Abstract
The management of livestock manures and slurries noticeably improved since the massive introduction of anaerobic digestion (AD) plants in Italy and other European Union (EU) countries. However, these plants heavily rely on incentives, and the recent switch of European biogas policies from electricity to biomethane potentially threatens the economic viability of manure AD. In this study, three retrofit options are analyzed for an installation in Piedmont (NW Italy) that is currently producing 999 kWel through combined heat and power (CHP). The techno-economic feasibility and the greenhouse gas (GHG) budget is analyzed for each solution. Results show that exploiting current incentives on electricity is vital to fund the retrofit of CHP plants to biomethane. Energy crop and electricity prices, the sale price of biomethane certificates after the end of incentives, and biogas productivity are the critical parameters for the economic profitability of manure AD plants, along with the possibility to deliver biomethane directly to the pipeline grid. This study provides insight to the reconversion of manure AD plants, addressing issues that affect hundreds of installations in Italy and other EU countries.
Highlights
The reduction of greenhouse gas (GHG) emissions and the increase in renewable energy production are two pillars of European policies
The new incentive regimes switched the target from electricity to biomethane with the aim to increase the share of renewable energy in transport
For anaerobic digestion (AD) plants operating with manures, this change potentially hampers their economic sustainability, which is more critical than plants operating with feedstocks with a higher biogas yield, such as organic or food industry waste
Summary
The reduction of greenhouse gas (GHG) emissions and the increase in renewable energy production are two pillars of European policies. 1990 [1], with an intermediate milestone of 32% renewable energy coverage for electricity, heating, and transport by the year 2030 [2]. In this context, bioenergy performs a key role and the production of biogas from anaerobic digestion (AD) has been rapidly increasing in recent years [3,4]. Biogas is produced with developed anaerobic digesters that use different feedstocks, among which are agricultural crop residues and/or dedicated energy crops, livestock manure, organic fraction of municipal solid waste, and wastewater sludge [7]. CHP largely prevails, biomethane production is increasing at a fast rate (+15% in 2019) [8]
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