How to Drill for Geothermal Energy | This Old House

[Music] hey roger hi rich nice to see you again you too you are the god of drilling around these parts what are you doing here today oh we're drilling a couple ball holes total 750 feet okay two holes into the ground correct now the system is geothermal let me explain how it works no matter what happens outside if it's 100 degrees on the hottest day of the summer or minus two degrees on the coldest day of the year below our feet about 20 feet down it's always 50 degrees and we can use that consistent temperature to great advantage first we dig a hole a loop of pipe is installed and filled with antifreeze and water we circulate the antifreeze through the pipe a geothermal heat pump is just like any standard air conditioner except it can also work in reverse in the summer a geothermal system uses 50 degrees from the earth to cool down the refrigerant in the winter a geothermal system uses that same 50 degrees to heat up the refrigerant these systems can save between 50 to 80 percent over conventional systems that is great technology but we still have to get the energy out of the ground that's a couple of holes out of you we do take me through that's why we brought that piece of equipment there all right so what's right below my feet dirt okay under the dirt is ledge we have to insert through the dirt so it doesn't cave in this pipe okay a steel pipe first all the way down to the bedrock and once we're in the bedrock we don't need the the pipe anymore because the rock itself makes its own borehole okay and this is our drill bit this is the drill bit we end up drilling a six inch bore hole they made a tungsten carbide yeah and that'll just keep going down three four hundred feet correct correct and then after we're done with that we have to come back out of the hole and we insert this u-bend or piping with a u-bend on the bottom so this is a polyethylene pipe that's going to be filled with anti-freeze right here correct and that drops all the way down that shaft yep and then after we insert that we have to put in the grout okay and that's the two bags we mix the two bags together with water and that's inserted down to the bottom of the hole and fill the whole hole all right now that's really important too because without the grout you'd have all the heat in the rock but it wouldn't transfer through the pipe and into this pipe with the antifreeze that's correct okay good all right well we've talked enough time is money ready to go ready let's go [Music] the heart of the drilling machine is that bit attached to the end of a long pipe when the machine pushes the pipe down as far as it can another pipe is attached and the drilling goes on this continues until the desired depth is achieved [Music] when the drill is complete the loop of pipe goes down the hole [Music] alright so that's our first one completed how far do you end up going on this 300 feet okay and how do you decide where you put these holes on the property the ease of getting the drill rig in close to the house okay great and you got two of them going in on this job yes that's going to be a 450-footer we keep 15 feet apart so that way they don't have any interaction with temperature okay great all right what do you got left on this one you haven't drilled this yet right yep we got the rest of today and tomorrow okay so if you've got another whole day i'm going to leave you we'll be back in about two weeks to put the inside equipment in thanks my friend for helping as always thanks peace thanks for watching this whole house has got a video for just about every home improvement project so be sure to check out the others and if you like what you see click on the subscribe button make sure that you get our newest videos right in your feed

Channel: This Old House

Views: 80,706

Keywords: This Old House, Ask This Old House, DIY, Home Improvement, DIY Ideas, Renovation, Renovation Ideas, How To Fix, How To Install, How To Build, Richard Trethewey, alternative energy, geothermal

Id: C1fttmKe-_Q

Length: 4min 51sec (291 seconds)

Published: Fri Mar 26 2021