24) Deep Wells, Green Roof & a New Woodchip Pile - November '17

Geothermal: What? Wells? Yep, the plan changed, it turns out that we just couldn't do the vertical coil field for the earth heating system. We had engaged UltraGeothermal out of Concord, NH to put in our system, and they believed the coils were feasible, that there was sufficient flat land to lay out the field, but it was our excavator that put the kibosh on the plan. While we had enough square footage (6000 square feet), Jim discovered that the ground was just too rocky... He was hitting 5 foot thick glacial erratics, and the cost of removal would just be too prohibitive.

I was completely disappointed.

The whole idea of testing out the woodchip and whey addition to the geothermal heating system was really engaging. But it was not to be. In discussing the options with the Darren, the principal at UltraGeothermal, he pointed out that rather than going horizontal, we could go vertical, by putting the heat-gathering piping down into the earth rather than across it. When I questioned their effectiveness, he told us that wells were actually MORE efficient than a coil system. This was great to hear, so wells it would be. Vertical, as opposed to horizontal systems, involve drilling wells deep into the bedrock to tap the latent heat far underground. Darren determined that for our expected heat demand, we would need two 340 foot deep wells. GeothermalGenius has a good explanation of how they work.

In mid-November the well-drillers from Gap Mountain Drilling rolled up:

It took three days to complete the drilling and install the casings and plastic loops inside. Here's a shot of a section of well casing going in:

Green Roof:

The crew made amazing progress in November, putting in windows, finishing the shingling and getting a good start on the clapboard siding. They turned their attention last to the hot tub room with its green roof. Here's a side photo:

From the main level you can see the enclosure that will ultimately contain the 8 inch thick growing layer:

We've been working on the engineering of the drainage pipes, membranes and that will go into it. And this is how we hope it'll turn out:

Wood Chips Revisited:

Not willing to give up completelyon the woodchip & whey concept, I wanted to test out a new idea. Rather than heat the house geothermallywith chips, how about we use them to heat the hot tub water? We've already seen that chips and whey can raise temperatures to 108° or more, is it possible that it could heat 300 gallons of water to a level that made sense? While our initial plan was to pre-heat the spring water inside the utility room to the ambient 70 degree room temperature, what if we moved the reservoir outside the building and buried IT in woodchips? To test the idea I filled a 50 gallon container with water and buried it out in the woodchip pile:

You can see the chip mound below. The 50 gallon tank is about 4 feet below the top of the mound with its thermometer in place.

Now we just have to wait...