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Hybrid Cars Today, Hybrid Buildings Tomorrow |
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Article Viewed 7344 Times 5 Comments |
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Geoffrey Young 3.12.03 |
The author makes some interesting and valuable points about the advantages of DC power in buildings. War has nothing to do with it, however.
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Lloyd Weaver 3.12.03 |
I agree with the hybrid building argument, but not with the DC/AC argument. Where’s the beef? Show the peer review study results that say it’s not economical to convert back and forth from AC to DC the few times it’s necessary? It’s moot anyway as we are AC for another hundred years of so, I suspect. Not mentioned was passive solar design for heating and cooling. Heat pumps will also be a central part of the hybrid building of the future. There is no cheaper energy to heat and cool with now than heat pumps (I don’t sell heat pumps, that’s just a fact of life right now). As I calculate it, heat pumps are $1.10 cent oil at Maine’s 11-cent power costs and northeast ground temperatures of 50F. We won’t likely see that kind of oil price for heating again. I’m not saying oil heat is dead, but presently it has priced itself out of the market by a wide margin. Oil heat is $15.50/million Btu’s now (boiler efficiency considered) versus $9.40/million Btu’s for heat pump heat energy. Lloyd Weaver, Harpswell, Maine
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Bill Roush 3.12.03 |
What voltage do you expect DC buildings to operate at? Is there an advantage to using the same voltage dc that the automotive industry is using (mass produced devices that are compatable)? I don't want these technologies 'legitmized by war'. I just want them bought and sold in a marketplace that is not rife with taxpayer funded fossil fuel subsidies (such as a war for oil).
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Paul Savage 3.12.03 |
For Lloyd Weaver: We have data-logged results on our website, under "News", Improving the ROI of PV" that demonstrate a 93% pick-up in integrated efficiency over an inverter-based system by direct coupling. This test was conducted with a small, 1000w system; expect the pick-up in larger systems to be smaller as the phantom load of the inverter becomes a smaller % of the total system output. Direct coupling losses are like line losses, on the order of 2%. Converters in electrical goods are typically between 60% and 85% efficient, wasting between 15% and 40% of the power we pay for to operate them as heat. For Bill Roush: We think it's 48v DC. I like the automotive compatibility point. In any event, below 50v DC is desirable to pick for a building standard because of code issues. I don't like the fact that it takes the prospect of war to pick up the pace in this arena either. I think efficiency strategies are "legitimate" in any event.
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Samuel Brown 3.22.03 |
I want to thank the author for writing about losing the inefficiency of converting from AC to DC. I have been talking about and done some letter writing about this for three years. As he states, not only is it more efficient to generate power next to the users but using DC generated power to run all our DC equipment (stereos, computers, clocks, etc.) adds to the efficiency by removing many AC/AC step-up and step-down transformer and line losses. Further, many products run by AC motors can be run just as efficiently by DC motors, e.g. refrigerators, washing machines, etc. Plus, fuel cells are being set up to use waste heat which can and will provide us with both our hot water needs and our space heating needs. Also, I envision a "smart plug" that is either a DC/DC step down transformer or a small intelligent circuit board that provides proper voltage to our many DC devices which is almost every item in our home. Perhaps even our TV picture tubes will be replaced by something that will use DC instead of AC power.
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