As countries search for alternatives to fossil fuels, biomass has gained attention as a renewable energy source capable of reducing greenhouse gas emissions. However, not all methods of burning biomass are equally environmentally friendly. A new study provides one of the first systematic comparisons of how different biomass combustion technologies influence environmental impact, offering practical guidance for cleaner energy production.
In a study published in Energy & Environment Nexus, researchers evaluated the environmental performance of four common biomass combustion methods using a quantitative exergy based approach. The research compared open burning, kilowatt scale grate combustion, megawatt scale grate combustion, and circulating fluidized bed boiler technology, often called CFBB.
Biomass combustion remains one of the most widely used thermochemical pathways for converting agricultural and forestry waste into heat and electricity. While biomass is renewable, burning it can release harmful gaseous pollutants such as carbon monoxide, carbon dioxide, and nitrogen oxides. The new study introduces a standardized method to measure the potential environmental impact of these emissions, helping policymakers and engineers identify cleaner combustion strategies.
"Our goal was to provide a unified quantitative framework to compare combustion technologies and reveal how operational conditions influence environmental performance," said corresponding author Yaning Zhang. "Understanding these differences is critical for designing biomass energy systems that balance efficiency and environmental protection."
The research team analyzed emission data from 31 previously published experimental studies covering a wide range of biomass fuels, including crop residues, wood materials, and mixed organic wastes. Using the exergy method, which evaluates both energy quality and environmental burden, the team calculated the potential environmental impact of key gaseous pollutants generated during combustion.
The results show that open burning produces the highest environmental impact, with values ranging from approximately 712 to 1538 kilojoules per kilogram of biomass. This is largely due to incomplete combustion, which generates high levels of carbon monoxide emissions. Open burning is still commonly used for agricultural waste disposal in many regions, highlighting the importance of transitioning to controlled combustion technologies.
In contrast, circulating fluidized bed boilers consistently demonstrated the lowest environmental impact across multiple fuel types, with values between about 450 and 841 kilojoules per kilogram. These systems improve combustion efficiency through enhanced mixing of fuel and air and often include emission control technologies that reduce nitrogen oxide formation.
Grate combustion systems showed mixed performance depending on design and operating conditions. While small scale grate systems can achieve relatively low environmental impact, they often require high excess air levels, increasing energy consumption and reducing cost effectiveness. Megawatt scale reciprocating grate systems performed well under certain conditions, but their environmental performance declined when biomass fuels contained higher nitrogen concentrations.
The study also highlights the importance of fuel characteristics. Biomass with higher carbon content tends to produce greater carbon dioxide related environmental impact, while fuels with higher nitrogen content increase nitrogen oxide emissions. These findings emphasize that selecting cleaner biomass energy technologies requires considering both fuel composition and combustion design.
Beyond providing new scientific insights, the researchers believe the method can support real world decision making. By quantifying environmental impact in a unified metric, the framework allows direct comparisons among technologies and operational strategies.
"Biomass energy can play an important role in global decarbonization, but only if it is implemented responsibly," Zhang said. "Our work helps identify pathways to reduce pollutant emissions while maintaining energy efficiency."
The researchers suggest future studies could expand the assessment to include particulate matter, heavy metals, and other pollutants, as well as evaluate economic costs to help determine optimal biomass energy solutions for different regions and industrial applications.
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Journal reference: Liu Z, Luo W, Zhang M, Zhao W, Mostafa E, et al. 2026. Evaluating the potential environmental impact of biomass combustion methods using quantitative universal exergy method. Energy & Environment Nexus 2: e005 doi: 10.48130/een-0025-0019
https://www.maxapress.com/article/doi/10.48130/een-0025-0019
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About Energy & Environment Nexus :
Energy & Environment Nexus (e-ISSN 3070-0582) is an open-access journal publishing high-quality research on the interplay between energy systems and environmental sustainability, including renewable energy, carbon mitigation, and green technologies.
