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Top2. Description Of The Solution
The area under study is located within Palermo province (Italy) and was chosen using GIS technology, by considering current agriculture in the area and the existing infrastructural network.
Through some 65,816 ha of cultivated wheat, a substantial amount of by-products (mainly straw) is generated yearly. This represents an important energy source, relatively easy to access both in terms of cost and collection.
Potential success of an agro-energy chain depends mainly by the logistics of a production organization and by power plant size. The latter should be dimensioned taking into account biomass availability on one side and cost/benefits of the installation on the other.
Some 3 t/ha of wheat straw dry matter are produced yearly through wheat cultivation (Pellerano, Pantaleo, Tenerelli, & Carone, 2007; Pantaleo, Pellerano, & Trovato, 2002). The farmers generally incur substantial costs to dispose of the straw. For this reason, the use of straw for energy production may represent an opportunity to create new economies throughout the wheat production value chain.
The area under analysis presents also 300 ha of forestry able to generate some 30,000 t/yr of residual wood. Using these products for energy production induces no substitution of food crops with energy crops, but only a sustainable way to dispose of by-products.
Power plant size was tailored to the area under analysis, considering biomass availability and the relative costs for collection and potential plant revenue based on the current national incentive schemes (Decreto del Ministero dello Sviluppo Economico, 2008).
GIS technology allowed delimitation of the area. The accomplished analyses suggest 1,000 kWel plant size for 8,000 hrs/yr running time. This requests some 11,000 t/yr of biomass with 14MJ/kg Low Heating Value (LHV).
For plants of this type, an Organic Rankine Cycle (ORC) generator coupled with a diathermic oil boiler (up to 300 °C temperature, Gaia, Scheidegger, Bini, & Bertuzzi, 2000) is a suitable choice.