At the Asian Sulphur Cap 2020 Conference in Singapore, experts quashed concerns over scrubber washwater, while delegates discussed the viability of LNG as a marine fuel and whether battery technology is finally becoming viable
At this year’s Asian Sulphur Cap 2020 Conference in Singapore, delegates complained that the timetable for the implementation of IMO 2020 is causing havoc with the schedules of ship repair yards. Pacific Green Technologies technical director Ken McClelland said a lack of coordination has led to pile ups and delays at shipyards and noted that key to a successful scrubber retrofit operation is a cooperative agreement between the supplier and the customer. “Adequate time should be spent on 3D scans, physical checks to ensure drawings are correct and that the components are indeed what the drawings say they are,” he said.
Baltec Marine commercial director, Göran Fransson, flagged up extended lead times, uneven skill sets at shipyards, as well as uneven welding skill sets of workers as further contributing to delays. “Two quality control personnel need to be deployed full time in the yard for a successful project,” he said.
Average installation time is between 21 and 28 days for a retrofitted scrubber system, according to experts who sat on the emissions panel at the conference. A few days can be shaved off this if all the material and equipment is already on standby when the vessel is docking in the yard. However, Shanghai Marine Diesel Engine Research Institute’s senior area sales manager Yao Yuxiang said time spent at the yard depends simply on the yard’s proficiency in scrubber retrofits. In the case of an open-loop system, yard time is typically two to three weeks, he added.
Mr McClelland noted it is common to have a lead time of five months between a shipping company’s decision to retrofit and the point when the company makes its final design review before going to the shipyard. He explained time is needed to conduct a complete 3D scan, which can take between a few days and a week. The 3D scan then has to be verified, the ductwork made accessible and other preparations made. However, Mr McClelland said it would be reasonable to expect that shipyards should be able to reduce average yard time by at least three or four days within the next six months.
Scrubber corrosion: is it really a problem?
One issue that came to the fore during the conference involved concerns over corrosion within scrubber units. According to some studies, such as Corrosion Problems with Wet Scrubbing Equipment, by A.B. Adams Jr, there is potential for the acidic washwater to corrode parts of the scrubber, leading to prolonged maintenance, repairs or even replacement. The problem apparently stems from the fact that while washing the exhaust gas, the sulphurous exhaust gas stream is introduced into the lower portion of the scrubber as spray; the acidic washwater flows down the walls of the scrubber tower.
In a typical scrubber tower, critics claim the bottom portion can be subjected to high levels of acidic corrosion. The top portion may also experience acidic corrosion, though to a lesser degree, since not all the SOx is removed. Residual sludge removed from the washwater is fed to a tank for eventual disposal to the shore, and the associated pipework can also experience acidic corrosion. In a closed-loop system, the washwater is re-circulated. The make-up water is dosed from the alkali tank and there is a risk of alkaline corrosion as a result. IMO guidelines require the washwater to be neutralised and diluted with additional seawater, so the pH level is more than 6.5 before discharge. The proper operation of these systems is critical, given concerns of corrosion damage stemming from scrubber washwater.
Commentating on the above concerns, Exhaust Gas Cleaning Systems Association (EGCSA) director Don Gregory accused the marine press of scaremongering. He believes a quality scrubber supplier will ensure the right materials are chosen for the scrubber system and believes coatings are only necessary in the overboard discharge section, where the washwater could impact on the hull coating.
Mr Gregory said that scrubbers have been part of inert gas systems on tankers for many decades and the industry has learned to design and operate them safely. He does add however, that many of the scrubbers now fitted on tankers use diesel exhaust from boilers, which has far less sulphur content and corrosive properties.
Mr Gregory said scrubber towers should be made of stainless steel, which is among the most corrosion- and acid attack-resistant materials available. If towers are made of stainless steel, there is no need for coatings, he said. Mr Gregory noted however, that the fabricator should know how to deal with stainless steel, since the layer of passivity that provides the resistance, though powerful, is only a few nanometres thin and can be destroyed by fabrication mistakes. “There is a prescribed process to handle stainless steel which should be adhered to,” he said.
Manufacturing mistakes to blame
A white paper by Sverdrup Steel titled “Scrubber material selection and fabrication challenges” illustrates Mr Gregory’s point. The paper highlights the significance of mistakes made during fabrication, especially during welding. Welding defects may introduce crevices, destroy the passive layer and introduce contaminants, all of which could contribute to the failure of scrubber material.
An appropriate mix of the alloy composition of the stainless steel is crucial. Nickel, chromium, molybdenum and nitrogen content must be correctly balanced. For instance, in the lower part of the scrubber, the paper recommends using special stainless steel with high temperature acid- and chloride-resisting alloys, such as nickel. “The lifespan of a marine scrubber system will depend significantly on the chosen material, its corrosion resistance and the manufacturing process performed,” the paper says.
Clean Marine’s chief operating officer Svein Ole Strømmen has issued a paper titled Washwater discharge from scrubbers is SAFE which reinforces the scrubber industry’s view, that washwater from scrubbers is not an issue. He points to several reports1 that refute the environmental dangers highlighted by environmental groups. He notes that human activity always results in the release of fossilised sulphur causing acid rain, but seawater is naturally alkaline: “This gives the seawater a substantial capacity to absorb and neutralize SO2,” he said.
He also points to a study by Nyman and Tokerud in 1991 (Nyman, G.B.G. and Tokerud, A. (1991) Seawater scrubbing removes SO2 from refinery flue gases, Oil and Gas Journal, 89(26), 52–54.), which illustrates the latter point by explaining: “If the sulphur in the sea were spread out as an even layer, the total ocean area of the world would be covered by a 5-foot thick (1.5 m) layer of elementary sulphur. If all the sulphur in all the known oil and coal reserves were added to this layer, the thickness would only increase by the thickness of a sheet of paper.”
