World Energy Efficiency Day is celebrated on 5 March, a date designated by the United Nations (UN), to reflect and raise awareness on the importance of the rational use of energy for the well-being of the planet itself.

The concept of efficiency refers to the optimal use of energy, so it encompasses any energy activity carried out that is not harmful to the environment. To achieve this, equipment and installations must be energy efficient, and it is also necessary to adopt responsible consumption habits and make use of renewable energy sources. In the current European political and environmental context, renewable energies and energy transition are of crucial importance, given the urgency of reducing the EU’s energy dependence and the consolidation of its actions to combat climate change.

According to data provided by Eurostat in 2020, in terms of EU energy consumption, petroleum was the most widely used energy source, accounting for 35% of total energy consumption. In contrast, renewable energies accounted for only 12%. The percentage of consumption of these energies varies according to each EU member state. In the specific case of Spain, according to Eurostat statistics for the year 2020, the total consumption of petroleum products reached 45%, while renewable energies did not even reach a tenth part, with a consumption of 8.9%. These data highlight the need to increase the use of renewable energies, promoting the hasty transition to green ones.

At EU level, several strategies, plans and regulations promote the use of renewable energies and the energy transition towards clean and green energy sources. Starting with one of the fundamental treaties of the EU, the Maastricht Treaty, which has established environmentally friendly growth as a substantial requirement. Later, the principle of sustainable development was incorporated into the objectives of the European Community with the Treaty of Amsterdam. Today, the European Green Pact and the RePowerEU plan are the most representative in this area.

LIFE ECODIGESTION 2.0 aims to promote biogas as a renewable energy source capable of being used to supply wastewater treatment plants (WWTP), thus reducing energy consumption costs and promoting the use of a green and clean source. The process of obtaining biogas characteristics are compatible with the principles of circularity and preservation of environmental resources, as it is obtained from organic waste through anaerobic decomposition. Furthermore, the innovative technology that this project proposes to expand, offers the possibility of generating a secondary use for the sludge processed in the wastewater treatment plants, as this digestate is rich in nutrients and is subsequently used as fertilizer for both reforestation and agriculture.

In short, as one of the main objectives of sustainable development in the EU is the transition towards green and clean energy, the LIFE ECODIGESTION 2.0 project is a viable alternative, capable and suitable for reproduction and replication on a large scale. Through the use of surplus biogas as an energy engine, attributing the developed technology to model cities, involving administrations and other public-private entities to encourage and promote its use.