Marine SCR

NOx Reduction

with SCR Catalysts on ships

H+H - For Cleaner Oceans and Better Air Quality – for Today – for Tomorrow – for the World.

NOx Reduction by SCR Catalyst on Ships

H+H Engineering & Service GmbH is a privately owned leading manufacturer of exhaust gas and exhaust air purification technology located in Sonnefeld in Germany. Our goal is to make an important contribution to reducing potential risks for human health and for the environment. Our focus here is specifically the limitation of nitrogen oxides (NOx) emissions. One of our core branches of our SCR systems are maritime applications in the sectors cruise, offshore, research, cargo, fishing and fish farming. In our further business unit service we differ significantly from other SCR providers. Our scope of services extends to the delivery of the new SCR system: We carry out maintenance and service with our own highly skilled colleagues and additionally with our highly specialized partners. With our SCR based emission control systems we keep our promise to act as pioneers in the SCR technology. Our core competences include the catalyst design, development, PLC programming, commissioning as well as service and maintenance. We support you to choose the best way to protect the environment by implementing an optimal concept for reducing NOx emissions. Especially our flexibility and the variable, small catalyst sizing as well as our experience in servicing more than 750 SCR systems worldwide are among our particular strengths.

Please download our SCR marine flyer


OffshoreFishingFish FarminWind Supply VesselCruise
AKOFS SeafarerHovden VikingTaupoEdda PassatSilja Symphony



  • Tailor-made System adapted to your specific (room) requirements
  • Compliance with Tier III  NOx limits, U.S. EPA Tier 4 Final and Stage V
  • Emission reporting in accordance with IMO’s NOx Technical Code (NTC 2008)
  • Compatible for all engines from 200 kW to 60 MW
  • All components made in Germany from one source
  • Vertical or horizontal reactor design for easy installation
  • Fully extruded catalyst designed by H+H with best mechanical stability
  • Urea mixer and 2-phase nozzle for fine atomization and even distribution of urea
  • No stainless steel mixing needed
  • Equipped with short mixing pipe
  • Only one single or double pump unit for one system for even pressure
  • Robust urea dosing unit for reliable performance
  • No use of automotive parts
  • In-house competence of PLC Programming based on Simatic
  • Specific training for operators and customers
  • High spare parts availability
  • Worldwide service locations and representations


 IMO Tier III Emissions Regulation

Ships´ engines produce harmful nitrogen oxides, these emissions from the maritime traffic have serious consequences for the human health. That is why strict legal limits apply. The IMO (International MaritimeOrganisation) reduces the limits for NOx / Nitrogen Oxides step by step.

The limits apply in the so called ECA zones (Emission Control Area). There are already plans to extend the areas. In the Norwegian waters a tax for the emissions of NOx applies. The Nox-Fondet ( raises a tax and subsidises the installation and operation of measures to reduce ships´ emissions.


Existing Emission Control Areas include:


  • Baltic Sea (SOx, adopted: 1997 / entered into force: 2005)
  • North Sea (SOx, 2005/2006)
  • North American ECA, including most of US and Canadian coast (NOx & SOx, 2010/2012).
  • US Caribbean ECA, including Puerto Rico and the US Virgin Islands (NOx & SOx, 2011/2014).  

We can help to meet the limits and safe money on tax and duties!


Excerpt from our references:

CARGO: Wilson Line | Reederei Braren...FISHING: Strand Rederi | Liegruppe | Teigenes...
CRUISE: Europa II | Fjord Line | Stena Line | Gotlandsbolaget...OFFSHORE: Farstad | DOF | Østensjø | Siem Offshore | Havila | PGS | Polarcus | Volstad | Remøy...