Mr Strømmen adds that using seawater to remove flue gases is not new: “Seawater scrubbing has been used to remove sulphur dioxide from flue gas, power stations and other industries, such as refineries and aluminium smelters around the globe. Please remember that all these land-based installations have been through a detailed permitting process, taking local conditions into consideration.”
According to Mr Strømmen, one factor not considered by environmentalists critical of scrubber washwater is that discharge occurs while the tanker is moving. There is no pooling of washwater to cause localised environmental stress, he notes, adding: “It is worth pointing out that scrubbers are not a “cheat option” to allow shipowners to meet the IMO 2020 regulatory requirements. Scrubbers are an important stepping stone towards transforming the shipping industry into becoming more sustainable from an environmental perspective, while also enabling shipowners to satisfy the IMO 2020 regulations. The shipping industry needs scrubbers – and so does the environment.”
The demand for scrubbers and the need for scale in the industry is one of the reasons behind Clean Marine and FMSI’s intention to merge together and operate solely under the name Clean Marine. Clean Marine founder and chief executive Nils Høy-Petersen said: “We are very pleased to announce the contemplated merger on the eve of IMO 2020 coming into effect. The transaction will provide additional scale to support our global operations.”
In total, the two companies have on order approximately 260 scrubber systems. The combined company will also enhance its R&D efforts to develop further competitive green technologies for shipowners as well as for other industries.
FMSI’s acting chief executive Nicolas Busch said: “We expect the combined company will achieve a substantial increase in market share and create a strong foundation for pioneering compliant scrubber technology for years to come.”
What about LNG?
Scrubbers are one way to allow tankers to continue to burn marine fuel with a higher sulphur content and achieve lower sulphur emissions. An alternative is the use of LNG as a marine fuel. While cost prohibits LNG as a retrofit option for most tankers, it can make financial sense on a newbuilding, when the extra cost (said to be US$15M on a VLCC) is financed as a single package. Recently, there have been a stream of media reports regarding vessels using LNG as a marine fuel and the impression given is that this is now the most popular option.
The reality is somewhat different. Dual-fuel tankers on order using LNG as a marine fuel total 32 vessels, from a tanker orderbook of 722 units. The LNG-powered portion of the tanker orderbook is currently less than 0.5% of the number of tankers on order. The main focus of LNG-powered tankers has been in the smaller sectors. An example is the two 28,000 m3 capacity tankers ordered by Rederi AB Donsötank and designed by naval architectural firm FKAB Marine Design. Propulsion power will be supplied by a Wärtsilä 10V31 DF main engine with the capability of burning LNG. Each vessel will be ice strengthened with a class notation of ice class 1A. The tankers will also have the capability to connect to shore power to lower emissions while in port and be ready to accommodate a 1,000-kW battery pack, which supports the WE Tech electric shaft drive solution (a nominee for the 2019 Tanker Innovation Award).
But while the sector remains some considerable distance from becoming battery powered, a major supplier of marine lithium cells has achieved DNV GL certification for its products. Leclanché is a Swiss company that specialises in large-scale lithium battery technology. Leclanché chief executive Aril Srivastava says that commercial shipping is a key strategic market for the company: “It is one area that we took leadership in, and in 2018 it [was] the fastest growing part of our business and frankly the most profitable as well.” He continues: “Right now, it is growing like crazy, whether cargo or ferries, every large shipping company has a programme for using electricity.”
For electric power to gain a foothold in the tanker sector, battery power must be reconciled with weight ratio and cargo capacity. Still, the technology is developing fast and Leclanché batteries have moved from 145 Wh per kg in 2015 to 210 Wh per kg in 2018.
In the shorter term, significant savings in tanker emissions can be made by slow steaming, which has been a feature of the sector for the last decade. The general fleet has slowed by 16% over that time, with average tanker speeds declining by 19% between 2008-2018, according to Clarkson Research Services (CRS). The slowing of the fleet has led to a reduction of fuel consumption from 330M tonnes in 2008 to an estimated 268M tonnes in 2018, during a decade that has seen the fleet grow 62% by capacity. CRS estimates that the premium of very low-sulphur fuel over current high-sulphur fuel oil might be about US$240/tonne. This increase in fuel cost during 2020 could lead to a further slowing of the fleet. As well as reducing operating costs and emissions, such a slowing would have a positive impact on the market by increasing supply. CRS estimates that a 0.5 knot decrease in average speeds would absorb 2-3% of supply capacity.
Somewhat ironic then that the last quarter of 2019 has witnessed the opposite take place. The geopolitical tensions that emerged mid-2019 steadily drove up tanker demand according to VesselsValue data and the average ballast speed of tankers returning to load areas began to pick up from around July onwards. By mid-August, the average speed of VLCCs in ballast had accelerated noticeably and at the start of September 2019 it had overtook the laden speed, which itself was accelerating.
Data shows the average ballast speed is now significantly higher that the laden speed (12.5 knots in ballast versus 12.2 knots for laden). Then the US imposed sanctions on some Chinese tanker companies and in the first week of October 2019, VLCC spot rates shot up by 367% week-on-week on the Middle East Gulf to US Gulf route. On the Middle East Gulf to China route, the time charter equivalent surpassed US$330,000/day.
With such extraordinary revenues on offer, operators were quick to speed up tankers on ballast voyages and to pull tankers out of the queues noted above for scrubber retrofits. VLCC operator DHT revealed it has delayed installing its final six scrubbers in order to capture the current spot rate strength. Perhaps this will relieve some of the pressures noted by attendees at the Asian Sulphur Cap 2020 Conference and increase the pool of tankers fitted with scrubbers post-2020.