Example of the Final Project Possible Reduction of Greenhouse Gas Emissions by Replacing Incandescent Lights with Compact Fluorescent Lights (CFL)
Outline • Introduction • What are CFLs and why are they more efficient than incandescent bulbs? • How much energy can be saved per year in British Columbia of all incandescent light bulbs are replaced with CFLs? • What is the effect on the CO2 emissions?
Introduction • Government web pages and media suggest replacing incandescent light bulbs with compact fluorescent light bulbs to save energy. • We want to know how much energy is saved per household and estimate the energy savings in BC if all the home lights were replaced by CFLs. • We also estimate the corresponding reduction in CO2 emissions. • In our estimates, we take into account energy used to manufacture incandescent bulbs and CFLs. For the estimate of the BC energy savings, we assume that ½ of all lights could be replaced by CFLs on average.
What is a CFL? • Ordinary incandescent light bulbs emit light due to electrical heating of a thin tungsten wire. They convert only a few % to visible light (Lab 8). 90% – 95% of the electrical energy is converted into heat. • A CFL is based on light emission from a gas discharge: An electric current is driven through a gas ionizing the gas molecules. The recombination of ions and electrons results in light emission. • For the same light output as a 60 W light bulb a CFL needs only 13 W of electrical power. • (Source: Wikipedia)
How much energy would be saved annually due to replacing these bulbs? • Assume each bulb is switched on an average of 4 hours/day • Average power 60 W. Replaced by 13 W CFL= Savings of 47 W per bulb replaced • Each home would save10 47 W (4 h/d 3600 s/h 365 d/y) ≈ 2.5109 J per household per year. • For the whole province:2.5109 J 1 600 000 households≈ 41015 J per year
What would be the total reduction in CO2 Emissions? • CO2 emissions in the US are 1.34 pounds (0.608 kg) of CO2 per kWh averaged over all methods of generating electricity • (1998 – 2000, Source: US Government, DOE). • Conversion between kWh and J1kWh = 1000 J/s 3600 s/h 1h = 3.6106 J • Annual reduction in CO2 emissions is: 41015 J per year (1kWh / 3.6106 J) 0.705 kg/kWh= 8108 kg of CO2 per year in BC
What would be the percentage decrease in energy consumption? • Total BC power production ≈ 53 000 GWhours ≈ 53109kWh3.6106 J/kWh≈ 21017 J • (http://www.bchydro.com/rx_files/info/info46749.pdf) • The savings of 41015 J by switching to CFLs would decrease our provincial energy consumptions by 2%
Conclusion • Replacing incandescent bulbs with CFL leads to significant savings in energy (and money). • BC’s energy consumption would decrease by approximately 2% if all households would replace. • Higher production cost of CFLs are offset by much longer lifetime. • Concerns about mercury content in CFLs could be addressed by mandatory recycling programs.