Life cycle inventory analysis

In the life cycle inventory analysis, the material and energy relationships between the lighting system being studied and the environment are recorded, i.e. the input flows from the environment and the output flows that are returned to the environment are noted. The goal is to establish a data inventory based upon functional equivalents for the selected variants. Since quantitative data for disposal are not available, calculations can only be made for manufacturing, inclusive of raw materials procurement, and the use phase.

The total absolute material and primary energy amounts needed for the manufacture of the quantity of lamps required to generate the set reference light quantity (RLQ) of 6.579 million lumen hours are listed in the table below. The total material flows for the five lighting variants can be found in Table 57 in the appendix.

Table 37. Material and energy requirements for the production of the lamps for the RLQ92

RLQ = 6.579

Variant 1

Variant 2a

Variant 2b

Variant 3a

Variant 3b

Mlmh

incandes-

Dulux EL

Dulux EL

White LED

White LED

cent lamp

15

Longlife

of today

of tomorrow

Material re-

669.4 g

453.3 g

253.8 g

2671.5 g

735.9 g

quirements

Product quan-

313.7 g

177.1 g

99,2 g

8.5 g*

2.3 g*

tity, total

Primary en-

14.7 MJ

32.6 MJ

18.3 MJ

5.9 MJ

1.6 MJ

ergy require-

ment

* Here only the LED chip is being referenced, not the complete LED light source.

* Here only the LED chip is being referenced, not the complete LED light source.

In looking at the material quantities for the first three variants, consideration must be given to the packaging. The ratio of materials required to product quantity is 2.1-2.6:1. The large material quantities for LED chip production in proportion to product quantity reflect the fact that semiconductor technologies require considerable volumes of raw materials such as ore and stone and auxiliary materials in order to produce a small, highly complex quantity of product. The ratio is 314:1. Moreover, an assessment of a complete LED lighting system must also consider materials for the housing, ballast resistor, packaging, etc.

The situation is different for the primary energy requirement. The primary energy requirement for LED chip production is lower than that for conventional light sources. The difference must again be put into perspective, as the missing system components in the LED lighting system must be included. Production of the circuit board for the ballast for the Dulux EL15 energy-saving lamp alone consumes 17.3 MJ of the indicated 32.6 MJ/BLM. It can therefore be assumed that the primary energy requirement of an LED lighting system is comparable to that of conventional lighting sources.

Table 38. Energy requirements for the use phase for generation of the RLQ93

RLQ = 6.579

Variant 1

Variant 2a

Variant 2b

Variant 3 a

Variant 3b

Mlmh

incandes

Dulux EL

Dulux EL

white LED

white LED of

cent lamp

15

Longlife

of today

tomorrow

Primary en

6.271 MJ

1.36S MJ

1.243 MJ

4.161 MJ

1.152 MJ

ergy require

ment

If energy consumption in the use phase is compared to that of the production phase, it becomes obvious that, depending on the variant, 97-99% of the energy is consumed during the use phase, with the result that the deviation caused by the incomplete consideration of the LED lighting system can be viewed as minimal. The central measure for the environmental assessment of light sources being used for illumination is energy consumption during the use phase and the associated emissions. Energy consumption for raw materials procurement und manufacture of the light sources is minimal. Moreover it becomes very clear that the current white LED is at a disadvantage by a factor of 3 as compared to the energy-saving lamp. Only, if the future scenario for the white LED comes to pass, i.e. a luminous efficiency above roughly 65 lm/W is achieved, will energy consumption become comparable to energy-saving lamps.

This fact is also generally confirmed by the calculated emissions, which accumulate as relative quantities. Here again, emissions resulting from power consumption during the use phase dominate. These emission quantities are shown in brief in the table below and in detail in Table 58 in the appendix.

1000 900 800 700 600 500 400 300 200 100 0

□ Carbon dioxide [kg] 0 Methane [g] ■ Sulfur dioxide [g] H Nitric oxide [g]

□ Carbon dioxide [kg] 0 Methane [g] ■ Sulfur dioxide [g] H Nitric oxide [g]

EL Longlife LED of today LED of tomorrow

Fig. 47. Selected emission quantities of the case-study variants relative to the RLQ94

EL Longlife LED of today LED of tomorrow

Fig. 47. Selected emission quantities of the case-study variants relative to the RLQ94

The total emission quantities expressed in the bar chart also make clear that the white LED of today is better than the conventional incandescent, but at a disadvantage by a factor of three when compared to the energy-saving lamp. Only if the future scenario for the white LED is realized, will the emissions become comparable to those of energy-saving lamps.

