Hey! Let Me Give a Public Demonstration of My Scientific Illiteracy!

I like to walk the dogs up and around a modest hill near my own neighborhood. It's the high rent district with McMansions going for around half a million each. They are clustered cheek to jowl on top of this hill. The kindest thing I can say is that most have nice landscaping which Harry likes to pee on. There is very little traffic and it's a safe, quiet, and scenic place to make our walks--the views across the valley are really nice.

I live in the Willamette Valley which contains several large river systems that ultimately drain more or less northwards into the Columbia River. The valley is filled with various types of volcanic sediment that have been reworked by these rivers for the past 30 million years or so. Grape vines like volcanic soil which is why there are so many vineyards in the Willamette Valley. Turns out trees and seed crops like it too. No active volcanoes are present in the Willamette Valley, but the topographic highs dotted around mark the former location of older volcanoes; some are still fairly substantial. The active volcanoes are to the west in the Cascade Range (volcanoes align in chains because they form on top of subduction zones and they tend to move landwards as the subducting plate advances with geologic time). So the hill that I walk the dogs up and around is one of these former volcanoes, long past its glory days.

Back in the summer, one of the homeowners on the north side of the hill started this major excavation project in his front yard between the house and the road. He was doing the work himself and was renting equipment like the backhoe so it took a really long time for it to get done. Our walking routes didn't take us past his house every day but over time I watched this enormous pit form in front of his house. It was roughly the size of a regulation swimming pool, squarish, and about 10 feet deep, with a level bottom. The pit sat for a few weeks until a bunch of flexible tubing, perhaps half an inch inner diameter, began to appear on the bottom. The tubing was laid out in a back and forth pattern. That sat for a few more weeks. Then the hole was filled, extra topsoil was laid down, and the only thing left now is a muddy brown expanse in front of the house. I was always curious as to the purpose of this effort and expense and mess and disruption. Possible theories: a swimming pool or a new form of septic drainage system. But the real purpose of the project never would have occurred to me in 30 million years because, well, I know a little bit about science. And physics. And basic mathematics.

For the very first time this morning, I saw the guy who lives in that house. He looked to be in his mid-twenties. Had a toddler with him. I asked him what the project in his yard was for, and he said, "oh, I put in a geothermal heat pump."

Wow. Just, wow. Where do you even start? Because it is physically impossible for whatever he built to function as planned. Where do you start?

1. Geothermal heat pumps require convection of hot water in the subsurface to exchange heat with water in tubes or pipes that you put in the ground. The most common systems are vertical since the pipes of the exchange system need to be positioned within the water table where the hot water is circulating.

2. The average geothermal gradient of the Willamette Valley is around 30 deg C per kilometer (I found this via Google; didn't need access to a fancy technical library). His 10-foot deep hole? At best, the temperature difference between the top to the bottom of the pit will be around 0.08 deg C (again, I don't even need to know any conversion factors except that 10 feet is around 2.5 meters). It is probably much less since that average geothermal gradient is based on data taken in the valley proper where the sediments are thickest, and this guy lives on a crystalline-rock-cored hill with a thin veneer of sediments.

3. Further, a little bit of research turned up the interesting fact that heat flow in the Willamette Valley is regionally conductive, not convective. In other words, the reworked volcanic sediments have a lot of clay, which reduces the ability of fluids to move around in those sediments. There isn't even any warm water circulating beneath the Willamette Valley that a geothermal heat pump could tap into. Sure, understanding the difference between conduction and convection in the context of regional heat flow requires some technical understanding--but that's my very point. If this clown was going to spend all that time and money, you'd think he would take half an hour to understand the basic physics of the matter.

4. A heat pump requires a temperature difference between the cold water entering and the warm water exiting and in most places on earth, this requires a vertical orientation as I mentioned above. However, this guy laid all his pipes on the same horizontal plane. The temperature differential of his "system" will be zero. Cold water will go in....and cold water will come out.

5. But let's say that perhaps we are in a magical corner of the Willamette Valley and there is a warm body of water circulating in this area. Hate to break this to him, but there are no water wells on the small hill, nor at its base, nor in the farms in the immediate area (the location of water wells is publicly available information). Even if the magical warm, circulating water was there, it's pretty damned deep. This guy would never be able to reach it from the hill. Ten feet? Laughable.

And in fact, I did laugh at him. He paused and said, "you don't think it will work?" I looked at him for a second, most of the above whirling around in my head, and I said, "I know it won't work." The dogs and I continued on our walk.

I'm so worked up I had to make a new tag for this post: science. Maybe I should change it "the lack of knowledge of science" but that sort of contradicts the point of a tag.

The failures of the American public school system are coming home to roost. Can't teach four years of math and physics in high school--it's too hard. Can't have the precious children read full texts anymore--takes too long. Can't give tests that evaluate critical thinking because those can't be scored by a computer. We are doomed.

**Update: I'd be remiss if I didn't add this. As two of you have pointed out, my neighbor was almost certainly installing a closed-loop ground-source heat pump (also see here). He won't be eligible for a tax exemption because he didn't use a state-approved contractor but he no doubt saved a lot of money by doing the installation himself. As TW noted, the pipes need to be below frost level. Temp data from around that depth from reasonably nearby water wells vary considerably so while we might reasonably infer that 10 feet is below the freezing depth (it doesn't get that cold here), the temp at that depth may not be high enough for the system to work effectively. From the videos and diagrams I could find from local contractors, I don't believe that the density of his pipe system is sufficient; it looked to be about half of what is normally installed. This is not an "off the grid" solution. It is renewable in the sense that the heat exchange part is "free" but it still requires a fairly extensive arrangement of pumps (which run off electricity) attached to the grid (to move the fluid) and in the house (to move the air). There is further some questions about whether heat pumps are economical for residential applications (see this very interesting article). The heat-pump or heat-exchange technology is fairly advanced and appears to be most successful in larger, industrial applications. For example, I found that OSU installed heat exchangers in the mechanical rooms of some buildings to heat the water used in the bathrooms in those buildings. These are air-coupled, not ground-coupled and the temperature differentials they are dealing with are much larger than those available to my neighbor.

Finally, I didn't talk about this much in my rant but my neighbor dug a 100-foot long, 10-foot deep hole downslope from his home. The upper edge of the pit was about 8 feet from the foundation of the house. The long axis of the pit paralleled the long axis of his house. He filled the pit with the very disturbed dirt that he removed from it. When the earthquake comes, his home could very well be damaged because that disturbed soil will behave very differently to the gravitational acceleration than the undisturbed soil around it.

As my friend DW said, "the road to hell is paved with good intentions."