Troy Media – by David Dodge
Of all of the sources of green energy, geothermal is probably the least sexy. Solar panels glint in the sunshine and wind turbines spin majestically, but there are few evocative descriptors for the humble ground source heat pump.
Once it’s installed there is little visible evidence of its presence in the home, except for a few pipes coming out of the basement floor into a furnace-like appliance.
Yet what it lacks in sex appeal it more than makes up for in effectiveness. With over 100,000 ground source heat pumps installed in Canada, it’s a proven way to heat and cool homes and buildings.
Geothermal energy, sometimes called geoexchange, is the classic example of an energy supply that is out of sight, out of mind. When student Preetpau Atwal started taking the Alternative Energy Program at NAIT in Edmonton, she found that studying geothermal was the most interesting part of her studies.
“It just blew my mind how effective it is – you take energy just sitting there in the ground and you can use it for cooling and heating. It amazes my mind,” says Atwal.
Energy is more than just electricity. Heating a typical single family home in Canada takes up 60 per cent of that family’s total energy consumption.
Leigh Bond of Threshold Energies estimates there are more than 1,000 geoexchange systems in the Edmonton area.
Bond is installing systems in new homes and even projects such as the net zero ready Brentwood 29-unit apartment project near Westmount in Edmonton. He hopes to be using geothermal heating in an entire neighbourhood soon.
How six degrees becomes 65 degrees
Bond explains that 46 per cent of the sun’s radiant energy is stored as heat in the top 150 metres of the Earth as geothermal energy. So from two meters down to 150 meters you have a fairly consistent temperature of six degrees Celsius. That is stored, latent energy just waiting to be tapped by an enterprising home or building owner.
We access this low level heat using a heat pump. Everybody already has a heat pump in their home – your fridge. A heat pump simply pushes heat from one area to another. In a fridge the heat pump pumps the heat out to keep your veggies cool.
A ground source heat pump functions like a fridge in reverse. It pumps the heat from the ground into your house.
Holes are drilled in the ground and pipes are inserted into the ground below the frost line. Water is circulated in these pipes and brought back to the ground source heat pump at six degrees Celsius. The ground source heat pump then strips three degrees off that flow of water and compresses it, which brings the fluid up to 65 degrees Celsius. That hot fluid is put into a radiator where air is blown over it and you have a pleasant, warm building. Geothermal systems can also work in reverse to cool buildings on hot summer days.
Yeah, yeah, yeah – but what does it cost?
Bond says the easiest way to ballpark what a geothermal heating system would cost in your home is to figure out how many cubic feet you have to heat. This includes the basement. A standard 2,000 square foot bungalow with an equivalent basement and eight-foot ceilings comes to 32,000 cubic feet. You multiply that by $1.81 and your rough cost comes to $58,000.
Seems high right? Let’s dive into the numbers a little more.
An equivalent natural gas furnace with air conditioning and a hot water tank is going to run you $24,000 to $26,000. Add another $6,000 for an in-floor system and add a bit more for touches like a tankless hot water system.
So the additional up-front cost for a geothermal system is an extra $20,000 to $30,000. However, by avoiding the need for a natural gas hookup you avoid a gas bill, administrative fees, municipal franchise fees and fixed delivery charges. This adds up to about $8,000 in fees over 22 years.
However, there is a corresponding rise in electricity charges. Bond says that, on average, your electric bills go up by 30 per cent with geothermal heating. Payback, according to Bond, can be 14 to 22 years depending on how you do the calculations and depending on the price of natural gas.
You may not have shiny solar panels to show off to the neighbours, but they will surely give their heads a shake when you say that you are heating your home with heat from the earth that is just six degrees Celsius.
Troy Media columnist David Dodge is the host and producer of Green Energy Futures, a multi-media series presented atwww.greenenergyfutures.ca. The series is supported by TD, Suncor Energy and the Pembina Institute.
Next week: Green lighting