The potential of methanol as alternative fuel

A major challenge that is faced by the marine industry is the reduction of greenhouse gases and harmful emissions like soot, nitrogen oxides (NO_x) and sulphur oxides (SO_x). Fuel selection criteria such as sustainability, scalability and storability has led to the selection of methanol as the most viable alternative for fossil fuels. As one of the most widely shipped chemicals in the world, methanol is already present in most terminals. It is also biodegradable and more environmentally friendly than oil-based fuels. Being liquid at atmospheric conditions is a major advantage in handling, distributing and storing methanol. Also, methanol burns cleaner and emits less pollutants than diesel. On top of this, methanol enables neutral CO₂-emissions when it is produced from renewable electricity and captured CO₂, the so-called green methanol.

In this Demo Case  a high speed marine diesel engine has been converted with a methanol retrofit solution to dual-fuel operation in which the engine runs on both methanol and diesel. Ghent University and its partners Dredging International, Volvo Marine & Industry Center, Abeking & Rasmussen, Damen Shipyards and Methanex Europe, chose for the fumigation technology as a retrofit solution. The design requirements were to provide an easy and cost-effective retrofit solution that makes use of non-proprietary equipment, still providing full redundancy by enabling switching instantaneously between diesel and dual-fuel operation. The main advantage of the dual-fuel fumigation concept is its low cost, thanks to the low pressure methanol supply system (injectors and pumps).

The engine that is converted is a Volvo Penta D7C-B TA (265 hp), a high speed diesel engine used for smaller vessels.  An extensive bench test program was performed on the converted engine and measurement data was recorded at different engine speeds ranging from 1000 to 2000 rpm and for varying loads, in total 28 load points were tested. At each load point the methanol energy fraction was increased until the boundaries for substitution were reached.

In dual-fuel operation methanol/diesel, a maximum relative increase of 12% in brake thermal efficiency was recorded and for respectively NO and soot emissions the average decreases over the entire load range were 60% and 77%. The maximum obtained methanol energy fraction amounted to 70%, and this without any major modifications or optimizations to the base diesel engine.

It is concluded from the measurements that dual-fuel operation on methanol/diesel has great potential. It allows efficiency increases while simultaneously reducing NO and soot emissions. When methanol is produced from renewable resources, it has the potential to become a viable alternative for fossil fuels in the marine industry, fulfilling all requirements for a suitable alternative fuel: methanol is sustainable, scalable and storable. It is recommended that further research and demonstrations are set up in the near future with research institutes, engine manufacturers, ship owners, equipment manufacturers and other relevant stakeholders to further develop and commercialize dual fuel and/or dedicated engines on methanol. In this way the marine industry can further strengthen its commitment to tackle global warming and local air quality issues.