Michael Boger, Edwards Vacuum, Yachiyo, Japan
The rapid expansion of photovoltaic (PV) manufacturing worldwide is driving growth in advanced vacuum and abatement solutions across all geographic markets. In particular, as PV fabrication technologies mature, more and more manufacturers are moving to advanced solutions such as dry vacuum pumps and combustion-based abatement systems because they satisfy the industry's fundamental imperative to achieve cost parity with conventional energy sources, while minimizing its own adverse environmental effects. The move to these technologies is well advanced in more mature segments such as Europe and North America, but most significantly, it is increasingly apparent in the high growth segments in Asia.
In the vacuum arena, the most basic change required is that from wet pumps, which use oil to lubricate and seal the mechanical pumping mechanism, to dry pumps, which dispense with oil and depend rather on close mechanical tolerances. Vacuum pump oil is highly specialized and expensive. During use it becomes contaminated and must be replaced periodically ? as often as once a month. Each maintenance cycle imposes significant costs for replacement oil, contaminated oil disposal, maintenance labor, and equipment downtime. During maintenance, personnel are exposed to dangerous contaminants and process equipment is at risk for contamination by backstreaming pump oil. Dry pumps greatly reduce these costs and risks by eliminating pump oil and extending maintenance intervals.
In addition to avoiding the problems associated with pump oil, modern high-performance dry pumps also provide significant improvements in energy efficiency, reducing both the operating cost of the power they consume and the environmental cost associated with its generation. The recent development of "green" operating modes, by which the pump can be automatically switched among various operating modes to match its energy consumption with the changing vacuum demands of the process equipment, promises energy savings of as much as 98% when compared to constant operation at full power.
The abatement of process gases and by-products is the second area where photovoltaic manufacturers are transitioning from older "scrubber" technologies to more advanced combustion based solutions. Fundamentally, scrubbers simply move the contamination from the process exhaust gas stream to the waste water stream. Many countries, China notably among them, are imposing strict regulations on wastewater discharge, and those regulations are likely to become more restrictive as the industry grows. Scrubbers also carry a significant cost for purchasing, treating and ultimately disposing of waste water.
PV manufacturing exhaust streams variously include materials that are corrosive, flammable, pyrophoric, poisonous, and/or "greenhouse" gases. A well-designed combustion abatement system completely converts these noxious materials to harmless gases and solids that can be safely returned to the environment. Proper design of the combustion chamber is also essential to achieving high energy efficiency. In some cases, the exhaust gas itself can be used to fuel the combustion process, reducing energy consumption to that required to keep the pilot light burning.
The PV industry's transition to high-performance vacuum and abatement systems has been compared to the similar transition that occurred in semiconductor manufacturing over a decade ago when manufacturers there realized that the benefits of advanced technologies far outweighed the increased acquisition costs.
Michael Boger is Strategic Marketing Manager at Edwards Vacuum, 1078-1 Yoshihashi, Yachiyo-shi, Chiba-ken, 276-8523, Japan; email [email protected]