Factory is where our computers eat up most energy

April 13, 2011

Home and office energy conservation must focus on more than developing computers, appliances and other electronics that require less power to operate. Engineers say there are big energy-efficiency gains to be achieved even before those products get plugged in.

The ENERGY STAR label seen on many products certifies that they draw less electricity during use than earlier models. This gives manufacturers an incentive to make things that run on less electrical power, says ASU engineer Eric Williams. Download Full Image

The certification – part of a program run by the U.S. Environmental Protection Agency and the U.S. Department of Energy – thus leads us to assume that most energy use occurs during operation of machines and devices, says Williams, an assistant professor in the School of Sustainability and the School of Sustainable Engineering and the Built Environment, one of ASU’s Ira A. Fulton Schools of Engineering.

“ENERGYSTAR is a great program, but there are also opportunities to save energy by using less power to manufacture products”, says Williams, who is working on energy-saving strategies with ASU colleagues and Callie Babbitt, an assistant professor at the Golisano Institute for Sustainability at the Rochester Institute of Technology.

The researchers make their case in an article published April 7 in the Journal">http://dx.doi.org/10.1016/j.jclepro.2011.03.004">Journal of Cleaner Production, which focuses on technologies, concepts and policies to achieve more energy- efficient and environmentally sustainable industrial practices.

They compare the amount of power used to operate a laptop computer over its typical life cycle to the energy consumption involved in the manufacturing process – and the amount of carbon dioxide and other greenhouse gases emitted by the process. Greenhouse gases are a contributing factor to climate change induced by human activity.

Williams and his collaborators find that 227 to 270 kilograms (or 500 to 594 pounds) of carbon dioxide are emitted in manufacturing a laptop computer. The range in the numbers is due to variability in materials used and different manufacturing processes.

The amount is surprisingly large, Williams says. It shows that the carbon dioxide emissions resulting from energy consumed in the manufacture of a laptop computer can in some cases come close to or equal the emissions resulting from the manufacture of a refrigerator – meaning computer manufacturing is relatively more energy intensive.

Researchers looked at power consumption and emissions resulting from the manufacture of 2002 model year laptop computers.

"The carbon emissions that resulted from supplying the demand in the United States for laptop computers in 2002 is roughly equivalent to the annual emissions from driving 676,000 automobiles," Babbitt says.

The research study shows that as much as 70 percent of the energy needed to make and operate a typical laptop computer throughout its life span is used in manufacturing the computer. Williams says the obvious conclusion is that more energy would be conserved by reducing power used in the manufacturing of computers, rather than reducing only the amount of energy required to operate them.

“The carbon emissions for materials in the laptop computer account for only 10 percent of the total, which means recycling materials can get back only  a small fraction of the energy investment,”  Babbitt says.

Designing computers that can be upgraded and more easily reused would help reduce the need for more and more new computers to be manufactured. Reuse has the potential to reduce carbon emissions more than recycling, she says.

The other side of the environmental equation is that computers clearly have environmental benefits, Williams says. For one significant example, computers enable people to telecommute for work, reducing traffic congestion and gasoline use.

“We should manage the impacts of manufacturing and using computer hardware, but not overlook the overall energy-saving and environmental benefits of using computers,” he says.

Joe Kullman

Science writer, Ira A. Fulton Schools of Engineering


Professor earns award for invention that removes water contaminants

April 13, 2011

A new technology that removes dangerous contaminants from water has earned Arizona State University inventor Bruce Rittmann prestigious Environmental Engineering Excellence Award from the American">http://www.aaee.net/">American Association of Environmental Engineers. The organization will present the award to Rittmann on May 4 at the National">http://press.org/">National Press Club in Washington, D.C.

Rittmann is the director of the Swette Center for Environmental Biotechnology in the Biodesign Institute at Arizona State University and a Regents’ Professor of environmental engineering in the School of Sustainable Engineering and the Built Environment, one of ASU’s Ira A. Fulton Schools of Engineering. His hydrogen-based membrane biofilm reactor (MBfR) removes contaminants, such as nitrate, perchlorate, selenate, chromate, and trichloroethene.  The presence of these contaminants in water supplies is a growing problem, but there is no cost-effective water treatment technology available to remove any of them, except for nitrate. Download Full Image

The MBfR has been extensively tested for its effect on many contaminants individually and in mixtures.  It is a versatile platform technology that can be used to treat drinking-water sources, ground or surface waters, industrial and agricultural wastewaters, and municipal wastewater. It is licensed and being commercialized by APTwater, Long Beach, Calif.

Perchlorate, for example, is a byproduct of rocket fuel that is found in the ground and river water throughout the southwestern United States.  According to the Centers">http://thyroid.about.com/od/toxictriggers/a/cdcperchlorate.htm">Centers for Disease Control, even low levels of it can affect the human thyroid.  So water treatment plants needed an efficient way to remove it from drinking water. That was what prompted Rittmann’s innovation.

“The hydrogen-based reactor relies on the natural processes of bacteria respiration to change contaminants to a harmless form,” explained Rittmann. “We combine our understanding of bacteria and create the environment they need to complete this cleaning process for us.”

The MBfR delivers hydrogen gas to bacteria that accumulate naturally on the outer surface of a gas-transfer membrane.  Through respiration, the bacteria oxidize and extract electrons from the hydrogen and transfer extra electrons to water contaminants, changing contaminants to harmless forms.

The key to the success of the MBfR is that it delivers hydrogen gas directly to the biofilm – the slime produced by bacteria colonies – by its diffusion through the wall of the gas-transfer membranes.  This makes hydrogen delivery nearly 100 percent efficient and virtually self-regulating.  In essence, the bacteria in the biofilm “pull” the hydrogen through the membrane wall when they consume it.

Rittmann was elected to the National Academy of Engineering in 2004 and is a Fellow of the American Association for the Advancement of Sciences. In 2009, he won the Research Excellence Award from the Arizona BioIndustry Association and the Simon Freese Environmental Engineering Award from the American Society of Civil Engineers.  He is listed as one of the world’s most highly cited researchers, with more than 440 publications, including more than 40 peer-reviewed publications on the MBfR.

For more information about the AAEE’s Awards Luncheon and Conference, visit http://www.aaee.net/.


About the competition
The Excellence in Environmental Engineering Competition rewards the best of today's environmental engineering. Its criteria define what it takes to be the best in environmental engineering practice: a holistic environmental perspective, innovation, proven performance and customer satisfaction, and contribution to an improved quality of life and economic efficiency.

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