ASTEREX - Alternative preheating system for efficiency increase in GPRMS based on expansion turbines and renewable heat

Short Description

The ASTEREX project aims to optimize a process as well as to implement low-CO2 heat supply technologies. When it comes to the expansion of natural gas, the energetically inefficient throttling process should be replaced with the use of expansion turbines.

Until now, the energy transferred to natural gas in compressor stations by increasing the gas pressure remains unused in downstream distribution stations, where the pressure is reduced. According to the current state of the art, the gas pressure in gas pressure regulating and metering stations (GPRMS) is reduced by throttling via a gas pressure regulator. Due to the cooling induced by the pressure reduction, the gas must be preheated. The heat is typically provided by low-temperature gas boilers. In Germany, this
process is responsible for an estimated heat demand of approx. 1.5 TWh/a for all GPRMS. Switching from a throttling process to an expansion process with an expansion turbine requires additional heat so that the cooling of the gas that accompanies expansion does not affect the operation of the station. By utilizing the pressure gradient, low-temperature heat can be converted into electrical energy in expansion turbines with a high efficiency.

The expansion turbines can be dimensioned for the base load gas flow rate in the station. The electrical energy generated can then be used to drive an air heat pump, for example, to cover not only the additional heat demand caused by the expansion turbine, but also the entire heating requirements of the station with renewable energy sources only. Surplus electricity could also be used to cover the power demand of the station itself or be fed into the grid. In principle, it is thus possible to fully decarbonize the operation of these stations, which were previously heavy CO2 emitters.


04/2022 until 03/2025

Cooperation partners

  • CeH4 technologies GmbH
  • EAM Netz GmbH
  • Enertracting GmbH
  • Stadtwerke Rostock AG


Funded by the Federal Republic of Germany

Awarding authority: Federal Ministry for Economic Affairs and Climate Action based on a resolution of the German Bundestag.

Funding reference number: 03EE5101A