Life cycle assessment of particleboard industry in Pakistan

Abstract

Particleboard is a composite panel comprising small pieces of wood bonded by adhesives. The particleboard industry is growing in Pakistan but there is little information on the environmental impacts associated with this product. Therefore, the aim of this study was to develop a life cycle assessment of particleboard manufactured in Pakistan and to provide suggestions to improve its environmental profile. The study covers energy use and associated environmental impacts of raw materials and processes during particleboard manufacture in the year 2015-2016. This study quantified the environmental impacts of particleboard production in Pakistan using a cradle-to-gate (distribution center) life cycle assessment approach. The system boundary comprised raw materials acquisition, transport, particleboard manufacture and finished product distribution. Primary data were collected tITIough surveys and meetings with particleboard manufacturers, whereas secondary data were taken from the literature. The reference unit for tIllS study was one cubic meter (1.0 m3 ) of finished, uncoated particleboard. Primary data from the particleboard mill surveys were combined with secondary database information, and modeled using CML 2000 v.2.05 methodology and a cumulative exergy demand indicator present in the SimaPro version 8.3 software. The results reveal that urea formaldehyde resin, transportation of raw materials, and finished product distribution, had the highest contribution to all the enviromnental impact categories evaluated. Heavy fuel oil and natural gas consumption was responsible for abiotic depletion, photochemical oxidation, ozone layer depletion, and marine aquatic eco-toxicity impacts. The rotary dryer and hot press was the most important sectors in terms of emissions from the manufacturing process. Furthermore, greenhouse gas emissions (GHG) from off-site industrial operations of the particleboard industry represented 52% of the total emissions from the production of 1.0 m3 of particleboard in Pakistan. Th~ on-site industrial operations cause direct GHG emissions and accounted for about 48% of the total emissions. These operations included energy consumption in stationary sources, the company-owned vehicle fleet, and the distribution and marketing of the finished product. The use of natural gas combustion in the stationary and mobile sources, raw material transport and urea formaldehyde resin production chain accounted for the highest emissions from the particleboard production in Pakistan. The total cumulative exergy demand required for manufacturing of 1.0 m 3 particleboard was 15,632 mega joule-equivalents, with most of the energy usage associated with non-renewable, fossil fuel sources. Among the seven impact categories, non-renewable fossil sources had the highest contribution i.e. 12,504 MJ-eq to the total exergy removed from the nature to manufacture 1.0 m3 particleboard. Similarly, renewable biomass was the second largest source with contribution of 1,455 MJ-eq exergies, whereas non-renewable minerals were responsible for only 25.40 MJ-eq in the total exergy required for 1.0 m3 particleboard manufacture. The embodied energy for the manufacture of 1.0 m3 of particleboard comprises of fossil fuels and purchased electricity consumed in stationary sources of the mill. The energy consumption in stationary sources of the particleboard mill was 5.457 GJ per m3 of particleboard production, whereas the total energy consumption in cradle-to-gate life cycle of the 1.0 m 3 particleboard production was 8.187 GJ during 2015-16. ix The wood materials used in the manufacture of particleboard can store and embodied carbon, which can be utilized to offset the carbon dioxide emissions from production chain of the particleboard mill as well as from product use and disposal, if forest management practices are on sustainable basis (scenario-II in the present study). Therefore, to manufacture 1.0 m 3 of particleboard, the carbon storage was equal to -1441 kg C02e, which can offset the cradle-to-gate carbon footprint (975.282 kg C02e) of per m3 particleboard produced in Pakistan during 2015-16. This also leaves a net carbon flux of -564.04 kg C02e per m3 particleboard manufacture as a carbon credit, which can also be used to offset the emissions from product use and disposal, consequently diminishing its impact on climate change. A sensitivity analysis was conducted for a reduction in the quantity of urea fonnaldehyde resin consumed and freight transport distances. The results indicated that reducing the urea fonnaldehyde resin use and freight distances could greatly decrease environmental impacts. Most of the surveyed mills did not have emissions control systems and most of the mills exceed the limits set by the National Environmental Quality Standards of Pakistan. Environmental impact improvements might be attained by reducing quantity of urea fonnaldehyde resin and transportation freight distances, and by installing pollution control devices. The identification of the major hotspots in the partideboard production chain can assist the particleboard industry to improve their environmental profile. More efforts are needed to investigate the urea-fonnaldehyde resin production chain and substitution of round wood with wood and agri-residues to assess the potential improvements. In addition, renewable energy sources should be encouraged to avoid GHG emissions by substituting fossil energy. This study also provides a benchmark for future research work to fonnulate comprehensive emissions reduction plans, because no previous research work is available on environmental profile of the particleboard produced in Pakistan. Keywords: Life cycle assessment, Cumulative exergy demand, SimaPro, Particleboard, Environmental impacts, Wood, Carbon footprint, Pakistan