CIMAC WG17 | Methane and Formaldehyde Emissions of Gas Engines

Unburned Methane emissions from gas engines are of concern because of their contribution on global warming. Formaldehyde – a toxic interstage product of the Methane oxidation process – is known for its strong smell and carcinogenic properties. The amount of and the reasons for these emissions depend very much on the gas engine design and its combustion system. This results in different engine internal and engine external strategies for optimizing Methane and Formaldehyde emissions. Due to their combustion system lean burn Otto-Gas-Engines generally show the highest rates of unburned Methane emissions among different gas engine concepts. But compared to Diesel engines modern gas engines definitely contribute to an effective reduction of NOx, CO2 and other toxic emissions in the exhaust gas. Due to their savings in CO2-emissions gas engines even with unburned Methane emissions close to 2% still show a lower Green House Gas (GHG) factor than comparable Diesel engines.

After treatment systems for Formaldehyde-oxidation are proven technology (for natural gas) and already in use in the gas engine market. However, reliable after treatment systems with catalysts to oxidize the residuals of unburned Methane are not available yet. For current systems the exhaust gas temperature of gas engines is significantly lower than that needed for efficient conversion. After treatment systems for Methane-oxidation definitely require further development.

The further optimization of the gas engine combustion process, the gas engine design and the after-treatment system is a major interest of the gas engine industry. Much effort is spent on the continuous development of new improved solutions.

Download Publication [PDF]

CIMAC WG 7 Fuels | ISO 8217:2024 - FAQ
In 2024, a new edition of ISO 8217 (edition seven) has been published. In the absence of an in-depth discussion of the various reports and associated background documentation that helped form the .. more
CIMAC WG7 | Statement - 2018 Fuel Incidents
In 2018, the industry experienced a series of marine fuel incidents impacting the operation of more than 100 vessels. The specialists of CIMAC WG7 Fuels have prepared a statement .. more
CIMAC WG07 | Guideline - ISO 8217:2017 FAQ
The CIMAC Working Group 7 Fuels has prepared and issued a guideline to provide answers to the questions that may arise with the publication of ISO 8217:2017, the latest specification of .. more
CIMAC WG07 | Questionnaire
This document intends to collect information about the situations experienced where the Ignition and Combustion properties of the fuel are suspected of having influenced negatively on the .. more
CIMAC WG05 | Emission Calculation Check Guide
On 10 October 2008, the IMO Marine Environment Protection Committee at its 58th session, by Resolution MEPC.177(58), has adopted amendments to the Technical Code on Control of Emission of Nitrogen .. more
CIMAC WG05 | Statement EPA NPRM
Control of Emissions of Air pollution from Locomotive Engines and Marine compression-ignition engines less then 30 litres per cylinder. This publication discusses the following issues: .. more
CIMAC WG02 | Proposal IACS Attendance TAT
Subject: Attendance at Type Approval Tests (TAT) Background: Within the last years quite some experience was gained during Type Approval Tests. We have realized that Class surveyors well attended .. more
CIMAC WG07 | Statement EPA CARB
Use of low sulphur diesel fuels in coastal waters. CARB / EPA propose that Ocean going ships must use only distillate fuels (diesel oil) with a low sulphur content and a low content of aromatic .. more