In less than a year, on January 1, 2021, the requirements of the International Maritime Organization (IMO) on the level of toxic emissions of nitrogen oxides by diesel ship engines with a capacity of more than 130 kW will begin to operate in the waters of Northern Europe. Tighter control over NOx emissions will affect all vessels under construction and launching. Necessity of modernization of a lineup sharply faces the European manufacturers not only huge dry-cargo ships, tankers or cruise liners, but also average size motor yachts.
Tier I, II, III
The Supplements to the International Convention for the Prevention of Pollution from Ships (MARPOL) concerning Nitrogen and Sulphur Oxide emissions were developed in 1997 and have gradually entered into force over the past 20 years. The first version of the NOx emission standards (Tier I) came into effect on January 1, 2000.
The current rules (Tier III) came into force 5 years ago, on January 1, 2016.
Compared to Tier I, the current Tier III requirements are 5 times tougher.
Until now, their areas of application - so-called Nitrogen Oxide Control Areas (NOx Emission Control Areas or simply ECAs) - have been restricted to the U.S. East and West coasts and Canada, the U.S. Gulf Coast of Mexico, as well as the surrounding areas of Hawaii, the U.S. possessions in the Caribbean Sea, and the French overseas community of Saint-Pierre and Miquelon (islands 20 km south of Canadian Newfoundland).
Starting next year, control zones will be allocated to the North Sea, the Channel and the Baltic Sea, where, according to MARPOL, only sulphur oxide (SO-) emissions are currently restricted.
The Tier II regulations, which came into force on January 1, 2011, continue to apply outside all ECA zones. They are not 5, but only 1.2-1.3 times tougher than Tier I.
The step-by-step introduction of Tier III is not just a question of the area in which the rules apply. More importantly, regardless of the water area, the five-year postponement concerned all recreational boats with a waterline length of 24 meters and a gross register capacity of less than 500 register tons launched before January 1, 2021.
From 2016 to 2021 the yachting industry was expected to have time to prepare for new regulations. However, the pledged time was not enough. In spite of the attempts of the association, which included representatives of such companies as Ferretti, Overmarine, Monte Carlo Yachts, Princess, Sanlorenzo, Sunseeker and Viking, it has not been possible to delay the entry into force of the new requirements.
Two meetings of the IMO Marine Environment Protection Committee are scheduled for 2020, during which a decision on postponement may still be taken.
Existing exhaust treatment systems
Selective catalytic reduction (SCR) has been successfully applied on large cargo ships for MARPOL compliance. The principle of work of this method is simple enough. An aqueous 32.5% solution of highly purified urea produced from natural gas is injected into the exhaust pipeline. There, under the influence of temperature urea decomposes into ammonia and carbon dioxide. As a result of further chemical reaction, nitrogen oxides and ammonia contained in the exhaust are transformed into harmless nitrogen and water vapour.
However, there are several obstacles to using SCR on yachts. The first of them consists in different use of the engine. The speed of the yacht is not constant and the engines are idle at anchorages for long periods of time. In this mode it is difficult to keep the exhaust temperature at a certain level that is required for effective SCR use.
Secondly, the installation of the SCR system makes the boat heavier, fuel consumption increases and this in turn increases the maintenance costs of the yacht.
Finally, even on many large models in the engine room, there is a banal lack of space for the installation of existing SCR systems. Particularly much space is required for the installation of a urea storage tank.
«A 50-metre (164-foot) boat doesn't have a lot of space to accommodate the SCR systems currently available on the market," says»Richard Boggs of Boat International, a spokesman for EnerYacht, which has developed SeaClean exhaust aftertreatment systems.
The technology of exact calculation of necessary quantity of a solution actually does not exist. This parameter can be linked to fuel consumption, but it is problematic to calculate how much urea will be used within the specified control zone. At the same time it is economically unprofitable to make a big mistake in calculations and to take on board too big stock, weighing up the boat. But an impressive financial cost will also result in a penalty for violation of emissions regulations, if the urea suddenly runs out at the most inopportune moment!
