Life cycle assessment of a hot-pressing machine to manufacture particleboards: hotspots, environmental indicators, and solutions

Abstract

Purpose

Green manufacturing (GM) is the environmental benign manufacturing of products with a minimal negative impact on the natural environment. Research studies on GM have increased in the last years with attention to the application of life cycle assessment (LCA). However, the manufacturing industry still faces some barriers and challenges that hinder a proper practical integration of GM using LCA. Accordingly, this paper performs an LCA-based GM case study of a wood-based industry that produces particleboards to investigate environmental hotspots and suggests GM indicators and solutions for a hot-pressing machine tool.

Methods

A case study of a wood-based industry that produces particleboards in Brazil was designed. A LCA-based GM framework was developed and applied according to its three phases: pre-assessment, environmental assessment and monitoring, and post-assessment. Each phase is composed of specific stages and each stage has its own activities and goals. To quantify the environmental life cycle impacts, the ILCD midpoint method with 13 impact categories was selected. Based on these environmental impacts, a set of indicators and solutions was designed to improve the product life cycle impacts through a greener manufacturing process of particleboards. A cradle-to-grave approach was used to model the particleboard life cycle and the manufacturing phase was modeled based on the unit process life cycle inventory (UPLCI) methodology.

Results and discussion

The particleboard manufacture was designed into five unit processes and results of the pre-assessment showed that the hot-pressing unit was the most relevant process because of its direct and indirect impacts mainly to human toxicity cancer effects, global warming, and photochemical ozone formation. During the environmental assessment and monitoring phase, the hot-pressing machine was then investigated based on the main contributors to the caused environmental impacts, i.e., electricity consumption and air emissions of free formaldehyde, as well as in terms of its most relevant process parameters: pressure (P) and temperature (T). Opportunities to reduce up to 21% upstream impacts and up to 41% downstream impacts were identified from making simple changes to the hot-pressing parameters. Further investigation in the post-assessment revealed that environmental impacts can be estimated based on the applied P and T values and GM indicators were suggested.

Conclusions

The proposed GM framework can be used in other case studies to integrate GM + LCA in practice. Results of the case study application showed that the hot-pressing machine was a hotspot into the cradle-to-grave life cycle impacts of particleboards and the proposed GM indicators can be used to predict life cycle impacts at manufacturing level.

APPENDIX I – Case study questionnaire

1.1 Part 1: Identification of the visited company

Date:_______________________

Company:__________________________________State:_______City:__________________________

Address:_____________________________________________________________________________

People for contact/interviewees:___________________________________________________________

Produced products:_____________________________________________________________________

Annual production of products:___________________________

1.2 Part 2: List of general questions for the selected company and product of interest

1. Have any previous LCA studies been done by/for the company? If yes, request a copy of it.

2. Provide a Process Flow Diagram of the manufacture processes for the product of interest.

3. What are the main technologies applied in the production process based on the Process Flow Diagram in Question 2? Describe machines and industrial equipment details, recycling/recovery processes, etc.

4. Product specification

a) Technical description of the selected product and its main function. Product’s Tree Diagram and/or Bill of Materials can be used in this process as well as a product’s user manual or its instructions for use.

b) List product’s quality requirements for the product of interest, i.e., make a list of its main physical, mechanical, and chemical properties.

5. Based on the product’s function, define a Functional Unit (UF) and a Reference Flow (RF) according to the LCA standards ISO 14040 and 14044.

6. How do the distribution, use, and end-of-life of the selected product occur after manufacture?

a) Distribution: Describe logistical aspects from the manufacture gate to the consumer gate (type of vehicles, distances, type of fuel, vehicles specification, etc.). Use the template model below:

Description of inputs for transportation	Transport system details (vehicle, payload, fuel):
	Distance (km)	Cargo (ton)	Return empty? (yes/no)

b) Use: What is the product’s useful life? Which are the main maintenance activities during the product’s use phase? Make a list of relevant environmental aspects at the product’s use phase.

c) End-of-life: Which strategies of end-of-life are applied to the product of interest? What is the predominant strategy? Make a list of relevant environmental aspects at the product’s post-use phase.

1.3 Part 3: List of questions about the main inputs and raw materials

7. Which inputs and raw materials are consumed during the product manufacture?

a) Provide an organized list with values of each flow adjusted for the reference flow defined in Part 2.

b) Provide additional information about average values of the inputs and raw materials’ main properties (chemical, physical, and mechanical properties), if necessary.

c) Describe how inputs and raw materials are transported to the factory. Use the same template from Question 6a.

8. What is the energy demand for the manufacture process defined in Question 2, as well as for the factory facilities? Which types of energy are consumed (e.g., biomass, oil, gas) and how are they internally managed by the company?

9. Which are the main emissions and waste generated during the product manufacture?

a) Provide an organized list with the values of each flow adjusted for the reference flow defined in Part 2.

b) Provide additional information about average values of the outputs main properties (chemical, physical, and mechanical properties), if necessary.

c) Describe how solid waste and emissions are transported from the factory to the final disposition (e.g., landfill, incineration, recovery). Use the same template from Question 6a.

10. What is the reference year for the collected data from Questions 1 to 9?

11. Provide a list of the main limitations and assumptions for the collected data from Questions 1 to 10.

1.4 Part 4: List of questions about the selected manufacturing process of interest

12. Description of the manufacturing unit process of interest:

_______________________________________________________________________________

_______________________________________________________________________________

_______________________________________________________________________________

_______________________________________________________________________________

_______________________________________________________________________________

_______________________________________________________________________________

13. Which process parameters are used to control the manufacturing process of interest? Specify average values and maximum and minimum tolerated values for each process parameter.

14. Based on Question 4b, which product quality requirements are most important for the manufacturing process of interest? How can the manufacturing process affect the product’s quality requirements?

15. Specify operation modes and machine subunits for the selected manufacturing unit process.

16. What is the time of operation for the selected manufacturing process to produce one unit of the studied product? Stratify this time in level of operation modes and machine subunits too.