Decarbonisation of refrigeration – storing energy and converting it into green steam

Status quo and challenge:

The refrigeration plant at the Leverkusen Chemical Park (Building D09) is used by the Currenta Group to generate 31-bar steam. A refrigeration unit or steam turbine is used for this purpose, which drives a process gas compressor that produces a -20°C cooling level.
This steam is currently still generated from fossil fuel. In order to convert the refrigeration plant to green refrigeration, either the drive technology or the energy source must be permanently changed.

Aim of the project:

The aim is to convert the base load of the refrigeration plant to green energy. One conceivable solution is to convert green electricity into 31 bar steam in future using a “power-to-heat” process. This would have the advantage that the existing units at the site would not have to be modified. In order to operate the project economically, the green electricity must either be partly produced in-house and/or largely purchased on the open market. As electricity prices fluctuate greatly, it makes economic sense to integrate a suitable energy storage system into the concept in addition to the power-to-heat approach. This could be implemented using battery technology or a green heat module (thermal storage), for example.

Before concrete measures are taken on the plant side, a simulation of possible solution options is to be carried out as part of the project. The simulation should consider the following aspects:

• What options are there for “utilizing” the green steam generated?
  • Only drive the chillers or alternatives?
  • Options for use for reconversion into electricity in other steam turbines (extraction, condensation, back pressure)?
  • Coupling with district heating supply?
• Which steam generators from the Chempark should be considered in the simulation in addition to the Green Heat Module, battery storage and electrode boiler?
  • Gas boiler?
  • Gas-and-steam (CCGT) plant(s)?
• Which electricity input should be taken into account?
  • Spot market (EPEX Spot Day-Ahead)
  • Own RE generators (PV, wind)?
  • Green electricity PPAs from PV or wind farms?
• Which scenarios for ancillary electricity costs should be considered (including grid charges)?
• How many GHM configurations should be considered (one variant for the “full expansion” or an additional small demo variant)?
• Which KPIs should be determined from the simulation?