Environmental and Economic Analysis of an Anaerobic Co-Digestion Power Plant Integrated with a Compost Plant

Sara Rajabi Hamedani,Antonio Pantaleo,Francesco Santoro,Andrea Colantoni,Maurizio Carlini,Mauro Villarini,Massimo Cecchini

doi:10.3390/en13112724

Sara Rajabi Hamedani, Antonio Pantaleo + Show 5 more

Open Access

https://doi.org/10.3390/en13112724

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Abstract

Italian power generation through anaerobic digestion (AD) has grown significantly between 2009 and 2016, becoming an important renewable energy resource for the country, also thanks to the generous incentives for produced electricity available in the last years. This work focuses on the economic and environmental issues of AD technology and proposes a techno-economic analysis of investment profitability without government support. In particular, the analysis focuses on an AD power plant fed by zootechnical wastewater and agro-industrial residues coupled to a cogeneration (CHP) system and a digestate-composting plant that produces soil fertilizers. We aim to determine the economic profitability of such AD power plants fed by inner-farm biomass wastes, exploiting digestate as fertilizer, using the cogenerated heat and taking into account the externalities (environmental benefits). Environmental analysis was carried out via a life cycle analysis (LCA), and encompassing the production of biogas, heat/electricity and compost in the downstream process. The un-released environmental emissions were converted into economic benefits by means of a stepwise approach. The results indicate that integrating a compost plant with a biogas plant can significantly increase the carbon credits of the process. The results were evaluated by means of a sensitivity analysis, and they report an IRR in the range of 6%–9% according to the Italian legislative support mechanisms, and possibilities to increase revenues with the use of digestate as fertilizer. The results significantly improve when externalities are included.

Highlights

Depletion of natural energy resources is compelling our planet to face crucial challenges
The thermo-economic optimization and optimal sizing of other hybrid systems composed by biomass and natural gas [23,24] or biomass and concentrating solar [25,26] have been recently proposed in literature. Feedstock availability is another advantage of anaerobic digestion (AD) power plants, since biogas can be produced from a wide range of feedstocks
Revenues generated by sales of electricity, heat and compost as well as biophysical sources including externalities were taken into account

Summary

Introduction

Depletion of natural energy resources is compelling our planet to face crucial challenges. The thermo-economic optimization and optimal sizing of other hybrid systems composed by biomass and natural gas [23,24] or biomass and concentrating solar [25,26] have been recently proposed in literature Feedstock availability is another advantage of AD power plants, since biogas can be produced from a wide range of feedstocks. To the best of our knowledge, no study assesses the overall environmental and economic performance of AD power plants, together with the downstream technologies required for their digestate management. This work aims to perform a Energies 2020, 13, x FOR PEER REVIEW comprehensive economic evaluation with the internalization of the monetized environmental benefits from a co-digestion plant,values coupled a downstream composting system. LCA methodology, the simulation model, the main components and cost–benefit approach; Section and discusses the main results of the work and Section 4 draws the conclusions

LCA and Global

MWh from co-digestion plant

Economic

Discussion

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