Energy recovery and GHG impact assessment of biomass, polymers, and coal

In recent decades, rising energy consumption, population growth, and material production have contributed to environmental degradation. Harnessing the chemical energy in these materials in a circular economy can mitigate these issues. While recycling processes recover valuable constituents, significant post-recycling fractions remain viable for energy recovery. This study investigates the energy recovery potential from biomass materials via combustion, gasification, and anaerobic treatment, and from polymers and coal through combustion and gasification. Some materials not typically considered for combustion, such as food and green waste, are included due to their potential processing in combustion plants. Using thermodynamic principles, we assess the limits and opportunities for sustainable energy recovery across 200 materials, identifying correlations between the heating value and compositional analyses. The study also estimates the potential products and environmental impacts of energy production from these materials. Despite their lower heating value, biomass materials offer considerable net carbon reductions, but land use, water consumption, public health issues, and feedstock supply risks warrant consideration. Biomass combustion yields lower carbon emissions than polymer or coal combustion. Biomass and polymer gasification show high potential due to their higher H2/CO ratios. Anaerobic treatment of biomass materials generates significant methane, offering modest energy output. Synthetic polymers possess high heating values, comparable to fossil fuels, and provide net CO2 emission benefits, although substantially lower than those of biomass materials. Biomass combustion or gasification results in significantly lower NOx and SOx emissions compared to polymers and coal. Accounting for energy output, biomass gasification generates the lowest emissions per MJ.