Battery / Hybrid energy

Battery and hybrid electric energy systems will be integrated with the hydrogen engine, waste heat recovery and wind sails

Figure 1. Visualization of the Otto cycle (gas mode) and diesel cycle (Bui 2011)

Engines that are capable of running on LNG, LBG or e-methane, can on a high level be divided into two categories. One comprises gas injection into the intake port at a low pressure. The other has a high-pressure gas injection towards the end of the compression stroke or just before the top dead centre. In both categories, a small amount of easily
ignitable liquid or pilot fuel ignites the air-gas mixture. In the Figure 1, the conceptual difference between the two is illustrated.

Figure 1. Visualization of the Otto cycle (gas mode) and diesel cycle (Bui 2011) Whilst high pressure gas engines are typically straight forward in terms of gas quality variations and related controls, low pressure gas engines require a more sophisticated combustion control system, enabling numerous advantages:

  • No fuel gas compressor is needed, reducing capital costs and parasitic load
  • Higher engine efficiency
  • NOx emissions compliant with IMO Tier III level without exhaust gas aftertreatment

Low pressure gas engines do have an unwanted feature called methane slip, i.e. a minor portion of the fuel gas passing unburned through the cylinder to the exhaust. This has been a focus area in Wärtsilä R&D activities during the past 25 years with substantial advancements, and further improvements are on the way including both in-engine development and catalyst solutions. With the latest low pressure gas engine technology, the methane slip is typically below 2 g/kWh, corresponding to 10% of the GHG emissions from a gas engine running on natural gas.

Wärtsilä offers both spark ignited (SG) and dual fuel (DF) low pressure gas engines. The controls in this report are relevant for both on a conceptual level, whilst both deeper analysis, development and upcoming testing activities within this task will be focused on DF engines. Thanks to the fuel redundancy and the robust ignition source, DF is namely dominant in the marine market. Wärtsilä’s DF engine portfolio for the marine market ranges from the 1 MW 6L20DF up to 20 MW with the 16-cylinder 46TS-DF. This development focuses on the new portfolio engines Wärtsilä 31DF and Wärtsilä W46TS-DF, both being suitable candidates both for cruise and bulker depending on the power demand. To make it possible to reach higher engine efficiency without engine knocking, larger low pressure gas engines are typically designed for so called lean burn combustion, meaning that the air intake is higher than what´s required for stoichiometric combustion of the injected fuel. Oftentimes the lambda can be around two, meaning that there is double amount of air compared to what is needed for theoretical complete combustion.


Waste-to-power systems integration to efficiently convert waste products into useful energy

H2 hydrogen

Hydrogen fuel will be used to provide continuous carbon-free power, electricity and heat on demand

Wind Sails

Provides a significant reduction in greenhouse gas emissions but requires integration with other technologies for a continuous power

Waste heat recovery

Maximises the conversion of fuel into useful power by converting waste heat from the engine process, which is low-temperature heat into useful electricity

Ultrasound anti-fouling

Keeps the hull clean by preventing the formation of biofilm and thereby minimise drag in the long-term

Air lubrication

Reduces the resistance of the vessels by reducing the frictional resistance on the flat bottom of the hull

Automated route optimization

Route optimisation can lead to significant fuel savings, and involves the consideration of weather and sea state ship operating conditions and logistics.

Gate Rudder

Significantly reduce ship resistance if integrated with an optimised hull shape. Their ability to be integrated with other systems such as wind propulsion systems is essential.

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