Energy Efficient Materials Processing: A “Transforming Energy” Lecture
Prof. Mark Kushner, Dean of Engineering at Iowa State presented an interesting lecture which gave attendees a glimpse of how optimized plasmas can contribute to efficiency gains in lighting and even moreso in materials processing. With respect to lighting, Kushner started his talk with lighting wherein he indicated that 22% of the electrical power generated in the United States is used for lighting and a nearly half of that is used to excite a single excited state of the mercury atom in a plasma for fluorescent lights. Small changes in the energy distribution of the mercury plasma in fluorescent lamps can eliminate the need for three 1-GW power plants in the US. After presenting the lighting example and a brief introduction of plasmas in general, Kushner proceeded to the specific applications of his research on plasmas for material processing through the lens of global energy consumption with a focus on the dramatic energy reductions possible through better use of plasmas.
Dr. Kushner’s research explores with numerical models the use of plasmas to modify surface properties, both for high-volume, low-cost polymer films and low-volume, high cost microelectronics. In the electronics industry, plasmas are essential for etching and deposition processes. Plasma etching reactors are used to mill nano-scale features at a very high energy cost. Kushner showed that a typical silicon wafer can cost about 1 kW-hr per square centimeter in energy, and a third of this comes from processing tools such as plasmas. By taking a systems-level approach, Dr. Kushner sees the potential to maximize the speed and minimize the error rate of the etching process through a voltage-controlled plasma. The other primary use of plasmas for improving materials properties is in the nearly 50 square kilometers of polymer films produced annually. Similar approaches can yield dramatic energy savings with even small efficiency gains, due to the large scale of these machines.
Dr. Kushner concluded with a passionate discussion of further potential uses for these technologies, including using the same process that makes immense quantities of low cost plastic bags to create biocompatible tissue scaffolding. Laboratory grown tissues for transplantation are quite expensive, both in terms of energy and dollars, but mass production using plasma technologies could lower the cost nearly 100 times.
Members of the audience were given the opportunity to ask several questions, ranging from the applicability of the polymer film technologies to mass production of solar cells, to the relative merits of additive and subtractive processes. The lecture concluded with a few forward-looking thoughts on energy from Dr. Kushner. As the cost of electricity can only be expected to increase in the near future, modern companies must begin making investments in efficiency today to be able to maximize their future profit potential.
February 1, 2008