Environmental performance assessment of retrofitting existing coal fired power plants to co-firing with biomass: carbon footprint and emergy approach

The results of the study showed that the addition of approximately 20% biomass to the mass of the combustion mixture causes the decrease in carbon-dioxide emissions for nearly 11-25% and total emergy flow for 8-15%. However, further results indicate that the co-firing process is environmentally acceptable if the biomass supply stocks are within the area determined by maximum supply distances. Nevertheless, the supply area radius resulting from the emergy evaluation is 49-62% shorter depending on the coal type combusted. Furthermore, the emergy loading ratio of co-firing was lower than for the pure coal firing (10.65 compared to 12.39, respectively) indicating that the co-firing process causes less pressure on the ecosystem.