Abstract
The primary aim of this study is to analyse the efficiency of heating systems focusing attention on the consistency between the estimated consumption based on the declarations made by greenhouse operators and the selected estimation model, and the amounts of fuel officially assigned by the public body. The Italian greenhouse cultivation systems are characterized by a relevant use of economic and material resources. Based on the periodical survey on agriculture carried out by the Italian government, the total national surface devoted to production under greenhouse was about 42,500 ha (ISTAT, 2016) according to ISTAT in 2011. Although many are the contributors to the equivalent energy consumption (about 16 Mtoe for the entire agriculture sector) (Campiotti, 2016), the protected cropping systems account for a consistent part of the total load (considering the limited cultivation area). The average consumption of fossil resources (for heating) and electricity was 23 MWh/ha and 0.8 MWh/ha respectively. In Marche region, the surface covered by greenhouses was about 203 ha (0.7 % of the total in Italy in 2011) (ISTAT, 2011). Focusing on consumption and related emission of fuels used for direct heating, the diesel (the most used fuel in Marche region) (Campiotti, 2013) is responsible of a medium emission level (266 g CO2 eq/kWh). In this study, the authors investigated the use of energy as fuel for heating in nursery systems, considering different production systems. Greenhouse types were grouped considering the characteristics of building structure, crops and type of heating system. Collected information regards: type of greenhouse and cover; heated surface; plants produced; installed power of heating system; operational period; fuel type; average fuel consumption; efficiency and greenhouse requirements. More in detail, based on bearing structure, the typologies of greenhouse individuated are three, eighteen types of cover considering the material used and five typologies of fuels/biofuels or a mix of them. The original sample consists of 62 Small and Medium Enterprises (SME) involved in nursery productions. Regarding the type of structure, the most represented types are tunnels with or without vertical walls or mixed systems. Plastic materials are the most used for cover representing the 76 % of all the materials employed. The most used fuel for heating is diesel (in 84% of enterprises). The covered surface varies between 0.004 ha and 4 ha and 89 % of nurseries have a covered area smaller than 1ha (mean 0.2 ha). The average heating power installed for diesel systems is about 250 kW, with about 59 l/day of fuel combusted. The research highlights the relation between the different aspects characterizing each greenhouse type. The goal of the study is to give useful information to the policy maker for a correct incentivization of greenhouse production by providing data of energy consumption more linked to the real greenhouse system employed in the region. The results of this study could support the creation of a more virtuous production chain and could support regional policies also on energy use efficiency and GHG emissions reduction.
