Design for the Environment/Street Lighting in Residential Region

Introduction and Motivation

Typical Residential Area Street Lamp.

Street light illumination is critical to everyday life. Pedestrians and drivers at night receive not only convenience but also safety from the brightness. In residential areas, the most densely populated place at night, people will normally have higher expectation of illumination. Therefore, stable performance under frequent usage is the minimum requirement. The client of this project is builder-developers.For this project, low Pressure Sodium (LPS) lamp, is selected as our baseline. Although it is the most electrically efficient lighting product, the short lifetime is a crucial problem. Therefore new lighting technologies have to be introduced, and two of the most popular choices are Light-Emitting Diodes (LED) and induction lamps.

In our in-depth analysis, Life Cycle Assessment (LCA) on LPS, LED and Induction Lamp will be conducted using Economic Input-Output LCA (EIOLCA), Streamlined LCA (SLCA), and economic analysis. In addition to the LCA, we will also analyze their functional, societal and environmental aspects.

Scope and Assumptions in the Life Cycle Assessment

Analysis is taken place in the Great Toronto Area (GTA), operated under 110V and used as street lights in residential areas.

We assume the timeframe is 100,000 hours (the lifetime of one Induction Lamp) and illuminating area is 5,000 meters square (1 km in length and 5 m in width).And the number of lamps used for LPS , LED and Induction Lamps are 116,64 and 9.5 respectively.

In addition, every light bulb is in its ideal situation, which will not break until the end of its lifetime. In Section 4 [Economic Input-Output LCA (EIOLCA)], we need to use eiolca database (www.eiolca.net), therefore we need to multiply the numbers of lamps by one million, which are 116 millions of LPS, 64 millions of LED and 9.5 millions of Induction-lighting lamps. Furthermore, we also assume the products are all manufactured and transported by truck from the United State, and the packaging is the same for all three products.

The entire assuptions are summarized in the following table.

	LPS	LED	Induction Lamp
Timeframe (hrs)	100,000	100,000	100,000
Lifespan (hrs)	18,000	50,000	100,000
Brightness (Lumens)	1570	1000	3400
Wattage (W)	18	13	40
Number of Lamps Needed within the Timeframe	116	64	9.5

Project Information

MIE315 section 02, Team B21
April 7, 2009

• Ka-Yeung Lee [Leekayeu]
• Yatu Shi [Shiyatu]
• Ping Kei Yan [Yanping]

Recommendation

After performing SLCA, EIOLCA and cost analysis for each of the light options, the modern Induction lamp is the way to promote green lighting. Reducing environmental impact and emissions are worthy goals which can make a difference in limiting environmental problem through reducing carbon dioxide emissions from electricity generation, decreasing waste and improving ease of recycling. Since street lighting consumes a significant amount of energy production, installing a lighting system that has greater energy savings is very essential.

Induction lamp is indeed the future of lighting. It is a way to implement environmentally friendly technology that reduces impact in areas such as conserving energy, reducing CO₂ emissions, reducing materials consumption, reducing mercury consumption, as well as streamlining recycling issues.

Fuctional Analysis

Baseline: Low Pressure Sodium Lamp

The usual configuration of an LPS lamp is a discharge tube enclosed by a vacuum glass tube. The inner pipe contains solid sodium and a small amount of noble gases (normally neon and argon) to have the gas discharge started. The lamp initially produces red light to warm up the sodium in about 15 minutes. After that, orange / yellow light will be emitted. Human eyes are most sensitive to yellow light. It can be seen as an effective illumination light source. This property can reduce energy waste in emitting other colors of light, thereby increasing the electrical efficiency. In addition to output light, this unique feature also limits its application in other fields. At the same time, the short lifetime, (a maximum of 18,000 hours), is still a crucial problem for LPS future development.

Alternative 1: Light Emitting Diode

The high power LED Street lamp analyzed in this report is based on the model EvoLux 13 WATT LED BULB manufactured by The Earthtech Products. It is a 13 Watt bulb with clusters of LEDs in ABS housing.

Traditional LEDs are very tiny and produce a little amount of light, so we use high power LED lamps, which consist of cluster of LED array in a housing case, for street lighting. Those lamps require transformer to step down the electricity and heat sinks to remove the heat generated which is destructive to the LEDs.

