Electrified Flexible Industrial Steam Generation - Linear Optimization of Costs and GHG Emissions

Abstract

Germany’s ongoing energy transition to climate neutrality and decarbonization of all sectors poses unique challenges. Electrification is one promising option to decarbonize the steam generation in the industrial sector. Optimal operation regarding minimal electricity costs and greenhouse gas (GHG) emissions in a system configuration with an electrode boiler and a modern heat battery is explored in a mixed integer linear programming (MILP) model with hourly resolved data for the year 2023 and 2024. The results, which considered different storage and steam generator capacities, show a significant dependency on steam demand profile, electricity data and objective, where the optimal solution with the smallest trade-offs between both objectives is defined in a pareto front. The costs optimization shows 8.22 % lower costs in 2024 and 7.11 % in 2023 compared to the GHG emissions optimization, while GHG emissions optimization shows 6.82 % lower GHG emissions in 2024 and 5.04 % in 2023. A comparison of the levelized costs of heat (LCOH) within the electrified system configuration and a conventional natural gas-fired water-tube boiler reveals a significant economic gap, where the conventional system configuration is 20.58 % cheaper in 2024 and 31.62 % in 2023. The impact of modified electricity is explored in this regard to figure out how the mechanism could serve as an incentive to enhance demand side flexibility. The intended function of the mechanism is to reduce electricity prices with low GHG emissions and to amplify prices with high GHG emissions to such an extent, that electrified systems become economically competitive with conventional ones. The modification is based on offsets with newly set average prices and amplification factors. The resulting findings show that system configurations with two independent steam generation paths oppose exploitive behavior in the presence of increased negative prices and leading therefore to additional GHG emissions. In this specific scenario, offsets have proven to be a better modification, reducing electricity costs to the desired level, while showing the lowest increase of GHG emissions. Recommendations for future works include the exploration of further modification mechanisms, that could reduce or eliminate the exploitive behavior. The Optimization should also be further explored in realistic applications with consideration of (modified) day ahead electricity prices and their GHG emissions under loosened demand profiles.