Energy Recovery from Forest Residues: Thermodynamic Modeling of a Rankine Cycle

The increasing demand for sustainable energy solutions has intensified interest in lignocellulosic biomass as a renewable alternative to fossil fuels. This study assesses the bioenergy potential from maintenance activities on a university campus in southern Brazil, typically underutilized resource for energy recovery. Residues, though poorly managed, present a viable pathway for waste valorization and renewable energy generation. A comprehensive physicochemical characterization was conducted through proximate and ultimate analyses, along with moisture content and higher heating value (HHV) determination. Biomass characterization recorded fixed carbon (20.14–22.45%), volatile matter (76.02–77.95%), ash content (1.56–2.39%), and calorific values (18.63–19.59 MJ/kg). The ultimate analysis recorded carbon (46.10–48.79%), hydrogen (5.96–6.35%), oxygen (44.30–47.14%), and nitrogen (0.32–0.79%). To evaluate its energy recovery potential, a steady-state thermodynamic model simulated the combustion of 50 kg/h lignocellulosic biomass in an incineration system coupled with a Rankine cycle power plant, achieving a peak output of 63.32 kW. The novelty lies in modeling the energy recovery potential of a highly heterogeneous biomass stream, derived from non-industrial forest maintenance, an area scarcely explored in the literature. This research provides valuable data and modeling insights to guide energy systems design using low-grade, heterogeneous biomass fuels. Additionally, the study demonstrates how targeted heat exchanger optimization in the Rankine cycle can improve overall efficiency. The findings advance waste-to-energy strategies and open opportunities for future research in scaling up this approach to regions and types of biomass waste.

Graphical Abstract