Hakan, et. al.: I am reminded of a review I read a few years ago when the first Hybrid Vehicle was introduced in the U.S. , the Honda Insight.
The reviewer mentioned that she found herself paying attention to the dashboard read-out on fuel usage, that it gave her a very interesting feedback on her fuel efficiency, and that she found her habits changing. She saw cars going by focusing on their speed, but she found herself changing from a focus on speed to a focus on her fuel efficiency, finding that it was just sort of naturally fun to see if she could improve even more the bar-graph (or whatever it was) that indicated her energy efficiency. I have read similar comments, once in awhile, from EV-owners and others. One of the lessons I take home from this is the importance of the interface between the person and their human behaviour and the appliance. If our appliances were able to speak, they might be able to say something like: "Hey, I'm a 20 year old refrigerator, and my coolant may or may not be low. Anyway, I'm using about 4 kWh per day of energy and that's about 2 or 3 or more kWh too many. I can't tell you what the latest fridges are like, but you might want to focus on making sure I'm repaired properly or looking into replacement options.... and let's see about environmentally-correct options for coolant, and while you're at it let's see about getting some water through the door and whether that works well with your habits to save energy or lose it...." etc. It took us many decades to make more progress in energy-usage-feedback-information and other feedback features in vehicles, and those are vehicles whose fuel we are very much "in touch" with. We often have to stop and refuel the vehicles by hand, and we know how much it costs, and we know very quickly if we are going through a time when prices are very high. So, in appliances, where we are not as in-touch with the amounts of energy we use, it would be great if we could make progress in building homes to give the homeowner more feedback as to which appliances are using how much energy, what type of energy, suggested options, etc. And the appliances (such as a fridge or a washing machine where both electricity and water and enviro-runoff are an issue) could have "dashboards" to give basic feedback info. Sure, it would cost a bit more, but whatever. We do it with cars, and we'll eventually do it with fridges (probably are already in some cases), so I don't see that as prohibitive. I was re-reading your web page discussion of rope curtains and you were discussing your frustration with how over many centuries people gained and possessed ingenious knowledge of how to deal with various engineering challenges, but in our time we seem to have lost many of those pieces of knowledge. It seems true enough. It's a tough problem though. We each only get a number of years on this planet, and we have to spend so many of those years learning and re-learning. There's no punch-line to this last paragraph, except that maybe one piece in the puzzle is improving the machine-human-information-interface. Appliance or vehicle owners, armged with greater knowledge of the energy they're using, can be more aware and maybe make somewhat improved buying and machine-using decisions. On Wed, 17 Mar 2004 02:44:25 +0100, you wrote: > >MM, > >Before we get too exited about savings by using DC instead of AC, we might >look at where and why we have this large differences in the energy use by >appliances. Let us first establish the fact that a conversion as such, will >cost us between 3 to 10%, depending on method, size and application. > >When you talk about appliances, we should also include the AC/Heat pump >unit in this and very large savings can be done. The losses are more >created by the use of electrical engines/compressors, than by the use of >alternate current or direct current. The large differences in energy use >does not come from the type of current, but from the way the capacity >control is done. The revelation control in AC engine used in the appliances >is governed by the fixed AC frequency and the capacity control is done by >starting and stopping the compressor. The revelation control in the DC >engine is governed by voltage/current and the capacity control is done by >varying the speed/force of the engine. Since you already are very familiar >with electrical engines, you are probably ahead of me now, about the >consequences of the different methods. I will anyway mention that the >consequences can be somewhere between 30 to 45% more energy use by the >capacity control of the AC engine. After the conversation losses, we end up >with around 25-30% difference in energy use for appliances. > >In the past it was very large differences cost and durability between the >AC and DC engines, in favor to the AC engines. By new development, these >differences are no longer an critical issue and the energy use have started >to be the absolute critical issue for certain engine applications. > >If you look at losses in distribution of DC, we must agree with the much >higher efficiency of AC. One very important issue is also the security >aspects, which more or less totally disqualifies high voltage DC in homes >and for general use in appliances. It is better and more manageable of >security design, if the conversion is done in the appliance and close to >the engine. The large loss of lives, that a general high voltage DC >distribution would cause, is not worth it. > >Hakan > > >At 22:13 16/03/2004, you wrote: >>On Mon, 15 Mar 2004 23:48:36 -0800 (PST), you wrote: >> >> > >> >Monday, March 15/04 >> >murdoch <[EMAIL PROTECTED]> wrote: >> > >> >>What about the issue of efficiency in converting from AC >to DC and >> >>then back to AC? >> > >> >>Each of these conversion actions may have >> >>consequences in terms of lost energy, but I haven't yet >figured out >> >>the losses. This has come up for me recently, so it's >on my mind. >> > >> >According to an "Inverter comparison chart," supplied by West Marine >> Co. Maximum efficiency of the inverters they list range from 88% to >> 94%. All of the products that they list appear to be made by Xantrex, >> (Heart Interface, Trace Engineering and Statpower are all now owned by >> Xantrex making them probably the biggest manufacture of >> inverters). Many of these products have built in battery chargers. I >> don't know if the efficiency of the charging circuit is equal to that of >> the inverting circuit. I don't have efficiency data on chargers. >> > >> >If we assume that a good charger will deliver about 90% efficiency on >> the conversion from 120 VAC to DC, and a good inverter will deliver about >> 90% back to AC, you can expect to lose about 20% in conversion. >> > >> >I hope this helps put you in the ballpark regarding efficiency. >> >>Yes, it does help, thank you. I was looking into a converter, to go >>from AC to DC, because there is a DC refrigerator out there >>(Sundanzer) that appears to be so efficient that I thought it might be >>worthwhile to consider. >> >>The price for an AC-to-DC converter was reasonable, but the salesman >>wasn't 100% sure about efficiency losses. We made sort of a little >>side-project about this, because nobody had really asked these >>questions before, and they're just starting to sell Sundanzer, >>alongside Equator and Sun Frost. >> >>He got a figure of 5% that we used as a sort of stop-gap. But I think >>to be safe, I'd add a bit more on to that 5%, and that "bit-more" >>jibes with your research. >> >>In the end, I think I'm going to get a Sun Frost RF-12, and eschew the >>separate Fridge-separate-freezer idea. I had that thought because >>there are times when I want a fridge but don't use a Freezer that >>often, and the savings of unplugging the freezer could be substantial? >> >>The Sun Frost is super-expensive compared to a decent small Energy >>Star Conventional Fridge I could buy at Home Depot, but it's still >>about twice-or-more efficient, and might in the end save me enough >>energy to save me money. And since it's AC, I'll be able to avoid >>this inconvenience of changing over my whole house to this or that. >> >>Sundanzer does have this one wild product... a fridge that is designed >>to operate solely on a modest (90-120 watts?) solar array in certain >>types of regions without any batteries at all: >> >><http://www.sundanzer.com/PDF/SunDanzer_Batt_Free_Tech_Sh.pdf>http://www.sundanzer.com/PDF/SunDanzer_Batt_Free_Tech_Sh.pdf >> >>MM > > > > >Biofuel at Journey to Forever: >http://journeytoforever.org/biofuel.html > >Biofuels list archives: >http://infoarchive.net/sgroup/biofuel/ > >Please do NOT send Unsubscribe messages to the list address. >To unsubscribe, send an email to: >[EMAIL PROTECTED] >Yahoo! Groups Links > > > > > Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://infoarchive.net/sgroup/biofuel/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Yahoo! 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