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7. Conclusions and Recommendations

The results for the study provide a robust estimate of the scale and significance of alternate product stewardship mechanisms for the environmental profiles of the following mercury-containing lamp products:

  • Fluorescent:
    1. Linear fluorescent lamp (LFL);
    2. Compact fluorescent lamp: external ballast (CFLe); and
    3. Compact fluorescent lamp: integral ballast (CFLi).
  • High Intensity Discharge (HID):
    1. High pressure sodium (HPS);
    2. Metal Halide (MH); and
    3. Mercury Vapour (MV). 

The lamps listed above represent the mainstream types used in New Zealand for residential, commercial and industrial applications and have been assessed for an operational period of 100,000 hours.  It should be noted that results cannot be compared across lamp types, as they are not functionally equivalent, due to differences in lamp output and application. 

The primary focus of the study has been to assess the whole-life environmental impacts from the use of mercury-containing lamps, and the trade-offs that arise from potential product stewardship options for end-of-life management (by increasing recovery and recycling rates) and for lamp design (by reducing the lamps mercury content).  Through interpretation and sensitivity analysis, implications in relation to mercury content, lamp lifetime and in use efficiency improvements have also been investigated.

The results show the environmental implications for increased recovery and recycling, for the following scenarios:

  • Baseline: 9% recovery and recycling;
  • Scenario 1: 50% recovery and recycling of end-of-life lamps;
  • Scenario 2: 80% recovery and recycling of end-of-life lamps; and
  • Scenario 3: 100% disposal (to landfill) of end-of-life lamps.

Additional sensitivity analyses, have also considered the potential impact of lamp warm-up power, closed-loop recycling, inclusion of fixture and fitting and packaging.

7.1 Whole Life Conclusions

When considering the whole-life environmental impacts, the results indicate that the use phase dominates the impacts across all impact categories, accounting for more than 90% of the total life cycle.  The manufacturing phase represents around 5% of total impacts and the disposal phase represents around 1% of total impacts across the total life cycle. 

The results demonstrate that an environmental benefit is achieved from increasing the recovery and recycling rates for mercury-containing lamps.  However, in the context of the whole life cycle, the environmental benefits are small. 

Table 16   Life Cycle Impact Results – Whole Life – (100,000 hours operation)

 

Unit 1. Linear fluorescent lamp (LFL)
35W, T8
2. Compact fluorescent lamp (CFL)
11W: external ballast
3. Compact fluorescent lamp (CFL)
20W: integral ballast
4. High pressure sodium (HPS)
150W
5. Metal Halide (MH)
400W
6. Mercury Vapour (MV)
250W
Abiotic depletion kg Sb eq 6.73 2.14 4.03 27.58 73.39 45.90
Acidification kg SO2 eq 3.41 1.14 2.21 13.04 34.51 21.64
Eutrophication kg PO4 eq 0.25 0.08 0.15 0.98 2.59 1.62
Global warming kg CO2 eq 874 278 517 3,553 9,450 5,912
Ozone layer depletion kg CFC-11 eq 0.00 0.00 0.00 0.00 0.00 0.00
Human toxicity kg 1,4-DB eq 88 29 69 349 904 561
Fresh water aquatic ecotoxicity kg 1,4-DB eq 6.82 3.05 7.53 16.42 41.23 26.23
Marine aquatic ecotoxicity kg 1,4-DB eq 18,332 6,924 15,821 51,675 132,550 83,883
Terrestrial ecotoxicity kg 1,4-DB eq 0.76 0.35 0.62 3.40 6.89 4.92
Photochemical oxidation kg C2H4 0.28 0.09 0.19 1.11 2.96 1.85

Note: a negative number represents an environmental benefit.

7.1.1 Mercury Contribution

In terms of mercury contribution to human toxicity impacts, the results indicate that mercury contributes a low level of total impacts.  Primarily, the contributions to human toxicity arise from generation of electricity in the use phase, resulting from combustion of gas and coal which release PAH and NMVOC to air.  The use phase contributes around 85% to 95% of the total life cycle impact.  This is the same across all lamp types, with the slight exception for the integrated CFL where the use phase contributes around 65% of whole life impact, due to the increased manufacturing burden associated with additional electronics.

