Is the cost of running a Geothermal heat pump less than an air-based heat pump?
I live in Montreal, Canada and have an oil furnace and standard heat pump. My heat pump runs until -12C at which point the oil furnace takes over full-time. I have a dual-energy electric rate, so the cost of my electricity is about 1c/kWh cheaper when the temp is above -12C, but shoots up to 3x the cost when it is colder than -12C. Although it gets more expensive on the really cold days/nights, it ends up being more profitable the other 95% of the year. Generally speaking, this solution works well. None the less, I go through about 2000-3500L of oil per year (depending on how cold the winters are). At an average cost of about 1$/L, oil alone costs about 3K/year. When I look at my electric bills, they average about 100$/mth, slightly higher in the heat of summer, and in the winter months.
I am now looking at adding floor to my house, and will likely have to do work on the HVAC system. So the obvious question is whether it is worth the $$$ to move to geothermal.
I've already had a quote which seem incredibly expensive, so I have to really sit down and decide if it is worth the investment. Obviously, I realize that I would save the cost of oil every year. However, what can I expect to see in electricity costs? Does a geothermal heat pump require less electricity than a conventional heat-pump? I presume that both use a compressor, so I can't imagine the consumption being that much less significant.
Additionally, do any geothermal systems use fosil-fuel as suppplemental (emergency) heat supply? Or do they all use electric coil only? Does the electric coil get used that often, or is it there truly for emergency purposes?
As you can see, I am very much in the preliminary stages of evaluation (I don't even have plans for the extension drawn up yet), but just wanted to start investigating my options.
Any advice, or good resources that you can offer would be greatly appreciated!