Abstract
In the pursuit of decarbonisation, process industries are turning to electrification as a solution to avoid fossil fuels for heating and processing raw material. Transitioning to renewable electricity couples the processes to varying electricity availability and requires more consideration for production timing and scheduling to support grid stability and avoid high electricity prices. However, practical challenges limit the capability for unforeseen rescheduling for large processes. This paper explores the idea of auxiliary flexibility in an electrified steel production process, where only the auxiliary systems can react to changing conditions. We model an H2-DRI-EAF inspired process with controllable Air-Separation unit, water electrolysis, pressurized hydrogen storage, gas liquefaction units, and a battery energy storage system to react to a production related demand delay. First, we compare hourly and 15-minute DA pricing and observe that without fast flexibility the cost difference is marginal, while fast-reacting flexibility (electrolyser ramping and batteries) enables a small additional benefit from 15-minute pricing, around 0.3% on average and up to 1% at maximum. Second, without a demand delay, allowing DA+ID decisions provides significant additional cost reduction via intraday arbitrage, yielding up to about 3% lower total costs compared to DA-only operation under perfect price knowledge. Third, when introducing 15-45-minute demand delays close to delivery, the model shows little to no cost increase on average compared to no delay. This highlights that price-taker models yield optimistic results in small markets, where open positions over 100 MW would realistically influence the market price significantly.