Evaluating the environmental performances of thermal power plants: A study on EMAS registered Italian sites

Transitioning to sustainable energy production is imperative to mitigate the environmental impacts associated with the reliance on non-renewable resources. However, thermal power generation still provides a significant share of electricity production, originating significant impacts that will need to be better understood and addressed along the transition period. This paper comprehensively analyzes the environmental performance of 73 Italian thermal power plants registered under the Eco-Management and Audit Scheme (EMAS) from 2014 to 2021. The key goals were to assess current performance levels, examine how plant characteristics influence performance, and analyze temporal trends. Using independently validated data, 12 key environmental performance indicators (energy production efficiency, emissions to air, water consumption, waste production, and electricity consumption) were analyzed. Natural gas (NG) plants consistently outperformed others. For instance, they achieved a higher net energy efficiency (46.7% median) compared to coal plants (32.1%), while emissions of NOx were significantly lower (122 g/MWh for NG vs. 447 g/MWh for others). From 2014 to 2021, NG plants exhibited performance improvements across all indicators (+18% overall), while coal plants' performance declined in 7 out of 12 indicators (−72% overall). Combined heat and power (CHP) plants also outperformed conventional plants, while plant size, age, and operational hours exhibited limited influence. This study highlights the need to promote the transition from coal to natural gas, even if anti-coal policies might have hindered coal plant performances. Also, CHP facilities should be encouraged when heat demand is high. Moreover, disclosing and mitigating emissions occurring under other than normal operating conditions should be prioritized to allow for fairer comparisons of plants' performances and to reduce environmental impacts. • Comprehensive analysis of the environmental performances of 73 thermal plants. • Natural gas plants show performance improvements, coal plants decline. • Fuel type and operational mode identified as primary drivers. • Significance of emissions under other than normal operating conditions. • Need to promote the transition from coal to natural gas.