Repowering Industrial Combined Heat and Power Units: a Contribution to Cleaner Energy Production

Repowering of industrial combined heat and power units allows reducing industrial greenhouse gases emissions. An existing industrial unit served as model in the gas turbines-based repowering study, aiming at fuel consumption and carbon dioxide emissions reduction. Following unit's model setup and verification, two conservative repowering options (hot windbox and separate gas turbine + heat recovery steam generator) were assessed from economic, energetic, and environmental point of view, including seasonal impact. blot windbox option leads to annual power production increase by 14.3% (72.8 GWh/year), accompanied by carbon dioxide emissions reduction by 3.9 % (29.5 ktons/year) compared to the base case. The second option delivered more significant power production increase (+261.9 to +298.6 GWh/year) with CO2 emissions, either slightly higher (+1.5 %) or modestly lower (-4.0%), than in base case depending on heat recovery efficiency from gas turbine exhaust. Both options show feasible economics with simple payback period as low as four years under favorable combination of fuel and electricity prices and CO2 costs. External CO2 emissions change due to the change in unit's power production further reduces the total CO2 emissions, strongly depending on the applied power production emission factor.