Composting-->heat---> Outdoor Shower!

[Kareem Shihab]

Recently I have been experimenting with "larger" scale composting on the side of my house. I was amazed at the heat that a compost pile gives off which can be in excess of a 140 plus degrees F! I thought about the prospects of creating an outdoor shower using water heated from a compost pile. I would need to heat water in a hose spread throughout the pile, then send it up about 8 feet and then over 12 feet to a small tank then to a spout for the shower. I want to keep it completely external.
I figure the toughest parts will be:
1. Creating enough pressure to send the water from the compost hose in the pile to a small holding tank above the shower.
2. Mixing cold and hot water without to much trouble to create warm shower water (This could probably be done by hand)
3. Easily replenishing the hose in the compost with new cold water.

I am not much of an engineer so I would appreciate any input in ideas, or tips in putting this together, including appropriate piping materials, tank materials ect..

thanks, Kareem

[Joe Blake]

Hi Kareem,

Presumably you're thinking of pumping the hot water for immediate use, rather than storing in an insulated tank.

You don't necessarily need "pressure". Have you considered using thermo-syphoning, and having a "closed" hot water circuit (with insulated hose and storage tank) that uses the heat itself to "lift" the hot water? This would then "dump" the heat via a heat exchange (a length of copper tubing? Old car radiator?) into the colder tank water, which would then cause the cooler hose water to sink down into the compost heap for reheating. In this way, you use a brine solution in the closed circuit, which from memory, is better than plain water at holding and transferring heat.

If you approach in this fashion, and perhaps use a solar powered pump to "recharge" your holding tank with cold water during the early part of the day, your third question would become meaningless, since you wouldn't need to put cold water into the compost heap immediately, but at a time convenient for pumping.

An interesting piece of lateral thought Kareem. Keep us posted on your progress. (But remember of course that taking heat from the compost heap will slow the composting process.)

Have a look here at one man's approach to handling heat in composting.

http://www.abc.net.au/tv/newinventors/txt/s1718339.htm

Regards,

Joe

[Mark Parsons]

Greetings Kareem,

Here is a link for a similar compost heat recovery application, if you haven't already ran across it.

http://ersson.sustainabilitylane.com/greenhse.htm

Keep the group informed of your progress and results.

Regards,
Mark

[Kareem Shihab]

Thanks for the input, and I have finally bought all the materials. I decided to simplify the whole system by just buying hose end caps for the water hose within the compost. When the water within the hose is heated enough by the compost I will just connect the end to a spout from my house and turn it on. The heated water will be forced out of the hose into a tank and I can mix it with regular water for the desired temp. I fashioned a spout and a valve so I can regulate the water for an outside shower. I will post Pics soon. -Kareem

[Kareem Shihab]

I started constructing the system to recover heat from compost microbial activity and use it to heat water. In the end the water will be sent to a tank to be used in an outdoor shower.



The first picture below are the parts I used to make the tank and the spout/shower head
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We just drilled a hole in the plastic 18 gallon tank and attached the pieces with silicone, then screwed on the shower head (cheap garden hose attachment). Everything here was bought for under 15 bucks.
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Here is the hose which will hold the water within the compost an allow it to heat up. Its coiled and kept together by twisty ties, so when its time to turn the pile I can take this out and put it back easily.
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[Kareem Shihab]

This is the beginning of the compost building, I have placed the hose on top of a few layers of browns and greens.
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The pile grows
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As I layer 1 inch of brown material to about 3 inches of green the hose gets completely covered177




This pile is finished. There is actually two fifty foot hoses coiled inside filled with water attached for one continuous hose. You can see the end of the hose sticking out the bottom and the other coming out of the top. To fill them with water I just attached the one coming out the bottom to my outdoor hose, filled it slowly then screwed on a hose end cap.
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-I plan to test this in the next day or two to give to a chance to heat up. Expect another round of photos soon.