8) On Whey and Woodchips
In researching green technologies that would be of value to the SunCottage I stumbled on this video about a guy down south who heated water to 112° by burying a can in a pile of brush compost.
The reason this is important is that the SunCottage has a basic embedded conflict: How can you create a net zero home with a hot tub? It takes energy to heat up a tea kettle to boiling, right? And that's only a few ounces. How can you ecologically warm up 250 gallons of water to enjoy a nice 104° soak without breaking the energy bank?
That's where Jean Pain came in, a pioneer in heating water with waste wood:
https://permaculturenews.org/2011/12/15/the-jean-pain-way/
So I decided to experiment with wood chips. With one overriding impetus: they're free! During site preparation for the SunCottage we decided to cut a number of trees down including several large white pines. I had them drop the chips right by the SunCottage. It turns out the tree services are always looking for places to dump their wood chips. In fact, there's a site where you can sign up to have all the free wood chips you want delivered to your house: Free Wood Chips
I called them and got another load. Wood chips galore!
But the idea morphed a little bit. At first I was thinking of using the woodchips in basic Jean Pain fashion, to heat water. But then, after viewing the graph of how underground temperatures are much more stable the deeper you go, I came up with the idea of covering the geothermal field with wood chips. Since depth is the key to harvesting free geothermal energy, what if you added piles of wood chips to, in effect, make the ground-sourced heat pump coils deeper? They're free and unlimited. An idea was born. So I buried an indoor-outdoor thermometer 4 feet deep in wood chips and began to record the temperature. Before I post the data, I have to talk about whey. I'm associated with the Vermont Farmstead Cheese Company, that's
located about ¼ uphill from the SunCottage. And it turns out that one of the waste products of cheese production is whey. A watery milky liquid that is often just spread on fields to get rid of it. It's also something that accelerates natural biomass decomposition.
So at several points in the following chart I added whey to the wood chip pile. The results are self-evident:
Date: Outside: In the pile:
1/25/17 20° 20°
2/27/17 39° 37°
3/3/17 31° 39°
3/6/17 16° 41°
3/9/17 34° 51°
3/13/17 15° 54°
3/17/17 27° 66°
3/26/17 23° 61°
4/12/17 50° 58°
4/30/17 49° 68°
5/4/17 51° 68° Added whey!
5/5/17 51° 85°
5/7/17 53° 104°
5/11/17 50° 98°
5/28/17 65° 86°
6/2/17 59° 79° Added whey!
6/5/17 75° 102°
6/7/17 69° 100°
7/5/17 84° 86°
7/28/17 70° 76°
8/8/17 75° 86° Added whey!
8/10/17 75° 104°
8/11/17 73° 106°
8/15/17 80° 96°
9/6/17 60° 73°
9/15/17 74° 74°
10/4/17 64° 68°
10/11/17 60° 70° Added whey
10/14/17 72° 108°
10/21/17 54° 84°
10/26/17 44° 76°
10/28/17 54° 75°
11/2/17 56° 69°
So what's the take? Adding whey to the pile pretty quickly raises the underground chip pile temperature, a minimum of 19° to a maximum of 38°, in just a few days. The top temperature of 108° isn't that far from what the southerner was able to achieve in his compost pile. As an aside, when I was explaining the concept here to people I brought up the idea of ice houses. In old New England before refrigeration, people kept things cold through the summer by enclosing pond or river ice in sheds insulated with saw dust. It seems that 4 feet of wood chips insulated the earth below from the cold during the winter months and actually create their own heat when properly moisturized.
So the idea is to add wood chips with healthy doses of whey to the geothermal coil on an ongoing basis. As the chips deteriorate, they turn into soil, and the coils are essentially getting deeper and deeper. That's the plan!
(chart data updated on Nov. 2, 2017)
