03/26/2007 07:23 pm ET | Updated May 25, 2011

SUVs as Cliche

In my last entry I took a page from the Weather Makers, and cited Tim Flannery's observation that one of the obstacles to decisive action on climate change is that the whole idea of global warming has become a cliche even before it has been understood.

My example of a cliche was the Kyoto protocol, which people talk about without really paying attention to. Kyoto is largely just a symbol of our feelings about global warming, rather than an indication that we're doing anything about them.

Here's another one: the contemporary battle between good and evil, with the hybrid cast as the hero and the SUV as the villain.

Please don't get me wrong. I love hybrids. I drive one. If I could magically transform every Suburban into a Prius, I would.

But here's the thing. If we're going to act decisively, we're going to need to do the smartest, cheapest things first, the things that deliver the deepest greenhouse gas cuts for the buck. And hybrids don't fit the bill.

Let's put it this way. If we traded in a million Toyota Highlanders for hybrid Toyota Highlanders, how much CO2 would we save? A conventional Highlander gets 21 mpg. A hybrid model gets 28. Driven for a year for an average distance of 16,000 kilometres, the switch to hybrid technology would save us 1.2 million tonnes of CO2 a year.

Not bad. But let's look at another option. Let's say we switch a million homes with natural gas HVAC systems to geothermal energy. Based on a standard annual consumption, the million geothermal homes would save 4.7 million tonnes of CO2.

In fairness, I haven't given the numbers for the classic Prius-SUV battle. But neither have I compared geothermal to the real energy hog: electric heating and air conditioning-which sucks so much power that urban electrical grids teeter on the edge of collapse on summer afternoons. Turning a million Highlanders into Priuses would save us 2.9 million tonnes of CO2. Switching a million homes with electric heating and cooling would save 7.2 million.

So much for the emissions savings. How about the financial implications? Well, the geothermal wins here too. A hybrid Highlander is going to save you about 120 gallons of gas a year. At $2.30 a gallon, that's $276 in savings.

A geothermal system is going to save you 2500 cubic metres of natural gas. At $0.36 per cubic metre, that's an annual savings of $900. Of course, the geothermal system will increase electricity demand by about a third, so we'll subtract $200.

Now, let's say that the difference between the cost of owning a hybrid Highlander for five years is about $10,000 more than the cost of owning a conventionally powered model ($52,544 compared to $42,023). And let's assume that the cost difference between a geothermal system and a high-efficiency natural gas system is also about $10,000 ($15,000 compared to $5,000).

At this rate, the Highlander will pay itself off in 36 years.

The geothermal system will pay itself off in 14.

Now, let's factor in the fact that as fuel prices rise, the geothermal system gets even more cost effective. And let's remember that the numbers above cover the costs of the SUV for only five years. It will keep getting more expensive as it ages, or as it gets replaced. Meanwhile the geothermal system gets cheaper.

Then let's remember that the added complexity of the hybrid will also show up as higher levels of embodied CO2.

Needless to say, I'd love it if every house had a geothermal system under the driveway, and a hybrid car (or electric car) parked out front.

But if we're going to do the most efficient things first, then let's start where the green option is cheaper than not only the other green option, but the conventional option as well. Then the savings can fund the next step.

You can take your savings from your geothermal system to make a down-payment on your Prius.