Re: [biofuel] AC vs. DC electricity, was: Electricity storage solutions.
Darryl McMahon wrote: I know there are motors called brushless DC, but for my purposes these are effectively AC motors. There are also universal motors, which can run on AC or DC, but in effect, these are AC motors with brushes, and seldom are found in sizes above 1/2 hp. Hi Darryl, I saw an article in IEEE Spectrum just last week about the new US military prototype humvee hybrid. It has a 50kW PM BLDC in each hub. -- -- Martin Klingensmith http://infoarchive.net/ http://nnytech.net/ Yahoo! Groups Sponsor -~-- Buy Ink Cartridges or Refill Kits for your HP, Epson, Canon or Lexmark Printer at MyInks.com. Free s/h on orders $50 or more to the US Canada. http://www.c1tracking.com/l.asp?cid=5511 http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/FGYolB/TM -~- 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 * To visit your group on the web, go to: http://groups.yahoo.com/group/biofuel/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [biofuel] AC vs. DC electricity, was: Electricity storage solutions.
Darryl, At 14:43 19/03/2004, you wrote: snip Picking the right size AC or heat pump unit for a house is difficult (based on correct scientific and mathematical formulae), which is why those in the trade rely on rules of thumb. The problem arise when the thumb replaces the brain. Empirical dimensioning served the humanity well, it is the revenual (new word) dimensioning that causes the problems. And the rules of thumb almost always are based on the worst case (slightly overestimate the area of the building, assume worst orientation to the sun, no shade, no thermal mass, maximum human occupancy... ) Because it is cheaper for the installer to put in too large a unit (the home owner pays for the extra size, and the inefficiency of the unit) than to have to come back, remove the unit that has turned out to be too small (perhaps only once and in a completely unusual situation) and replace it with a larger one. So long as energy prices remain cheap and hidden (one hydro bill for 60 days at a time, provided to the customer a full month after that period is over, for the entire building) instead of realistic and up front (appliance-based readouts, instantaneous and with logs), given my experience with human nature, I don't see much hope for change with the mass of consumers. To borrow a phrase from my business consulting days, you can't manage what you can't measure. It certainly applies to our energy consumption. It seems almost innate, we try to maximize what we can measure or sense. Put somebody in a conventional gasoline-powered car today, equipped with a speedometer and little else in the way of instrumentation, they will drive to maximize speed. Put in instrumentation that displays fuel economy (e.g. the Prius hybrid or a Chryser New Yorker I owned a long time ago), and people start to drive to maximize fuel economy. Your point makes sense. snip Hakan Yahoo! Groups Sponsor -~-- Buy Ink Cartridges or Refill Kits for your HP, Epson, Canon or Lexmark Printer at MyInks.com. Free s/h on orders $50 or more to the US Canada. http://www.c1tracking.com/l.asp?cid=5511 http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/FGYolB/TM -~- 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 * To visit your group on the web, go to: http://groups.yahoo.com/group/biofuel/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [biofuel] AC vs. DC electricity, was: Electricity storage solutions.
MM, I thought that I was loosing this very interesting issue. Regarding links of appliances, we can revisit SunDanzer. http://www.sundanzer.com/PDF/SunDanzer_Batt_Free_Tech_Sh.pdfhttp://www.sundanzer.com/PDF/SunDanzer_Batt_Free_Tech_Sh.pdf At the beginning they say The unit operates using a variable speed compressor, peak power tracking, thick insulation, and a internal thermal storage to optimize cooling efficiency.. They are actually describing what I have been saying so many times. It works for fridges and it works for large office buildings. The large efficiency gains are not because it runs from solar panel, because if it ran from a AC driven AC to DC converter, it would still be a very efficient fridge and outperform most fridges in the market with large margin, in the very worst case using 10W more. The large gains are from variable output and control methods. Then it have added insulation and thermal storage, instead of charging batteries, also very smart and necessary for a solar only driven unit. http://www.toshiba-aircon.co.uk/products/flysheets/DIGITAL%20INVERTER%20BROCHURE.PDF http://www.aar.co.nz/brands/toshiba.html http://www.eastsiderefrigeration.co.nz/Heat_Pumps.shtml Look at Inverter Technology. http://www.fujitsugeneral.co.jp/english/new/spl/spl.html http://www.infineon.com/cmc_upload/migrated_files/document_files/Others/Airconbrochure-2.pdf http://www.bdt.co.nz/comfortmaster/apps.asp http://www.bdt.co.nz/comfortmaster/apps.asp Search for air conditioner inverter technology or variants, you get a lot of non US sites. I was surprised about that. They are using a lot of marketing BS, but it is simple - DC driven compressor - and control to utilize it. I already explained how it worked. Have been used in large computer room AC systems for years, were it important to keep both temperature and humidity within certain limits. It is so long time ago, that I encountered the technology, that I do not remember when. Only needed development of consumer products. As I said ready for use energy saving and maybe a silver bullet type of technology. Have been there and known for many years, not a new and exiting technology, only a technology that does the job.. They say that the purchase price is around 10% of the life time cost, so you can easily claim that the first you buy would be paid back by savings in 3 to 5 years. VERY GOOD INVESTMENT IN ENERGY EFFICIENCY ! Hakan At 00:35 19/03/2004, you wrote: I'm not sure what you're talking about as far as offending anyone, so I don't think there's any danger of that, except that to some extent we get off-topic. Could I please ask