A Life Cycle Sustainability Assessment of Cellulosic Nanofibers Used in Green Building Materials
Nanotechnology is expected to play a significant role in influencing future global markets of products and services. Engineered nanomaterials are expected to increase from 2000 tons in 2004 to an estimated 58,000 ton by 2020. Products containing nanomaterials are already on the market and generating billions of dollars in industry profits. Some estimates indicate that a worldwide market in the trillions of dollars could arise in the coming decade. It offers tremendous potential to enhance our quality of life, from improving the performance of commercial products, to enhanced diagnosis and treatment of disease, to refining water and cleaning up the environment, to develop applications ranging from new antimicrobial materials and tiny probes to sample individual cells in human patients to vastly more powerful computers and lasers. Products with already nanotechnology built in include golf clubs, tennis rackets and antimicrobial food storage containers. Nanocomposites are a new class of composites that have a dispersed phase with at least one ultrafine dimension, typically a few nanometers. The reinforcing phase in nanocomposites can be comprised of nanoclays, nanofibers, Single-Walled Carbon Nanotubes (SWCNT’s) or Multi-Walled Carbon Nanotubes (MWCNT’s). In this work, we will consider the cellulosic nanofibers (derived from woods) which is applied in nanomaterials.
However, there is increasing concern within industry as well as from consumer and environmental groups that the environmental, health, and safety (EHS) consequences of nanotechnology are as yet largely unknown, and that real or perceived risks could dampen the growth of the market. According to a report published on Nov. 25 in the journal of Nature Nanotechnology, the unknown human health and environmental impacts of nanotechnology are a bigger worry for scientists than for the public.
The life cycle of nanoproducts may involve both risks to human health and environment as well as environmental impacts associated with the different stages. Most of the current developments in nanotechnology are not evaluated to quantify claims about their potential benefits via a holistic analysis of their environmental impact during their life cycle. Consequently, it is possible that the societal costs of some of the emerging technologies may outweigh the potential benefits. Researchers have identified the need for the life cycle assessment of potential nanoproducts. It is critical to collect environmental, health data before encouraging the widespread use of products based on these nanoparticles as well as perform their LCA to study the environmental impacts throughout a product’s broader life cycle to ensure that the environmental impact is not just being shifted to other stages of the life cycle. Thus, there is a need for protocols and robust assessment tool can provide a comprehensive assessment to support decisions in the development of appropriate nanotechnologies. Such a tool is highly sought after but has yet to be fully developed. Decision makers will be able to determine which emerging technologies are suitable for immediate field application and which are in need of further improvement. Pertinent aspects of this research project include the application of life cycle assessment methodology to create a holistic, cradle-to-grave view of the environmental and human health impacts of nanoproducts and nanomaterials.
However, LCA of nanotechnology poses several formidable challenges. These include the severe lack of inventory data for each step in the nanomanufacturing life cycle and about the fate, transport and impact of new nanomaterials and products. Such data are difficult to find for radically different and emerging technologies. Data and knowledge about resource consumptions, emissions and their impacts are either unknown or not readily available. This requires the use of fuzzy linguistic approach to address data uncertainty at the early stage of product development. The goal of this work is to develop a fuzzy linguistic based decision-support framework for stakeholders to apply to a wide variety of nanomaterials and nanoproducts. The proposed research will attempt to develop original life cycle inventory data for the manufacture of polymer nanocomposites, use fuzzy linguistic based streamlined Life Cycle Assessment (LCA) and impact assessment to account limited information, and develop a tool for exploring economic and environmental aspects of producing cellulosic nanofibers in nanomaterials.
The potential impacts related to nanotechnological products which needs further analysis are:
- Increased exploitation and loss of scarce resources;
- Higher requirement to materials and chemicals;
- Increased energy demand in production lines;
- Increased waste production in top down production;
- Rebound effects (horizontal technology);
- Increased use of disposable systems;
- Disassembly and recycling problems.
Exploitation and loss of scarce resources is a concern since economic consideration is a primary obstacle to use precious or rare materials in everyday products. When products get smaller and the components that include the rare materials reach the nanoscale, economy is not the most urgent issue since it will not significantly affect the price of the product. Therefore, developers will be more prone to use materials that have the exact properties they are searching.
Besides the issue of exploitation and loss of scarce resources, the extraction of most rare materials uses more energy and generates more waste. Table 1 illustrates the energy intensity of a range of materials (Kuehr, et al. 2003).
|Material||Energy intensity of materials (MJ/kg)||Material||Energy intensity of materials (MJ/kg)|