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Forwarded on
behalf of Pete Giansante.
(The server had
rejected it:
I think it was
because there was a hyperlinked "mailto" in one of the
included headers.)
Tim -----Original Message----- Judith is correct in her preference for using renewable resources like solar energy wherever they are appropriate. Tim is correct in his assertion that intensive, reliable, on-demand power generation is not one of those applications. NOTE:The economics of installing engine-driven generators must indeed be balanced by the ROI such an investment would make. In addition to the capital cost of the power generating, distribution, & switching equipment, and the facilities to house it, there's the expense of storing and recycling fuel (usually Diesel No. 2) -- with all its associated regulatory hassles. Add to that the personnel cost of maintenance & operations, and you have to have a very compelling reason to load that kind of cost into the goods/services you offer your customers. In fact, if your competitors decide against going that route and the market prefers the resulting lower prices of their goods/services, you won't have any customers. Gas turbine technology has improved, but it's more costly in capital & maintenance. Regardless, if you want reliable backup and your market provides the economics to support it, you're going to be going with some form of combustion engine-driven generating plant. Solar energy works pretty well in a thermal application -- that is, for heating water and living space. Electrical power generation from solar energy is an entirely different matter. It can be used to generate electrical energy via photovoltaic conversion, as long as one is willing to accept conversion losses on the order of 90%. Even if such losses are acceptable, you still can only collect and store enough energy to operate things like radios, stereos, and high-efficiency lighting (e.g., fluorescent or metal halide vapor lamps; forget about incandescent -- thermal losses are too high). But if you want to do a lot of intensive usage (e.g., air conditioning, electrical appliances, power tools), you're not going to be able to run that kind of stuff using photovoltaic conversion without prohibitive equipment & maintenance costs. The cost in lead-acid storage batteries alone would eat you alive -- assuming you even wanted to have that much hazardous stuff lying around. I sympathize with the hopes of solar energy enthusiasts, but they would perhaps be better served by a somewhat more realistic appraisal of the ability of solar-powered infrastructure. As a source of large-scale, intensive, reliable power generation, solar/photovoltaic conversion is more mythology than technology. Consider the physical constraints. The maximum terrestrial incident power flux of solar radiation is ~1 kW per square meter when the sun is directly overhead and is unobstructed. The sun's output imposes that physical limitation, given the radius of Earth's orbit, and there isn't much we can (or should) do about it. Perhaps some concrete examples will help to illustrate how that limitation affects our ability to use the sun as a practical source of electrical energy. To convert the incident solar power to energy, multiply by the amount of time that the 1 kWh/m^2 condition is in effect. First, you must account for the seasons. The maximum solar collection time that you can squeeze out is 12 hours per day, twice per year... if your latitude is somewhere between the two tropics. The rest of the year you have considerably less daylight, and more atmospheric interference as the sun's path drops to the horizon seasonally, so on average you have maybe 10 hours of usable sunlight per day, under ideal conditions. If your location is between one of the tropics and the nearest pole, it goes downhill from there. Now you must also account for the daily rotation of the Earth. Even under the best of conditions (desert, during the summer, with no cloud cover), you have that condition for maybe one hour before plus one hour after the sun is at zenith. Of course, the sun isn't directly overhead for the other 22 hours in the day, but let's say that you can devise some complicated tracking mechanism to keep the perpendicular axis of your solar collector(s) always pointed directly at the sun. However, the average incident power won't be the full 1 kW/m^2 for the entire 10 hours. Call it 0.70 -- again being generous. That gives you ~0.7 kW/m^2 x 10 hr/day = 0.7 kW-hours/m^2/day of incident solar energy. Assume that you fill the entire 1-meter area with photovoltaic cells and capture all the incident energy. With a conversion efficiency of ~10% (that's typical of current technology), here's your maximum electrical generating capacity, under ideal conditions: Now, since we've already accounted for the seasons in our average daily capacity, we can annualize that capacity: 0.07 kW-hours/m^2/day x 365 days/year = 25.55 kWh/m^2/year Now, compare that capacity to the energy-intensive sources that we typically find in fossil-powered electrical generating technology. That's how Southern California Edison generates most of its power... by burning fuel oil or coal, so for comparison, the same capacity can be converted to the equivalent amount of fuel oil or coal: Fuel Oil: Anthracite Coal:My average annual usage over the last 36-month period is 20,385 kWh. Allowing for peak usage months, and based on my existing 0.25-acre lot size, I could replace the energy I'm currently getting from the grid if I were to cover 98% of my property with photovoltaic cells... if I had ideal conditions, and the money to spend on such things, and the desire to live amidst that sort of ugly junk, and the inclination to spend my time or my money servicing/maintaining such a preposterous facility. I don't. Most people don't. More to the point, neither do the most vocally active "public figures" who advocate the mythology of "soft energy" technology, and mislead others to believe that such technologies are feasible. I find the idea of energy self-sufficiency attractive as a means of sustaining oneself when living in a remote location, but even then, I would