Increasing the level of recovery and recycling of lamps reduces the levels of mercury released to the environment.  A reduction in the human toxicity impact, in the order of 1.5% is observed when increasing from 9% to 80% recycling and recovery. 

7.1.2 Lamp Performance

When considering other lamp performance parameters, such as lamp lifetime and energy efficiency, then significant environmental benefit can be achieved by longer lifetimes and higher efficiencies.  An increase in lamp lifetime reduces production burdens and waste management and results in significant benefits.  Similarly, reduction in energy consumption higher lamp efficiency reduces the use phase burdens significantly. 

7.2 End-of-Life Conclusions

When considering the end-of-life phase only, the results indicate that increasing recovery and recycling levels of lamps from 9%, in the baseline, up to 80%, then the environmental benefits for the end-of-life phase increase significantly.  The benefits arise primarily from the benefit associated with avoiding the production of new materials that would have otherwise taken place if the lamps were not recycled in other materials.  Recycling of metals and glass offer the most significant benefits, primarily due to the proportionally larger mass of the lamp.  Table 17 shows the results for a CFLi lamp with varying recycling and recovery rates. 

Table 17  Life Cycle Impact Results – End-of-Life Only – Compact fluorescent lamps (CFLi) 20W: integral ballast (100,000 hours operation)

 

Unit Baseline: 9% recovery and recycling Scenario 1: 50% recovery and recycling Scenario 2: 80% recovery and recycling Scenario 3: 100% landfill
Abiotic depletion kg Sb eq 0.000 -0.001 -0.001 0.000
Acidification kg SO2 eq -0.001 -0.005 -0.005 -0.002
Eutrophication kg PO4 eq 0.000 0.000 0.000 0.000
Global warming kg CO2 eq -0.009 -0.051 -0.075 -0.029
Ozone layer depletion kg CFC-11 eq 0.000 0.000 0.000 0.000
Human toxicity kg 1,4-DB eq -0.143 -0.106 -0.111 -1.132
Fresh water aquatic ecotoxicity kg 1,4-DB eq -0.005 -0.071 -0.076 -0.007
Marine aquatic ecotoxicity kg 1,4-DB eq -12.89 -80.69 -86.97 -48.49
Terrestrial ecotoxicity kg 1,4-DB eq 0.147 0.061 0.122 0.933
Photochemical oxidation kg C2H4 0.000 0.000 0.000 0.000

Note: a negative number represents an environmental benefit.

The benefits from closed-loop recycling are negligible as the only real differences arise due to the additional oceanic transport, for closed-loop recycling, back to the original place of manufacture.  The benefits associated with avoided virgin materials are almost equal for both open-loop and closed-loop recycling. 

7.2.1 Mercury Contribution

In terms of mercury contribution to human toxicity impacts, the results indicate that mercury release from landfill contributes a significant proportion of the end-of-life impacts (ranging from around 25% to 90%).  Increasing the levels of recycling considerably reduces the impacts from mercury at end-of-life. 

For end-of-life product stewardship options, overall, it can be concluded from the results that increasing the levels of recovery and recycling of mercury-containing lamps will provide significant benefits to the environment. 

7.2.2 Lamp Performance

When considering other lamp performance parameters, such as lamp lifetime and mercury level in the lamps design, then significant environmental benefit can be achieved by longer lifetimes and reduced mercury-content for end-of-life.  An increase in lamp lifetime reduces burdens of waste management and results in significant benefits.    Similarly, a reduction in mercury level reduces the human toxicity impacts associated with emission of mercury from landfill disposal. 

7.3 Recommendations

The recommendations section outlines the areas where improvements could be made to the life cycle assessment study that has been conducted.  For this study, the following improvements in relation to data could be made:

  • Further clarification of potential future improvements that will increase lamp lifetime and the associated design changes.  Currently, the study makes a theoretical assumption of ± 50% of total lifetime. 
  • Further clarification of potential future improvements for improved energy efficiency of the lamps and the associated design changes.  Currently, the study makes a theoretical assumption of ± 10% improved efficiency.
  • Improved life cycle inventory data for the production of raw materials.  The study uses modified datasets (electricity and transport) to represent geographic locations of manufacture.  Country specific datasets would improve the results. 
  • Further confirmation that recovered materials from the recycling process deliver the associated benefits of avoiding the virgin material production.

Whilst this would improve the robustness of the study, the additional data are unlikely to change the results in a material way.