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Bryce Du EE 306 Sustainability Analysis

Light Emitting Diodes Sustainability Analysis

In laboratory experiment 4, we tested and observed the characteristics of diodes and diode circuits. One specific type of diode that this sustainability project will focus on is the ‘Light Emitting Diode’ or L.E.D. for short. An LED is a diode that emits light (at specific wavelengths/colors) as long as there is sufficient voltage. The LED has many benefits as a light source ranging from better efficiency to cheaper operation costs. LEDs should be used worldwide as the primary source for lighting not only to improve the current situation of our planet but to also improve the future for our upcoming generations. We will examine the LED’s energy, environment, economic, and equity properties and compare them to the current lightning sources (fluorescent and incandescent bulbs) to prove that LEDs will reduce our ecological footprint.

Environment

I must state, first and foremost, that almost all of today’s electrical equipment is detrimental to our environment. Silicon is the main substance in electrical equipments including Diodes, and silicon is non-biodegradable. So why do we continue to use silicon as the primary ingredient to electrical components, it is due to its abundance in the earth’s crust; more than 25% in mass. The goal for sustainability is “to meet the needs of the present without compromising the ability of future generations to meet their own needs” which is why we will compare LED lighting to its opponents; which is more sustainable? The two primary choices for lighting are fluorescent and LED bulbs but what are their key differences? The key difference between LEDs and fluorescents is the key substance in their manufacturing: silicon for LEDs and mercury for fluorescents. When silicon is combined with doping agents to improve conductivity (doping), silicon is toxic to humans, but in its normal state (Si) it is not toxic to humans. However, the production of silicon is different. When producing silicon the excess result is CO2 (carbon dioxide – good) and CO (carbon monoxide – very bad), these excess escapes into the atmosphere causing negative effects such as global warming and destruction of the O-zone layer. On the other hand, fluorescents contain mercury which if ingested can never be broken down causing vital organ damage (including cancer) [2]. Fluorescent bulbs approximately contain 12 mg of Hg which is released in vapor form when the bulb is broken. When these bulbs are broken, the mercury is released into the surrounding air and soil. Within a one year period (2002 - 2003) almost 2544 metric TONS of mercury was released into the surrounding air and soil. [2] Both fluorescents and LEDs have harmful environmental effects so which is the optimum choice? Again, LEDs! The Life Span is the key factor (more detail in Energy). It will require 6 fluorescent bulbs to equal a single lifespan of a LED bulb, meaning 72 mg of Hg into the air compared to the silicon in one LED bulb [2]. Continuing our analysis, can these used materials be re-used? Recycling is a great tool to improve sustainability. The silicon within a used semi-conductor is 98% – 99% pure [3]. However, recycling mercury from fluorescent bulbs is a challenge, if the bulb is to break the mercury would release in a non-recyclable state. Between the years of 2002 – 2003 only 23% of the 670 million fluorescents bulbs were recycled [3]. In a comparison, LEDs ability to be recycled cannot be overlooked. LED’s decrease in waste, abundance in material, and ability to be recycled sets it as the most environmentally sustainable lighting choice.

Energy

When examining the properties of an electrical circuit we will begin with its energy efficiency. LEDs are currently the most efficient lighting tool. The power required to activate a LED is 6 watts; averaging 10 times LESS than that of the original incandescent bulbs (60w – 120w bulbs) [1]. In addition to being 10 times more inefficient, incandescent bulbs emit heat which is dissipated power or power lost. LEDs, on the other hand, emit little if no heat, require no maintenance, and not as physically vulnerable as its lighting predecessors (i.e. incandescent and fluorescent bulbs). Currently, LEDs are clearly the best choice in terms of energy use. LEDs have their advantages but what about their disadvantages? The negative side to LEDs is the production cost. LEDs require more energy (and material) to make compared to the incandescent or fluorescent bulbs. The primary material in LEDs is Silicon which requires a chemical reaction to synthesize. The retail price will reflect the amount of energy and materials required to create a bulb. The cost (energy and materials) for a LED averages $16 per bulb which is noticeably more than the incandescent ($1.25/bulb) or the fluorescent ($2.98/bulb) bulbs [1] so an LED bulb will require more energy to create. Although the LED requires more energy to make, there’s another factor to consider: Life Span of the bulbs. The lifespan of the incandescent (1 200 hours) or fluorescent (10 000 hours) bulbs fall far in comparison to its competitor. The average life span of a LED is 60 000 hours. With lower power consumption, lower maintenance, and increased life span, LEDs are the best choice for lighting when regarding efficiency and sustainability.

