Key methods to enhance energy efficiency and mitigate emission without decelerating your vessels

30 July, 2024

With the increasingly important requirements of sustainable development and environmental protection, several standards have been introduced such as the Energy Efficiency Existing Ship Index (EEXI) that vessels have to comply by actively reducing the emission and improving its efficiency throughout all processes. Slowing down the vessel may be the preliminary option when considering saving energy, however it is practically not a feasible option when prolonging the process. 

 

The second option, which this article particularly mentions and discusses, is purely making your vessel more efficient by reducing the amount of energy consumed to propel it through the water. The foundation here is generally basic – the better efficiency we implement, the less fuel to require and the fewer emissions to the environment. More importantly, it enables us to maintain reasonable speeds and advance our competitiveness.

 

Four conventional methods aiming to improve vessel efficiency

There are various techniques and methods that can interfere with energy efficiency of vessels, nevertheless, in the contemporary era of the marine industry, improving energy efficiency and reducing emissions without slowing down your vessels can be implemented with the prevalence of 4 key methods including:

 

  • Install new energy saving technologies
  • Install shaft generator systems
  • Adopt hybrid systems
  • Consider alternatives of fuels

  • Application of energy saving technologies

Energy saving technologies refers to the method of installing a variety of devices that are manufactured based on proper numerical analysis and measurement directly to directly influence on the vessel’s propulsion efficiency, for example by reducing hull resistance and improving propeller thrust. This method has become a popular option for a wide variety of vessels because it is generally easy to install and the initial costs are relatively low. There are several proven choose from a wide variety of proven technologies, including:

 

  • Propeller Boss Cap Fins: a simple but powerful device, which is merely an extra hub with small fins attached to the propeller cap to increase power efficiency. It has been widely installed and recognized for its economic value in fuel saving and low initial investment, especially for medium and large vessels.
  • Rotor sails: it refers to the technology that aims to harness the wind power to provide additional propulsion for vessels. It is normally mounted with its axis vertical. When the wind blows from the side, the Magnus effect creates a forward thrust and strengthens the propulsion for vessels. 
  • Devices that integrated propeller and rudder design – this technology requires to adjust and gauge the propeller so that it can enhance propulsion. 

 

  • Shaft generator systems

Shaft generator is recommendable for various vessels, especially those require substantial power for heating or cooling, and sailing long distances. In essence, shaft generator systems have a long history of application in the marine industry. Using shaft generator systems can supply all the required electricity for the vessel while operating using the main engine to generate, instead of the auxiliary gensets. The latest shaft generator configurations can be used independently of shaft speed and maintain a stable voltage and frequency output; thus can optimize each route with parallel auxiliary operation. Using shaft generator systems can result in numerous benefits consisting of decreasing maintenance costs and lubrication costs for the auxiliary engines, optimizing the number and size of the auxiliary engines, and also mitigating noise and vibration. Because of numerous positive impacts on a vessel’s Energy Efficiency Design Index, shaft generator systems are installed for the majority of new vessels.

 

It is known that installing a shaft generator on the typical main engine can be more efficient than producing the same power via a smaller and less efficient auxiliary, but for many cases the shaft generator would additionally escalate the total load of the main engine reaching the optimal load point with minimum fuel oil consumption. It is generally estimated that installing a shaft generator system can lead to 3-5% change in the energy efficiency of vessels and it can be even higher when combined with energy saving technologies. In essence, shaft generator systems are fairly seen as a top technical option to improve vessels’ energy efficiency.

 

  • Hybrid systems

Just like hybrid cars are revolutionizing the automotive industry, hybrid systems of vessels are making waves in the maritime world. These initiative powertrains combine conventional engines with batteries, offering a compelling solution for optimizing vessel operation and reducing environmental impact. It only requires a dedicated energy management system (EMS) to optimize the usage of different power sources and protect the battery by directly controlling the converter that determines the charge and discharge rate.

 

A hybrid system on a vessel can be helpful in diminishing fuel consumption and emissions by nearly 15–25% compared to the traditional diesel-fuelled propulsion. It also reduces the maintenance costs on auxiliary gensets as these can be off when using the battery system.  When the vessel is operating on battery power it also leads to reduced noise and vibration, which means the vessel’s operation can be more comfortable with minimal noise. The application of hybrid systems can be enlarged in the near future with the installation of new technologies, such as enhanced PV panels that generate electricity from solar energy.

 

  • Alternative fuels

The invention of new, and more environmentally-friendly fuels can play a crucial role in improving energy efficiency and reducing emissions for the maritime industry. Fuels are the core energy of vessels, and when the quality of fuels is improved, the operation of vessels can be significantly improved as well. However, the availability of new fuels is generally limited with some options that can be considered including:

 

  • LNG, which instantly and drastically reduces CO2, NOx, SOx and particulate emissions
  • Methanol, which can be carbon neutral when made using hydrogen from renewable electricity and recaptured carbon
  • Ammonia, which emits no CO2 when combusted and can be carbon free when it’s made using renewable energy
  • Biofuels, which are produced from renewable biomass like vegetable oils, animal waste and crop residues.

 

When not limited to the usage of a single method but to combine several methods, it can be observable that we can achieve a substantial change in energy efficiency enhancement and emission reduction for the operations of vessels.

 

Please contact QPEC for the best support in providing solutions for owners and operators of vessels: 

  • Address: 145B Nguyen Van Hoi, Thanh To Ward, Hai An District, Hai Phong City, Vietnam
  • Phone: (+84) 937-628-668
  • Email: info@qpec.vn
  • Website: https://qpec.vn/