Course:HIST106/YourStuff 4

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Life Cycle of a Light Bulb
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HIST 106
Section: 99C
Instructor: Eagle Glassheim
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Introduction

Like many household products, incandescent light bulbs are engineered to last a particular amount of time based on cost of materials and production among other considerations. Manufacturers have managed to maximize profits by using cheaper materials and methods, and giving the bulb a limited life span. This requires greater consumption and maintains production levels. However, there has been a recent push for increased energy efficiency in the light bulb market. In 2007 U.S. Congress even passed new light bulb standards which required 100W bulbs to have a 25% increase in efficiency by 2012.


Composition

A standard incandescent light bulb contains three main components: the filament, base, and bulb. Several different materials were originally tested for the incandescent filament including carbon and platinum, however the light bulb we know today uses a Tungsten filament. Tungsten is more fragile than some materials but is able to withstand higher temperatures, up to 2480 degrees Celsius [1]. The base is commonly made of aluminum, while the bulb is made of glass. This glass is made using the silica in industrial sand and gravel. Canada is a large producer of industrial sand and gravel, but does still import some from the United States, who are the world leader in producing this.

Production

There are many steps in processing and production before these raw materials get to your house in the form of light bulbs. The thin fragile Tungsten filament is coiled and then attached to the lead in wires, commonly nickel-iron. The base is usually made out of aluminum and is poured into screw-shaped molds. The bulbs themselves are made of glass and are most commonly produced using what is called a ribbon machine. The first ribbon machine design was created by Corning Glass Works in 1926, and is the basis for modern manufacturing. These were designed to replace the time consuming process of human glass blowing and allow for mass production. The ribbon machine uses moulds and air nozzles to replicate this glass blowing process, and can produce up to 50 000 bulbs per hour [2]. Each of these machines accounts for about 2 billion glass bulbs each year. This corresponds to a requirement of only 15 machines to supply the world’s demand for standard incandescent light bulbs.


Energy

A study was conducted, by the Technical University of Denmark, on how much energy is put into producing a light bulb, before you even screw it in. Light bulb energy consumption is commonly thought of as the electricity used when you turn on the switch, however, the energy during production must also be taken into consideration. This includes the extraction of raw materials, the processing of these, and the manufacturing of the light bulbs. The majority, by weight, of incandescent light bulbs is made up of glass and brass. A standard bulb has about 22g of glass and 9g of brass. In extracting and processing the raw materials for one of these bulbs about 0.11 kWh are used for the glass and 0.18 kWh for the brass. This equates to a total of about 0.29 kWh per bulb. Now, add an additional 0.11kWh to manufacture each bulb, and you end up with a total energy cost of 0.4 kWh per bulb [3].

Consumption

Material Culture

Lighting up our homes since the days of Thomas Edison, incandescent light bulbs have become a staple in modern life. They are cheap, easy to install, and very accessible. Unfortunately, incandescent bulbs are not energy-efficient. These bulbs waste most of the energy they consume. Compact fluorescent lights (CFLs), however, are more energy-efficient and have less of an impact on the environment. They are not as popular as incandescent bulbs because they cost about four times more.

Energy

According to the International Energy Agency (IEA) World Energy Outlook, lighting consumes about 19% of global power, and energy consumed for lighting is expected to increase by 60% over the next 25 years. In 2007, 22% of the total electricity demand was used for lighting in the U.S, with 27% of this demand used for homes [4].

Incandescent bulbs produce light by heating the filament inside the tube until it is extremely hot. About 90-95% of the energy output is used solely to produce heat, not for emitting light. Despite their inefficiency and contribution to energy emissions, most households are still highly dependent on incandescent bulbs. Natural Resources found in 2003 that of the 26.4 light bulbs consumed by the average Canadian household, 77% or 243 million bulbs, are incandescent [5]. A standard 100-watt incandescent light bulb lasts for 750 hours. It produces about 1700 lumens [6].

