The paper covers a conceptualisation of the meaning of energy and energy policy as well as an empirical analysis of economic growth, energy consumption and CO2 emissions. The empirical research aims at evaluating the advancement of the transformation of the energy sector. It was carried out on the basis of numerical statistics and with the use of percentage indicators to present the changes in energy consumption and CO2 emissions in highly developed and emerging economies. The indicators of the share of traditional and renewable energy resources in the group of largest consumers were employed to display structural changes in the energy sector as well as the simple correlation coefficients to test the intensity of the relationship between the pairs of the following variables: GDP, energy consumption and CO2 emissions. The empirical analysis revealed: 1) in the field of the transformation of the energy sector: a decrease in energy consumption in highly developed countries (mainly in Japan and the EU) and its rise in developing countries with high GDP dynamics (China, Iran and India), 2) a fall in shares of global CO2 emissions in the USA and the EU (by 10.0 pp and 6.9 pp) and a surge in analogous indicators in China and India (15.1 pp and 3.1 pp), 3) the biggest increase in the share of renewables in energy consumption was attained by Brazil and the EU (by 5.3 pp, 4.1 pp), whereas India, Indonesia and China had a considerably greater share of renewables in 2000 compared to 2018 (by 20-23.7 pp).