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Forum Index : Other Stuff : Home Energy Use -- A Reality Check
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MacGyver Guru  Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Crew Being retired and living alone, I do all my own cooking. Come to think of it, I do all my own everything else as well. Anyway, I was sitting here weighing how I use energy and came up with some not-so-obvious conclusions, which I thought I'd share with the rest of the crew. One of my favorite cooking tools is a crock pot or 'slow cooker'. It's electric and draws a maximum of about 1500 watts. It doesn't draw that much constantly unless it's on the high setting, but suffice to say it draws a hefty amount of amps. I thought of powering it with my stationary bicycle coupled to a small alternator and started breathing heavily at the mere thought of it. My conclusion was, using electricity to heat stuff is not very effecient, even if the electricity is obtained free. By free, I mean obtained using green, renuable power like wind, solar or hydro. A better way to 'heat' stuff is with raw fuel. Yesterday, I made a batch of pot roast in the slow cooker. I figured it used approximately between 5 KWh and 7 KWh all day long. The cost of that is nill, but I was thinking about the actual effeciency compared to burning raw fuel. Today, I cooked the same meal only I used a cast iron pot and lid and cooked it for the same amount of time, but I used propane gas. The burner was set at its lowest possible setting and the meal cooked the same, although it was actually "done" about two hours earlier than when I used electricity. The down side is, if you want to go away, leaving an open flame is more chancey than leaving an electric appliance running unattended. Still, an electric appliance could catch the plase on fire just as well, but you get my point. Comparing the two methods, I'm sure beyond any doubt that cooking using fuel is way more effecient than using electricity. Reverse-engineering this goes something like this: How much raw fuel would I have to burn up to make enough steam to run either a steam piston or steam turbine engine, which in turn would pull an alternator and make single-phase alternating current sufficient to cook my pot roast? See what I mean? The two methods are worlds apart. It's been said before here on this forum and I'll restate it: The bigger picture of renewable energy stems more from usage than from methods of production and I guess that's why I took the time to post this at all. As a result of my little "experiment" using electricity versus fuel gas, I'm giving away all my aluminum cookware and both my electric crock pots. I'll keep the Orville Redenbacher Air Popper, but that's used only every once in a while for a treat; it's electric and does not require cooking oil. A big plus for me will be once I've given away my aluminum cooking utensils, it'll make more room inside my land yacht. All I intend using for cooking from here on out are three cast iron cookware items and a propane gas burner, which need burn no hotter than its lowest setting to turn out gormet meals in the same or less time than using electric appliances. Now, if one of us could come up with some handy method of turning electricity into methane gas, we'd have the world by the tail! . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Good post Mac Your right, using electricity for heating is expensive. Gas ( Down under we call gas gas, and the stuff we put in the car is petrol or fuel, not gas, unless the car actually runs on gas  ) is very cheap for making heat, and its also one of the cleanest burning fuels we can use. When I finally find a house to settle into, I'll be using gas for all my cooking and heating, and backup hot water if the solar isn't working too well. Cooking on gas gives better results too, I hate electric elements.
Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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shawn Senior Member  Joined: 30/03/2010 Location: New ZealandPosts: 210 |
Yes good read! I use gas to cook with always have, i also prefer it to electric but i know a fellow down the road that also lives offgrid his system was giving him so much power he threw away his gas oven/cooktop and bought electric just to save him spending money on gas. wish my system was this good 
ooh and while im dreaming it might as well charge my electric car  |
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| davef Guru Joined: 14/05/2006 Location: New ZealandPosts: 499 |
I am quite happy with the conclusion you have arrived at, but suggest that you actually measure the power used by the crock pot! The Van Wyck Crock pot we use draws 140 watts on High. Over an 8 hour period that works out to just over 1KWh. Like you I'd rather save the precious electricity from the and solar for the computer and lights! |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
davef I came up with the power requirement data merely by looking on the bottom of the thing and it said 1500 watts. You're probably right that it's not that high. The cast iron cookware actually cooked the same meal in less time using the lowest flame setting my stove has. My guess is a full 8-gallon propane bottle will last nearly a year using only the lowest heat setting. Based on a friend's prompting, I'm going to purchase a "Dutch Oven" and try baking something in it soon. Try THAT with an electric crock pot! A different subject: I am building a small heat exchanger that will sit inside my portable propane-gas bar-b-q with the intent of using it as a back-up heat source for my solar domestic water heating system should I be plagued with cloud cover. Currently, the back-up system is electric. If it works well, I'll then use an identical heat exchanger inside my land yacht coupled with a 12-volt fan to heat my little ark. I'll post that build when it happens. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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powerednut Senior Member Joined: 09/12/2009 Location: AustraliaPosts: 221 |
For stews and other slow cook items we have started using a "magic pot" (can't find the exact model online, but similair to: an ecopot This thing is pretty cool, basically you cook everything up (brown meat, then bring to water & veggies etc to the boil) then stick it inside the insulated outer pot. Then you close the pot and let it cook from the heat already in the ingredients. Stays hot for ages. Stuff comes out hot and tasty. This seems like a much more efficient method of cooking to me. oh, and we are using bottled gas as the initial heat source. eventually i hope to switch over to methane from a digester, but that project is a while off. |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
powered nut Hey! Thanks for that link. I'll have to look into that; it looks cool. As for a digester, I've actually done that once too, back in the day. I can save you lots of time and energy by telling you the BEST way I was able to keep things under control: I used an inverted canister filled with water as the storage vessle. The output hose from the digester ran under the submerged lip of the canister (submerged inverted in another slightly-larger canister of water) and as the gas was produced by the rotting (mostly chicken) s*it, it bubbled out and floated the can, which was tethered by 4 poles with a ring from the can to each pole. As gas production got to just past half way up the inverted canister, I added weights evenly around the top side (which was actually the bottom of the inverted canister) to slightly increase the working pressure of the trapped gas. The methane was then used in a naturally-aspirated cooktop burner and I cooked on it. If you become woried about a back-fire, just install a small water trap after the storage vessle and before the burner. That way, if the flame gets away from you, it won't propagate past the water trap, catching your storage tank ablaze. Great fun way to manufacture your own raw fuel and reasonably safe as well! Edit: Changed wording for clarity. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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