Although invariably in the headlines as the answer to future fuel and transportation challenges, hydrogen fulfils a significant role in a multitude of applications.
Often termed as the ‘fuel of the future’, hydrogen (H2) is the most abundant element in the universe, but is almost absent from the atmosphere.
Individual molecules in the upper atmosphere can gain high velocities during collisions with heavier molecules, and therefore become ejected from the atmosphere.
Hydrogen is the lightest of all gases, approximately one-fifteenth as heavy as air and with the highest combustion energy release per unit of weight of any commonly occurring material.
Hydrogen can be produced in several different ways, but economically the best processes involve the removal of hydrogen from hydrocarbons. Commercial bulk hydrogen is produced by the steam reforming of natural gas, where at high temperatures of around 700-1100°C, steam (water vapour) reacts with methane to yield carbon monoxide and H2.
Another important method for H2 production includes the partial oxidation of hydrocarbons.
2 CH4 + O2 → 2 CO + 4 H2
Some industrial processes with relatively small hydrogen requirements produce some or all of their needs using compact generators. In the past, ammonia dissociation was a common technology choice. More recently, improvements in small packaged electrolytic and hydrocarbon reforming systems have made these routes to small volume hydrogen production increasingly attractive.
Hydrogen finds applications in a plethora of industries. It is most widely used in the production of ammonia – a chemical substance used for fertilisers, explosives and dyes and produced using the Haber process.
In this process, hydrogen and nitrogen react together in the presence of an iron catalyst at around 450°C and 20 MPa pressure. A second important application is in petroleum refining, where it finds use in the removal of sulphur contained in crude oil. Hydrogen is catalytically combined with various intermediate processing streams and is used, in conjunction with catalytic cracking operations, to convert heavy and unsaturated compounds to lighter and more stable compounds.
In the electronics segment hydrogen is used as a carrier gas for such active trace elements as arsine and phospine, and in the manufacture of semiconducting layers in integrated circuits.
In float glass manufacturing, hydrogen is required to prevent oxidation of the large tin bath, while in the food industry it is employed to hydrogenate liquid oils (such as soybean, fish, cottonseed and corn), converting them to semi-solid materials such as shortenings, margarine and peanut butter.
User Industries share
Total worldwide installed capacity of hydrogen is around 600 Billion Nm3 per annum, consumed by varying industries.
Demand and Prices
Hydrogen is a key component in the production of heavy and non-conventional crude oil, such as tar sands or shale oil. Since such production is growing rapidly, hydrogen consumption has increased accordingly and demand for hydrogen has maintained a far higher value when compared to the whole industry average.
Input costs have a direct bearing on the prices and as with whole industry, prices of hydrogen have risen in the range of 10-20%. As the latest company to do so, Praxair announced a price hike of 10-20% for hydrogen in the US.
Fuel of the future
Much has been said about hydrogen being the ‘fuel of the future’ due to its abundance and its non-polluting combustion products. But our industry should consider the fact that other forms of energy must be used to produce the hydrogen which will be used as fuel.
Most hydrogen is bound up in compounds such as water or methane, and energy is required to break the hydrogen free from these compounds, then separate, purify, compress and liquefy the hydrogen for storage and transportation to user segment.
Widespread production, distribution and use of hydrogen will require many innovations and investments to be made in efficient and environmentally-acceptable production systems, transportation systems and storage systems. Which hopefully should happen in the near future.
Along with the current using industries, which all are showing a very healthy growth rate, many major car companies including Honda Motor Company (HMC) and Bayerische Motoren Werke AG (BMW) have released cars that use liquid hydrogen as a fuel source.
While these vehicles are not yet ready for mass consumption, hydrogen-powered vehicles do have the potential for commercialisation in the future. However, in addition to the further development of hydrogen-powered technology, new infrastructure such as hydrogen refuelling stations would need to be built and hydrogen-powered vehicles would have to meet stringent safety requirements.
Health and Safety
Hydrogen poses a number of hazards to human safety, from potential detonations and fires when mixed with air, to being an asphyxant in its pure, oxygen-free form. In addition, liquid hydrogen is a cryogen and presents dangers of frostbite.
Hydrogen dissolves in some metals and in addition to leaking out, may have adverse effects on them such as hydrogen embrittlement. Hydrogen gas leaking into external air may spontaneously ignite. Moreover, hydrogen fire, while being extremely hot, is almost invisible and thus can lead to severe burns.