Improving the greenhouse energy efficiency through the reuse of agricultural residues.

The consequences of changed global climate conditions, connected to the increase of greenhouse gas, made the European Union set challenging objectives in terms of improving energy efficiency and use of renewable energy sources. Within this framework, agriculture plays a significant role, mainly by energy use for protected cultivation. In the present paper the potential of biomass resources for bioenergy production on a farm and use for tomato greenhouse production was investigated. One of the characteristics of a greenhouse farm in Southern Italy, as in many similar cases in the Mediterranean basin, is its production diversification in order to spread economic risks by diversified agricultural production. A greenhouse farm located in Basilicata Region (Southern Italy) was therefore analyzed. Biomass residues from additional agricultural production (i.e., cereals, olives, grape and livestock), such as straw, pruning from orchards, livestock manure, etc., could be used for heating and electric power in the greenhouse. The quantity of these agricultural residues, the lower heating value (LHV) and the humidity for different types of biomass were estimated, and an energy balance for the greenhouse farm formulated. An analysis was carried out comparing the energy production from agricultural residues and the energy demand for greenhouse tomato production, then the global energy efficiency of the system was estimated. From the results it can be concluded that 50% additional energy was necessary. Renewable energy sources (i.e., solar panels or small wind turbines) can be used, so the general energy efficiency and self-sustainability of the greenhouse farm was improved.