Undisputedly, Carbon Dioxide (CO2) has gained a reputation as the most controversial of the industrial gases, nine out of ten times hogging the headlines and often for the wrong reasons, rather than the right ones.

Existing in Earth’s atmosphere as a gas, it currently has a global average concentration of approximately 387ppm (parts per million) by volume. It also has the rare distinction of being one of the first gases to be described as a substance distinct from air.

Carbon dioxide is a valuable industrial gas with a large number of uses that include the production of chemicals such as urea, use in refrigeration systems, as an inert agent for food packaging, carbonation in beverages, welding systems, fire extinguishers, water treatment processes, as a precipitated calcium carbonate for the paper industry, and many other emerging large and small scale applications.

Demand/Supply & Prices
Short supply was witnessed in various markets both last year and this. South Africa has been experiencing an imbalance in its demand/supply equation for almost two years, due to erratic power supply. The country was dependent (and to some extent still is) on the import of CO2 to meet domestic demand, while the UK and Ireland too, were under tight supply last year.

In Australia, an explosion at the Apache Plant has forced BOC Gases Australia to cease production of CO2, thereby creating a tight supply for the local market.

Rising energy and input prices (particularly steel) have forced the manufacturers in different geographies to raise prices for carbon dioxide. Starting from January, all the companies have given notices about the price hikes in the range of 10-20%. Praxair had increased the carbon dioxide price in America in January 2008, closely followed by European and Asian companies.

Production
Unlike atmospheric gases, air separation is not the primary source of carbon dioxide. Though sometimes it is derived from directly combusting a fuel, the most economical way to produce carbon dioxide is to recover it as a byproduct from other companies’ manufacturing processes or from natural wells.

CO2 production can be classified into 3 main segments:
Ultra Pure - 99.999% pure CO2
Beverage and Food Grade - 99.985% pure CO2
Industrial Grade - 99% pure CO2


The most common operations from which commercially produced carbon dioxide is recovered are industrial plants which produce hydrogen or ammonia from natural gas, coal, or other hydrocarbon feedstock, and large-volume fermentation operations in which plant products are made into ethanol for human consumption, automotive fuel or industrial use.

Breweries producing beer from various grain products are a traditional source, while corn-to-ethanol plants have been the most rapidly growing source of feed gas for CO2 recovery, particularly in the US.

There is a marked difference among continents in terms of feedstock for CO2 production. In Europe for example estimated installed capacity is around 5 million metric tons, with approximately 70% based on raw gas from ammonium production and the remaining which is derived from reformers at refineries, ethylene oxide production and from natural wells.

Industrial CO2 is also produced from limekilns, such as those used in the production of sodium carbonate and in the Kraft wood pulping process. This involves the heating of a raw material such as limestone.

In the US, Italy, Norway and Japan, some CO2 is extracted from natural CO2 wells. It is also recovered during the production and treatment of raw natural gas that often contains CO2 as an impurity. A large proportion of all CO2 recovered is used at the point of production to make further chemicals of commercial importance, chiefly urea and methanol. The CO2 recovered for other commercial uses is purified, liquefied, delivered and largely stored as a liquid, at 20 bar pressure.

Applications
A simple, yet versatile gas used in a growing number of applications and in a wide range of industries, carbon dioxide is inert, colourless, odourless and tasteless. It can be easily and safely liquefied, solidified, handled, and stored. In its liquid form, it readily interacts with water to form carbonic acid or carbonated water, and is commonly the beginning point for the worldwide beverage industry.

In its solid form of dry ice, it has twice the cooling capacity of water ice.

CO2 is most widely used in the food industry, with food grade CO2 (in gaseous form) finding application in the beverage industry to carbonate soft drinks. It is also used in the production of beer, wine and champagne, while liquid carbon dioxide is used widely for the freezing of meats, poultry, vegetables, and fruits.

Dry ice is used to cool meats prior to grinding and also to refrigerate meat and poultry during transit. Foods in packages can be kept fresh by creating a CO2 atmosphere in the package.

It is used in the freezing of food products such as poultry, meats, vegetables and fruit and the refrigeration and maintenance of ideal atmospheric conditions during transportation of food products to market.

This prolongs the products’ shelf life and preserves the taste. Food processing involving meat requires that temperatures be kept low (during the process) to avoid bacterial activity and smearing of fat when cutting, milling or forming.

In its gaseous form, CO2 is utilised on a large scale as a shield gas in MIG/MAG welding, where the gas protects the weld puddle against oxidation by the surrounding air.

It can also be found in many fire extinguishers and can be used on flammable liquids or electrical fires.

Dry ice is used to create surface embrittlement and abrasive action to strip paints, remove deposits from turbines and remove radioactive contamination from plants and machinery. Rice dry ice is the most useful form in these applications.

Outlook
With the growing usage of CO2 in different forms, demand is maintaining a healthy rate and is likely to grow further, with the living standard and purchasing power of developing countries increasing, CO2 demand will increase in food and beverage industry, which is its most significant usage sector.

With crude oil prices hovering at an all time high and threatening the global economy, Enhanced Oil Recovery (EOR) is one field where CO2 application and usage are bound to grow in future. Paper and pulp industries have shown growing usage of CO2, so summing all the factors, we are anticipating a strong and accelerating demand in the short and medium term.