A new study has identified circulating fluidized bed boiler (CFBB) technology as the most environmentally efficient option for biomass combustion, offering lower emissions than conventional combustion methods and providing a new framework for evaluating renewable energy systems.
Published in Energy & Environment Nexus on January 28, 2026, the research was led by Yaning Zhang’s team at Harbin Institute of Technology and examined environmental performance across multiple biomass combustion technologies using a quantitative universal exergy method, Newswise reported.
The findings are intended to support policymakers and energy planners in selecting combustion systems that reduce gaseous emissions while maintaining practical feasibility for agricultural and forestry waste utilisation.
Biomass combustion remains the most established thermochemical route for renewable energy generation. However, most environmental evaluations have traditionally focused on greenhouse gas emissions through life cycle analysis, offering limited comparison across different combustion technologies.
To address this gap, the researchers applied an exergy-based approach that evaluates both the quantity and quality of energy and allows different pollutants to be assessed under a common framework.
The study analysed 31 samples from published literature covering four biomass combustion categories: open burning, kilowatt-scale grate furnaces, megawatt-scale grate furnaces and circulating fluidized bed boilers.
Researchers calculated environmental impact using pollutant exergy indicators for carbon monoxide (CO), carbon dioxide (COâ‚‚) and nitrogen oxides (NOx). Emission factors were derived from combustion data and converted into environmental impact values expressed per kilogram of fuel.
To reduce the influence of differences in biomass composition, results were further standardised according to carbon and nitrogen content.
The analysis showed that open burning generated the highest environmental burden, recording pollutant exergy impact values ranging from 712 to 1,538 kJ per kilogram of fuel. High carbon monoxide emissions were identified as the primary reason, reflecting incomplete combustion and poor air-fuel interaction.
By comparison, CFBB systems consistently produced the lowest environmental impact, with values ranging from 450 to 841 kJ per kilogram across different biomass types. The technology achieved lower carbon monoxide and nitrogen oxide emissions, particularly when combined with staged air supply and emission control systems.
Megawatt-scale grate furnaces delivered moderate performance overall, although reciprocating grate systems showed increased nitrogen oxide emissions when used with biomass containing high nitrogen levels.
Kilowatt-scale grate systems were capable of achieving relatively low environmental impact but required substantially higher excess air ratios, which reduced economic efficiency.
Based on the findings, the researchers concluded that CFBB currently offers the strongest balance between environmental performance and operational effectiveness for biomass combustion. They noted that inclined reciprocating grate systems may remain suitable for low-nitrogen biomass, while open burning should be reduced wherever possible.
The research team said future studies will expand the assessment to include particulate emissions, heavy metals and economic performance to identify the most effective deployment strategies for different biomass applications.
