The most important factor which can act as a constraint on economic growth of a country is the availability of energy:

1. There is a direct correlation between the degree of economic growth, size of per capita income and per capita consumption of energy.
2. Energy is an essential input for all productive and economic activities like agricultural, industrial and service sectors providing services of banking, telecommunication, communication, etc. Energy is used for non-commercial purposes also for lighting, heating and cooking, etc. More than 60 percent of Indian households depend upon different sources of energy for their regular needs.

Differentiate between Commercial and Non-commercial sources of energy:

1. Commercial sources of energy are generally exhaustible i.e. non-renewable whereas the noncommercial sources of energy are generally renewable in nature.
2. Example of commercial sources of energy are coal, petroleum, electricity whereas example of non-commercial sources of energy are firewood, agricultural waste and dried dung.
3. Commercial sources of energy are bought and sold in the market, whereas non-commercial sources of energy are found in forests/ nature, so are available free of cost, i.e., are provided by nature.