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Energy efficiency: Stretching America's resources

High-visibility conditions in the Smoky Mountains-100 miles (top) and low-visibility-20 miles (bottom)
Click here for a high resolution photograph.

The United States and the world face enormous energy challenges. Petroleum prices are at record highs with no end in sight. The emergence of China and India as major contributors to global demand brings new urgency to political and economic concerns about oil dependence. Simultaneously, sustained price increases and extreme volatility in natural gas markets are prompting renewed anxieties about this environmentally valuable fuel.

In the wake of the largest cascading power outage in North America's history, the U.S. has not developed sufficient improvements to an outdated electric grid that is essential to nearly every facet of modern life. Each of these issues lies in the context of deteriorating air quality that continues to impair human health and adds to growing concerns that increased fossil fuel use may be contributing to global climate change.

Using energy more efficiently can help address each of these challenges. The offer of a "no regrets" approach makes energy efficiency particularly valuable as a "front-line" strategy. Investments in energy efficiency hold the promise of saving consumers money while reducing pollution and greenhouse gas emissions and stretching our limited energy resources.

Energy efficiency has already played a significant role. Before the 1970s, America's energy consumption grew in parallel with the nation's gross domestic product (GDP). Had that trend continued, current U.S. energy demand would be roughly doubled. Reductions in energy intensity (E/GDP) have resulted from a combination of energy efficiency investments, structural shifts away from energy-intensive manufacturing toward a service and information-based economy, and the pressures brought by historic increases in the cost of energy.

Despite three decades of "clean air" legislation in the United States, air pollution continues to be a serious environmental problem. Americans are experiencing a rise in respiratory illnesses. Visibility continues to degrade at least in part as a result of power plant and vehicle emissions. The Great Smoky Mountains National Park, ORNL's neighbor to the east, is a case in point. Ozone alerts dissuade visitors from hiking and prevent rangers from working several weeks each year. Once breathtaking, visibility in the Smoky Mountains now rarely achieves its "natural" limit of 93 miles. Today, average annual visibility has decreased in winter to an average of 25 miles and in summer to an average of 12 miles.

Attacking the Problem

ORNL is contributing a variety of energy-efficient technologies for future generations. Every kilowatt saved through energy conservation, i.e., "negawatt," displaces the same amount of energy generation, thus reducing air emissions from power plants.

The buildings sector uses 70% of the electricity consumed in America, meaning that energy-saving construction and building equipment technologies can dramatically impact air quality. ORNL's energy-saving technologies for buildings include advances in water heating, heat pumps, air-conditioning, and building materials.

Microturbines are used in distributed energy systems.
Click here for a high resolution photograph.

Over 25 years, due in part to ORNL research, the amount of electricity consumed by American refrigerators has dropped by more than two-thirds, saving $9 billion. A new refrigerator developed jointly by the Laboratory and industry uses 60% less electricity than comparable conventional units. ORNL advances in supermarket refrigeration, including sophisticated approaches to recovering waste heat, are also cutting energy costs. The Laboratory has developed "calculators" for evaluating the energy performance of roof and wall systems. Its Insulation Fact Sheet, the second most requested DOE publication, is used on virtually every insulation package sold in the United States.

For industry, ORNL has developed advanced materials, including novel alloys and nano-engineered, high-performance steels. For DOE's Best Practices program, ORNL helps minimize waste streams while upgrading energy efficiency, particularly in heavy industry. New metal-processing technologies pioneered at ORNL have a high potential for lowering energy use even as they reduce waste and enhance product performance.

One success story involves nickel aluminide alloys, which are extraordinarily strong, hard, and heat-resistant materials now widely used in fixtures for high-temperature manufacturing. These ORNL-developed alloys can cut energy use 10 to 35% by making it feasible to operate furnaces at higher temperatures with fewer shutdowns and greater throughput. In 2003, Delphi Automotive Systems initiated the use of nickel aluminide trays for steel-carburizing, heat-treating furnaces and announced plans to use them in worldwide operations. Bethlehem Steel, now ISG, installed 100 rolls made of nickel aluminide alloys in its steel mills. Use of the new rolls has resulted in an increase in up-time by 30%, a higher yield of steel with improved quality, lowered operating and maintenance costs, and a 35% reduction in energy use.

For the transportation sector, ORNL researchers helped develop lightweight composites present in production vehicle parts such as truck beds, Aston-Martin body panels, and Delphi Class 8 tie rods. Each 10% reduction in weight enables a 5 to 6% improvement in fuel economy.

Every advance in fuel efficiency and emissions control for vehicles translates into tailpipe emissions avoided. ORNL's extensive research and development portfolio in advanced technologies will improve the efficiency of internal combustion engines (ICEs) for both transportation and power applications. At the National Transportation Research Center, ORNL researchers are developing technologies to allow more effective control of ICE emissions without a fuel economy penalty. ORNL's research on advanced power electronics is developing smaller, cheaper, longer-lasting inverters to enable competitive U.S. hybrid vehicles. For the long term, ORNL is conducting research on gas separation, advanced sensors, and materials to help enable a hydrogen economy.

Using Waste Heat Well

In the power sector, distributed energy technologies can more than double today's average electric system efficiency through the use of integrated cooling, heating, and power (CHP) systems that capture and use waste heat productively instead of venting it to the atmosphere. The improvement in fuel efficiency means corresponding improvements in air quality. Working with industrial partners, ORNL project managers have helped demonstrate the practicality of using industrial gas turbines, microturbines, and reciprocating engines in CHP systems at a number of different sites.

Commercial market potential for integrated energy systems that use waste heat productively, raising fuel-use efficiency from 32% to 70%.
Click here for a high resolution photograph.

DOE initiated the Advanced Turbine Systems program because projections indicated that natural gas turbines, which generate from 3 to 30 megawatts, would make up 80%+ of new capacity during the 1990s. To increase efficiencies, the gas turbines had to operate at higher temperatures and pressures than ever before.

ORNL researchers identified ceramic composite materials for combustor liners in these turbines, enabling them to operate at higher temperatures without violating environmental regulations. Coatings were added to protect the materials from degrading when exposed to corrosive reactions. The result was Solar Turbines' Mercury 50, a new class of industrial gas turbine that incorporates advances stemming from ORNL research, including an improved stainless steel alloy. By applying this alloy to recuperators, heat can be recovered from the exhaust to pre-heat inlet air, raising the gas turbine's efficiency to 40%.

More recently, ORNL has developed a facility to evaluate metals and ceramics that are potential candidates for microturbine components in the quest to raise microturbine efficiency from 27% to 40%. ORNL researchers are also applying control techniques to reduce combustion variability in reciprocating engines.

Recognizing that transmission is a critical part of the energy equation, ORNL also is a leader in developing superconducting technologies that could dramatically improve the efficiency and reliability of the U.S. electric grid. The use of new superconducting cables to reduce the substantial losses that occur as electricity is transmitted from generator to end user will proportionately reduce the need for power generation and will help stabilize the electric grid.

As the demand for energy services grows, technologies developed at ORNL and elsewhere that generate "negawatts" will be increasingly important, helping to ensure that America's economic vitality is not sustained at the expense of our health and environmental quality.


óMarilyn Brown, director of the Energy Efficiency and Renewable Energy Program at ORNL.


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