(i) Hydrogen economy:

It refers to the techniques of efficient usage of dihydrogen. It also involves the transportation and storage of hydrogen in the form of liquid or gas.

Hydrogen has a very high calorific value as compared to petrol and also it is the most eco-friendly fuel as it burns to give water vapour and hence it can be used in fuel cells to produce electricity. Hydrogen economy is about the transmission of this energy in the form of dihydrogen.

(ii) Hydrogenation:

The process of addition of hydrogen to a given reactant in the presence of catalyst is termed as hydrogen. Hydrogenation is also used to obtain alkanes from alkenes and alkynes. This process is used to reduce a compound in the presence of a suitable catalyst. For example, hydrogenation of vegetable oil using nickel as a catalyst gives edible fats such as vanaspati, ghee etc.

(iii) Syngas

The mixture of carbon monoxide and hydrogen is termed as syngas. Since the mixture of the two gases is used for the synthesis of methanol, it is called syngas, synthesis gas, or water gas.

Syngas is produced on the action of steam with hydrocarbons or coke at a high temperature in the presence of a catalyst.

(iv) Water shift reaction:

It is a reaction of carbon monoxide of syngas mixture with steam in the presence of a catalyst. This reaction is used to increase the yield of dihydrogen obtained from the coal gasification reaction.

(v) Fuel cells:

Fuel cells are devices for producing electricity from fuel in the presence of an electrolyte. Hydrogen is considered to be one of the best fuel for fuel cells as it is eco-friendly and also gives more energy per unit mass of fuel as compared to other substitutes like petrol or diesel etc.