Continuous-process plants: where can you find electricity flexibility?

Why is a plant never 100% linear?

“We run continuously, we have no flexibility at all”: that is often the first answer from manufacturers operating 24/7. It is true for the core process, which cannot stop. It is far less true for everything else.

Even a continuous plant makes decisions every week that shift its consumption:

• maintenance shutdowns, preventive or planned, which can fall on one day rather than another;
• product changeovers, between grades, series or products, whose order is often flexible;
• overcapacity periods, when the plant produces more than needed and can slow down some lines;
• auxiliary equipment, which supports the process without being part of it;
• heating, air-conditioning and refrigeration systems, whose thermal inertia makes it possible to bring operation forward or delay it by a few hours.

Each of these decisions can be made when electricity is cheapest, without touching the process itself.

Where does flexibility hide in a continuous process?

Two examples from our discussions with manufacturers, plus one lever found in almost every plant, show where to look.

In metals, auxiliaries rather than the process. At an electrolysis site, the cells never stop: that is the very definition of a continuous process. But around them run pieces of equipment that don’t need to operate all the time, such as the conveyor belts that carry raw materials. By shifting their operation to the cheapest hours, the site identified around €58,000 in savings a year, without touching electrolysis.

In paper mills, the pulper and the order of paper grades. A paper machine runs continuously, but two levers remain open. The pulper, which prepares the pulp upstream, works in batches: it can run during off-peak hours and fill tanks that feed the machine later. And the order in which different paper grades are produced is a choice: scheduling the most energy-intensive grades in the cheapest time slots lowers the bill without changing output.

Everywhere, heating, air-conditioning and refrigeration. Buildings, workshops, clean rooms, warehouses and cold rooms all have thermal inertia: temperature doesn’t change instantly when equipment is switched off or restarted. You can therefore preheat or precool ahead of an expensive period, then reduce power for a few hours, while staying within the temperature ranges the process or comfort requires.

How do you turn this potential into savings?

Three steps are enough to turn these levers into real gains:

1. List everything that isn’t the core process: auxiliaries, heating, air-conditioning and refrigeration, intermediate storage, batch operations, plannable maintenance. That is where the room for manoeuvre lies.
2. Value each lever with upcoming prices: the gain from a shift depends on the price gap between two time slots. Without a forecast, there is no way to know which slot to choose.
3. Build it into the schedule: a lever only pays off if it is used every week. It therefore has to become part of the production teams’ tools and habits.

Summary

A continuous process doesn’t mean a plant without flexibility. Shutdowns, changeovers, auxiliaries, heating, air-conditioning and buffer storage almost always offer levers, provided you know when to use them.

Highcast forecasts electricity prices up to 14 days ahead and values every possible shift at your site. Think you have no flexibility? Contact us and we’ll explore it together.

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