As bulkers and tankers sail towards a decarbonised future, owners and operators are facing unprecedented demands. Energy efficiency in design (EEDI) and for existing ships (EEXI) – plus the complexity of adhering to initiatives such as the Carbon Intensity Index, the Poseidon Principles and the Sea Cargo Charter – all mean that new solutions are needed. In this webinar we learn how a next-generation smart propulsion setup will change conventional thinking on how newbuilds are designed.
With the design requirements for newbuild vessels becoming more demanding all the time, Wärtsilä collaborated with the classification society RINA to assess the various challenges and design a next-generation propulsion setup that can future-proof new bulkers and tankers. In this webinar hosted by Jeremy Crossman, General Manager, Sales Excellence & Coaching, Wärtsilä Marine Power, we hear more about the solution from Antonios Trakakis, Technical Director, Marine, RINA and Johnny Kackur, General Manager, Merchant and Gas Carrier Segment, Wärtsilä Marine Business.
“Reaching IMO targets means embarking on the decarbonisation journey as soon as possible, and LNG offers everything we need to get started,” begins Trakakis. “It’s the cleanest burning and fastest growing fossil fuel, and confidence in it can be seen in the rise in demand in non-energy sectors and from countries that have announced mid-century net-zero carbon emission targets. At the same time, producers such as Qatar have announced big increases in supply. Compared to liquid fuels over the last ten years, LNG’s price is low and, more importantly, stable. Trakakis goes on to explain that as it is fossil based, LNG is quite rightly seen as a transition fuel, but the transition period could last for decades. Several studies have concluded that in a best-case scenario, zero-carbon fuels will only be available in substantial quantities for shipping after 2040, and even in 2050 shipping will still need LNG for a large part of its energy needs. In the near future, carbon taxes will increase operating costs. This means it is very risky to postpone inevitable investments, rely on speed reduction alone to comply with more stringent regulations and simply sit back and wait for 20 years until zero-carbon fuels to arrive. LNG also offers fuel flexibility, as a dual-fuel engine can run on LNG with any percentage of zero-carbon fuel as soon as it becomes available.
“Average ship speeds have decreased by about 20% in recent years, from 14 knots in 2008 to 11.5 today,” explains Kackur. “This may sound like a very small reduction, but in terms of propulsion power it translates to a drop of almost 50%. However, the optimisation point for new ships is still around 14.5 knots, meaning at today’s slower speeds the average main engine load for a Suezmax, for example, will be well below 40%, as both the main engines and propeller are operating far from their optimum design points.” Kackur goes on to outline how the propulsion setup today is therefore misaligned between design speeds and actual speeds. This means that equipment is not performing optimally, and electrical power generation is not very efficient either, as it relies on small auxiliary gensets.
“Our smart solution requires a smaller engine room than conventional solutions and is optimised for total energy consumption at actual ship speeds of 10 to 13 knots, rather than for propulsion at hypothetical design speeds,” explains Kackur. “It comes with two main engines – in normal operation only one engine is used, powering both propulsion and the hotel load. This means that the engine can run at higher loads and at very high efficiency levels. The second main engine is only needed at speeds above 13 knots.” Because future fuels can be used in the engines from the start, the solution is future proof as no major conversions will be needed. With only one of the main engines used in normal operation, the solution also improves redundancy and, as shaft generators are used for all onboard power generation, only one auxiliary genset is needed.
Kackur explains that it would not be possible to achieve improved performance with a standard medium-speed engine, so the main engine selected is the Wärtsilä 31DF, the most efficient and modern medium-speed engine on the market today. It has already been tested and verified that the engine works on a mix of hydrogen and natural gas, and ammonia tests are ongoing with targets of mixing up to 40% ammonia at full output and an even higher proportion at lower output. Bio LNG and synthetic LNG have also already been tested and verified. And this is without any conversions needed – the engine can be used with these fuels as it is delivered today. “Wärtsilä is a clear market leader when it comes to dual-fuel engines. We have already sold more than 2,600 dual-fuel engines which have generated almost 50 million running hours. So, with more than 26 years in operation our dual-fuel technology is fully proven,” Kackur points out.
While the medium-speed engines used as prime movers for tankers and bulkers have in the past had a reputation for needing more maintenance than slow-speed engines, the Wärtsilä 31DF has been designed to run with an extended time between overhauls. Indeed, its maintenance overhaul intervals are as long, if not longer, than those of a conventional 2-stroke engine. Reduced total maintenance costs for this smart propulsion machinery, compared to conventional machinery with a 2-stroke engine, are achieved primarily because only one Wärtsilä 31DF is in operation most of the time and partly because the auxiliary genset only needs to operate for a very limited number of hours. In addition to the intrinsically low maintenance requirement, Kackur also reminds us that remote monitoring and control is constantly developing, and a lot of support activities can be handled remotely through Wärtsilä’s Expert Centres. Experts at these centres can support the crew in optimising equipment performance and minimise downtime, helping customers to get the most out of their assets.
Kackur notes that in a comparison between a Wärtsilä 32 engine and the new Wärtsilä 31DF engine, both operating on heavy fuel, there is quite a big efficiency gain with the new-generation engine, but not a very big impact on CO2 emissions. However, even with methane slip included, the total equivalent CO2 emissions are drastically reduced when using LNG as fuel. In conclusion, smart propulsion machinery that is optimised for real-world shipping speeds and operates on LNG and future fuels offers lower operating costs, lower total energy consumption and reduced maintenance costs. It also provides maximised efficiency for electric power generation and, being highly fuel flexibile, provides a roadmap to meet IMO targets, ultimately maximising the vessel’s residual and resale value.
To find out more about Wärtsilä smart propulsion machinery for bulkers and tankers check out our dedicated webpage here