Chart-light-bulbs3.gif

Average Life of Incandescent Bulbs
Type Average Hours of Life
100-watt 750
65-watt 1000
25-watt 2500

As an alternative, compact fluorescents use small amounts of electricity to activate a gas in the tube. The gas produces an invisible ultraviolet light that reflects off of the white bulb to produce light. CFLs consume 75% less energy than incandescents and they last 10 times longer. See CBC News: Fluorescent vs. Incandescent. There are 12 million households in Canada, and according to Natural Resources Canada, if every household exchanged one incandescent bulb for a compact fluorescent bulb, we would save $73 million in the collective electricity bills. Greenhouse gas emissions would be reduced by 397,000 tonnes, the same as 66,000 less cars on the road [7].

Disposal

Mercury in Lightbulbs

The disposal of light bulbs is something that should be taken into careful consideration, considering the harmful effects to people as well as the environment that it could ensue if disposed in a careless manner. Household light bulbs, specifically compact fluorescents, contain about five milligrams of mercury, an element that is essential to a bulb’s ability to emit bright light. There has been no other element found that has proved to be as efficient. However, it is a highly toxic chemical that is dangerous to the brains of both fetuses and children [8].


Effects on People and Environment

Careful disposal of light bulbs is absolutely necessary mercury is a toxic chemical when it is exposed to air. When this happens, it can cause many harmful health effects, including nerve, brain, and kidney damage, severe allergic reactions, diarrhoea, and vomiting. In the most severe cases, damage to certain areas of the brain could lead to a dramatic decline of learning abilities, vision, muscle coordination, as well as memory.

Besides having detrimental effects to human health, mercury can contaminate water sources and make them highly acidic. If the mercury reaches surface waters or plant soils, microorganisms can convert the mercury concentration to methyl mercury, a notorious substance that causes nerve damage in a variety of life forms. Unfortunately, fish have already been affected by methyl mercury, as they continually absorb considerable amounts of methyl mercury into their systems. Not only does this mean that the fish we eat can contain toxins, but it also means that the entire food chain that fish are a part of could be negatively affected as well. If absorbed, mercury could cause kidney damage, upset stomachs, intestine damage, reproductive failure, as well as alterations to genetic compositions. [9]


Disposing Fluorescent and Incandescent Light bulbs

Many parts of the light bulb, such as the glass and metals, can be reused over again. Fluorescent light bulbs contain mercury, which should never be directly put into landfills. Containment of the bulb is essential for the protection of the environment [10]. One good way of preventing hazardous chemicals from escaping is to place the bulbs inside boxes (such as laundry soap boxes) and containers that are non-recyclable to prevent glass from scattering in case the bulb breaks when they are thrown into landfills, dumpsters, garbage cans, or incinerators. After, just locate a local recycling depot that will help you dispose it in a safe and professional manner. Some will dispose light bulbs free of charge, while for others, you may have to pay a minimal fee. If you need help finding a local waste collection agency, you can visit Earth 911.com. This website makes it easy for you to find recycling centers where you can drop off bulbs for safe disposal.

Incandescent light bulbs, on the other hand, do not contain mercury. To dispose the bulb, just wrap it up in some old newspaper, place the wrapped bulb in a plastic bag and tie it tightly. Now, just put the contained bulbs in your trash can and you're done [11].


Disposing Light Bulbs in case of Breakage

In dangerous cases where breakage does occur, mercury can escape as mercury vapour around your home, and will continue to spread until it has been cleaned up appropriately and removed from the premises. Make sure to ask all members of the household to leave the room where breakage has occurred. Let your pets out of the home to prevent exposing them to toxic chemicals. For the time being, it is receommended that you open the windows and doors to let fresh air circulate around the house for about ten minutes, and shut off the air-conditioning system to prevent the spread of the mercury vapour [12]. Clean up the broken shards of the light bulb with a broom and dustpan. Make sure all shards and any visible toxic powders from the mercury have all been cleaned up. Put all the debris into a trash container until they can be disposed of properly.