The Difference With One Light

Earth Hour 2008 came and went last Saturday. I still haven’t seen any reports about the reduction of energy usage from the event but I look forward to reading about it. After Earth Hour I began thinking more about my own electric usage. I decided to go to Florida Power & Light (FPL) to see what I could find. There I was able to look at reports of my past electric usage, tips for reducing energy consumption, they reviewed their Sunshine Energy Program and provided a link to their Online Energy Store.

At FPL’s Online Energy Store, hosted by Energy Federation Incorporated, I first spotted some data on the advantages on low-mercury compact fluorescent light bulbs. How much difference can one light bulb make? Can we start with baby steps and change one bulb at a time. Is it any use?

Below is a composite picture of the Chicago Skyline before and during Earth Hour 2008. You have to look closely to see a difference but there are differences.

Baby steps

photo by jatherton

Perhaps it is a little easier to notice the differences in this time lapse movie.


video from jough

How Much Electricity Do I Use?

First it helps to get an idea of how they measure your electric usage and that is by kilowatt-hour (kWh). A kilowatt-hour is equal to 1000 watts being used for 1 hour. In comparison, a 100-watt light bulb uses 100 watts per hour or 0.1 kilowatts per hour. Based on nearly 4 years of data I am averaging the use of 23.56 kWh per day. I tend to use more in the summer because of the increased usage of the air-conditioner. During the summer also appears to be the time the utility companies increase the price of each kWh.

How Much Electricity Does The Average Household Use?

Next I went to the Energy Information Administration and checked out Energy Basics 101. Their latest yearly report was for 2006. There were 121,471,071 residential electric customers in the U.S. and they used 1,351,520,036 megawatt hours (a megawatt hour is 1000 kWh or 1,000,000 watt hours). Thus, the rough average electric usage for each residential customer is 11.13 megawatt hours per year or 30.48 kWh/day. So my usage of 23.56 kWh/day is about 78% of the average residential usage.

How Much Difference With One Light?

Let’s assume you leave a lamp with a 100-watt bulb burning in the other room each evening. For 5 hours that bulb consumes 100-watts/hr times 5 hours or 500-watt hours (which is 0.5 kWh). Now if we just turned that one light off we would save 0.5 kWh per day. In my case my usage would drop from 23.56 kWh/day to 23.06 kWh/day. That is equal to a 2.1% reduction in my electricity use.

Who Cares About My 2.1% Reduction in Electricity Use?

Well, at 0.5 kWh/day that is a 182.5 kWh reduction per year. With the 2006 average retail price of 10.4 cents/kWh that equates to a savings of $18.98/year. OK, so to the individual an extra $19 isn’t going to mean a lot but keeping in mind to turn that extra light off isn’t all that hard to do either. Now, if each household turned that same light off it would equate to saving nearly 61 million kWh/year.

According to the E.P.A. Greenhouse Gas Equivalencies Calculator

For the individual, this means 182.5 kWh saved = 0.15 Tons of CO2 avoided, which is equal to:

  • Consuming 15.9 gallons of gasoline, or
  • Consuming 0.33 Barrels of crude oil, or
  • The CO2 absorbed by 3.6 tree seedlings grown for 10 years.

For all of the households, this means 61 million kWh saved = 52,277 Tons of CO2 avoided, which is equal to:

  • Taking 8,686 cars off of the road for a year, or
  • Powering 4,186 homes for a year, or
  • The CO2 absorbed by 1,216,023 tree seedlings grown for 10 years, or
  • The CO2 absorbed by 10,778 acres of pine forest

No matter if you look at the big picture or the little picture the simple task of turning the lamp off in the other room does make a difference. If all else fails, at least turn it of on Thursdays.

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