6 megajoules per litre (38.6 MJ/L) for diesel fuel, and >>> 40 litres per 100 kilometres (40 L/100 km) fuel consumption, then >>> an average truck consumes 15 440 joules of energy for each metre it travels >>> (15 440 J/m). >>> >>> *Average (school) bus* >>> 38.6 megajoules per litre (38.6 MJ/L) for diesel fuel, and >>> 35 litres per 100 kilometres (35 L/100 km) fuel consumption, then >>> an average truck consumes 13 510 joules of energy for each metre it travels >>> (13 510 J/m). >>> >>> *Average Boeing 747* >>> 34 megajoules per litre (34 MJ/L) for diesel fuel, and >>> 16 litres per 100 kilometres (16 L/100 km) fuel consumption, then >>> an average truck consumes 5 440 joules of energy for each metre it travels >>> (5 440 J/m). >>> >>> *Summary* >>> Car 3 200 J/m >>> Boeing 747 5 440 J/m >>> School bus 13 510 J/m >>> Truck 15 440 J/m >>> >>> As usual, I commend to you the simplicity of SI units and the ease of >>> understanding using whole numbers (see >>> http://www.metricationmatters.com/docs/WholeNumberRule.pdf ). >>> >>> Sadly, I could not find comparative figures for electric cars – even at >>> http://www.optimalenergy.co.za/news/article.php?pk_news_id=112v >>> Cheers, >>> Pat Naughtin >>> Author of the ebook, /Metrication Leaders Guide,/ that you can obtain from >>> http://metricationmatters.com/MetricationLeadersGuideInfo.html PO Box 305 >>> Belmont 3216, >>> Geelong, Australia >>> Phone: 61 3 5241 2008 >>> >>> Metric system consultant, writer, and speaker, Pat Naughtin, has helped >>> thousands of people and hundreds of companies upgrade to the modern metric >>> system smoothly, quickly, and so economically that they now save thousands >>> each year when buying, processing, or selling for their businesses. Pat >>> provides services and resources for many different trades, crafts, and >>> professions for commercial, industrial and government metrication leaders >>> in Asia, Europe, and in the USA. Pat's clients include the Australian >>> Government, Google, NASA, NIST, and the metric associations of Canada, the >>> UK, and the USA. See http://www.metricationmatters.com >>> <http://www.metricationmatters.com/>for more metrication information, >>> contact Pat at [email protected] >>> <mailto:[email protected]> or to get the free >>> '/Metrication matters/' newsletter go to: >>> http://www.metricationmatters.com/newsletter to subscribe. >>> >> >
