RORO vessels go
with hybrid scrubbers

Wagenborg Shipping recently awarded Royal Niestern Sander the contract to install a hybrid scrubber system on board its RO-RO vessels – m.v. Bothniaborg and m.v. Balticborg.

IMO tightens up sulphur emissions regulations

Sulphur is a substance that occurs naturally in large quantities on earth. 95% of it is dissolved in seawater and completely harmless. However, when the sulphur mixes with the moisture in the atmosphere, acid rain is produced, with all of its harmful consequences, e.g. for forests, human and animal health, as well as damaging buildings. 

In order to save the environment, it is essential to minimise sulphur emissions. The shipping industry also has to make a contribution. As of 1 January 2015, only fuel with a sulphur content not exceeding 0.1% (compared with 1% previously) can be used when sailing in “Sulphur Emission Control Areas” (SECA). In addition, the international standard must fall from the current level of 3.5% to 0.5% by 2020. These stricter international IMO laws and regulations concerning sulphur emissions are included in “Marpol Annex VI” and the updated EU directive. 

The following SECA areas are currently designated in Europe: the Baltic Sea, North Sea and English Channel. In addition, the 200 mile zone operated by the US and Canada has also been classified as an SECA area. Central America, the Caribbean, the Mediterranean Sea and possibly also Singapore and Japan are expected to follow as SECA areas within a few years.

Impact of sulphur standard on shipowners

The regulator, IMO, is therefore looking at sulphur emissions in exhaust gases, and not the type of fuel that powers a ship. In order to conform to the standard, a shipowner has the choice of either using fuel whose sulphur content is low enough to comply with the limit or using sulphur-containing fuel in combination with an installation that cleans the exhaust gases. The sulphur standard is therefore having an enormous impact on the shipping industry.

Wagenborg is also carefully considering different scenarios that would allow its ships to comply with the IMO standards, based on the service life of its ships, navigation areas, the payback period of any investments, fuel consumption and practicability in terms of time.

Sail more slowly on MGO or LNG, or use scrubbers?

The easiest and most obvious option is to switch from heavy fuel oil to cheaper low-sulphur gas oil (MGO). This is because only relatively minor adjustments have to be made to the engine room to make it suitable for low-sulphur fuel. However, the increased demand for low-sulphur fuel is likely to increase its cost considerably in the short term. Part of this cost increase can be made up by sailing ships at a lower speed, as calculations show that a 10% speed reduction in terms of knots can deliver a theoretical fuel saving of about 38%.



Another alternative fuel is Liquefied Natural gas (LNG). However, Bart Boosman, Fleet Development Engineer, Projects & Newbuilding, at Wagenborg Shipping argues against this option: “The energy value of LNG is lower than that of oil. For the same radius of action, the LNG tank takes up a lot of space and there are a lot of safety risks. For example, if LNG in its liquid state (-163°C) leaks onto the steel of the ship, it will cool so quickly that it could crack. In addition, there is of course a risk of fire in the event of leaks. All of these risks are perfectly manageable in themselves, but at a high cost. The crew will also have to be trained how to sail safely on gas. What is more, ships’ engines will have to be completely refurbished”. 



One final option is to wash exhaust gases using a “scrubber” to reduce the emission of sulphur oxides to below the standard. If a scrubber is used, it is possible to continue sailing on HFO in a SECA area and still comply with the stricter regulations. However, choosing a scrubber is no easy matter, as several factors influence the purchase decision, such as the relatively high investment and future price difference between HFO and MGO. Other factors include the time spent by the ship in the SECA area, the commercial service life of the ship, the high cost of installation and expected payback period for the investment and fuel consumption. 


A number of studies show that, if a ship – equipped with four 10,800 kW main engines, two propellers, two 1,800 kW shaft generators – spends 50% or 100% of its time sailing in a SECA area, the payback period for a scrubber will be 1.6 and 0.8 years respectively. However, the smaller the installed power, the longer the payback period in reality. Payback periods of two to four years, which are realistic in this case, could still make a scrubber system more profitable than sailing on MGO.


