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February 02, 2005

The Heat Pump is On

A while back I raved about heating homes with geothermal heat pumps, which can be incredibly energy efficient, generating two or three times as much usable heat as is contained in the electricity they consume. The Northwest Power and Conservation Council identified heat pumps as the second most important source of electricity savings in people's homes (see page six, here--but be careful, it's a big .pdf download) -- which is one reason why many Northwestern electric utilities offer rebate programs to homeowners who elect to install them.

But apparently some utility conservation managers are skeptical of the heat pump rebates, as discussed in this article in Northwest Current (an online energy-issues newsletter).  They seem to have several objections to the rebates, some of which are fairly reasonable, but one of which shows a flaw in how we treat energy efficiency investments.

Among the sensible objections:  the backup heating systems for freezing weather--when some heat pumps don't perform well--are pretty inefficient; and some customers may take the heat-pump rebate even though they have leaky ductwork that severely compromises the system's efficiency.

The flawed objection is this:  some people may be swayed by the rebate to switch from propane furnaces to electric heat pumps.  And that increases, rather than decreases, total electricity consumption--the exact opposite of what the rebate program was designed to accomplish.

From a utility's standpoint, I can understand why that's a legitimate beef.  Energy efficiency rebates are supposed to reduce electricity consumption -- thereby avoiding the construction of expensive new power plants.  If the rebate program does the opposite, it's a double whammy: not only does the utility pay for the rebate, it pays for the new power plant the rebate helped necessitate.

But from a big-picture environmental standpoint, that objection doesn't hold much water. Compared with the best heat pumps, propane heaters produce more CO2, and probably more pollution overall.  So switching from propane to a heat pump is probably a net boon for CO2 emissions, even if poses problems for the utility that's providing the juice.

The problem here, obviously, is that the rebate programs are managed by utilities -- which, understandably enough, are looking out for their own interests.  But those interests may not always line up with the interests of society at large.  A more comprehensive program to limit CO2 emissions -- such as the cap-and-trade system envisioned under the soon-to-be-effective Kyoto protocol -- could help line up the incentives of those sorts of programs with the larger public interest of keeping climate-warming emissions in check.

Posted by ClarkWD | Permalink


In April 2003, I was bummed to discover that the house I was purchasing did not have natural gas. Instead, the builder had installed this "electric heat pump" and claimed that it would only cost 3% more per year to operate. Like you, my first reaction was "electric?" So I did some research on it and was plesantly surprised with what I found. Over my past two years in this home, the heating costs are quite comparable to natural gas. Plus, the heat pump can pump the heat out of the house in the summer...effectively making it an air conditioner, too! Unfortunately, our heat pump is among the least efficient currently being produced (I would have chosen something better if the builder hadn't already installed it), and it's air-source instead of ground-source (cheaper installation but less efficient), but still far more efficient than 'resistance' based electric heating.

Next I'd like to find a way to integrate the heat pump with our water heating system, effectively pumping the hot air in the house into the water while saving a bunch of power. I'm also looking into adding a humidifier to reduce the amount of heating I need to do in the winter while improving the indoor air quality. I've also learned that many communities have central heating systems that provide steam heat to many homes at a higher efficiency; here in Seattle, Seattle Steam provides a similar service to several buildings downtown. I've also wondered if we could pump the heat from the computer rooms operated by our region's many technology companies and turn it into hot water. It seems there's still a lot for us to learn about in efficient heating systems.

Posted by: Rodney Rutherford | Feb 4, 2005 2:29:59 PM

I recently decided to install a geothermal heat pump in our new home rather than a gas boiler. While gas may appear to be slightly more economic because of the lower install cost, I decided that the efficiency of this unit, coupled with lower maintenance costs and quiet operation tipped the balance toward geothermal. There is also the “cool” factor but that’s another issue entirely.

The most difficult part of the decision revolved around total CO2 emissions related to my choice. Since I purchase electricity from Puget Sound Energy a substantial amount of my power comes from coal power plants. On the other hand, PSE is building new wind power plants and has a substantial amount of hydropower available to them. Total CO2 emissions related to my heating system choice could be higher or lower depending on where my power came from:

Electricity from wind or hydro? CO2 emissions are virtually eliminated.
From combined cycle natural gas? Lower than if I burned the gas directly.
From coal? Definitely higher.

In the end, I figured that the natural gas I didn’t burn would more useful generating electricity. (Of course, at current prices, power companies will probably just burn cheaper coal instead – You just can’t win)

Posted by: Matt Leber | Dec 22, 2005 2:15:13 PM