Total energy consumption (sometimes also referred to as energy supply) is the amount of energy necessary to satisfy the energy needs of a country. It is calculated as the sum of the total energy consumption in the form of solid, liquid, gaseous, nuclear fuels and renewable energy sources and the net import of electricity.

The data on total energy consumption by fuel with regard to different environmental impacts of fuels enable an assessment of the environmental impact of energy consumption. The use of fossil fuels causes greenhouse gas emissions and air pollutants, whereby the emissions are significantly lower in the use of natural gas than in the use of coal. Furthermore, the production and transport of fossil fuels is an important pollution element of the environment. The use of fossil fuels is also limited with supplies. On the other hand, the nuclear energy use does not cause greenhouse gas emissions and air pollutants; however, it is problematic due to nuclear waste. The use of renewable energy sources is the least harmful for the environment with regard to emissions; however, the consumption of this energy can still affect an ecosystem or landscape. As a result, the consumption of any energy influences the environment. The reduction of the impact is possible with a change of the share of fuels and, primarily, by lower energy consumption.

Total energy consumption in 2008 amounted to 7,749 ktoe. In comparison with 2007, it increased by 5.6 %, which is significantly more than the average annual growth during the period 1992-2008, when it increased by 2.4 % annually, and more than the average annual growth after 2000, when the average annual growth was 2.5 %. In the structure of total energy consumption in 2008, liquid fuels prevailed (37 %), followed by solid fuels (20 %), nuclear energy (21 %), gaseous fuels (13 %) and renewable energy sources (RES) (11 %). The net import of energy represented -2 % (more energy was exported than imported) of total consumption.

The use of fossil fuels increased by 15 % in the 1992-2000 period. This is largely due to an increase in the use of liquid fuels, followed by an increase in the use of gaseous fuels; the use of solid fuels had significantly reduced on account of the cessation of the use of coal in final consumption sectors. The nuclear energy use increased by 20 %, and the use of renewable energy sources by 43 %, primarily on account of the new assessment of the use of wood biomass in households. The total energy consumption increased by 20 %.

In 2008, the use of all fuels, including nuclear energy and renewable energy sources, was higher with regard to 2000. The use of fossil fuels increased by 20 %, which is largely due to liquid fuels, which contributed almost two thirds of the total use, followed by solid and gaseous fuels almost in an equal share. The nuclear energy use increased by 32 %, primarily due to new evaporators, other technical improvements and a year without repairs. A favourable hydrologic year has by far influenced the increased use of renewable energy sources the most, which increased by 12 %. The total energy consumption increased by 22 %.

The most important renewable energy sources in Slovenia are hydropower and wood biomass. Since the consumption of wood biomass in households is only estimated, it is impossible to follow the trends of use of wood biomass in households. In industry, the data on the use of wood biomass are obtained on the basis of questionnaires, while the use of hydropower on the basis of the generated electricity. The capacities for electricity generation from hydropower increased in the period 1992-2008; however, the production is dependant also on the river stage. Other renewable energy sources (biogas, solar energy, etc.) have only a small share.

Due to differences in the growth of the use of individual fuels, shares in the total energy consumption changed as well. In 2008, the share of liquid fuels, with regard to 2000, was higher by 1 percentage point, and with regard to 1992 by 6 percentage points. Nuclear energy also increased its share by 1 percentage point with regard to 2000 and 1992. Gaseous fuels have the same share in all three years. In 2008, the share of renewable energy sources decreased by 1 percentage point with regard to 2000 (data on the use of RES before 2000 are not comparable with the data after this year – see indicator EN18). The share of solid fuels decreased with regard to 2000 and 1992, which is positive, since they are the biggest pollutant of the environment. They are used only in the generation of electricity and heat as well as in the industrial sector (paper and pulp industry, concrete production). In 2008, more encouraging trends can be noticed in renewable energy sources with regard to the previous year; on the other hand, trends for liquid fuels are more problematic, since in 2008 their use significantly increased after a decrease in 2007.

Due to changes in the share of fuels in the total energy consumption, the CO₂ intensity in the total energy consumption is changing as well, which influences the total CO₂ emissions. The structure of the total energy consumption did not essentially change in the past; moreover, the consumption increased. The consequence is that the emissions of energy sources in the period 1992-2007 increased by 23 %.

In the structure of the total energy consumption, bigger changes are expected in wider consumption towards a reduced impact on the environment and lower CO₂ emissions due to future technological improvements in the transformation sector, which will also include a replacement of fuels (gas units in the Šoštanj thermal power plant were constructed in 2008, while additional gas units are planned in other locations as well as a new coal block in Šoštanj) and the continuation of the trend of replacing liquid fuels with gaseous fuels and wood biomass.

In the period 2000-2007, the growth of the total energy consumption in the EU-15 was 0.5 %, which is 1.4 percentage points less than in Slovenia. In 2007, the growth was negative in the EU-15 (–1.2 %), while in Slovenia it amounted to 0.2 %. In the structure of the total energy consumption in the EU-15, the share of liquid fuels is bigger than in Slovenia; namely, 38 % (in 2008, Slovenia strongly closed in on this share). The share of gaseous fuels is also significantly bigger (25 %), while the shares of nuclear energy (14 %), solid fuels (15 %) and renewable energy sources (8 %) are smaller. In the comparison of the trends of shares of fuels, the decrease in the share of RES is most striking, since in the EU-15 and EU-10 this share is increasing.

The total energy consumption provides us with a review of the energy consumption in the country. It is influenced by the entire legislative spectrum from the area of energy (efficient energy consumption, renewable energy sources, etc.) and the reduction of greenhouse gas emissions (emissions trading) and air pollutants (threshold concentration of emissions for individual equipment). Since the objectives of policies in the indicated areas are directed towards a reduction of the impact of energy on the environment, larger structural changes towards an increase in the use of natural gas, renewable energy sources and higher efficiency of energy consumption are expected in the future. The last package of EU regulations in the area of energy and climate change, which was adopted in 2008, also alluded to that.