###### Abstract
The study highlighted that transitioning to a solid biomass-fueled boiler system in the case-study could cut CO\({}_{2}\)eq emissions by up to 42%, while a biomethane-fueled solid oxide fuel cell achieved up to a 27% reduction. Both methods increase operating costs, but the biomass system costs EUR 0.05-0.11 per kg CO\({}_{2}\)eq reduced annually, significantly less than the fuel cell's EUR 0.69-1.14. As [PERSON]'s research was conducted with a primary focus on economic viability and emission reduction, insights about expected corrosion values or VOCs analysis remain elusive in the existing literature [12]. Many authors have researched the potential of converting waste into energy as a viable source for industrial boilers. [PERSON] et al. [13] investigated the use of shoe manufacturing waste as a fuel for a CFB boiler system; however, high chlorine contents can cause severe deposition and corrosion issues. [PERSON] [14] investigated the calorific value and emissions profile of tea waste for steam generation, revealing a promising energy potential. [PERSON] et al. [15] investigated the potential of rice husk as a boiler fuel from both environmental and techno-economic perspectives, concluding that rice husk can be utilized as a primary fuel source alongside coal. [PERSON] et al. [16] investigated the use of dry tobacco stalks, a waste generated during cigarette manufacturing, as an alternative fuel to feed a biomass boiler. The results of that study concluded that the waste presented environmental and economic advantages compared to traditional systems. Animal by-products, including those from the pet food industry, have been identified as viable renewable energy sources, showing promising potential for energy recovery through thermal and biological conversion processes [17]. Recent studies have demonstrated that dog and cat food waste can be effectively used in anaerobic digestion, yielding high methane content and enabling energy recovery from non-commercial pet food residues [18]. As previously mentioned, the pet food industry generates batches that fail to meet commercial quality standards and are consequently discarded as waste. To the best of the authors' knowledge, no prior research has explored the potential use of this pet food waste in pellet form as an alternative energy source for industrial or domestic boilers, particularly from a technical and environmental perspective. This study investigated the feasibility of utilizing discarded pet food products as a biofuel within the energy system of a pet food production facility. Emphasizing energy conservation, GHG emissions reduction, and circularity, the research explicitly investigated whether these materials could be used as biomass to power the industrial boiler of the manufacturing facility, which currently runs on natural gas. The analysis involved determining the calorific value of the samples to evaluate the energy potential of the residues. Additionally, it included the assessment of ash content, the presence of heavy metals, emissions of volatile organic compounds (VOCs), and potential corrosion effects on boiler chimneys. Furthermore, GHG emissions resulting from the combustion of these pellets were estimated to assess their environmental implications. This approach aligns with global sustainability trends, such as waste-to-energy and circular economy practices, aiming to reduce fossil fuel dependency, mitigate emissions, and valorize industrial residues. By transforming production waste into a local energy source, the pet food industry could enhance both its environmental and economic performance, contributing to a more sustainable manufacturing model.