24 2. EXPANDING VIEW OF BAT DETERMINATION THROUGH A VALUE CHAIN PERSPECTIVE
Common themes among value chain approaches While value chain approaches described here vary significantly, all are guided by the ultimate goals of environmental sustainability. Some of the approaches focus on specific resources; green chemistry pertains to the production and use of chemicals, whereas decarbonisation focuses on fossil fuel resources. Compared to these more targeted frameworks, resource efficiency and circularity are much broader in scope. Circularity, in particular, seeks to reframe current patterns of consumption, use, and disposal. Regardless of differences in target and scope, common themes underlie many of these value chain approaches. These themes are described in Box 2.
Box 2. Common themes of value chain approaches and examples Pollution prevention and waste minimisation - The first principle of green chemistry is “Prevent waste: design chemical syntheses to prevent waste. Leave no waste to treat or clean up.” Similarly, “designing out waste” is a principle of circularity. Much of decarbonisation is aimed at designing fossil fuel combustion out of energy production. Resource efficiency - The green chemistry principle “maximizing atom economy” is guided by resource efficiency to ensure that more of the starting materials in a chemical process are incorporated into the product. Similarly, catalysis is a strategy to avoid the inefficient use of stoichiometric reagents during synthesis, often with reaction conditions closer to ambient conditions. The reframing of waste as a resource in resource efficiency is one of the main principles of a circular economy, where the waste from any process may serve as an input for another use, displacing other raw material usage. Use of renewable feedstocks and raw materials - All approaches highlight the importance of renewable feedstocks and raw materials. Decarbonisation seeks to eliminate the use of fossil fuels and petroleum-based resources through use of renewable feedstocks and resources. The concept of a circular economy relies on the use of renewables as a key link in the biological cycle (e.g., composting and anaerobic digestion of consumer waste for production of renewable chemical and energy resources). Recycling and material recovery - Reframing waste as a resource is a common theme in the approaches. A goal of resource efficiency is to decouple production from consumption of natural resources with recycling and material recovery necessary to achieve this end. In the concept of a circular economy, these strategies ensure minimal leakage of resources from the system. In biological cycles, waste collection is key in the production of biochemical feedstocks and the restoration of biological systems for renewable feedstock production. In technical cycles, the recovery and recycling of metallic and mineral resources is necessary to maintain circularity for part and product manufacturing. Hazard reduction - Green chemistry focuses heavily on hazard reduction in terms of chemical inputs as well as products. Similar themes appear in resource efficiency and circularity, where minimizing the hazard associated with inputs may be a strategy to minimize use of resources dedicated to risk management at the installation level. Minimizing hazard associated with products is also key in ensuring that materials may be recycled and reused at other links in the value chain. Material substitution is a key strategy for hazard reduction, but usually requires a priori knowledge of any potential impacts on other links in the value chain and during product use to avoid regrettable substitutions. Note: Many systems and process changes that will deliver environmental benefits require more energy which makes the supply of sufficient decarbonised energy is critical and can be considered as a pre-requisite for a change to other production processes.
BEST AVAILABLE TECHNIQUES (BAT) FOR PREVENTING AND CONTROLLING INDUSTRIAL POLLUTION © OECD 2022
