BenG
Posts: 841
Joined: 5/5/2009 From: Australian in Idaho Status: offline
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quote:
ORIGINAL: Sean McGrath Ben, for these use cases you want a gasoline generator. Either a simple one, or an all-house with automatic on. When the lights go out at our cottage in Michigan, within fifteen minutes most of the houses' lights are back on. Yes, you're right, it's still much too small for a wine cellar. I did some calculations to work out how much energy (very roughly) would be required - I can't remember how big Eduardo's cellar is but say if it was a 1000 bottle cellar, it might be 50 square feet and 7 foot tall, making 350 cubic feet. One cubic metre is around 35 cubic feet, so a 1000 bottle cellar would be around 10 cubic metres. The amount of energy to heat one cubic metre of air one degree celsius is 0.993 mJ, so to heat 10 cubic metres by 10 degrees celsius (57F to 75F) is 99.3 mJ (although it would be a bit more than 99.3 mJ because the bottles and shelving would slow down the heating a bit). One watt is 3,600 joules per hour, so to apply 99.3 mJ in an hour would require 27.6 kW. I'm not sure how air-conditioning works (do you need to apply the same amount of energy to keep the heat out?) but if the above figures are in the right ballpark, that means requiring at least 27,600 watts to keep the wine at 57 degrees F (on the day that Eduardo was talking about). Let me know if I've missed out major assumptions (or applied the wrong number of zeros!). Incidentally, the Duracell battery is only 478 watt hours, so you would need 60 or so per hour (at $500 a pop!).
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