Sustainable Development Through the Principles of Green Engineering
JULIE BETH ZIMMERMAN
University of Virginia
As concerns about population growth, global warming, resource scarcity, globalization, and environmental degradation have increased, it has become apparent that engineering design must be engaged more effectively to advance the goal of sustainability. This will require a new design framework that incorporates sustainability factors as explicit performance criteria. Sustainability has been defined as “meeting the needs of the current generation without impacting the needs of future generations to meet their own needs” and is often interpreted as the simultaneous advancement of prosperity, environment, and society. The 12 Principles of Green Engineering developed by Anastas and Zimmerman (2003) provide a design protocol for moving toward engineering design for sustainability.
The impact of population growth has long been understood as a grand challenge to the advancement of sustainability goals. The data demonstrate that the vast majority of population growth is occurring in the developing world and that population is stagnant, in some cases declining, in the industrialized world (Figure 1). This may suggest that in the complex equation of a growing world population, including birth and mortality rates, socio-political pressures, access to health care and education, cultural norms, and so on, there is an empirical correlation between the rate of population growth and the level of economic development, often equated with quality of life.
This relationship suggests that one approach to meeting the challenges of stabilizing population growth and advancing the goals of sustainability is to
expand economic development and improve quality of life. Historically, however, increased development and higher quality of life have been inextricably linked with environmental degradation and resource depletion. A significant amount of evidence suggests that the growing human population has increased the strain on natural resources used for consumption and waste assimilation.
Although there is no single index of the state of the environment, the relationship between population and environment can be analyzed in terms of resource depletion or dimensions of environmental quality, such as land use, water quantity and quality, pollution (particularly from energy demand), biodiversity, and climate change. A brief review of each of these indicators supports the notion that population growth has traditionally had a detrimental impact on the environment.
The question, therefore, is how to bring about continued development and improved quality of life in both the developing and developed world without environmental degradation and excessive resource consumption. The goal of green engineering and green chemistry is to use science and technology to en-
sure that quality of life, or economic development, is improved through benign chemicals and materials and life-cycle-based design, as well as material and energy efficiency and effectiveness (Anastas and Warner, 1998). Achieving this goal would decouple the historical links between improved quality of life, population growth, and environmental degradation.
THE 12 PRINCIPLES OF GREEN ENGINEERING
The 12 Principles of Green Engineering (see Table 1) provide a framework for designing new materials, products, processes, and systems that are benign to human health and the environment. A design based on the 12 Principles goes beyond baseline engineering quality and safety specifications to sustainability factors, which are considered fundamental factors from the earliest stages of design of a material, product, process, building, or a system. These principles were developed to frame design architecture—whether molecular architecture to construct chemical compounds, product architecture to create an automobile, or urban architecture to build a city. The 12 Principles are applicable, effective, and appropriate for all of them. To function as global design principles, they must be independent of local parameters and system conditions.
TABLE 1 The 12 Principles of Green Engineering
Principle 1. Designers should ensure that all material and energy inputs and outputs are as inherently non-hazardous as possible.
Principle 2. It is better to prevent waste than to treat it or clean it up after it is formed.
Principle 3. Separation and purification operations should be a component of the design framework.
Principle 4. System components should be designed to maximize mass, energy, and temporal efficiency.
Principle 5. System components should be output-pulled rather than input-pushed through the use of energy and materials.
Principle 6. When making design choices on recycling, reuse, and beneficial disposition, embedded entropy and complexity should be considered an investment.
Principle 7. Targeted durability, not immortality, should be a design goal.
Principle 8. Design for unnecessary capacity or capability should be considered a design flaw. This includes engineering “one size fits all” solutions.
Principle 9. Multi-component products should strive for material unification (minimal material diversity) to promote disassembly and value retention.
Principle 10. Design of processes and systems must include integration of interconnectivity with available energy and materials flows.
Principle 11. Performance metrics should include designing for performance in commercial “afterlife.”
Principle 12. Design should be based on renewable and readily available inputs throughout the life cycle.
Source: Anastas and Zimmerman, 2003.
Two fundamental concepts engineers should strive to integrate at every opportunity are (1) life-cycle considerations and (2) inherency. The materials and energy that enter each life cycle stage of every product and process have their own life cycles. If a product is environmentally benign but requires hazardous or nonrenewable substances to produce, the environmental impacts have simply been shifted to another stage in the overall life cycle. Thus, designers must consider the entire life cycle, including the life cycles of materials and energy inputs. This strategy complements the selection of inherently benign inputs that will reduce environmental impacts throughout the life cycle.
Making products, processes, and systems more environmentally benign generally follows one of the two basic approaches: (1) changing the inherent nature of the system; or (2) changing the circumstances/conditions of the system. For example, inherency may reduce the intrinsic toxicity of a chemical. A conditional change might be to control the release of, and exposure to, a toxic chemical. Inherency is preferable for various reasons, most importantly because it precludes “failure.” In the example just described, technological control of system conditions could potentially fail, which could lead to a significant risk to human health and natural systems. With an inherently benign design, regardless of changes in conditions or circumstances, the intrinsic nature of the system cannot fail.
The 12 Principles provide a structure for creating and assessing the elements of design to maximize sustainability. The application of the 12 Principles on different scales and in different disciplines has been documented with case studies from a variety of sectors (Zimmerman and Anastas, 2005; Zimmerman et al., 2003). Although designers of molecular systems, designers of industrialized systems, and designers of systems for developing communities use different terminology and jargon, the fundamental approaches and guidelines apply to all of them. The case studies illustrate how the framework of principles has worked in the past and provide a blueprint for applying them in future designs for improving quality of life and ultimately advancing sustainability.
ADVANCING GLOBAL SUSTAINABILITY
Science and technology are vital to advancing global sustainability through the next-generation design of fundamental products, processes, and systems that not only maintain and/or improve quality of life, but also protect the planet. The current operational model of unilateral knowledge transfer from the industrialized world to the developing world could also be expanded to include knowledge exchange (dialogue), which would allow for learning about indigenous knowledge and traditional designs that have been developed and adapted for local people and places. Knowledge exchange would provide an opportunity for integrating the knowledge from different sources and different methodologies, techniques, and practices from the developed and developing worlds. The examples
of innovations in science and technology from the developing world would highlight alternative strategies to delivering services, such as clean drinking water, medical treatment, energy and power production, material and product development, and building technologies and techniques.
Developing nations typically have a long history of practical innovation and successful application of indigenous knowledge systems to serve individuals and communities (Mihelcic et al., 2005). Innovations in science and technology can lead the way to fundamental changes in the quantity and types of energy and materials used to improve quality of life and advance prosperity while protecting and restoring natural systems. The incorporation of cutting-edge thinking and traditional ways will create a robust effort to achieve the common goal of sustainable development.
Achievements based on green engineering principles are examples of how products and systems have been designed with a new sustainability perspective. To address the challenges of sustainability, in both industrialized and, especially, developing nations, where development will be most consequential for the environment and society, new design imperatives must be systematically incorporated into the next generation of products, processes, and systems. In this context, the dialogue between the developed and developing world must include not only a high-level understanding of complex systems, but also the simple elegance of solutions based on millennia of experience and tradition. Designing more sustainable systems and products will require diverse sources of technological inspiration.
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