How Geothermal Works: Cartoon Edition

For a long time I went around saying (very confidently) “oh, yeah, we’re putting in a geothermal system,” which lasted right up until some person asked me what the hell a geothermal system was, anyway?

And I was all, “Well obviously it uses the, uh, geo, to generate the thermal. Duh. ” And then I went an googled it so I would look like slightly less of an idiot the next time.

So, thanks to The Google I eventually figured out why I’m going to be able to heat my house to an obscene 85 degrees in winter without having to take out a second mortgage to pay for my 2000 square foot sauna. This is me, simplifying:

I’m pretty sure my illustrations here are so awesome that no additional explanation is needed. Except maybe that glycol is like water but with a better “heat transfer coefficient”. It’s basically antifreeze and it runs through the geothermal pipes.

I put one “well” in my illustration, but for a system to support our 2000 sq ft house, we actually have two wells.

My understanding is that the 50-degree glycol is compressed to create a hotter liquid used to heat the air in the winter (because god knows I set the thermostat higher than fifty).

Also interesting: I find my perception of the ambient temperature of the earth changes depending on the season. Right now–in below-thirty weather– fifty-degrees seems like a tropical breeze. In the summer I’d take fifty as a welcome arctic blast. That’s the midwest for you.

Currently we’ve got the wells dug, and the unit inside the house working, it’s just that damn horizontal bit that’s been holding us up. We’re hoping to have it done tomorrow and the glycol in Wednesday.

More actual progress pics to come.

5 Responses

  1. LOL I just spit water all over my computer!! The fact that you took the time to create these cartoons…and that everything has faces…hilarious! Oh my where to start… Well let me just say that what you called “glycol” is actually a water-glycol mixture of only 30% glycol or so.

    You better get that system up and working because Jan & Feb are when the ground is the coldest (there is a delay between the ambient temp and the ground temp)!

    1. OMG, I knew my resident blog-geothermal-expert was going to have something to say about this! lol. I also thought probably I was wrong about how the cooling works (no compression?) but making cartoons was far more entertaining the complaining about my subs yesterday, so I went with it.

      And we’re so hoping to have the glycol (aka glycol water mixture) in next week. Fingers crossed.

      I’m so going to harass my own engineer for calling it just glycol and feeding me misinformation. You can’t trust anyone these days.

      1. No you were on the right track. In both heating and cooling mode there is a compressor, condenser, expansion valve, and evaporator. It runs exactly like your refrigerator only your heat pump has a reversing valve so it can both heat and cool. This might help but they only walk you through the cooling process:
        http://en.wikipedia.org/wiki/Vapor-compression_refrigeration

        Someday I’ll get around to finishing my geo series and I’ll go into more detail with graphics (that I might have to make myself) and it will all make sense. But those posts take FOREVER to write and they hinder my other posts I’m trying to write…ugh I just need to get them done.

  2. We have geothermal at work…and I just tell people that ask that our cool air comes from the earth. People seem to accept that as an answer. I like your cartoon so much better than my explaination.

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