According to a recent study, new manufacturing systems are anywhere from 1,000 to 1 million times bigger consumers of energy than more-traditional industries. In short, pound for pound, making microchips uses up considerably more energy than making manhole covers, for example.
Manufacturers have usually been more concerned about factors like price, quality, or cycle time, and not as concerned about how much energy their manufacturing processes use, said Timothy Gutowski, a professor in the Massachusetts Institute of Technology’s department of mechanical engineering, who led the analysis. If energy prices rise again or if a carbon tax is adopted, energy use will become more important as the new industries scale up, Gutowski said.
New processes will be optimized and improved over time. But over the past several decades as traditional processes such as machining and casting have increasingly given way to newer ones for producing semiconductors, MEMS and nano-materials and devices, energy and materials consumption has increased dramatically.
“New processes are huge users of materials and energy," said Gutowski. “We have increased our energy and materials consumption by three to six orders of magnitude.”
At first glance, it may seem strange to make comparisons between such widely disparate processes as metal casting and chip making. But Gutowski says such a broad comparison of energy efficiency is an essential first step toward optimizing these newer manufacturing methods as they gear up for ever-larger production.
"The seemingly extravagant use of materials and energy resources by many newer manufacturing processes is alarming and needs to be addressed alongside claims of improved sustainability from products manufactured by these means," Gutowski said.
Solar panels are a good example. Their production, which uses some of the same manufacturing processes as microchips but on a large scale, is escalating dramatically. The inherent inefficiency of current solar-panel manufacturing methods could drastically reduce the technology's lifecycle energy balance—that is, the ratio of the energy the panel would produce over its useful lifetime to the energy required to manufacture it.
The study, which is "the first step in doing something about it," Gutowski said covered everything "from soup to nuts" about standard industrial methods. Researchers included heavy-duty old fashioned industries like a cast-iron foundry, all the way up to semiconductors and nanomaterials. It includes injection molding, sputtering, carbon nanofiber production and dry etching, along with more traditional machining, milling, drilling and melting.
The researchers did not analyze production of pharmaceuticals or petroleum, and they looked only at processes where electricity was the primary energy source. And, they say, the figures the team derived are actually conservative because they did not include some significant energy costs such as the energy required to make the materials themselves or the energy required to maintain the environment of the plant (such as air conditioning and filtration for clean rooms used in semiconductor processing). "All these things would make [the energy costs] worse," he says.
The study, which was funded by National Science Foundation, was recently published in the journal Environmental Science and Technology.
—By David Chandler/MIT News Office.