CelloMom's stingy streak is totally gratified by the conservation aspect of the green movement: Conservation of energy, done in the name of doing your bit for the planet, usually leads to serious dollar savings.
You know the kind of thing those of us do who try to be responsible citizens of planet Earth: We improve our home insulation. We set the thermostat at 60F in the winter, 85F in the summer. We shop locally. We trim the grass with a push mower. We're ready for the lighting revolution: not only are compact fluorescent bulbs found throughout the house, we actually turn them off when leaving the room.
After determined energy auditing, insulating, whittling, and replacing of old appliances, we emerge triumphantly clutching our utility bills, which prove beyond a doubt that we beat the national average by a factor of two.
Actually, average energy use in the US is stunning: about 12,000 kWh of electricity, and close to 80 MBTU (million British thermal units) for gas heating every year. It's more for suburban homes, less for city dwellings, and higher for regions that get very hot or very cold, but overall we burn a lot of coal and gas to be comfortable and go about our daily business.
And because the burning of coal and gas makes CO2 as a byproduct, all that energy use comes to a load of CO2 going up through our collective chimneys. To be precise, on average it's 1.35 lbs CO2 for every kWh of electricity, and 117 lbs CO2 for every million BTU of natural-gas heat (or 13.4 lbs CO2 per therm).
Armed with these numbers and your latest utility bill, you can estimate your personal household CO2 emission. For comparison, in the average US household the emissions are:
Electricty 12,000 kWh * 1.35 lbs CO2/kWh = 16200 lbs CO2
Gas heat 80 MBTU * 117 lbs CO2 / MBTU = 9440 lbs CO2
Total about 26,000 lbs CO2.
Now we've dealt with all the low-hanging fruit: buying a new fridge is fun (if you like doing that kind of thing), and super easy compared to, say, installing a geothermal unit on your property. But wait, the driveway is part of the property too, and parked right there is the elephant in the room - or rather, the dinosaur on the driveway.
Okay, our car is 11 years old: not as old as the dinosaurs who went extinct from a drastic climate change 65 million years ago. And they, in turn, came way after the carboniferous, during which most coal beds on the planet were laid down, and which ended 300 million years ago.
Still, if a car the size of a VW Golf gets just 20mpg, in CelloMom's mind it qualifies for the "dinosaur" designation. It's SO twentieth century. Replacing it with a more gas-frugal car could save a huge chunk of the household CO2 emissions, since the burning of every gallon of gas gives 23.4 lbs CO2.
15,000 miles per year at 20mpg == 750gal == 17,550 lbs CO2. ($2400)
15,000 miles per year at 40mpg == 375gal == 8,775 lbs CO2. ($1200)
15,000 miles per year at 50mpg == 300gal == 7020 lbs CO2. ($975)
15,000 miles per year at 0.25kWh/mi = 3750 kWh == 5000 lbs CO2. ($ 400)
Here is an opportunity for CO2 savings, especially when switching to an electric car (whose honest emissions are not zero, but merely quite small). There is savings in the gas expense too; the annual gas expense are listed above assuming $3.25/gallon for gas.
Why not go to the dealer tomorrow? Because a new car is expensive: here is one example where doing the green thing does not get you ahead dollar-wise. You don't trade in your gas-guzzler for a new car just to lower your gas expenses, because gas is still too cheap for that.
But when it is time to replace your car anyway, consider the extra savings you can get from buying a gas sipper. Keep in mind, just going without excessive horsepower that you don't really need, e.g. by by buying the model of your choice but outfitted with a smaller engine, saves both in the purchase and at the gas pump. And if you wait a little, CAFE2025 rules will kick in and models will finally be for sale in the US that are real gas sippers.