I agree that getting our numbers is right and I also agree that there are alot of numbers out there. It is particularly difficult to get the numbers exactly right for each person because it is dependent on a number of factors, including the state you live in and who provides your energy. That is because the amount of carbon dioxide released depends on the mix of fuel sources your energy provider uses. Coal power, for instance, emits far more CO2 than hydro-electric power, and renewables, such as wind and solar, emit the least. So the numbers are often based on national averages and assumption of use.

My statement of about 600 lbs CO2 was based on the following information and formula. A 100 watt lightbulb which is expected to last approximately 1000 hours equates to 100 kWh (100 watts divided by 1000 = .10kW and .10kW x 1000 hrs = 100kWh). 100kWh x 6 light bulbs = 600 kWh. We know that every kWh hour of electricity produces approximately 1.34 pounds of carbon dioxide. (This number is the national average emissions rate.) Thus, 6 incandescent 100 watt light bulbs will produce 804 lbs of CO2 ( 600 kWh x 1.34 lbs. = 804 lbs. of carbon dioxide). On the other hand, the comperable Compact Fluorescent or CFL produces around 25 watts (it ranges between 23 and 26) and has around 10,000 hours of use. This equates to .025 kW (25 watts divided by 1000 = .025 kW) and to 25 kWh (.025kW x 1,000 hrs(the same time that the incandescent bulb worked)). 25kWh x 6 CFL bulbs equates to 150 kWh for 6 bulbs. 150kWh x 1.34 = 201 lbs of CO2. The difference between the pounds of carbon dioxide 6 incandescent light bulb puts out and the pounds put out by the 6 CFL lights for the life span of the incandescent light bulb equates to approximately 603 pounds (804 – 201 = 603).

There are ways you can calculate your personal energy use that are more accurate. I used the national average of 1.34 lbs. CO2/kWh, but you can find the multiplier for your state at http://tonto.eia.doe.gov/FTPROOT/environment/e-supdoc-u.pdf. For example, here in Washington, our average CO2 pounds/kWh emissions is .25. (Recognize that this information is based on data obtained between 1998-2000).

Thus, if you know the wattage of an item or appliance, you can calculate the CO2 emissions with this formula (here I used a 75 watt bulb as an example): (75 Watts x 2 Hours Used Daily x 365 days)/1000 x 1.34 lbs. CO2/kWh = 73 lbs. CO2/year (or use your state’s carbon coefficient from the web site above).

On the issue of the 75% of home energy use, you are right that my statement was not correctly stated. The Department of Energy actually says that in the average home 75% of the electricity used to power home electronics is consumed while the products are turned off. I should have been clearer that the 75% does not apply to all home energy use but to the electricity used to power home electronics. Thank you for helping clarify.

Thank you again for your comments and for your support.

Similarly, claiming that 75% of a home’s energy usage is caused by standby power on a few computers, TVs, microwaves, etc. can’t possibly be accurate, unless the home owners don’t watch TV, use air conditioning, dishwashers, clothes dryers, etc. I went to the Dept. of Energy and found that the actual report states that up to 75% of the power of the machines that have a standby mode is used in the standby mode, not 75% of the total home power usage. And even that is assuming minimal use and maximal standby.

I think it would behoove us all to make sure the numbers that are being thrown around are as accurate as possible, in order to not leave openings for the mass consumers to negate our arguments and issues. It’s going to be hard enough to make progress in this country as it is.

Having said all that, keep up the good work here and Go Earth!

Second, with our activities, we often have to weigh the environmental impacts. In weighing the impacts, our consciousness and due consideration will most often lead to the best choice – though it is not always clear what is the best choice.

The compact flourescent light v. incandescent lightbulb debate is one of those choices that I think is easier to make. Compact fluorescent lights are more energy efficient and have a longer use life than incandescent lights. Most incandescent (including halogen) bulbs waste 90% of their energy because they provide heat. Not so with the CF bulb, which uses 75% less energy to produce the same amount of light.

Jeff brings up a real concern, but it is a concern that can be significantly reduced. The standard fluorescent lamp contains approximately 20 milligrams of mercury. There are no known health hazards from exposure to lamps that are intact. If a compact fluorescent bulb or fluorescent tube breaks, the U.S. Environmental Protection Agency (EPA) says your greatest risk is being cut by the glass because the amount of mercury in the bulb is so small. With approximately 800 million bulbs being replaced each year, improper disposal of fluorescent lamps can contaminate the environment. Mercury is most toxic when it leaches from landfills into the water and then into fish and humans.

Mercury is also found in coal. When coal is burned, mercury is released into the environment. The largest man-made source of mercury in the atmosphere is fossil fuel combustion (58% of total). Coal burning power plants are the largest human-caused source of mercury emissions in to the air in the United States (making up over 40% of all domestic human-caused mercury emissions). “On average, fossil-fueled power plants emit 0.04 milligrams of mercury per kilowatt-hour sold.” When the mercury in a fossil fuel is heated in a combustor, it turns into a vapor and escapes into the atmosphere. This mercury eventually returns to the earth, settling in water or on land where it is washed into streams, lakes, and other waterways. http://www.epa.gov/mercury/about.htm.

The first step then is to reduce your energy use by turning off lights when not in use. This will extend the life of your bulb as well as reduce the amount of energy generated from coal burning power plants. (Going Green Power is also another way). After reducing your energy use, seek out more efficient energy sources, like compact fluorescent. “Reducing energy through compact flourescent energy-savings reduces more mercury in the environment than is added by the potential disposal problem of the bulb.” http://www.worldwise.com/recfluorlig.html Also, seek out bulbs with low amounts of mercury. Recently, lighting manufacturers who are members of the National Electrical Manufacturers Association (NEMA) made a voluntary commitment to cap the total mercury content in fluorescent bulbs less than 25 watts at 5 mg per unit and for 25-40 watts at 6 mg per unit. Philips and GE make a very low mercury content already.

The next step is to properly recycle your fluorescent bulbs. When this occurs there is a major reduction in environmental mercury from the energy savings, with little or no added mercury from the bulb. During the recycling process, the phosphor power, the glass, metal and other materials are sorted out for recycling. They claim that 100% of the glass, aluminum, and other materials can be reclaimed and reused, and that up to 99.9 percent of the mercury can be recovered and used for other purposes. When storing for recycling, store them in cardboard tubes and in boxes to protect them from damage. In the Washington state, go to http://www.takeitbacknetwork.org for a list of retailers that will take your fluorescent bulbs and tubes and recycle them.

Thus, the right choice here I think is flourescent. Now the choice between flourescent bulbs and beeswax candles may be a more difficult one.

And most importantly, did you know that there is something you can do to stop this?

GreenDimes will stop your junk mail and plant a tree for you each month. Tell your friends!

Kendra