TEXTE Environmental Impacts of Exhaust Gas Cleaning Systems for Reduction of SOx on Ships — Analysis of status quo 
Report compiled within the framework of the project ImpEx 
Den Boer and Hoen, 2015). Lahtinen (2016) measured a specific consumption of 50% alkali 
about 10 kg/MWh-%S in a small test EGCS and around 6 kg/MWh-%S in a commercial EGCS. 
Figure 2: Required water volume flowrates as a function of the achieved level of reduced 
emission for six different natural waters at different temperatures 
dyOpen ocean 
D) Kattepai 
= © 
500 
O+ 
500- 
% 
Raltic Proper 
m Bothnian Sea 
= 1000| 
001 
00 
5 ® 
500 
— Bothnian Eat 
Ca 
AA 
f) Rıver Geshwater 
— 0°C 
— 5°C 
— 10°C 
=— 15°C 
20°C 
25°C 
30°C 
35°C 
Emi15s10ns corresponding to S,., (%) 
Assumptions: combustion of fuel with 3% sulphur content, engine power of 12 MW and specific fuel consumption of 185 
kg/MWh. Thus, the values on the Y-axis 500, 1000 and 1500 t/h correspond approx. to specific flowrates of 41.7, 83.3 and 
125 m?/MWh, respectively. 
Source: Hassellöv and Turner (2007). 
2.3 Hybrid EGCS 
Hybrid systems can be operated in either OL or CL modes. This require special arrangements 
'hat make the system more complex than OL or CL systems individually. The OL mode is 
typically employed in open sea, where the alkalinity is sufficient for efficient SOx removal 
“EGCSA, 2012). The CL mode, on the other hand, is commonly operated only in sensitive areas 
with local regulative restrictions (in zero discharge mode) or in waters with insufficient 
alkalinity or with poor quality (to protect the systems) (Lloyd’s Register, 2012; Woodfall, 2020). 
Manufacturers also offer OL systems “hybrid ready”, designed to facilitate future upgrades. 
2.4 Discharge water composition 
The EGCS discharge water is characterized by low pH, elevated temperature, increased chemical 
oxygen demand (COD) and decreased dissolved oxygen concentration (US EPA, 2011). It does 
not only contain removed sulphur oxides but also pollutants present in exhaust gas, including 
PAHs, oil residues, heavy metals and nitrate (Endres et al., 2018). The specific composition of the 
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