Question

How many pounds of carbon dioxide would you prevent from entering the atmosphere in one year, if you were to replace a 100-watt light bulb with a CFL bulb that uses 12 watts in a fixture that you have on 4 hours per day?

Answer 1

You would save approximately 118.20 pounds of carbon dioxide per year by replacing a 100-watt incandescent bulb with a 12-watt CFL running 4 hours per day.

Step-by-step explanation:

The question is asking for the amount of carbon dioxide savings by replacing a 100-watt incandescent light bulb with a 12-watt compact fluorescent lamp (CFL) that is running for 4 hours a day over a year.

First, we need to calculate the total energy savings in kilowatt-hours (kWh). Since a kilowatt is 1000 watts, we'll use the formula:

Energy savings = (Power of incandescent bulb − Power of CFL) * Time (in hours) / 1000.

For the incandescent bulb: 100 watts * 4 hours/day * 365 days/year / 1000 = 146 kWh/year.

For the CFL: 12 watts * 4 hours/day * 365 days/year / 1000 = 17.52 kWh/year.

The savings in energy would therefore be 146 kWh/year − 17.52 kWh/year = 128.48 kWh/year.

To convert the energy savings to pounds of carbon dioxide (CO2) prevented, we use the average emissions factor for the U.S. electric grid which is approximately 0.92 pounds of CO2/kWh (this number can vary based on the source of the electricity).

Total CO2 savings = 128.48 kWh/year * 0.92 lb CO2/kWh.

This results in around 118.20 pounds of CO2 savings per year.

Answer 2

That's an excellent question but we don't have enough information to answer it. We would need to know how the electrical energy is generated. Nuclear, hydroelectric, coal burning, wind, and natural gas burning all produce different amounts of carbon for the same amount of electrical energy. If the utility that supplies your house uses nuclear or wind, then you can leave both bulbs shining 24/7 and they're not responsible for any carbon.