you to go over this a bit more: My belief is that variable output DC engines in appliances, AC units and heat pumps, are very important. These (up to 30% savings), together with CFL lamps (more than 60% savings), are probably the closest we can come to simple silver bullet and ready for use saving technologies, in domestic electricity use. When you say variable output DC engines in appliances, AC units and heat pumps, what are you saying? That variable output DC engines are a potential 30% savings *over* comparable AC units, or they can be 'part of' the technology inside of AC units? I just want to make sure I understand precisely what you're saying here. Maybe you could provide a link to an example appliance? A lot of work, I know. Yahoo! Groups Sponsor -~-- Buy Ink Cartridges or Refill Kits for your HP, Epson, Canon or Lexmark Printer at MyInks.com. Free s/h on orders $50 or more to the US Canada. http://www.c1tracking.com/l.asp?cid=5511 http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/FGYolB/TM -~- 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 * To visit your group on the web, go to: http://groups.yahoo.com/group/biofuel/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [biofuel] AC vs. DC electricity, was: Electricity storage solutions.
Actually Hakan, I thought you pretty much covered the topic for electric motors at a high level. For me, the AC vs. DC decision comes down to what each one is good at. I have some experience with the subject (and the electric vehicles and appliances from antique to modern to back that up). AC motors strengths. No brushes, for reduced maintenance, and reduced drag. Best in low torque, fixed-speed, relatively constant load operation. Work-around for demands with high start torque is to use a capacitor start. So, with some good design work around sizing, they should be good for things like refrigerator compressors and furnace fans (with the capacitor start), and also cooling fans, pumps, rotisseries, clocks, etc. AC motors weaknesses. Providing efficient operation at varying speeds and loads requires modifying frequency in conjunction with voltage and current in non-linear fashion, a complex control issue. Therefore, varying loads and speeds are a headache for AC control. Certainly can't just hook it up to the mains and expect reasonable operation and efficiency. DC motors strengths. Several configurations available, series, shunt, compound, separately excited, which can be tailored to meet specific load and speed requirements. Typically can handle heavy starting torque demands quite easily. Varying speed and load fairly easy by simply controlling voltage. DC motors weaknesses. Brushes reduce efficiency, increase maintenance. I know there are motors called brushless DC, but for my purposes these are effectively AC motors. There are also universal motors, which can run on AC or DC, but in effect, these are AC motors with brushes, and seldom are found in sizes above 1/2 hp. So, if you want your electric motor to operate efficiently, the most important things are to pick the right type of motor for the job to be done, then pick the right size for the expected load, then focus on getting a quality unit that will reduce operational losses. In my opinion, in most commercial appliances, the motor and control are usually not the main focus for efficiency gains. Outside of mass-produced automotive units, motor efficiencies will exceed 85% in their specified operational range. Better than 90% is not unusual. Especially in household applications, where lack of efficiency is expressed as objectionable noise and heat, there is an incentive for manufacturers to keep those losses to a minimum. (In automobiles, there is already so much heat and noise being produced that the amounts coming from electric motors simply is not noticed, so the standards are lower.) For example, in the case of a refrigerator or freezer, it would probably make more sense (energy saved per dollar invested) to improve/increase the insulation in the refrigerator to reduce heat infiltration, and improve the seal of the door(s) to reduce air exchange. Where DC motors in refrigerators were deemed to be more efficient than AC motors, my analysis concluded that the gains actually came from operating the unit from batteries rather than mains (AC) power, or the refrigerator was smaller (because battery power, usually off-grid, is more precious than mains power), or the unit was better insulated and sealed (again to meet the different needs and values of off-grid customers). In areas that get more insolation than we do, it usually turned out to be cheaper to buy an additional solar panel, an extra battery and an efficient, relatively small, mass-market refrigerator (one that would qualify for an Energy Star rating now) than to buy one of the specialty, hyper-efficient DC- powered refrigerators developed for the off-grid market. (The analysis assumed there would already be an inverter in the household that could be used.) Now, you probably wished you had killed the thread. grin Darryl McMahon (off to do some sewing on an antique Pfaff sewing machine - the kind where the foot- powered treadle was replaced by a small electric motor with a pulley to the same pulley driven by the treadle) To: biofuel@yahoogroups.com From: Hakan Falk [EMAIL PROTECTED] Date sent: Thu, 18 Mar 2004 22:31:38 +0100 Subject:Re: [biofuel] AC vs. DC electricity, was: Electricity storage solutions. Send reply to: biofuel@yahoogroups.com MM, I seams to have done it again! Killed off a very interesting discussion. I do not know if I maybe am to abusive or what is wrong? Not good for me and the goals that I thought that I was championed. If I offended you or anyone else, I must apologize to both you and the list, but I hoped that this could lead to an important energy saving discussion. My belief is that variable output DC engines in appliances, AC units and heat pumps, are very important. These (up to 30% savings), together with CFL lamps (more than 60% savings), are probably the closest
Re: [biofuel] AC vs. DC electricity, was: Electricity storage solutions.
