Technology

From Thermal-FluidsPedia

The third factor impacting the environmental damage is technology (a). Technology can influence the environment both positively and negatively. On one hand, technology makes it possible to design machines that have better efficiencies and make elaborate tasks much easier to perform. On the other hand, technology promotes automation, usually at the expense of faster resource depletion and additional waste. Consider, as an example, the impact of technology on automobile use. Automobiles have given us mobility by allowing us to move around faster but have also limited our physical activity, which affects our health and general wellbeing. Increased efficiency, measured as miles traveled per gallon of fuel, has not helped either, as it has only caused people to buy larger, heavier cars and travel longer distances. Fortunately, technological advances are on the horizon which, if used wisely, give us the promise of a sustainable future, affecting everything we build and consume from microchips to potato chips. The most promising innovations are in the fields of manufacturing, transportation, agriculture, and energy.

1 Manufacturing
2 Transportation
3 Agriculture
4 Energy
5 References
6 Additional Comments
7 Further Reading
8 External Links

Manufacturing

Manufacturing is undergoing major changes in reducing both material and energy consumption. For example, optical fibers have forty times the carrying capacity of copper, which can potentially save an enormous amount of materials and energy during extraction, manufacturing, and implementation of conventional copper cables. The same can be said of new composites that can replace heavy steels. Molded plastic parts produce far less waste than metals, potentially saving a great amount of material.

More versatile design tools and better manufacturing techniques allow for the design of better and more efficient devices without sacrificing their functionality. The manufacturing practices prevalent in the past have been based mostly on the one-time use of materials, creating a large amount of waste that must be disposed. Just-in-time manufacturing and made-to-order manufacturing are two approaches being popularized in many manufacturing sectors; they use the exact amount of materials that are being delivered at the exact time they are needed. This reduces the volume of the scrap materials, eliminates the need for on-site storage, and minimizes the risk of spoilage and environmental damage.

New CAD/CAM (computer-aided design and computer-aided manufacturing) tools are available that help design products that weigh less and are stronger, while consuming less energy and material. This is achieved primarily by making them less bulky while assuring thermal and mechanical stresses in critical areas are kept below their safe limits. Rapid prototyping is a relatively new concept that uses CAD software to manufacture three-dimensional prototypes of a device at only a fraction of the cost, energy, and material. The design for manufacturing is based on minimizing material and energy use during the entire chain of product development from material extraction, to processing, to manufacturing, to use, to reuse, and to disposal. Making products lighter and more durable is obviously the best choice. Proper reuse of material and recycling waste will play a large part in creating a sustainable society. For example, we can re-pulp paper products into cardboard, shred them and use them as insulation, or incinerate them to generate heat. Clothing and furniture can be reused by more needy individuals, recycled into new products, or burned to generate energy. Glasses can be refilled over and over again or be crushed and made into new products. Metals can be re-melted and reused to manufacture new products.

Question: A beer canning company intends to reduce material waste by redesigning the shape of their beer cans. What do you suggest?

Answer: For the same volume, beer cans that are fatter and shorter have the lowest total surface area and a smaller mass. It is left as an exercise to show that minimum surface area is achieved when a can’s height is equal to its diameter. Another factor that can affect the choice is the practicality of the design.

Transportation

As we discussed in Transportation, transportation systems are changing with major impacts on the world energy supplies. These include a complete redesign of cars using lighter and stronger materials, more efficient hybrid and fuel cell cars, maglev rail, and more aerodynamic sea and air vehicles. Development of low-cost public transportation systems, faster communications that allows efficient home offices, and new architectural concepts to build modern residential communities and financial centers will greatly reduce the driving needs.

Agriculture

Figure 1 Corn grenade: the winning image from the Greenpeace Seeds of Trouble competition, 2002.

Scientists have already developed bacteria that can absorb nutrients more effectively and a natural antifungal agent that protects wheat and other seeds staves off frost development in plants. It is predicted that by the end of this century making better farming and irrigation systems, developing hybrid seeds, producing food from municipal waste, planting trees and growing food in unfriendly climates and salty soils, and hydroponics (a method of growing plants without soil by providing food and water directly to the roots of the plant) will alleviate the food shortage in many poor countries (1), eliminating the need to transport food across continents (b). Genetic engineering will also play an important role in accelerating the growth of livestock and modification of crops. Genetic engineering enables scientists to create plants, animals, and micro-organisms by manipulating genes in ways that do not occur naturally. The approach, however, is highly controversial as there is not adequate scientific understanding of the impact on the environment and human health (Figure 1) (2).

Energy

The energy industry will be affected in two fundamental ways: by finding new and alternative sources of energy and by reducing energy need through more energy-efficient designs and practices.