The advantages of using LED lamps are their long life and high efficiency. For example, the EvoLux 13W model has a product life 50,000 hours , which is about 10 year of lighting (assuming it operates 12 hours a day). This can significantly reduce the environmental impact from transportation and solid waste produced from replacing the lamps.

Unlike traditional street lamps, which emit yellow colored light, LED lamps can generate pure white light. White light is more pleasing to human eyes “and people can see and judge objects more accurately.

The downside of using LED for lighting is its higher cost per unit compared to other alternatives. For example, the price of the EvoLux is US$79.98. The high cost for LED lamps will discourage people from using them. Another disadvantage is that LED lamps require transformers to step down 110V electricity to its operating voltage (24V). There is power loss in the process and therefore the LED lamps may require more energy than its manufacturer’s claim.

Alternative 2: Induction Lamp

One of the modern solutions for lighting application is induction. Induction light is a system based on the compact fluorescent lamp. The composition of induction lamps is same as compact fluorescent lamps. In contrast with CFLs, where an electrode transfers power to the lamp, an induction lamp eliminates the electrode. Instead, there is an inductor inside the bulb connected to the ballast. The power is transmitted by means of electro-magnetic fields.

There are 3 major advantages of electrode less induction lamp:

1. Less mercury per lamp than most commercial lamps;
2. The solid amalgam mercury used is less volatile than the liquid mercury found in most lamps;
3. Long 100,000 hour lamp life compared with other commercial lamps.

The life span is greatly extended as the electrode, the limiting factor of most lamps, is eliminated. The mercury found in every other light product is highly volatile liquid, while mercury in induction lamps is stable solid amalgam. During any onsite cleanup of broken lamps or disposal, a solid form is easier and safer to handle. Moreover, induction lamps uses less mercury compared to other commercial lamps

Economic Input-Output Life Cycle Analysis

From the SLCA in previous section and the graphs below, Induction Lighting has the least environmental impact during the pre-manufacturing and manufacturing stages. The manufacturing process emits the least air pollutants, greenhouse gases and toxic substances. It also uses the least amount of energy. The high level of environmental impact caused by LPS is due to its shot life span. In our timeframe, the fact that amount of LPS lamps needed is almost twice the amount of LED lamps and a magnitude of order higher than the amount of induction lamps needed results in vastly compounded energy consumption and environmental impact. On the other hand, LED lamp is slightly worse then Induction Lighting lamp and far better then LPS lamp in terms of energy usage.

Although LPS has the smallest air pollutants per unit lamp, the short lifespan results in more lamps are requried within the lifeframe (100,000 hours), which is about 12 times more than Induction lamp and 2 times more than LED.

From the graph above, induction lamps contribute least GWP (global warming potential) to the environment.

LPS is said to be the most elecrically efficient previously. But considering the entire life cycle of these three products, we find that much more energy is consumed by LPS, and it is mainly from the prodution of the product.

LED and Induction lamps both contain a small amount of mercury, but this toxic substance is not easily released, therefore it does not have a large effect to the environment. By analyzing the whole cycle, LPS has the largest reponsibility for this issue due to its large amount solid residues in the end of life.

From the results of EIOLCA, Induction Lighting lamp would be the best option available in street lighting, LED lamps closely follow behind and LPS lamps are the least attractive alternative.

Streamlined LCA

Assumptions:

1. The delivery stages of all three alternatives are the same process. Only energy is used and gaseous residues are released.
2. The lamps only consume electricity in the use stage. Thus only the energy use environmental stage is concerned.
3. The lamps contain no liquid and therefore no liquid residues in disposal.

It is clear that the SLCA rating shows that Induction lamp is the most environmental friendly street lighting option. This is mainly because it exerts less environmental impact during the disposal stage, due to the long life span and the advanced design of the lamp. On average, induction lamp lasts 100,000 hours. Within the 5000m^2 area, 9.5 lamps are used which is much less than 63 lamps and 117 lamps usage for LED and LPS respectively further minimizing energy consumption, disposal emissions and harm to the environment. Moreover, the lamp is designed to increase the ease of disassembly and hence the ability of recycling. Another important issue brought by induction lamp will be the mercury inside the lamp. Since the mercury is in solid form rather than volatile liquid, the disposal of mercury becomes much simpler.

