The technical and economic assessment of plants producing electrical and/or thermal energy from renewable sources (biomass, wind, photovoltaic, hydroelectric) is essential to design the plant itself and monitor its performance. The system's theoretical energy capability is calculated starting from the plant's technical features, and namely the specifications of the renewable source used. The figures obtained from the technical analysis are then used to reconstruct the plant's Profit and Loss Account and the assessment of the main indicators of interest (Internal Rate of Return IRR, Net Present Value NPV, Payback Time). Following plant commissioning, its consistency with respect to preliminary assessments is monitored, production capacity is verified through the comparison between the actual energy production data recorded by the plant's control system and by the meter and the estimated energy capability.
Overall view of an assessed biomass (biogas) plant.
The assessment makes it possible to have a comprehensive picture of the structure of small-medium sized (P<1 MWe) energy production plants from renewable sources and to compare designer estimated energy capabilities with those extracted from literature data (often generic) and/or from LEAP's experience in the field of energy production from renewable sources, informing the plant's operator in order to take them into account during operation. This knowledge is fundamental to achieve distributed energy generation: a high number of small-medium sized plants to replace the traditional large-sized plants.
A variety of company types interested in constructing and operating renewable energy production plants: from individual farms to farming cooperatives or consortia (mainly for photovoltaic and biogas plants), from manufacturing companies to corporations (other photovoltaic and biomass plants, wind and hydroelectric systems).
Energy capability of a photovoltaic plant and windiness of a site for mini-wind system.
Technical economic assessment of an anaerobic digestion plant from plant biomass and livestock waste of a farming company
For a farming Company located in the Parma province, a two-stage anaerobic digestion plant supplied with corn and triticale silage plus cattle slurry and equipped with alternative motor with 999 kWe of power was analyzed. The technical economic assessment has surveyed the features of the supply systems of the materials conveyed to digestion, of the fermentation system itself (primary digester + post-digester), of the system for biogas conversion into electricity (internal combustion engine), of the system for separation and storage of the digestate and injection into the national electricity grid. Annual biogas production and the number of hours/year of system operation were estimated, from which the annual production of electrical and thermal energy were obtained, as well as the amount of produced digestate. The cash flows generated by the plant were then reconstructed, in view of the suitable incentives of the produced electricity, and IRR, NPV and Payback Time of the investment were calculated. After commissioning, consistency with the preliminary project was assessed and the correspondence between electricity produced and that fed into the grid and the estimated figures. The initial investment features an 18% IRR, NPV equalling to 9 M€ and Payback Time between 5 and 8 years depending on the discount rate considered. The technical assessment has shown that calculated biogas capability is lower than the estimated one, however the plant is consistent with the project and the motor is able to deliver the nominal power.
Leading Italian Banking Group Farming Company located in the Parma province
Bortoluzzi G., Gatti M., Sogni A., Consonni S. Biomethane Production from Agricultural Resources in the Italian Scenario: Techno-Economic Analysis of Water Wash - Chemical Engineering Transactions vol. 37, 2014
Average monthly electrical power delivered by the plant's motor.