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Page added on July 20, 2012
How Big is Your Pile of Coal?
The first half of 2012 has been the hottest on record in the U.S., and in many regions, people are blasting their air conditioner 24 hours a day to keep their homes comfortable and safe. Not only is the electricity used to power these air conditioners expensive, but in many regions of the country, it is generated by burning coal.
Unfortunately, converting coal to electricity is an inefficient process with 70% of the coal’s potential energy lost during the conversion to electricity at the power plant and another 9% lost over the power grid. Since only 28% of coal’s potential energy is delivered to the home, using that energy efficiently can have a major impact in reducing the amount of coal that each home uses.
Our Math
To cool the average home in the Southeast, a central air conditioner consumes 4,050 kilowatt-hours (kWh) annually. For electricity generated from coal, the process of delivering those kWh’s looks like this:
- Start with 4,870 pounds of coal, which contains the equivalent of 14,830 kWh of potential energy.
- Convert that coal to electricity at a typical power plant and you lose 70% of the potential energy, which brings you to 4,449 kWh.
- Of the remaining potential energy, 9% is lost as the electricity travels along the grid, resulting in 4,050 kWh delivered to the home.
Given the inefficiency of generating and delivering electricity from coal, it’s important for people to be smart about how they use the kWh’s that reach their homes. By making cost-effective improvements to their homes’ energy efficiency, homeowners can reduce the amount of coal it takes to cool their homes this summer.
By upgrading the central A/C for an average home in the Southeast from a SEER 10 to an ENERGY STAR rated central A/C with a SEER of 14.5, a homeowner could reduce the home’s cooling consumption by a third to 3,300 pounds of coal.
Combining this A/C upgrade with duct sealing and duct insulation as well as sealing the leaks in the home’s exterior could reduce the amount of coal burned to cool the home to just 2,000 pounds–less than half of what the average home in the Southeast consumes.
Reducing the original coal pile to 2,000 pounds prevents nearly 6,300 pounds of carbon dioxide, 36 pounds of sulfur dioxide and 16 pounds of nitrogen oxide from being emitted into the atmosphere annually (Environmental Protection Agency). It could also save the home around $300 on their electricity bills each year.
To find out how you can reduce your coal pile this summer, complete this easy online home energy survey to find out what upgrades make the most sense in your home. If you decide to upgrade your air conditioner, don’t miss out on rebates from utilities and governmental agencies in your area.
If you happen to live in an area of the country that doesn’t use a lot of coal to generate your electricity, you’re not off the hook. Similar calculations can be made for any fuel source for electricity: we encourage everyone to use energy in their home wisely.
Assumptions: This is a simplified calculation based on average home conditions and use, as well as average climate data; therefore, actual annual consumption may vary from these estimates depending on home location and size, the SEER rating and size of the current AC unit and the current year’s weather conditions. Assumed characteristics of the average home in the Southeast:
- Southeastern states include those relying on coal for 50% or more of their electricity generation (TN, KY, GA, NC)
- 1,700 square feet built in 1982
- Central air conditioner, 3 tons, SEER 10 (U.S. government standard until 2006)
- Programmable thermostat
- Two-story home
- Ducts average insulation R-4.2; 15% air leakage on supply and return and average duct efficiency based on Nashville, Lexington, Atlanta and Charlotte.
- Averaged cooling energy consumption based on same locations as above
Assumed characteristics for upgraded home:
- 1,705 square feet built in 1975
- Central air conditioner, 3 tons, SEER 14.5 (current ENERGY STAR standard)
- Programmable thermostat
- Two-story home
- Duct leakage decrease to 5% (from 15%); increase in duct insulation to R-8 (current ENERGY STAR standard)
- Reducing overall home exterior air leakage decreases cooling usage by 20%.
Conversion factors using weighted average of energy content from the four major coal types found in the U.S.:
- 3,412 BTU/kWh
- 1,392.5 BTU/lb of coal
- 0.03283lb/kWh
2 Comments on "How Big is Your Pile of Coal?"
BillT on Sat, 21st Jul 2012 2:40 am
First…A/C is NOT a necessity. I live in the Philippines which is much like the American south east in climate. Most Filipinos do NOT have A/C. Yet, they survive, go to work, eat, sleep, and enjoy life.
I also grew up in an America without A/C. Pennsylvania summers were hazy, hot and humid. 100+F. was not unusual. I did fine as did everyone else.
American’s need to realize that most of the stuff they consider necessities are NOT. They will soon learn that lesson the hard way.
Norm on Sat, 21st Jul 2012 10:07 am
First of all, I dont think anybody really cares whats on these posts. I am basically typing to myself only cause nobody else will read it.
But just incase I am wrong… I have extensive experience with unique little modifications to a house that make a huge difference. There’s a type of attic fan which can cool down the whole attic very effectively, but that fan itself uses very little wattage. A Home Depot attic fan uses almost 500 W power which is absurd. I have devised attic fans which cool equally well, for only 28 W power. Bit of a savings yes? IF you put in an attic fan, it makes a tremendous difference on reducing the air conditioner load.
What about your hot water pipes? If you insulate them, it reduces the burden on the A/C. Thats because, the hot water energy content, stays in the pipe instead of rapidly radiating outwards. But who has insulated pipes? Almost nobody, thats who.
For kitchen fluorescent lighting, or workshop, I have done huge mods there also. Instead of a fluorescent kitchen light which draws 390 W, how about 62 W instead. With light thats comparable or superior.
But the real point is, I have extensive experience with crooked business management. Those lyin cheatin execs at the top, could care less, about any product that works, makes sense, or saves energy, and all the worse if it saves a LOT of energy.
So if you can’t fix the crooked CEO’s, then you can’t save any energy, so then your house will keep burnin up lots of coal so that your A/C keeps you cool.
Funny, and the more coal you burn, the more money those crooked CEO’s make. Guess it all makes perfect sense !!