To reduce atmospheric pollution from ships, the global standard limiting the sulphur content of marine fuel to 0.5% m/m will officially take effect on January 1, 2020. Currently, ships mainly have three ways to meet this standard:
✓ Installing and using low-sulphur fuel
✓ Adopting marine exhaust gas scrubbers (exhaust gas cleaning systems)
✓ Using liquefied natural gas (LNG) as an alternative fuel
Survey data shows that about 85% of ships worldwide will choose to use low-sulphur fuel for compliance. In addition, some ships have decided to install scrubbers. According to Clarksons Research, before 2020 as many as 10% of ships will be fitted with scrubbers, and this figure will rise to 15% by the end of 2020.
Scrubber Lifecycle
As a new development, to give everyone a more intuitive understanding of scrubbers, this article collects and organizes the hot topics and points to note at each stage in the order of the scrubber lifecycle, for the reference of relevant parties.
I. Current Status of Domestic Parties
Shipowners| Scrubbers can be said to be a new development that has attracted much attention in the shipping industry over the past two years. However, as of now, the vast majority of ships fitted with scrubbers are non-Chinese flagged.
Shipyards| Compared with the caution of domestic shipowners, major domestic shipyards are currently busy, working intensively to install scrubbers on ships that are "coming one after another." According to statistics from the Exhaust Gas Cleaning Systems Association (EGCSA), currently globally60% of scrubbers are installed at Asian shipyards.
Equipment Manufacturers| According to DNV GL classification society data, the number of scrubber manufacturers worldwide has now increased to 45, while domestic scrubber manufacturers account for about 10% of the global market share.
II. Before Installation
1
Should a ship install one? When?
Simply put, the more fuel a ship normally uses, the more cost can be saved by installing a scrubber, and the more necessary it is for the ship to install one.
As can be seen from the figure above, the greater the main engine power, the more fuel the ship consumes, and the larger the price difference between high- and low-sulphur fuel, the more cost is saved by using high-sulphur fuel, the shorter the payback period, and the more necessary it is for the ship to install one.
In addition, the payback period of a scrubber is also related to the ship's operating area.
The longer a ship operates within emission control areas, the shorter the scrubber payback period, and the more necessary it is for the ship to install one.
In summary, the necessity of installing a scrubber on a ship follows this relationship:
⏰ Regarding installation timing, for cost recovery considerations, most ships choose to install before 2020. However, considering port policies and the uncertainty of the high/low-sulphur fuel price spread around 2020, some ships may choose to install after 2020.
2
How to choose the type?
Scrubbers are mainly divided into three types: open-loop, closed-loop and hybrid, each with its own advantages and disadvantages.
❖Open-loop scrubber:
More suitable for seawater areas, using weakly alkaline seawater to neutralize and desulphurize ship exhaust gas containing sulphur oxides. The advantages are low cost and simple structure. The disadvantages are high energy consumption, and many countries and ports restrict its use.
(Schematic diagram of an open-loop scrubber)
❖Closed-loop scrubber
More suitable for freshwater and port waters, using wash water mixed with alkaline chemicals to neutralize and desulphurize ship exhaust gas containing sulphur oxides; the wash water after desulphurization is discharged into a holding tank, awaiting reception onshore or by a third party. The advantage is that it is not affected by seawater alkalinity and does not pollute the ocean. The disadvantage is high installation and operating costs.
(Schematic diagram of a closed-loop scrubber)
❖Hybrid scrubber
is a combination of the above two, with the advantage of flexible switching and complementary strengths. The disadvantages are high cost and system complexity.
The ship can choose according to the characteristics of the three types as needed, to meet the ship's navigation requirements in different emission control areas. Data from DNV GL shows that among currently installed scrubbers, 80% are open-loop scrubbers. Next are hybrid scrubbers, accounting for about 18%.
(Scrubber installation types)
In terms of tower structure, scrubbers are further divided into various designs such as I-type and U-type, single-inlet and multi-inlet, and each vessel can select according to its own ship type and the characteristics of fuel-consuming equipment.
(U-type and I-type scrubbers)
3
Will open-loop scrubbers pollute the ocean? Which ports restrict them?
Countries have long debated whether washwater from open-loop scrubbers pollutes the marine environment, and for environmental and other reasons, some countries and ports have begun to restrict them.
"Harmful theory"
✍ Swedish researchers tested wastewater from open-loop scrubbers, and the results showed that untreated open-loop scrubber wastewater is seriously polluting, containing substances such as heavy metals, aromatic carbon compounds, and soot particles.
