Biomass in District Energy Systems

Buildings are one of the major users of energy in the European Union, accounting for almost half of the total consumption. In this scenario, renewable energy sources play a fundamental role in the transition towards a low-carbon society, and promoting their use is vital for the future of Europe. This work focuses on the use of district heating networks supplied with energy from biomass as a form of sustainable development for cities and communities, with attention to the Italian situation. After a first introductory part dealing with the European context of district energy networks, the focus shifts to Italy. It is introduced the diffusion on the national territory of district systems with a description of the most used energy sources that power these systems. To demonstrate how the use of biomasses in district energy networks represents a valid alternative to fossil fuels an analysis of the utilization of forests for wood harvesting in the Italian energy sector is carried out, showing how greenwoods and forests can withstand even greater exploitation for the collection of wood material for energy production. In order to prove the feasibility of the switch, a case study district, representative of the Italian residential building stock, is analysed. The district is firstly studied to evaluate the energy demand for space heating, and subsequently investigated by comparing different strategies for its energy efficiency improvement, all dealing with materials coming from wood processing, and switching from a decentralized energy system based on fossil fuels to a centralized network supplied by biomass. The results of the analysis show interesting results in primary energy consumption savings at least 38%, highlighting the potential of the demonstrated approach. Final remarks explain that, with the correct support of policies and awareness on the status of national forestry ecosystems, benefits are achievable through more intensive use of forests, leading to a higher share of natural feedstock in materials for the energy enhancement and energy production, that will help in reaching European sustainability goals.