Get to know hydrogen
Hydrogen is the simplest and most abundant element in the universe. It is a major component of water, oil, natural gas and all living matter. Despite its simplicity and abundance, hydrogen rarely occurs naturally as a gas on Earth. It is almost always combined with other elements. It can be produced from oil, natural gas and biomass, or by splitting water using renewable solar or electrical energy. Hydrogen is an energy carrier used to move, store and deliver energy produced from other sources.
Hydrogen is very widespread on Earth and is also the most abundant element in the universe (about 75% by mass of the matter in the universe is hydrogen). It is present in water, in almost all organic compounds and in biomass.
Hydrogen, an element consisting of just one proton and one electron, is the simplest and lightest diatomic gas. On Earth it is found in the largest quantities in bound form, mainly in water. The first element of the periodic table was discovered by Henry Cavendish nearly 250 years ago. Under normal conditions it is colourless, odourless, highly flammable and a very good conductor of heat. Its density is about 14 times lower than that of air under normal conditions, and its diffusivity is very significant, i.e. it mixes very well and quickly.
Hydrogen can be produced, for example, by the electrolytic splitting of water, which yields oxygen and hydrogen, and the end product of burning hydrogen is again water, which thus returns to the cycle. Industrially, it can also be obtained from natural gas by steam reforming, and it can also be produced from methanol, ethanol and biomass.
Because its properties are favourable in many respects – it is non-toxic, non-corrosive, non-carcinogenic, not a greenhouse gas and not radioactive; if accidentally released into the environment it causes no lasting pollution; and its calorific value is one of the highest of all known elements – thousands of researchers and engineers worldwide are currently working to exploit its potential.
Hydrogen can be used as an energy source and fuel in countless areas, and it may play a dominant role in energy distribution in the future.
The use of hydrogen is nothing new: it has been used for nearly 250 years and extensively in the chemical industry for about 100 years. Nearly 80 million tonnes of hydrogen are currently produced worldwide each year, and in Hungary too there are several industrial hydrogen production facilities, e.g. in Százhalombatta, Kazincbarcika and Budapest. It is typically used in ammonia production, oil refining and many other industries, and industrial gas companies also produce hydrogen as a routine operation, albeit in much smaller quantities.
The traditional way of producing hydrogen in the laboratory, often demonstrated at school, is to pour hydrochloric acid onto zinc. This produces hydrogen gas and zinc chloride:
Zn + 2HCl = ZnCl2 + H2
Another well-known method is reacting an alkali metal, such as sodium, with water. The vigorous reaction produces hydrogen gas:
2Na + 2H2O = 2NaOH + H2
The above reactions are not used for industrial-scale, large-volume hydrogen production. Hydrogen occurs in a great many substances, so in principle it can be produced in many different ways, but in current practice the absolutely dominant method is production from fossil fuels, within which production from natural gas, or more precisely methane (CH4), is decisive. This latter method is also called steam reforming, abbreviated SMR (Steam Methane Reforming).