How Much Coal Can A CFL Save?

Imagine one light bulb consuming electricity around the clock for one full year. How much coal would it take to light that bulb if it were an incandescent? How about if it were compact fluorescent? Let’s do the calculation:

The thermal energy content of coal is 6,150 kWh/ton of coal. If 40% of the thermal energy in coal is converted to electricity, then:

0.4 x 6,150 kWh/ton = 2,460 kWh/ton of coal burned

One 100-watt light bulb burning for one full year:

0.1 kW x 8,760 hours = 876 kWh

So that: 876 kWh/(2,460kWh/ton) = 0.3561 tons = 712 pounds of coal burned per year

One 23-watt CFL burning for one ful year:

0.023 kW x 8,760 hours = 201 kWh

So that: 201.5 kWh/(2,460kWh/ton) = 0.0819 tons = 164 pounds of coal burned per year

The difference? 712 – 164 = 548 pounds of coal saved per year!

Carbon Dioxide Savings

There are, on average, 2.2 pounds of carbon dioxide per pound of coal burned.

548 pounds of coal saved annualy x 2.2 pounds of carbon dioxide/pound of coal = 1,206 pounds CO2 per 23-watt CFL changed!