Mercury Isotopes for Efficient UV Lamps and Fluorescent Lighting

Mercury-discharge lamp technology is the basis for fluorescent lighting and UV lamps for water purification. We showed that by modifying the ratios of the seven stable isotopes of mercury from their natural relative abundances, lamp efficiencies can be improved by over 20%. In parallel, recent methods of isotope separation can make the cost of the optimized isotopic mixtures economically competitive. We review these recent developments and discuss implications for future lighting and UV lamp technologies.

I. Introduction

Mercury-Discharge fluorescent lamps have dominated the lighting market for many years. Despite the rapid growth of the LED market, it is likely that linear fluorescent lamps will continue to persist for several decades due to the many billions of fixtures installed worldwide. Development of new phosphors that do not require rare earths was reported recently in a press release by the Department of Energy, indicating an ongoing investment in fluorescent lighting technology [1]. Other advances include a steady decrease in the amount of mercury used in each lamp, enabled by more precise methods of dispensing as well as improvements in materials to reduce the absorption of mercury inside the lamp. Further improvements in energy efficiency and lamp lifetime are incremental but have been steady over the years. Recently, we proposed a method for dramatically improving the energy efficiency of fluorescent lighting, simply by using an optimized mixture of mercury isotopes instead of natural mercury [2]. This is a drop-in replacement, which requires no redesign of lamps, that could be readily adopted for use.