terra, not terror

sharing ideas about a simpler way to live

Eco Math April 1, 2008

Filed under: alternative, education, energy, solar, wind — terra @ 7:00 am

We’re going to do a little math story problem. It’s pretty easy.

If you choose alternative energy for your home, your investment has a payback period of several years. You pay for the technology all at once, in the beginning when it’s installed. (Often, it’s paid for with grants and other incentives, but we’ll assume you pay for it out of pocket) The payback period explains how long it will take for you to have saved enough money on energy bills to cancel out the initial investment.

These are examples, and not exact. I used 10 years for everything to make the math really easy. These are exaggerated hypothetical numbers for our story problem, based on Akron, OH.

Solar = 10 years
Wind power = 10 years
Green roofs = 10 years
Geothermal = 10 years

Question: If you use all of these technologies on your home or building, how many years will it take for your investment to pay off?

Answer in the comments section. You can be anonymous if you want. I’ll give the answer at 5:00 today.

Answer: If each of your renewable sources takes 10 years to pay off, the total payoff time is 10 years. Not 40 years. Just 10. You’re paying for them all at the same time, and they all pay off at the same time. Think of it this way, you’re paying a utility company for gas and electric right now, forever. If you had renewable energy, you’d buy, pay for it for 10 years, and then never have to pay for it again. That sounds like a deal!


2 Responses to “Eco Math”

  1. anonymous Says:

    thanks for the post.
    here’s another question:
    monitary payback is one consideration. energy payback is another.
    not using hypetheticals, how long does it take for the energy saved to equal the energy used to manufacture the alt energy systems?
    same question for hybrid vehicles, and other forms not mentioned.
    hydrogen is an interesting consideration. energy has to be spent to extract and compress it. unless that energy doesn’t use any fossil fuels, does it *ever* save more energy than used to extract/compress it?

    i don’t know the answers, but would be interested in hearing opinions.

  2. terra Says:

    Yes, energy savings is the most important element. But people think in terms of how much money they can save. The answer is – a lot!

    There are many ways people can save energy, such as a hybrid, tankless water heater, etc. Hybrids probably don’t take much longer to manufacture than other cars. Their energy payback time is certainly less because they are Ultra Low Emission Vehicles.

    Hydrogen takes just as much gas/oil to create it as a gas engine, so it’s not a great alternative. We would still be dependent on oil to create the fuel we use in our cars or homes. And then we’d have to create a new fueling infrastructure to replace our millions of gas stations.

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