was better insulated and sealed (again to meet the different needs and values of off-grid customers). In areas that get more insolation than we do, it usually turned out to be cheaper to buy an additional solar panel, an extra battery and an efficient, relatively small, mass-market refrigerator (one that would qualify for an Energy Star rating now) than to buy one of the specialty, hyper-efficient DC- powered refrigerators developed for the off-grid market. (The analysis assumed there would already be an inverter in the household that could be used.) Now, you probably wished you had killed the thread. grin Darryl McMahon (off to do some sewing on an antique Pfaff sewing machine - the kind where the foot- powered treadle was replaced by a small electric motor with a pulley to the same pulley driven by the treadle) To: biofuel@yahoogroups.com From: Hakan Falk [EMAIL PROTECTED] Date sent:Thu, 18 Mar 2004 22:31:38 +0100 Subject: Re: [biofuel] AC vs. DC electricity, was: Electricity storage solutions. Send reply to:biofuel@yahoogroups.com MM, I seams to have done it again! Killed off a very interesting discussion. I do not know if I maybe am to abusive or what is wrong? Not good for me and the goals that I thought that I was championed. If I offended you or anyone else, I must apologize to both you and the list, but I hoped that this could lead to an important energy saving discussion. My belief is that variable output DC engines in appliances, AC units and heat pumps, are very important. These (up to 30% savings), together with CFL lamps (more than 60% savings), are probably the closest we can come to simple silver bullet and ready for use saving technologies, in domestic electricity use. Hakan At 02:44 17/03/2004, 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
Re: [biofuel] AC vs. DC electricity, was: Electricity storage solutions.
There are definitely AC motors (and DC motors) that are built (even designed) so badly that they are inefficient. As I stated in my last post, the automotive industry is noted for these. Even when we start with a good motor, there are situations where it is misapplied, and that affects efficiency. You have pointed out one, where the motor cycles on and off frequently, which forces the motor into its inefficient operation region frequently (e.g. capacitor start mode). Another cause is a commercial decision to use a single type of motor across a line of different sized products to get a longer production run of motors (hoping for economies of scale in manufacture of the motors and the goods in process inventory for manufacture of the units that use the motor). In the case of refrigerators, this means that there may be a mid-line unit that uses the motor efficiently, a small unit for which the motor is too big (so it runs often for short periods, so spends a higher ratio of its time in an inefficient mode), and a larger unit where the motor is too small, so the load may force the motor to work too hard, saturating the field, producing excess heat, thus lowering efficiency. It is hard for the consumer to know what design work and decisions went into the creation of a specific appliance or machine they are purchasing. However, the EnerGuide and EnergyStar (and similar in other jurisdictions) systems give some idea of relative efficiencies (not absolute efficiencies, and the consumer also needs to know to keep as many other variables constant as possible). For heat pumps and air conditioners, there are also standards related to the CoP (Co-efficient of Performance). Provided this data is available from a reliable source, it should be possible to compare across machines to establish relative efficiency. Picking the right size AC or heat pump unit for a house is difficult (based on correct scientific and mathematical formulae), which is why those in the trade rely on rules of thumb. And the rules of thumb almost always are based on the worst case (slightly overestimate the area of the building, assume worst orientation to the sun, no shade, no thermal mass, maximum human occupancy... ) Because it is cheaper for the installer to put in too large a unit (the home owner pays for the extra size, and the inefficiency of the unit) than to have to come back, remove the unit that has turned out to be too small (perhaps only once and in a completely unusual situation) and replace it with a larger one. So long as energy prices remain cheap and hidden (one hydro bill for 60 days at a time, provided to the customer a full month after that period is over, for the entire building) instead of realistic and up front (appliance-based readouts, instantaneous and with logs), given my experience with human nature, I don't see much hope for change with the mass of consumers. To borrow a phrase from my business consulting days, you can't manage what you can't measure. It certainly applies to our energy consumption. It seems almost innate, we try to maximize what we can measure or sense. Put somebody in a conventional gasoline-powered car today, equipped with a speedometer and little else in the way of instrumentation, they will drive to maximize speed. Put in instrumentation that displays fuel economy (e.g. the Prius hybrid or a Chryser New Yorker I owned a long time ago), and people start to drive to maximize fuel economy. For appliances, this is probably a ways off. I have built a set-up with batteries, DC ammeter and an inverter that permits me to get a good sense of what any specific machine (12 volts DC or 120 volts