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 efficiency for ships
Improving total ship efficiency reduces life-cycle costs and emissions. By combining our knowledge of automation, machinery, propulsion and ship design into a single integrated solution, a truly efficient ship operation can be achieved. From a longer viewpoint, 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 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%
- counter-rotating propulsion
- optimisation of the hull design.
Several joint development programmes with customers are currently on-going and are aimed at significantly reducing their operating costs.
System integration enables efficiency improvements while at the same time customers benefit from having proven solutions from a single supplier. Yards can better optimise their building schedules and owners get proven solutions, with lifecycle support, that are easier to manage.
Engine efficiency has always been high on our agenda. However, the improvement of efficiency is becoming 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 have several on-going programmes aimed at ensuring the high efficiency of its engines, while at the same time significantly reducing their emissions. Innovative technologies, including two-stage turbocharging, variable inlet and exhaust valve timing and electronically controlled fuel injection such as common-rail, are important contributors in this task. During 2010 Wärtsilä has announced its first product with 2-stage turbo- charging.
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. Organic rankine cycle products are being brought to the marine market and its use in stationary side is being considered. Further improvements can be expected by designing engines for secondary cycles.
Propeller efficiency upgrades
Successful conversions to achieve propeller efficiency increases up to 10% can be established in different vessel markets, such as the dredging industry, ferries, fishing vessels and tankers. This improvement is made possible by exchanging the open type propeller for one operating in a nozzle. Wärtsilä continued exploring project specific knowledge regarding the interaction between the propulsor and the ship‘s hull in order to avoid added resistance.
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 lead to efficiency losses of 3-7%. For ships such as oil tankers and container vessels with annual fuel costs exceeding 5 million euro, such propulsion degradation can easily cost several hundred thousands of euro a year. The deliverable of on-going 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.