  The flexible operation of electrified chemical processes, powered by
renewable electricity, offers economic and ecological incentives, paving the
way for a more sustainable chemical industry. However, this requires a
departure from the traditional steady-state operation, posing a challenge to
process design and operation. We propose an approach for flexible biodiesel
production by utilizing intermediate and final buffer tanks. These tanks serve
to decouple the dynamics between different process unit operations. We
investigate the flexibility of three different process configurations and
compare the outcomes of their dynamic optimization strategies with those of a
steady-state operation, considering a typical demand-side response scenario.
For all strategies, we employ local gradient-based optimization and solve them
using our open-source optimization framework DyOS. Our findings indicate that
by incorporating intermediate buffer tanks, we fully exploit the process
flexibility potential, leading to total energy savings of up to 29%. We also
propose an implementation based on distributed optimization problems, yielding
similar savings while significantly reducing computational costs by over
10-fold and improving convergence, thus paving the way toward online
application. Overall, this study highlights the potential benefits of
incorporating buffer tanks and optimization strategies in the flexible
operation of electrified chemical processes, even those initially designed
solely for steady-state operation.