AC, with alllowance for inverter losses) is using in the way of energy. No automated logging. There are such units available commerically as well. However, until these are in widespread use, and possibly built into large devices (e.g. household-scale heat pumps), I think mass concern over the efficiency of such devices will not happen. Darryl McMahon To: biofuel@yahoogroups.com From: Hakan Falk [EMAIL PROTECTED] Date sent: Fri, 19 Mar 2004 06:56:22 +0100 Subject:Re: [biofuel] AC vs. DC electricity, was: Electricity storage solutions. Send reply to: biofuel@yahoogroups.com Thanks Darryl, I appreciate your explanation and your support. Because of several factors, the common equipment for compressors are very in inefficient, especially AC/Heat pump units. The way they have been designed and then dimensioned, are a great robbery and rip off. The customers know nothing and the common HVAC engineer is trained by the suppliers. It must be someone in the design and development of them, that know much more than me. The large majority of people involved, are probably quite ignorant and belive what they learn in school
Re: [biofuel] AC vs. DC electricity, was: Electricity storage solutions.
It seems almost innate, we try to maximize what we can measure or sense. Put somebody in a conventional gasoline-powered car today, equipped with a speedometer and little else in the way of instrumentation, they will drive to maximize speed. Put in instrumentation that displays fuel economy (e.g. the Prius hybrid or a Chryser New Yorker I owned a long time ago), and people start to drive to maximize fuel economy. We seem to be of like mind on this issue of addressing human behaviour and the technology-human interface. You weren't responding to my post directly, but I'll assume that you read through it. Obviously you're way ahead of me if you've already built some of these devices. What I wanted to add was even a bit more offbeat. I was thinking the other day of some of the excellent farming-related and rural-related posts that we sometimes see here and elsewhere. And I was asking myself why we see relatively little coverage of such matters in major press-areas. And I think it's in part because city-folks, including many journalists, have little but city-issues in front of their faces. So, even though they may want to take some interest in other issues, they go with the lifestyle and issues that present themselves readily rather than issues that might make a more well-rounded presentation and might appeal to a broader range of readers. This is not to say this can't be changed in part just to try to figure out why there is (in my view) this disconnect where some challenging rural issues don't seem to get as much 4th estate coverage as I would have thought they warranted. For appliances, this is probably a ways off. I have built a set-up with batteries, DC ammeter and an inverter that permits me to get a good sense of what any specific machine (12 volts DC or 120 volts AC, with alllowance for inverter losses) is using in the way of energy. No automated logging. There are such units available commerically as well. However, until these are in widespread use, and possibly built into large devices (e.g. household-scale heat pumps), I think mass concern over the efficiency of such devices will not happen. Darryl McMahon 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 * To visit your group on the web, go to: http://groups.yahoo.com/group/biofuel/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [biofuel] AC vs. DC electricity, was: Electricity storage solutions.
MM, I seams to have done it again! Killed off a very interesting discussion. I do not know if I maybe am to abusive or what is wrong? Not good for me and the goals that I thought that I was championed. If I offended you or anyone else, I must apologize to both you and the list, but I hoped that this could lead to an important energy saving discussion. My belief is that variable output DC engines in appliances, AC units and heat pumps, are very important. These (up to 30% savings), together with CFL lamps (more than 60% savings), are probably the closest we can come to simple silver bullet and ready for use saving technologies, in domestic electricity use. Hakan At 02:44 17/03/2004, 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
Re: [biofuel] AC vs. DC electricity, was: Electricity storage solutions.
I'm not sure what you're talking about as far as offending anyone, so I don't think there's any danger of that, except that to some extent we get off-topic. Could I please ask you to go over this a bit more: My belief is that variable output DC engines in appliances, AC units and heat pumps, are very important. These (up to 30% savings), together with CFL lamps (more than 60% savings), are probably the closest we can come to simple silver bullet and ready for use saving technologies, in domestic electricity use. When you say variable output DC engines in appliances, AC units and heat pumps, what are you saying? That variable output DC engines are a potential 30% savings *over* comparable AC units, or they can be 'part of' the technology inside of AC units? I just want to make sure I understand precisely what you're saying here. Maybe you could provide a link to an example appliance? A lot of work, I know. 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 * To visit your group on the web, go to: http://groups.yahoo.com/group/biofuel/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