Within the next couple of decades, innovative processes that convert coal, oil shale, and tar sands to gaseous and liquid fuels, and possibly, breeder technology will help supply our immediate energy needs. Advances in the field of synthetic biology will enable scientists to produce an artificial genome and re-engineer new organisms that efficiently, and at much-reduced cost, turn plant fiber into ethanol and other biofuels. Scientists at the University of California, Riverside have discovered new strains of petroleum-degrading bacteria that thrive with no light or water, breathe carbon dioxide instead of oxygen, and break down toxic petroleum compounds to give off methane gas (3). These properties can pave the way to develop new and cheap class of biofuels, not to mention cleaning up oil and other hydrocarbon spills.

Figure 2 Efficient appliances are authorized by the DoE with special Energy (Green Star) labels. These models can save as much as 30% in energy.

Figure 3 Compact fluorescent lamps.

In the near future we will witness fuel cells become ready for commercialization for providing premium electricity at efficiencies of 50-60% for building applications. The waste heat provided by high-temperature fuel cells can be recovered to produce steam that can be used directly in industrial applications or expanded in a gas turbine to produce more electricity. The waste heat from low-temperature fuel cells can be used for cooking and is ideal for hot water heating and space air conditioning. Further advances in solar, wind, wave, and ocean thermal technologies are expected to bring down prices, making renewable energy competitive or cheaper than fossil fuels or nuclear fission, alleviating many of our concerns about energy and its effects on the environment. Fusion technology, although currently not available, may prove to be our ultimate source of clean and inexpensive energy for many centuries.

In the relatively near future, more energy-efficient devices are expected to flood the market (Figure 2). These devices operate by automatically adjusting to consume the least amount of energy required for the task they are designed to perform. Washing machines will be equipped with fuzzy controllers (c) that adjust the amount of detergents, water, etc., depending on how dirty clothes are. Dryers, microwave ovens, air conditioners, refrigerators, and vacuum cleaners are being designed that work based on similar principles.

Lighting and illumination is making great progress toward energy efficiency. Incandescent lamps can be replaced with compact fluorescent and tri-chrome lamps with significantly higher efficiencies. An incandescent bulb contains a tungsten coil filament that turns red when electricity flows in a vacuum. Only 5% of the electricity is converted to light. The remaining 95% is used for heating the element. On the other hand, fluorescent lights operate by exciting the mercury gas through electric discharge to emit ultraviolet light, which in turn converts to visible light by phosphorous coating of the tube. Fluorescent lights are four times more efficient than incandescent lights. Compact fluorescent lights and tri-chrome lamps with rare-earth elements emitting in the visible range that increase efficiency even further are becoming available (4).

New architectural concepts allow construction of “green” or ecologically-friendly smart buildings that incorporate many energy-saving measures at lower costs without sacrificing convenience or safety. For example, passive heating and cooling systems, solar walls and roofs, solar collectors deploying newer phase change materials, window overhangs, improved insulation, double-glazed air-tight glass, low-emissivity window coatings, windows with aerogel glazing, and better sensors are some of the technologies that are finding their way into average households (5). Photovoltaic cells can eventually be shaped to directly replace walls and windows, or rolled out like a blanket, or layered like paint onto curved surfaces. Wind turbines can be designed as an integral part of future buildings, making these buildings a net exporter of energy (See Figure 3-15). Future communities can be designed to eliminate repeat trips and reduce commuting, both of which are essential for designing a sustainable future.

References

(1) Kahn, H., et al., The next 200 years: A scenario for America and the World, Morrow Publishers, New York, 1976.

(2) Greenpeace International (http://www.greenpeace.org/international/campaigns/genetic-engineering).

(3) Kim, J. and Crowley, D., “Microbial Diversity in Natural Asphalts of the Rancho La Brea Tar Pits,” Applied and Environmental Microbiology, April 6, 2007.

(4) Schuman, J., et al., “Technology Reviews: Lighting Systems,” LBL-33200, September 1992.

(5) Rosenfeld, H., et al. “Technologies to Reduce Carbon Dioxide Emissions in the Next Decade,” Physics Today, Nov. 2000, pp 29-34.

(6) Toossi Reza, "Energy and the Environment:Sources, technologies, and impacts", Verve Publishers, 2005

Additional Comments

(a) Much of the material in this section has been adapted from Natural Capitalism: Creating the Next Industrial Revolution, Rocky Mountain Institute, 1999. (See list of additional reading at the end of this chapter).

(b) Today in the United States, food travels an average of 1300 miles from farm to plate; often the energy needed to produce it is many times the energy contained in the food itself.

(c) Unlike traditional on/off controllers, fuzzy controllers work by assigning a weighting function that can vary by any number between zero and one.