Economics

Whether you are a corporate business owner or a family house-hold, switching to diode lighting will reduce operation costs. We went over the efficiencies of the three types of bulbs (LED, fluorescent, incandescent) and came to the conclusion that LED lighting is superior but how can that relate to the economics? Let’s look at a cost analysis between a LED and fluorescent bulbs over a 60 000 hour period. 1.	LED bulbs a.	60 000 hr life span i.	Require 1 bulb (~ $16/bulb) b.	6 Watt bulb c.	360 KWh used over 60 000 hr period (~ $0.20/KWh) d.	Cost over 60 000 hours = ~$87.98 2.	Fluorescent bulb a.	10 000 hr life span i.	Require 6 bulbs (~ $3/bulb) b.	14 Watt bulb c.	840 KWh used over 60 000 hr period (~ $0.20/KWh) d.	Cost over 60 000 hours = ~$185.88 [1] Looking at the cost analysis, by switching one fluorescent bulb to LED one would save almost $100, only purchase one bulb, and significantly reduce the amount of power used. This per-bulb analysis not only affects specific people but the country as a whole. Business owners are reluctant to make the switch because of the expensive initial investment due to high bulb prices. Regardless of the initial investment, the economic benefits affect the entire country. By reducing the business’s operating cost the business can 1) profit more or 2) increase employee salaries. By reducing the power used, power companies can either reallocate unused energy or require less energy to provide to its customers which in turn can also reduce power plant waste. And lastly, the United States is the second largest producer of silicon in the world. In 1996, US produced more than 400 000 tons of silicon, only second to China’s 720 000 tons. [4] Converting to LED lighting would increase LED and silicon production creating more jobs and improving the economy.

Equity

As we progress through the years we will notice a substantial increase in silicon produced. This is the key challenge that Environmental engineers must overcome because we are mining and using more silicon then the earth is re-creating or humans are recycling. Although the silicon in a used semi-conductor is still 98-99% pure, extracting the silicon from the used semi-conductor is difficult [3]. If it is cheaper to dump the used semi-conductors in an undeveloped country then recycle then 100% of businesses will choose the best for business. Between the years of 1992 – 1996, the amount of silicon recycled is negligible to the amount produced [4]. This is the limiting factor for silicon sustainability. LED lighting will improve Silicon equity. Unlike ‘modern’ devices today that have a lifespan of one year (if even), these LED bulbs have a lifespan of almost 6.5 years requiring less silicon per year. Although this is an improvement, this will only ‘buy’ us some time to figure out a solution for our current sustainability crisis.

References: [1] LED Lighting Products, "Information on LED Lighting Products & Energy Saving Calculator/Comparison Chart", LED Starlight Inc. [Online]. Available: http://www.ledstarlight.com/led-comparison-chart.php , [Viewed: 18 Nov 2009].

[2] Impact of Pollution Prevention, "Light Bulb Facts", Iowa Waste Reduction Center, September 2006 [Online]. Available: http://www.iwrc.org/downloads/pdf/LightBulbFacts.pdf , [Viewed: 18 Nov 2009].

[3] Recycling Market Development Zone, " RMDZ Business Success Story: ersol Silicon", California Integrated Waste Management Board, March 2009 [Online]. Available: http://www.ciwmb.ca.gov/RMDZ/BizProfiles/SiliconRec.htm , [Viewed: 18 Nov 2009]. [4] Mineral Commodity Summaries, "Silicon", US Geological Survey, February 1997 [Online]. Available: http://minerals.usgs.gov/minerals/pubs/commodity/silicon/760397.pdf , [Viewed: 18 Nov 2009].