With respect to critical substances used in the light sources, mercury (found in the energy-saving lamp) and arsenic (used in the manufacturing process for the white LED), in particular, must be considered. Technological improvements in recent years have made it possible to significantly reduce the proportion of mercury contained in fluorescent tubes. The energy-saving lamp Dulux EL by OSRAM contained as much as 10 mg of mercury in 1994; currently the compact fluorescent by OSRAM contains roughly 4 mg of mercury; this represents its emission potential, in the case of release caused by improper disposal. If lamps break at the waste disposal site, mercury can escape directly into the environment. Mercury and numerous mercury compounds are volatile and highly poisonous, which is one of the main reasons for disposing of these lamps as hazardous waste or recycling them. Furthermore, mercury emissions in the production phase and the use phase must be considered in the overall assessment, as emissions also take place, for example, during power generation.

Table 39. (Potential) mercury emissions of the case-study variants95

RLQ = 6.579 Variant 1 Variant 2a Variant 2b Variant 3a Mlmh incandes- Dulux EL Dulux EL white LED

cent lamp 15 Longlife of today

Variant 3b white LED of tomorrow

Hg emissions in raw materials procurement / manufacturing (mg)

Hg emissions in use phase (mg) Hg quantity contained in product and potential release risk (mg) Total (mg)

0.004

6.65

0.26

6.65

11.71

0.15

1.45

10.00

1.32

2.24

3.70

0.03

4.44

0.01

4.41

1.22

1.23

The (potential) mercury emissions mostly arise during the use phase. Only in energy-saving lamps are considerable emission quantities added by the mercury contained in the product itself. Here it is clear that current energy-saving lamps with respect to total quantity still are better than current white LEDs. Only in the white LED of tomorrow scenario would a significant avoidance of mercury emissions be possible.

No quantitative data for arsenic and its compounds was available for evaluation. The most common materials for the production of LED chips are aluminum indium gallium phosphide and aluminum gallium arsenide (AllnGaP and AlGaAs) for red and yellow LEDs, and indium gallium nitride (InGaN and GaN) for green and blue diodes (FGL 2003 and others). Since the production of white LEDs requires either blue, green, and red diodes or else blue-emitting diodes, these substances might also be present in white LEDs. Gallium arsenide, like gallium nitride and gallium phosphide, belongs to the semiconductor groups III/V. With respect to handling and disposal, arsenic and its compounds are of the greatest significance. The toxicity of arsenic and its compounds varies greatly, but the substances used in the semiconductor industry tend to represent a certain hazard potential. The carcinogenicity, mutagenicity, and reproductive toxicity of many arsenic compounds is indisputable (BLU 2002).

As a semiconductor material, gallium arsenide is not poisonous. But in the presence of oxygen and water, an ultra-thin, very toxic layer may form on the surface of the material, which could cause environmental damage at a conventional landfill disposal site. Furthermore, an extremely poisonous gas is produced in the manufacture of gallium arsenide: arsine (arsenic hydrogen), chemical formula AsH3, which is used to guarantee the purity of the semiconductor material. Even minimal concentrations of a few arsine molecules per million gas particles in the air can cause severe health damage or be even lethal. The arsenic-hydrogen bond is highly toxic. It blocks nerve receptors and can impede the transport of oxygen in the body.

Therefore, light-emitting diodes also require special disposal treatment and supervision due to the possibility that they may contain arsenic, gallium, and phosphor compounds. According to the European directives, listed products must be accepted in return by the manufacturers and properly disposed of. A recycling procedure for LEDs does not yet exist (Grez-cmiel 2001). Researchers at the University of Marburg found an alternative to arsine years ago. The alternative substance is less volatile and has a much lower vapor pressure. It is considerably less harmful for the environment than arsine. The substance is of interest for semiconductor industry, because the much lower hazard risk reduces the costs of a semiconductor production facility. Waste quantities are also much lower (Thimm 1999).

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