The 2 biggest decisions you can make about your impact on the Climate are building a new home or buying your next car. Few us us ever have a new home built for our families but we all buy cars.

You may wonder why this is so important since you may drive only 10,000 miles a year. The thing to keep in mind is that someone will buy and own your car long after you trade it in. New cars today will last 20 years or more and run for 250,000 miles! Every new car purchase commits the planet to that car’s eventual carbon output.

Let’s take a few examples:

  • A car that gets 20 miles/gallon will use 12,500 gallons of fuel – at today’s cost = $34,375 and produce 250,000 pounds of CO2

  • A car that gets 30 miles/gallon will use 8,333 gallons of fuel – at today’s cost = $22,917 and produce 167,000 pounds of CO2

  • A car that gets 50 miles/gallon will use 5,000 gallons of fuel – at today’s cost = $13,750 and produce 100,000 pounds of CO2

So what should a New or Used Car buyer look for? Buy the car that produces the least CO2 over its lifetime and still meets your needs. Don’t buy a huge car just because you will take your kid and all their stuff to college twice a year.

Buy a car that meets your needs 95% of the time and borrow or rent something bigger when you need it.

Here are some very good options for lowering your transportation costs and their Climate Impact:

  • An Electric Car powered by your own Solar Array or Community Solar Array = Zero CO2

  • An Electric Car powered by the grid = Very Very Low CO2

  • A Plug in Hybrid = Very Low CO2

  • A Hybrid = Low CO2

  • A High MPG car (for example 35 mpg) = Moderate CO2

For those of you who wonder why your car uses so much energy here are a few thoughts:

  • Cars weigh between 3,000 and 5,000 pounds and it takes a lot of energy to get them moving. The heavier they are the more energy is needed. Think about your effort to move a lightly loaded garden cart vs. a heavily loaded cart.

  • A moving car has to overcome the rolling resistance of its tires and the internal friction of its parts to keep moving. Remember how riding a bike with nearly flat tires takes a lot of effort?

  • The faster a car moves the greater the wind resistance to it is and the more energy that is required to keep it at that speed. Think about when you were a kid, how your hand was pushed back when you put it out the window.

  • In a normal car all that energy used to get you going is wasted and turned into heat when you apply the brakes to stop.

  • Bigger engines waste more energy just making themselves rotate (moving pistons, operating valves, etc) and make the car heavier.

  • The more gears in your transmission (providing better gear ratios), the slower the engine needs to turn to keep your car moving at highway speeds.

  • A car with an internal combustion engine produces 20 units of useful energy (the energy that gets you moving and keeps you moving) for 100 units of energy that you put in.

So, smaller cars with smaller engines and more gears (or better gear ratios) are inherently more efficient. Driving more slowly reduces wind resistance and thus improves gas mileage.

Why does a Hybrid get better “gas” mileage and produce less CO2?

  • Hybrid cars come with a small battery, and a combined electric motor and generator.

  • When you apply the brakes, a hybrid car uses the generator to convert much of the energy from braking into electricity to charge the battery (instead of into heat like conventional brakes).

  • When you drive, the hybrid can use the electricity from the battery to run the electric motor to assist the gas motor to power your car.

Why does a Plug-in Hybrid get even better “gas” mileage and produce even less CO2?

  • Plug-in Hybrid cars are like the Hybrid described above but come with a bigger battery that can be charged by plugging it in at your house or a charging station.

  • These cars have enough energy stored in the battery that they can run between 12 – 50 miles before the gas motor has to come into use.

Why is an Electric Car better?

  • Electric cars convert about 60+% of the energy used to charge them into useful energy to get you moving and keep you moving.

  • If you are charging your car from Green Mountain Power, 70% of the energy they provide comes from sources that produce no CO2! This number will get even higher as GMP continues to improve their energy supply. Overall, and electric car in GMP service territory creates much less CO2 than a gas or even an Hybrid or plug-in Hybrid car.

Why is an Electric Car charged by your own Solar Array or Community Solar Array best?

  • The electricity you use to run your car by plugging it into your house or a charging station is put back into the grid when your solar panels are producing electricity. Thus, over the course of a year you may produce as much energy as your Electric Car needs and thus create no CO2 in the process.