require a small generating plant if I wanted to maintain the quality of life that I currently enjoy. The maximum conversion efficiency attainable with current non-nuclear technology is approximately 50%, provided by high-speed gas-fired turbines. I suppose that when they can be made reliable enough and can be mass-produced cheaply enough, it would be feasible for individuals to own them. Nevertheless, such a decentralized system would sacrifice the economies provided by large-scale, centralized power generation and distribution. As long as we rely on combustion-based technologies, we might as well minimize the combustion by-products via economies of scale. I should think that would be an article of faith among anyone who is concerned with global warming (I'm not). Of course, the longer-term solution is to drop our reliance on combustion-based technologies altogether. We have the capability to do that safely right now, but (sigh) I'm not inclined to pursue such a controversial subject in this forum... and besides, the content of this post has probably wandered too far off-topic for this list as it is... PVG Tim Gwinn wrote: -----Original Message----- From: ROSEN Forum On Behalf Of Judith Rosen Sent: Friday, November 07, 2003 10:35 PM To: *** Subject: Re: FW: L-Soft service unavailable on Saturday, November 8, 2003 Why can't they invest in a couple generators? Better yet, why not go solar??? That's what I'm doing... I've got a handicapped child who has medical equipment that needs electricity. But even if I didn't; energy dependence and vulnerability to grid disturbance is the single biggest immediate threat to the welfare of this country, the way I look at it. There are plenty of reasons, from all areas, ranging from health to environment to finances to national security to global stability, but in this case, it's about commerce. Purely from a business point of view, how much money isn't "made" when lack of electricity forces shutdowns like this one? Lost economic development because of something so preventable is a damn shame.Well, I think exactly because it is about commerce that they are probably not investing in generator backup. :) Statistically, an outage of more than several hours is extremely low, and the capital cost and ongoing costs for generators would have a very poor ROI (return on investment). I'd imagine they have their systems on battery backups, which typically will hold systems up for 2-8 hours depending on what they've chosen. So, to have invest in generators would serve to probably only change their uptime from 99.99% to 99.999% or something like that. They probably have more downtime due to hardware/software failures than power issues. Also, since mailing lists are not "mission-critical" services (like a hospital or 911 system, or in business, like a stock-trading biz), the rare outage of a day or less are not enough to make customers go elsewhere. As for solar, at this time it is simply not very feasible. The conversion efficiency is very low, so to run real-time off of panels requires alot of square footage. Plus, because solar supply is so intermittent, based on time-of-day and weather, real-time usage of solar is impractical and instead it requires a huge investment in some kind of power storage (batteries) if you intend to have it "on-demand" or for mission-critical applications for any length of time beyond what a normal battery-backup system would handle. A warehouse full of storage batteries and power inverters would be a big cost, and in a business environment would probably be classified as hazardous materials by OSHA & EPA. Maybe thin-film photovoltaics and fuel cells will help some this situation some. Speaking of fuel cells, I am skeptical about hydrogen as a ubiquitous power storage medium - it strikes me as much too volatile and difficult to safely store in a density that wouldn't require a huge vessel. Maybe I'm just a cynic, but I think that the "hydrogen economy" is way oversold as being viable anytime soon. These methodologies have one thing in common: they are all entirely mechanistic.In the long run, I wonder if it would probably be better to have biological partners to generate our power needs or act as power storage resources: growing mats of electricity-producing moss on our house roofs, etc. Maybe we can make use of the way in which different observers "see" items differently, by storing energy in forms that are, to us, non-volatile, but to a colony of some certain microbe are an energetic feast. Certainly these are things that are not near-term, but I find the idea of living in such a world fascinating.Judith PS: On an unrelated issue: RoadRunner has lost me as a customer as of Monday. They have a nasty policy of blocking whole internet service domains based on suspected spamming by anyone in the domain. If anyone has tried to send me email and had it bounce with a security notice attached, that's RoadRunner. They do not even notify me that this is happening. I'm moving to Earthlink as my ISP. The new email address is *** and it's up and running already. Tim, you can unsubscribe this RoadRunner address and substitute the Earthlink one, by Sunday. Thanks, folks, and sorry for the inconvenience!I'll change the email. Not that its any consolation, but Roadrunner isn't the only culprit. AOL is notorious for blocking domains erratically supposedly because of spam. Comcast, too. List admins on Lsoft are very frustrated with this, since companies like AOL or Comcast willl not listen to them, and sometimes not even to Lsoft. Earthlink has been good for me over the past several years, and I still keep an account going with them.----- Original Message ----- From: "Tim Gwinn" <***> To: <***> Sent: Friday, November 07, 2003 7:18 PM Subject: [ROSEN] FW: L-Soft service unavailable on Saturday, November 8, 2003To all listmembers: This notice arrived on the list administrators support forum. Tim -----Original Message----- From: L-Soft EASE Home Support Forum [mailto:***]On Behalf Of Nelson Chen Sent: Friday, November 07, 2003 3:50 PM To: *** Subject: L-Soft service unavailable on Saturday, November 8, 2003 On Saturday, November 8, 2003, the electricity will be shut off |