The two sister vessels caught in one eye upon in the port of Delfzijl to be outfitted with a scrubber installation - photo: Johannes Doornbos
The two sister vessels caught in one eye upon in the port of Delfzijl to be outfitted with a scrubber installation - photo: Johannes Doornbos

Wagenborg Shipping’s B-series

With around 170 ships, ranging from 1,000 to 23,000 tons, with an average age of 8.5 years, Wagenborg Shipping is one of the largest shipping companies in the Netherlands. Although its ships sail all over the world, Wagenborg’s main areas of trade are the Baltic Sea, the North Sea, the Mediterranean Sea and the Great Lakes. Many ships are deployed under long-term contracts for the worldwide shipping of bulk cargoes and paper or wood products. These include m.v. Bothniaborg and m.v. Balticborg. 

Built in 2004, these RO-RO carriers operate under a long-term charter contract with Smurfit Kappa to provide weekly shipments of paper products between Haraholmen, Bremen, Sheerness, Terneuzen, Cuxhaven and Södertälje, a trade route that lies fully within the SECA area. To conform to the sulphur standard, Wagenborg Shipping decided to equip its m.v. Bothniaborg and m.v. Balticborg with Wärtsilä Hybrid Scrubbers.

“For many years we have enjoyed a successful business relationship with Wärtsilä and use a lot of Wärtsilä products in our ships. This relationship was one of our reasons for choosing Wärtsilä as the supplier of the scrubbers for our b-class vessels.”

Wärstsilä Hybrid Scrubbers

The Wärtsilä Hybrid Scrubbers enable the B-ships to sail in what is known as closed or open loop technology. When they are sailing in open loop mode, exhaust gases are sprayed with sea water. The sulphur oxides in the exhaust gases react with the water by forming sulphuric acid, which is then neutralised by the natural alkalinity of the sea water. The washing water is pumped overboard after it has been filtered. The solid particles from the water, oil and soot, are stored in a sludge tank and disposed of ashore.


In areas where the natural alkalinity of the sea water is insufficient for open loop mode, the ship switches over to closed loop mode. In this mode, the washing water is circulated, when the increasing acidity of the washing water due to the inclusion of sulphur from the gases is compensated by injecting sodium hydroxide. Here, too, the washing water is continuously filtered and the solid matter is stored. The water, which contains sulphur, but is otherwise clean and pH-neutral, is dissolved in sea water. In areas where this discharging of sulphur-containing water is undesirable or prohibited, e.g. in some ports or canals, it can be stored temporarily on the ship. This is known as “zero-dumping mode”. 
This hybrid system, which is of course much more complicated and costly than having open loop mode only, makes it possible to sail in all areas and also anticipates any even tougher emissions standards that may be imposed in future.


Watch the scrubber installation for m.v. Bothniaborg by Royal Niestern Sander

Niestern Sander proves its strength in the marine cluster in the north of the Netherlands

ased in the port of Delfzijl in the northern Netherlands, the Royal Niestern Sander shipyard has proved itself to be one of the top players in the international shipbuilding industry with the delivery of the offshore maintenance support ship “KROONBORG”. So it’s no wonder that Wagenborg once again chose this shipyard to carry out then retrofit of m.v. Bothniaborg and m.v. Balticborg. Niestern Sander teamed up with a number of companies in the northern marine cluster, including Cofely West Industry, Eekels Technology and CIG Centraalstaal, to complete the installation of the scrubber.

To guarantee the speedy return of m.v. Bothniaborg to its trade route, Niestern Sander applied a strict project schedule during which the special housing for the scrubber had already been manufactured by its new building department at an early stage. On arrival in Delfzijl, m.v. Bothniaborg was put into dry dock, after which this housing measuring 11 metres in height and 5 metres square and weighing 40 tons, was installed behind the existing funnel by Wagenborg Nedlift.
At the same time, all kinds of modifications were being made inside the ship to connect the scrubber system. 

For example, a technical room about 70 m2 in area, containing tanks, pumps, filters and other equipment for controlling the scrubbing process, was built on the upper deck. 

The large pumps for pumping sea water to the scrubber were installed on the port side of the engine room. This was a considerable challenge, as the engine room in this type of ship was not designed to be retrofitted with such large components. The last step was to modify the funnel itself, so that the exhaust gases could be conveyed over the top of the funnel to the scrubber.

All in all, the short time allowed for the retrofit made the installation of the scrubbers on m.v. Bothniaborg a very challenging project. In addition, the departure of m.v. Bothniaborg was immediately followed by the arrival of m.v. Balticborg on schedule for the same retrofit procedure.