Improving efficiency

Energy efficiency has always been a priority for Wärtsilä, and remarkable gains in the efficiency of our products and solutions have been achieved over the years. For example, a peaking efficiency of 52% for the best engines is one of the highest efficiency ratings among existing prime movers. However, improving the efficiency of a single component does not necessarily guarantee the best overall outcome. For instance, more can be achieved through comprehensive ship design, systems integration and machinery optimisation. Similarly, in power plants, by combining various technologies an overall efficiency rating of 90% is possible.

Total ship efficiency

Improving total ship efficiency reduces lifecycle costs and emissions. By combining our knowledge of automation, machinery, propulsion and the control of them with an optimised ship design into a single integrated solution, a truly efficient ship operation can be achieved. From a long-term perspective, the potential for improving energy efficiency has been estimated to be 30-50%. This will be achieved by optimising component performance, ship design, waste heat recovery and the recovery of other losses, weather and voyage routing and by taking advantage of potential new technologies.


The efficiency of the ship can be improved also by using concepts, such as:

  • the Low Loss Concept, which reduces the losses in the electrical power train by 30-50%
  • optimisation of the hull design

Several joint development programmes with customers are currently ongoing and aimed at significantly reducing their operating costs.

System integration enables efficiency improvements, while customers benefit from having proven solutions from a single supplier. With lifecycle support yards can better optimise their building schedules and owners get proven solutions that are easier to manage.

Engine efficiency

Engine efficiency has always been high on our agenda. However, the improvement of efficiency is becoming more challenging by the day as the emissions requirements become increasingly stringent. Amongst the reasons for our success in this field, integrated engine functionalities that enable low emissions and high engine efficiency have been a major factor. Air and fuel admissions are controlled by an automated system that provides optimal combustion under all operative conditions.

Wärtsilä's extensive experience in component design has led to the development of combustion chambers capable of withstanding higher cylinder pressures and temperatures. This contributes to engine efficiency directly and positively.

Wärtsilä has several ongoing programmes aimed at ensuring the high efficiency of its engines, at the same time significantly reducing their emissions. Development of innovative technologies, for example two-stage turbocharging, is an important part of achieving our goals.

Wärtsilä engine fuel efficiency development

The amount of fuel energy content, which an engine is able to turn into useful power.


Heat recovery and energy conversion improvements

The utilisation of fuel energy can be further improved by using heat recovery concepts and secondary cycles. Steam-based combined cycles are applied widely in diesel engine applications and are expected to gain a foothold also in bigger gas engine plants. Further improvements can be expected by designing engines for secondary cycles.

Propeller efficiency upgrades

The propeller's efficiency, amongst other parameters, is an important consideration for achieving economic sailing. Fouling, surface roughening and leading edge damage to the propeller, when in service, can result in efficiency losses of 3-7%. Also, by replacing outdated existing propellers with new ones designed based on the latest knowledge, propeller designs and operating profile of the vessel, significant savings with short payback periods can be achieved. For ships such as oil tankers and container vessels with annual fuel costs exceeding EUR 5 million, propulsion degradation can easily cost several hundred thousands of euros a year. The results of ongoing projects investigating the efficiency loss of propellers in service will be the performance based maintenance of a ship's propeller and will thus increase the vessel's overall efficiency throughout its lifecycle.


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