Continuing the prior note, I'd like to comment on footnote 2 regarding the net renewable energy balance of ethanol. This is a very controversial field. Authors like Pimenthal have argued the figure is negative as you do. On the other hand, Dr. Michael Wang at Argonne National Lab. has run several apparently well controlled studies and authored several papers showing it is positive. Wang seems to be using real data from the four principal corn producing states, while Pimenthal is using data from New York, not a major corn state. I would refer you to this or others of Wang's papers at the Argonne site: http://www.transportation.anl.gov/pdfs/TA/267.pdf Unfortunately, Wang's data is all Customary, but he shows the energy balance or net renewable energy as 20400 BTU/gal of the total 76330 BTU/gal LHV. This translates to +7.16 MJ/kg out of total LHV of 26.8 MJ/kg. Part of the difference is how credits are assigned to co-products, distillers grain, corn oil, and corn gluten feed. The rest is mostly due to differences in farming inputs.
--- On Fri, 4/3/09, Stan Jakuba <[email protected]> wrote: From: Stan Jakuba <[email protected]> Subject: [USMA:44288] RE: Energy and power units To: "U.S. Metric Association" <[email protected]> Date: Friday, April 3, 2009, 8:49 AM I agree with Pat. The SI unit of energy (any kind) is the joule and that of power (any kind) is the watt, as we all know. Using SI units "create a level playing field," indeed. It is obvious to anyone who works in several fields or professions concurrently that using SI (a coherent set of units) enables one to switch among values without conversions. Among the many engineering professions, only the electrical people insist on Wh; everybody else goes with Btu, cal, ft-lb, quad, etc. The joule only is hopefully in the future for all. Can you imagine the attached table in Wh? To illustrate the stupidity of unifying on kWh, I had a manuscript rejected recently because the editor did not distinguish between W and Wh and consequently thought that my numbers were incorrect. Fortunately, he informed me of the rejection and pointed to the "wrong" numbers. Being a considerate person, he did listen to my defense and accepted that there is a difference between kW and kWh. How many such occurrences are happening daily? How many editors would bather with checking themselves? Accepting J and W is a way to avoid such mistakes. Unfortunately, it requires a bit of education many are unaware is needed. It is so much easier to say - "nobody uses the joule." How would the newton or pascal caught on if everybody were waiting for it to catch on without anyone ever using it. The author of the book I recommended (withouthotair) is guilty of the anti-joule attitude also Fortunately, I see the new graduates publish papers in SI. So there is a hope. Soon we'll be celebrating 50 years of SI existence. Stan Jakuba ----- Original Message ----- From: Martin Vlietstra To: U.S. Metric Association Sent: 09 Apr 02, Thursday 17:21 Subject: [USMA:44281] RE: Energy and power units Pat, While you might be correct, I was stating the actual position in the UK . I checked some recent statements and the cost of my gas is 2.26p/kWh, while the cost of my electricity is 9.02 p/unit [sic]. As long as I am aware that a “unit” of electricity is one kWh, I can see that the cost of electrical energy is four time the cost of gas energy. Thus, heating using electricity is much more expensive than heating using gas. If I am interested in the cost of the energy to the planet, then yes, I will take into account the cost of production and transmission. In the UK (where there are a number of gas-fired power stations), I believe that there are considerable losses in the generation of electricity, so gas heating does less harm to the planet that electrical heating. When I was living in South Africa , the inverse was true. Regards Martin From: [email protected] [mailto:[email protected]] On Behalf Of Pat Naughtin Sent: 02 April 2009 07:50 To: U.S. Metric Association Subject: [USMA:44279] Energy and power units On 2009/04/01, at 4:17 PM, Martin Vlietstra wrote: “What is the rationale for billing in kilowatt-hours?” To create a level playing field with the electrical industry. Dear Martin, With respect, using kilowatt-hours to bill people for electricity and for gas does not, In my opinion, create a level playing field. I think that many people have difficulty distinguishing between kW and kWh and between their related physical quantities power and energy. It seems to me that power and energy are more clearly identified when power is measured in kW and energy is measured in kJ (rather than power measured in kW and energy measured in kW.h). Consider an example where natural gas is supplied directly to your home with an energy content of (say) 53 MJ/kg compared to the same gas supplied to an electricity turbine to produce electrical energy that is then transmitted through the grid to your home. The gas that is supplied to you directly should not be compared to the energy supplied as electrical energy because of the production and the transmission losses via this pathway. Cheers, Pat Naughtin 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 for more metrication information, contact Pat at [email protected] or to get the free 'Metrication matters' newsletter go to: http://www.metricationmatters.com/newsletter to subscribe.
