Sustainability of gasification-based cogeneration with agri-food residues and heat recovery technologies: Techno-economic and life cycle analyses

The valorization of agri-food waste through biomass gasification integrated with heat recovery technologies is a promising option for sustainable renewable energy. Comprehensive evaluation of such energy systems requires both life cycle assessments (LCAs) and techno-economic analyses (TEAs). This study investigates the potential of three agri-food residues—almond hulls, exhausted olive pomace (EOP), and date palm fronds (DP)—as biomass fuels for gasification from a sustainability standpoint. Two configurations for combined production of electricity and heat in the form of hot water are evaluated: one using a cleaning and cooling unit coupled to an internal combustion engine (ICE), and another using an externally fired gas turbine combined with an organic Rankine cycle bottoming unit (EFGT_ORC). Results reveal that the EFGT_ORC cogeneration system consistently requires lower biomass input than the ICE cogeneration unit, with DP fronds demanding the highest biomass input in the ICE configuration at 36 g/s, followed by almond hulls at 32 g/s, and EOP at 28 g/s. ICE cogeneration contributes to higher climate change environmental impact, with emissions around 2.95 × 10−2 kg CO2 eq. for all fuels. In terms of human health, DP fronds have a greater impact in EFGT_ORC cogeneration than in ICE. Almond hulls exhibit slightly better economic performance compared to EOP and DP fronds. However, regardless of the biomass fuel, biomass and electricity price variations significantly affect system sustainability. The ICE system offers faster returns on investment, but is more vulnerable to increasing biomass prices, whereas the EFGT-ORC system demonstrates more resilience to biomass price fluctuations.