A life cycle assessment (LCA) is an evaluation tool that measures the environmental impact of a process or product. Novozymes conducted an LCA comparing an entirely chemically based approach to leather treatment with one that substituted enzymes for chemicals. The LCA calculations were based on figures from a major Chinese tannery that used both chemical and enzyme-assisted methods.
Results of comparison show no comparison
The LCA demonstrated considerable environmental savings for enzyme-based processing – results that significantly outweigh the small amount of energy and CO2 emissions required for their production. The figures show that using enzymes in the soaking process led to shorter soaking times, lower tenside and soda requirements, and effecting savings in energy, CO2, and costs. Using enzymes in the unhairing process lessened the need for sulfides, thereby lowering the sulfide content of the wastewater, as well as reducing the energy consumed and the CO2 emitted during sulfide production.
20 times less environmental impact
Unlike enzymatic processes, chemically based operations depend on large amounts of harsh chemicals that are produced using much greater amounts of energy. The savings in sulfide turn out to be the most important environmental benefit of enzyme use. A large quantity of coal is used to produce sulfides, and consequently a large quantity of carbon dioxide is emitted during their production. As a considerable amount of sulfides are required for processing, the impact of chemical methods on global warming is significant. Other environmental hazards (acidification, toxicity, nutrient enrichment, and smog formation) are also reduced in enzymatic processing. Overall, the environmental impact resulting from enzyme production is at least 20 times less than that incurred by the saved chemicals and energy consumption.
Global impact
The global supply of bovine hide for leather production was about 8.8 million tons in 2005. Today, less than 10% of bovine hides are soaked and unhaired in enzyme-assisted processes. Assuming that the environmental improvements observed in this study are applicable worldwide, the global potential savings from using enzymes is in the order of 8 million GJ of energy and 0.7 million tons of CO2 per year. The saved CO2 emissions would be equivalent to the annual load from 75,000 average world citizens or 170,000 cars.