Although Induction lamp has the highest rating, it is obviously not perfect. If we look at the production phase, the scoring is low since there are large amounts of toxic materials such as lead used in the process of making the ballast, and intensive energy input during phosphor coating production. The problem is compensated by the long life span and the small number of lamp use.

All of the above is in comparison with LPS, with a short life span of 18,000 hours. Although the wattage is just 13 W, because of the fact that it uses 117 lamps within the time frame and control volume it to be the most energy inefficient alternative. Also the pre-manufacturing earns significantly lower scores because of the glass production and mining and extracting of virgin metals. Although Induction Lamp also experience the same problem in pre-manufacturing, but the impact is greatly lowered by the small amount of lamps. For same reason, the impact of LPS in disposal phase is significant due to the short life span.

Light emitting diode is the intermediate option between the two. The most significant impact is during the production stage where large amount of toxic materials are used in the process of manufacturing semiconductors. From the SLCA matrix, we can see that the score of each category fall between induction lamp and LPS since the life span and number of lamp usage falls between the two.

Comparison with result from EIOLCA

For the pre-production stage, the scores of the alternatives match with the result from EIOLCA. The same result which induction Lighting is better then LED while LED is better then LPS. However, when we focus on the production stage, LPS surprisingly scores higher then both LED and Induction Lighting. It is because materials used in LPS production is not toxic relative to those used in LED and Induction Lighting. Therefore it has the highest score for Material Choice. Production of LEDs releases liquid residues from semiconductor cleaning while manufacturing of LPS has little or negligible liquid residues. Thus it scores a higher mark. LPS is the worst in EIOLCA because of its highest demand in our timeframe. If we take that into account, the rating in SLCA may match the result from EIOLCA. However in the production stage of the SLCA, we cannot consider that effect together with all other factors easily. The overall rating matches the result from EIOLCA. Induction Lighting Lamps remain the best alternative while LPS is the worst.

Cost Analysis

The total cost is composed of direct operating cost, selling price, disposal cost and indirect cost.
Direct operation cost is analysis for both summer and winter time. For indirect cost, it is assumed to be the cost of illness due to CO2 emission. The total cost for LPS, LED and Induction lamp are as follow. It turns put that induction lighting is the most economical.

The option with lowest cost is always the most desired one. The total direct cost incorporate the operation cost in both summer and winter and the unit cost. Indirect cost is mainly the cost of illness cause by air pollutant generated indirectly from street lighting.

From the results of the cost analysis, induction lamp has the lowest total cost, which is $11901.89 US, while operation cost is the highest. From our calculations, total operating cost for induction lamp is $1194.3; for LEDs and LPS the costs are $388.11 and $563.61 respectively because of the fact that each induction lamps consume 40W of power. But again, it is compensated by its long life span. The total cost of induction lamp relative to the 100000 hours time frame and 5000m^2 is much lower then the other two as only 9.5 lamps are needed. Induction lamps save cost in dealing with medication related to respiratory illness. The main reason of that is the significant small number of lamp used relative to the other two alternatives. Obviously, Induction lamp is a preferable option.

Street lighting is an essential need. Costing is also a very important issue for managing a city. For a long-term approach, Induction Lamps outperforms the other two lighting options in both direct cost and indirect cost. This alternative is most suited for future street lighting projects.

Societial Analysis

Low Pressure Sodium Lamp

LPS has had one hundred years development, and their functions are familiar to users. Changing the broken light bulbs is one of the most frequent maintenances in our normal life. Although this drawback is generally accepted, the large amount of residues creates immense trouble to society and the environment. This kind of glass product is everywhere in the landfills, because it is hard to natural decompose and expensive for recycling processes.

Induction Lamps

The major environmental concern of induction lamp is the mercury contained inside the lamp. But compared to other mercury containing commercial lamps, the mercury in induction lamp is in solid amalgam form rather than in form of volatile liquid.

The mercury amount is just 3.8 mg for a 40W lamp. Moreover the use of solid form mercury greatly reduces emission and improved the ease of recycling. As induction lamp significantly promotes energy saving with a longer lifespan and higher lumens then LPS lamps and LEDs, the mercury emission problem should be a negligible concern by society.