Frontiers in Environmental Protection

Chemical engineers continue work on new production techniques to reduce the environmental footprint of the chemical, pharmaceutical, semiconductor, pulp-and-paper, petroleum-refining, and electric-power-generation industries.

The ability to reuse waste materials helps reduce our dependence on costly and scarce natural resources. New techniques to store energy help minimize the need for new power plants. Enabling more efficient use of solar energy will help the United States achieve a greater energy independence.

Pollution Prevention

Chemical engineers have developed many "end-of-pipe" control technologies to capture and destroy hazardous pollutants produced by industrial operations. The next challenge is to develop pollution prevention strategies that reduce or eliminate unwanted by-products and hazardous pollutants earlier in the process.

Eliminating the problem

In the 1980s the chemical-engineering community began developing ways to eliminate the formation of pollutants early on in the production process. With this advance it was no longer necessary to rely on "end-of-pipe" treatments to make waste streams suitable for safe discharge into the environment.

Benign by design

Chemical engineers are regularly involved in the design and optimization of complex industrial operations, applying their engineering ingenuity to pollution prevention efforts. The objective is to develop techniques and processes that minimize or even eliminate the formation of unwanted by-products and hazardous pollutants—in other words, to make industrial operations "benign by design."

Chemical-engineering contributions to pollution prevention include:

• Improved engineering technologies and advanced machine designs that save raw material and energy,
• Higher-activity catalysts,
• Re-engineered processes designed for "closed-loop" and "zero-discharge" operation,
• Enhanced maintenance procedures,
• Advanced monitoring and diagnostic instrumentation,
• More efficient process control systems with less waste, and
• Environmentally friendly, biodegradable solvents.

Sustainability

Chemical engineers actively seek to minimize the environmental impact of human endeavors and industrial activities. Through sustainable development, they try to meet present world needs without compromising the capability of future generations to meet their needs.

Maintaining our Eearth

Conservation of the world's limited resources, especially nonrenewable raw materials, is an important legacy for the future. Chemical engineers have already begun to move past pollution prevention and are taking the next step into sustainable development.

In the sustainable mode the objective is to leave the earth in the same or better condition for future generations.

Chemical engineers play a central role in achieving sustainability goals. They are concerned with:

• Improving the chemical processes that convert raw materials into finished products,
• Reducing fuel consumption through better energy efficiency and product yield,
• Maximizing the reuse of valuable by-products,
• Decreasing the use of scarce natural resources and fossil fuels, and
• Eliminating the release of harmful pollutants into the environment.

These goals may be achieved through the aggressive use of such relatively simple techniques as recycling and reuse of materials and through more complex efforts, such as highly engineered closed-loop or zero-discharge industrial operations. Here process waste-stream operations are reused as raw materials or energy sources for other processes.

In order to become greener, new chemical-engineering processes are being developed:

• Innovative catalysts are used to produce finished products in greater quantity with less by-product, and
• Biological processes are being used to produce desired products.

To minimize the consumption of increasingly scarce raw water, wastewater streams are now being treated to allow for maximum reuse within a facility. Chemical engineers are also working to develop imaginative technologies that will maximize the reuse of gaseous, liquid, and solid waste streams. All these innovations help minimize the amount of virgin raw materials, fuel, and power required in product manufacturing.

Reducing greenhouse gases

The proper management of CO2 and other key greenhouse gas emissions is critical to the reversal of global warming. Chemical engineers are at the forefront of efforts to develop and commercialize cost-effective strategies to control and counteract these harmful emissions.

Blue skies ahead

Chemical engineers are helping reduce harmful emissions through the development of technologies used to convert biomass into fuel. Courtesy DOE/NREL.

The term greenhouse gas, or GHG, refers to a gas that has high heat-trapping potential in the atmosphere. The ability to trap heat is why GHGs are implicated in global warming.
The six main GHGs are:

• Carbon dioxide (CO2),
• Methane (CH4),
• Nitrous oxide (N2O),
• Hydrofluorocarbons (HFCs),
• Perfluorocarbons (PFCs), and
• Sulfur hexafluoride (SF6).

Where do GHG emissions come from?

GHG emissions are produced primarily as a result of:

• Combustion of fuels for electricity, steam, and heat generation;
• Combustion of fuels for transportation (cars, trucks, buses, airplanes); and
• Physical and chemical processing operations.
• Addressing emission control

Chemical engineers play a leading role in the design and implementation of effective technology-based solutions to control CO2 emissions. Current projects include

• Advanced combustion systems that reduce the formation of CO2 and other combustion-related GHGs;
• Pollution-control systems engineered to capture CO2 emissions; and
• Use of cleaner-burning alternative energy sources, such as biomass-derived fuels and solar- and wind-generated power.

Other efforts involve the development of mechanisms for sequestering CO2 emissions underground to prevent their accumulation in the atmosphere. Sequestration, not yet practiced on a commercial scale, involves the injection of compressed CO2 into stable, subsurface geological reservoirs.