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The Lowest Cost Light Bulb
September 6, 2012 | 5 Comments
Overall cost for a light bulb is a consumer’s goal for environmentalists to hard-nosed green eyeshade number crunchers. Today’s light-emitting diode light bulbs have a slight environmental edge over compact fluorescent lamps and that edge means money to you and me.
The U.S. Department of Energy’s Pacific Northwest National Laboratory (PNNL) and UK-based N14 Energy Limited (N14EL) teamed up, examined and reports total environmental impact, including the energy and natural resources needed to manufacture, transport, operate and dispose of light bulbs. The report examines the complete life cycles of three kinds of light bulbs: light-emitting diodes, also called LEDs, compact fluorescents, or CFLs, and traditional incandescent light bulbs. The report was commissioned for the Solid-State Lighting Program of the DOE’s Office of Energy Efficiency & Renewable Energy.
Fifteen different impacts were considered when evaluating environmental footprints, including the potential to increase global warming, use land formerly available to wildlife, generate waste and pollute water, soil and air.
Marc Ledbetter, manager of PNNL’s solid-state lighting testing, analysis and deployment efforts offers a quick summary with, “The light-emitting diode lamp is a rapidly evolving technology that, while already energy efficient, will become even more so in just a few short years. Our comprehensive analysis indicates technological advancements in the near future will help people who use these lamps to keep shrinking their environmental footprints.”
PNNL and N14EL offer the first public report to examine the environmental impact of LED manufacturing in depth.
Incandescent and Florescent Bulbs. Click image for the largest view.
A brief background: Incandescent light bulbs produce light when an electric current runs through a wire inside the bulb’s glass globe causing the wire to heat up and glow. Compact fluorescent lamps, (CFLs), emit light when electricity excites a mix of gases inside the bulb, creating invisible ultraviolet light that is absorbed by the bulb’s fluorescent coating and transformed into visible light. Light-emitting diodes, (LEDs), generate light when electricity flows through an electronic component called a diode.
LED Diagram. Click image for the largest view.
The report’s main claimed advantage is understanding and calculating in the manufacturing costs. Manufacturing processes contribute substantially to a light bulb’s overall environmental impact, but companies generally keep manufacturing information private. The research team was able to gather manufacturing data with the help of industry consultants and some companies on the condition that the final report would not reveal individual company data. How accurate this is – is better than nothing, but still uncertain. But a useful comparison is practical.
To do the analysis, the team chose specific bulbs that best represent what’s most typical and widely available for each of the three types of lights they studied. They then used a database to calculate the resources needed to produce the various components of the three light bulbs.
That analysis revealed both LEDs and CFLs are substantially more environmentally friendly then traditional incandescents, which consume far more electricity. For example, to create the about same amount of light, the specific incandescent light bulb the team studied consumes 60 watts of electricity, while the LED model they studied uses just 12.5 watts and the representative CFL only uses 15 watts.
How accurate the data acquired is might not be so critical if the error level isn’t way off.
Ledbetter explains, “By using more energy to create light, incandescent bulbs also use more of the natural resources needed to generate the electricity that powers them. Regardless of whether consumers use LEDs or CFLs, this analysis shows we could reduce the environmental impact of lighting by three to 10 times if we choose more efficient bulbs instead of incandescents.” The manufacturing data can be pretty far off and still safe consumers money.
With power consumption being similar between LEDs and CFLs when they are lit, the research team found the difference between those two bulbs’ overall environmental performance is largely determined by the energy and resources needed to make them.
At the crunch – CFLs were found to cause slightly more environmental harm than today’s LED lamp in all but one of the 15 impact areas studied. That one standout category was generating hazardous waste that must be taken to a landfill. It’s because LED lights include a component called a heat sink, a ribbed aluminum segment that is attached to the underside of an LED diode. The aluminum heat sink absorbs and then dissipates heat that’s generated by the diode, preventing it from overheating. Aluminum requires processes to mine, refine and manufacture heat sinks that are energy-intensive and create several byproducts such as sulfuric acid that must be taken to a hazardous waste landfill.
But coming up from research and development are likely improved LED efficiencies, which in turn will reduce the amount of heat they produce and the size of heat sink they require. The research team found that this, and other improvements in manufacturing processes and electronics, should set LED bulbs to be even more environmentally friendly and cost efficient than CFLs in five years or so.
The team expects the LED bulb of 2017 will have 50% lower environmental impacts than today’s LED lamps and 70% lower impacts that those found in today’s CFLs, which are not expected to change significantly in the near future.
Drawing down the manufacturing costs is going to help get more LEDs and CFLs into use. With a 75% cut in operating cost and lighting using about 20% of the power generated the effect will be lower costs and quite welcome.
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I am quite shocked by this article. The toxic issues of mercury in CFLs is not discussed. Because of the mercury, my city requires that I separate the CFLs from my regular garbage, and turn it in as “hazardous waste”.
In addition, my experience of CFLs is that they have a vastly shorter lifespan than they are purported to have. This increases the manufacturing costs as well as the disposal costs.
I am really hoping that the coming LED solutions will be significantly better than CFLs have been.
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