A CFL with a 14 watt electrical power input emits
approximately 800 lumens (similar to a 60W incandescent)
of light, which is approximately 57 lumens per watt of input
electrical power. A 14 watt CFL costs approximately $1 and
will last approximately 8,000 hours.
Figure 3 shows the construction of an LED lamp
which uses a number of individual LEDs wired together
to produce the desired amount of light. An LED with a
six watt electrical power input emits approximately 800
lumens (similar to a 60W incandescent) of light, which
is approximately 133 lumens per watt of input electrical
power. A six watt LED lamp costs around $10 and will
last approximately 25,000 hours. With improvements in
manufacturing and an increase in consumer purchases, the
costs of LED lamps should drop in the future.
Table 1 gives a cost comparison of incandescent, CFL,
and LED lamps based on using the 800 lumen light output
lamp six hours per day, and an electrical power cost of
$0.12 per Kilo-Watt-Hour ( 12 cents per KWH).
Based on the life of 11. 4 years for an LED lamp, the
operating costs of the incandescent lamp are 6.84 times
that of an LED, and 4. 25 times that of a CFL. The operating
costs of the CFL are 0.23 times that of an incandescent and
1.60 times that of an LED. The operating costs of the LED
lamp are 0.15 times that of an incandescent and 0.62 times
that of a CFL. Clearly, the LED is superior in the long run.
My recommendation is to replace the existing bulbs
a few at a time so you don’t incur a tremendous drain
on your pocketbook. I used this approach to replace
incandescent bulbs with CFLs which save me a tremendous
drop in electrical costs. My calculations have convinced me
to start replacing the CFLs with LEDs in the near future.
Besides saving money and work replacing lamps for
myself, I will save the power company’s capacity which
will lower their operating costs. Plus, I will save carbon
emissions to the atmosphere which everyone agrees
will help regardless of your stance on climate change.
Replacing the CFLs will also reduce the mercury hazard
that may leach into the environment.
I hope this short analysis helps you to decide which
type of electrical lamps you need to use. It sure has helped
Is “Green Energy” Really Green?
QI see a lot on TV and in magazines about green energy that is supposed to be environmentally friendly, but are these devices really as benign as they are purported to be?
AThis is both an emotionally and politically charged question. I will try to stay as neutral as possible with my answer, but if I hit one of your hot buttons let me know and we can discuss
Green energy is also known as renewable energy
which can be replaced or regenerated on a short time
frame as opposed to the span required to replenish fossil
fuels (coal, crude oil, and natural gas). I will stick to the
green energy sources that are used to generate electricity
since there are a number of papers about green energy
sources for heating, cooling, and transportation for those
who are interested.
Green energy sources include solar photovoltaic, wind,
tidal/wave, hydroelectric, geothermal, biofuel, biomass,
and solar thermal. I will divide these green energy sources
into thermal (geothermal, biofuel, biomass, solar thermal)
and non-thermal processes (solar photovoltaic, wind, tidal/
wave, hydroelectric) because of similar characteristics.
First, let’s look at fossil fuels and some potential
reasons to not use them for our long term energy needs.
According to scientists, fossil fuels are derived from
carbon bearing materials that were buried millions of years
ago. The combination of heat and pressure converted
to hydrocarbon gases, liquids, and solids known to us
in modern times as natural gas, crude oil, and coal,
respectively. Natural gas and coal can be burned to
generate heat (thermal) energy, but crude oil must be
refined to produce gasoline, kerosene, diesel, and fuel oil
which are burned to create thermal energy.
These hydrocarbon fuels burn in the presence of
oxygen (chemists call this oxidation) to create water (H20),
carbon dioxide (CO2), and heat. This combustion process
occurs according to the chemical equation for burning
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n FIGURE 3.
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