The design of chemical products and processes which reduce or eliminate the generation of hazardous substances is called Green Chemistry.
There is an increasing awareness among scientists and engineers that the Earth’s resources are limited and the ever-growing world population and rapid technological development place increasing stress on the available global resources. The rapid advancement of technology without regard to the negative impacts on human health and the environment will eventually have disastrous consequences. This realization has led scientists and engineers to promote the “Green Chemistry” and “Green Engineering” initiatives. Green Chemistry focuses primarily on the elimination or reduction of the use and generation of substances that are hazardous to human health and the environment.
Green Engineering has a somewhat broader view. It focuses on the design, development, and use of products, processes, and systems that are economically feasible while minimizing the risks to human health and the environment. Basically, green engineering seeks to conduct its professional activities in a manner that lessens the negative impacts on the planet and its ability to sustain life and focuses on how to achieve economic, social, and environmental sustainability through the application of green science and technology. These goals go beyond the impacts of the products or processes themselves and must include the entire life cycle of the materials and forms of energy used in the design.
Life cycle design begins with the impacts of the acquisition of the necessary raw materials. These could include the environmental effects of the mining, drilling, or harvesting techniques used to obtain the raw materials. The life cycle assessment continues through the manufacturing, distribution, use, and eventual disposal or recycles of a product. Many times, products are presented as green because the product itself has no negative impacts on the environment.
However, a thorough life-cycle analysis can sometimes reveal toxic effects in its manufacture or disposal. Green Engineering seeks to assure that all materials and energy sources involved in a process, as well as final products, are as nonhazardous as possible while minimizing energy consumption and material use and preventing waste generation. Materials and energy sources should be renewable rather than depleting and final products, processes, and systems should be designed from production to disposal or recycle with this concept in mind.
The principles of Green Engineering have been outlined by the American Chemical Society and the Environmental Protection Agency. These principles are intended to be used as guidelines to achieve the optimization of sustainability in the design of products, processes, and systems.
The major points in both these lists of green principles are:
• The use of materials and energy sources that are inherently nonhazardous.
• To prevent waste rather than rely on after treatment.
• To minimize the consumption of energy and materials.
• The use of renewable materials and energy.
• To minimize the number of material types used in a process.
• To make use of local sources of materials and energy.
• To design for recycling.
• To maximize efficiency.
• To choose simplicity over complexity.
•To maximize durability without environmental immortality.
• To meet needs while minimizing excess.
These principles of Green Engineering are built on the idea that it is easier, more efficient, and less costly to incorporate the prevention of negative environmental impacts at the beginning of a design rather than relying on clean up after they occur.
Choices must be made to minimize these impacts as much as possible while still meeting the needs of society. Engineers make decisions daily that have potentially significant impacts on the environment. These decisions can either contribute to our environmental problems and the depletion of our natural resources or they can reduce the negative effects of technology on the environment and help us achieve environmental, social, and economic sustainability.
The National Academy of Engineering lists mitigation and adaptation to climate change and the development of clean energy sources at the top of the“Grand Challenges for Engineering” in the next millennium. These global problems are listed as threatening the future itself.
Slowing the effects of climate change will require new methods for capturing carbon produced during the combustion of fuel and sequestering it in an environmentally benign form. At the same time, the emissions of carbon and other greenhouse gases need to be reduced as much as possible. Adapting to the impacts of climate change will require designing infrastructure and agricultural processes that can withstand more severe storms, heat waves, floods, and drought.
Although the use of carbon-free energy sources such as solar or nuclear is attractive, their wide use will require the development of more efficient, economical, and less hazardous manufacturing and operating processes. These challenges bridge across the fields of engineering and chemistry and meeting them will require a broad knowledge of both disciplines. The development of sustainable solutions to meet these challenges will require engineers and chemists working together in interdisciplinary teams on a global scale.
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