✍ In May 2019, 28 EU countries jointly submitted a document to the IMO, stating that the use of open-loop scrubbers "may lead to deterioration of the marine environment because the discharged wastewater contains toxic substances."
"Harmless theory"
✍ Cruise company Carnival conducted a three-year study on the environmental impact of scrubbers, and the results showed that the wastewater discharged by scrubbers meets IMO standards and is within the limits of relevant regulations.
✍ Japan's Ministry of Land, Infrastructure, Transport and Tourism (MLIT) also conducted similar research, and the results proved that open-loop scrubbers do not cause "unacceptable" impacts on marine organisms and seawater quality during use.
❖ In May 2019, in response to the above discussions, the IMO ultimately stated that it would continue to carry out environmental risk assessments of open-loop scrubber wastewater. Nevertheless, for environmental and political reasons, many countries and regions have now decided to restrict open-loop scrubbers.
(Countries and ports restricting the use of open-loop scrubbers)
Note: For specific provisions, see Annex 1 to the CCS circular on the implementation plan for the survey of ship exhaust gas cleaning systems (EGCS)
☞ In areas where open-loop scrubbers are prohibited, vessels using open-loop scrubbers can switch to low-sulfur fuel oil, while vessels using hybrid scrubbers can switch to closed-loop mode to cope. Therefore, in any case, it is necessary to carry a certain amount of low-sulfur fuel oil on board.
III. During installation
1
What is the specific installation process?
The IMO's 2015 Guidelines for Exhaust Gas Cleaning Systems contain relatively detailed provisions on scrubber installation.
① Scrubber assembly
② Scrubber transportation
③ Removal of old funnel
④ Scrubber lifting and installation
2
How does the classification society survey it?
On the basis of the 2015 Guidelines for Exhaust Gas Cleaning Systems, the China Classification Society has developed the Guidelines for the Design and Installation of Ship Exhaust Gas Cleaning Systems, the Guidelines for the Pre-installation of Ship Exhaust Gas Cleaning Systems, and the Guidelines for the Testing and Survey of Ship Exhaust Gas Cleaning Systems.
(Monitoring device survey)
(Equipment operation survey)
IV. After installation
1
How does the maritime administration supervise?
In May 2019, the IMO developed the 2019 MARPOL Annex VI Chapter 3 Port State Control Guidelines to provide guidance for maritime administrations on ship emission control. These include requirements related to scrubbers.
During the initial inspection:
❖The PSCO should check the relevant approved documents—SECC (SOx Emission Compliance Certificate, if issued), ETM (Exhaust Gas Cleaning System Technical Manual), OMM (Onboard Monitoring Manual), SECP (SOx Emission Compliance Plan), and any installed exhaust gas cleaning system (EGCS) or equivalent method for reducing SOx emissions;
❖The required EGCS monitoring records need to be retained and kept compliant.
❖The EGCS record book must contain nitrate emission data and performance records, or an approved alternative method must be used to record them appropriately.
During the detailed inspection:
❖The PSCO should check, together with the relevant approval documents in accordance with the inspection procedures in the OMM, whether the monitoring system is installed and operated.
❖As marine equipment, the PSCO may also inspect the appearance, control panel, main components, and alarm monitoring and control units of the scrubber.
(Schematic diagram of scrubber structure)
❖The PSCO should verify that the system can work normally and is in operation; the system should be equipped with a continuous monitoring system that prevents data recording and processing from being tampered with. The inspection may include but is not limited to: emission ratio, pH, PAH, turbidity limit values given in ETM-A or ETM-B, and operating parameters listed in the system documentation.
2
What to do if the scrubber fails?
In May 2019, the IMO (International Maritime Organization) considered and approved a guidance on scrubber failure response (MEPC.1/Circ.882), which introduced the relevant requirements.
✍If a scrubber installed on board malfunctions and the fault is a single monitoring instrument failure, alternative documents proving compliance should be provided in accordance with the EGCS guidelines.
✍If the EGCS unexpectedly shuts down and cannot be restarted within a short period (1 hour), the ship experiencing the unexpected fault should switch to compliant fuel oil.
✍If the ship has no compliant fuel oil or does not have sufficient compliant fuel oil on board, in order to bunker compliant fuel oil or repair the EGCS, the management authority and competent authority of the relevant destination port should be notified immediately to seek their consent.
✍Any EGCS failure lasting more than 1 hour or recurring should be reported to the competent authority and the management authority of the relevant destination port, including the efforts made by the ship operator to address the failure. The competent authority and the management authority of the relevant destination port will decide whether to take action.
