A growing number of colleges and universities are using deep underground pipes to heat and cool their buildings without burning fossil fuels.
When administrators at Princeton University decided to cut the carbon emissions that came from heating and cooling their campus, they opted for a method that is gaining popularity among colleges and universities.
They began drilling holes deep into the ground.
The university is using the earth beneath its campus to create a new system that will keep buildings at comfortable temperatures without burning fossil fuels. The multimillion dollar project, using a process known as geoexchange, marks a significant shift in how Princeton gets its energy, and is key to the university’s plan to stop adding greenhouse gases to the atmosphere by 2046.
The drilling makes an almighty muddy mess, but when all is said and done, the more than 2,000 boreholes planned for the campus will be undetectable, despite performing an impressive sleight of hand. During hot months, heat drawn from Princeton’s buildings will be stored in thick pipes deep underground until winter, when heat will be drawn back up again.
The change is significant. Since its founding in 1746, Princeton has heated its buildings by burning carbon-based fuels, in the form of firewood, then coal, then fuel oil, then natural gas.
“This moment is singular,” said Ted Borer, director of energy plants at the school. “This is when we’re switching to something that doesn’t require combustion.”
Ground source heat pumps are great.
We had one installed in our old 1960s home a few years ago and it’s amazing, AMA.How much did it cost?
All said and done, it was around $23 or $24k CAD, including everything from the thermostat to the well, to taking out the old combo oil-electric furnace and its aged tank.
To be fair, there were federal/provincial subsidies at the time, think maybe $30k ish CAD before the subsidies.
That was 3-4 years though, not idea how the prices have changed since.It’s definitely on the expensive side to have installed, and not something a house flipper would do, but we saw it as an investment.
The old oil furnace was on its last legs, the tank too.
Geo is cheaper to run in the long run, has little/no maintenance, long lifespan, has the same efficiency no matter how cold it is outside.No smells, no refills, it just… works.
For comparison,
We used to burn through about 500L of fuel every winter, and that’s with using the oil furnace only on colder days.
The resistive electric heating was doing the work on days hotter than -15C, so we had a hefty electric bill on top of that.The geo heatpump now costs about $600 or $700 to run, yearly.
(Maybe half of that is because I like to run the main fan continuously to move the air around.)
It also doubles as AC in the summer, which we didn’t have before, so it’s not an exact 1:1 comparison.Even on cold days (< -30C), the aux heat never kicks in and the house is at a toasty 22.5C pretty much 24/7 in winter, and a cool 24C in summer.
The only time the aux heat is on is when I test it manually before the winter, just in case (and also to burn some of the dust on the elements)Sorry, I’m ranting now.
How deep is your well and what kind of geology are you on top of?
325’ deep.
Pretty much right on top of bedrock.There’s maybe an 8’ length of protective steel sleeve between the top of the well and the bedrock then it’s all bedrock all the way down.
Aside from the loop of 1 1/4" tubing up and down the well, the space in the well is filled with bentonite clay.That’s pretty cool. I live over a particularly gassy shale deposit, I wonder if they could pull something like that off here.
There’s also the option of using a horizontal field just below the frost line instead of a deep vertical well.
The process is really similar to a drilling a water well.
No idea how that works over a shale deposit, although I imagine some of the tech they use to dig for shale oil could also be used to dig a geothermal well.I’ll have to look into that.
