Xenon is now a gas in demand particularly in the increased use of plasma displays, headlights and flash bulbs.
Xenon, best known till a few years back as an inert gas filled inside incandescent lamps, is named after a Greek word, which means ‘stranger’. These days xenon, the rarest of the noble gases, is becoming increasingly familiar and is finding increased uses and usage in many fields. This colourless, heavy and odorless gas occurs in the earth’s atmosphere in trace amounts, roughly 0.087 parts per million. Although generally non reactive, it can undergo a few chemical reactions.
It is a key element in the production of plasma displays – behind every pixel on a plasma screen is a minute amount of xenon. It also generates the brightest white light of any gas, a property which makes it ideal for devices like flash bulbs and headlights.
Xenon is produced commercially in an air-separation plant. It is obtained as a by-product of the separation of air into oxygen and nitrogen, the air is then liquefied and distilled. The oxygen is redistilled; the least volatile portion contains small amounts of xenon and krypton, which are adsorbed on silica gel directly from the liquid oxygen.
The crude xenon and krypton thus obtained are separated and further purified by distillation and selective absorption, at controlled low temperatures, on activated carbon. Remaining impurities are removed by passing the xenon over hot titanium, which reacts with all but the inert gases. Extraction of a litre of xenon from the atmosphere requires around 220 watt-hours of energy.
Xenon – Applications
Xenon is most famously used in light-emitting devices called xenon flash lamps, which are used in photographic flashes and stroboscopic lamps. Continuous, short-arc, high-pressure xenon arc lamps have a colour temperature closely approximating noon sunlight and are used in solar simulators and some projection systems.
Xenon has been increasingly used as a general anaesthetic, though the cost is slightly higher. In nuclear energy applications it is used in bubble chambers, probes, and in other areas where a high molecular weight and inert nature is a desirable quality.
It is the preferred fuel for Ion propulsion due to its high molecular weight and can be stored as a liquid at near room temperature, yet easily converts back into a gas. However, there is an emerging controversy over its possible future widespread use in the aerospace industry, as it is permanently lost to space, further decreasing the limited supply in the Earth’s atmosphere.
Soaring demand and supply constraints
Demand for xenon is rising at a rate far higher than the industry average and is outstripping the supply. This in turn has led to higher prices, though major producers around the world are gearing up to increase the production of this rarest of rare gases.
The usage of xenon is spreading throughout the semiconductor industry and anaesthesia, with the European market alone is estimated to consume more than a million litres of xenon as anaesthesia.
But fame brings problems, and with xenon the problem is its rarity. It exists in the atmosphere, though it accounts for less than one part in 10 million. There are only a few (around 80) air separation units in the world capable of producing it cost effectively and their combined annual production, amounts to nine to ten million litres.
The cost of xenon has been on the rise due to a number of novel new uses for the rare gas. With demand and prices on the rise, there is a growing concern that cost or availability will hamper its applicability.
This is the situation within most of the users segment and most particularly in semiconductor manufacturing, where the price of xenon has risen while device prices have continued to decline.
With demand and prices on the rise, there is a growing concern among all the user segments that costs will affect their profit margins. Increased costs are due primarily to product sourcing and energy costs, as well as supporting investment in production, transportation and storage.
All the industrial gas producers have increased the price of xenon several times in the last year. Over the period of last twelve months the price has risen by more than 300%. Demand is anticipated to remain strong for the next few years, with little or no additional capacity expected until 2010.
Furthermore, because xenon is such a rare gas, there are a limited number of additional operating air separation plants of sufficient size to justify the economics for extracting xenon, though Air products has recently launched a xenon recovery system, which according to the company is capable of saving 50% of xenon cost by recovering the gas.