Technologies such as ORC, heat pump, and absorption chillers offer effective solutions to recover low-grade heat present in the flue gases emitted during the thermal decomposition of biomass. While these technologies address the reduction in energy consumption by generating electrical energy or streams of heating/cooling, the added impacts of using additional chemicals in the form of working fluids or energy need to be investigated. In this regard, a life cycle assessment (LCA) methodology was used to assess the environmental performance of each technology to generate 50 kWh of equivalent energy when applied to biomass-derived flue gas streams. The assessment was carried out in SimaPro, and the impact indicators from the ReCiPe (2016) and IPCC (2021) methods for each technology were used for comparative evaluation. It was observed that the LiBr-water absorption chiller demonstrated the highest impact including a global warming potential of 4.47 × 104 kg CO2 eq (IPCC GWP-100 fossil) and ranked highest across all ReCiPe 2016 impact categories. The ORC showed lower impacts in the IPCC (2021) impact categories, but higher impacts for ozone formation and water consumption in the ReCiPe (2016) method compared to heat pumps. Overall, the LCA identified key environmental hot spots within each system and proposed strategies to enhance the sustainability of WHR technologies.