According to the International Boat Industry, to install the system, the standard engine room needs to be increased by at least 30%. On a small yacht, this can only be done by sacrificing a guest cabin, which will reduce the attractiveness for owners.
On an average 60m yacht, it is estimated that the tank size can reach 10 cubic meters and add an extra tonne to the boat without being full, and 12 tons along with the contents.
«For comparison, a sports car of about the same volume weighs about two tons, -»noted in Feadship.
However, according to Boat International, MAN has already offered a good solution for the 1650 hp engine for the Horizon Taiwanese shipyard: a compact SCR system with a small pump that can run without a compressor. The company is also working hard to develop the SCR for the 2000 engine series. The first prototypes of the system are already assembled and tested.
The Dutch company MarQuip also offers customised solutions for small machine rooms.
«We have the possibility to combine a silencer and an exhaust treatment system. This is something that engine manufacturers do not offer,"»says MarQuip.
According to Boat International, a similar system installed above the engines of a 28-metre semi-displacement yacht under construction for a Dutch client is approximately 2.3m x 1.4m.
In order to be compatible with SCR, Volvo Penta is upgrading both its engines (with IPS drives and shaft drives) and generators. The company began developing an exhaust treatment system in 2018 and has had 35,000 hours of testing. The system will not only filter the exhaust, but also work as a silencer, reducing noise by 35 dB. In the engine room, Volvo Penta offers the flexibility to install the system: the tank can be hung above the engine, placed on the engine or on the floor next to it. All data about the system (including not only the level, but also the quality of urea) will be displayed on the railway screens at the control station.
In Rolls-Royce also decided not to invent the bike and to adapt MTU engines to SCR technology. In autumn 2019 the company showed its achievements at the yacht shows in Cannes and Monaco. The MTU 4000 range has been modernized with engines from 2830 to 3900 kW. By 2021, the 2000 series will be ready, covering the 1270-1940 kW range. Like the Volvo Penta, the Rolls-Royce has made sure that information about the state of the system is visible to the steering wheel.
One of the first yachts to meet the new standards with an MTU engine was the 80m Bilgin 263 built in Turkey. It was handed over to the owner in February 2020. Just one month later, the 62-metre CRN 137, certified to Tier III standards, was handed over to Italy. CRN claims that all megayachts under its brand are now guaranteed to be Tier III certified.
Feadship started working with the Netherlands' largest research centre, the Netherlands Organisation for Applied Scientific Research (TNO), to develop its own exhaust treatment methodology. The Oxywash system, divided into two modules, created as a result of this cooperation, requires neither much space nor a urea tank.
In the first stage nitrogen oxides make water soluble. For this purpose, a reaction with ozone obtained from ordinary air is carried out at low temperature, and a catalytic reaction at high temperature. Subsequently, when combined with sea water, the oxides are converted into nitrites and nitrates, which are already in nature. Moreover, these nitrites and nitrates are essential components for the life of marine plants and animals.
The already mentioned Sea Clean system, developed by the American company EnerYacht, uses ceramic filters for soot. They are coated with metal, which acts as a catalyst, oxidizing hydrocarbons, soot and aromatic compounds in the exhaust gas. Only carbon dioxide and water vapor remain at the outlet. Thus, the filter removes up to 95 % of particles contained in the exhaust.
Another important feature of this system is that it does not require an initially high exhaust temperature for efficient operation. Excess generator energy is used to maintain the required temperature: the exhaust heats the electric heater before it is fed into the filter.
Despite the existence of different ways of exhaust treatment, some shipyards, when the Tier III regulations come into force, have to simply give up producing a number of models.
If the postponement from 2016 to 2021 is not extended, Viking Yachts will follow this path. During the Fort Lauderdale show in the fall of 2019, President and CEO Pat Healey has already announced the discontinuation of production of models over 24 meters long such as the Viking Yachts 92 Convertible and Viking Yachts 93.