A lot of ship owners / managers face the challenge of selecting a Ballast Water Treatment System (BWTS) for their ordered new buildings. The selection of a BWTS is a complicated issue. A techno-economical study is necessary to assess many different parameters, in order to shortlist the BWTS that match the requirements of a vessel’s owner/operator.
The criteria for the selection can be divided in three main categories:
• Ships’ and service / trade characteristics.
• Treatment technology factors.
• Vendors’ considerations.
In a new building project, the major selection factor is equipment’s cost. Apart from that, and since installation is a “headache” for the builder mainly, one of the most important considerations for the selection of a system is the Operational Expenses (OPEX).
The OPEX can be divided in two main categories:
• The running cost.
• The maintenance cost.
Running cost:
The running cost depends on the type of each system and can be:
• The power consumed (concerns all systems), which is translated into quantity of HFO or MGO burnt in order generators to produce the required power and therefore highly dependent on fuel prices.
• Cost of chemicals (for systems using chemicals), which depends on chemicals’ prices.
• Cost of MGO burnt (for de-oxygenation systems), in order stripping gas to be mixed with ballast water, which also depends on MGO prices.
• Cost of neutralization agent (for systems that create active substances, like electrolysis and ozonation), which depends on the volume and price per unit of the agent consumed.
Considerations on the running cost:
• The power consumption is not fixed and depends on various factors. For example in electrolysis systems it depends on the salinity of sea water (the lower the salinity the higher the consumption) while in UV systems depends on the turbidity and solid particles (the higher the turbidity / number of solid particles the higher the consumption).
• Since ballasting and de-ballasting rarely take place in high salinity crystal clear ocean waters, but usually in ports with “dirty” waters or nearby (or inside) rivers with brackish waters, the operator should consider selecting the conservative scenario of maximum power consumption for each system.
• While all BWTS are treating the water during ballasting, there are systems that some treatment process is taking place during de-ballasting as well (UV and de-oxygenation systems). Since running time is higher, the running cost is higher as well.
• Long term agreements for chemicals’ prices can be achieved.
• Some electrolysis systems require minimum temperature of used sea water, therefore cost of heating (electrical or steam) must be calculated when operating in cold waters.
• In de-oxygenation systems, the MGO consumption on the stripping gas generator increases when temperature of the sea water decreases.
• The volume of neutralization agent depends on the holding time prior de-ballasting and can be insignificant on long time voyages in ballasted condition. Furthermore, most of the vendors are using caustic soda as neutralization agent, the cost of which is relatively small.
Maintenance cost:
The maintenance cost may include the following:
• Filters’ consumables / spare parts replacement.
• UV lamps replacement.
• Electrodes replacement.
• Service works for inert gas generators.
• Preventive maintenance of all equipment.
• Replacement / calibration cost of sensors.
• Overhauling / replacement of parts in various pumps.
• Electrical equipment normal preventive maintenance.
• Cost of chemicals refilling procedure.
Considerations on the maintenance cost:
• There are big uncertainties regarding the maintenance cost of the BWTS, due to lack of operational experience. In this respect, provided “guarantees” for lifetime of various parts, like UV lamps, filters’ candles or mesh, electrodes or electrolytic cells cannot be justified, since the only experience gained for some of the vendors is from land applications.
• The maintenance cost is not being paid from the day one of operation. It is therefore recommended a life cycle of at least 10 years to be taken into consideration when calculating maintenance cost, when, subject to running hours and operational conditions, most of the consumables / spares should be at least once replaced.
• It is recommended maintenance / consumables and spare parts replacement cost to be provided from each vendor for the selected life cycle.
• The life time of the electrical parts depends on the reliability of the products used by each vendor. It is therefore recommended that a full list of the makers’ used on each BWTS is reviewed prior selection of the system.
• The standard maintenance requirements in connection with actual treatment conditions can increase the workload of vessel’s crew (i.e.: dismantling, cleaning and refitting of a clogged filter).
• Initial supply of spare parts (in additional to those delivered with the initial scope of delivery) to be taken into consideration. That initial supply of spare parts should be based on a FMEA (Failure Mode and Effect Analysis) of the system which will highlight which parts, prone to failure and without redundancy, may stop the system’s operation and treatment and consequently the ship’s ballasting or de-ballasting.
The above cost analysis and considerations is only a part of the results of the techno-economical studies which ARGO NAVIS has performed during the last two years in various types of vessels and various operational and trading patterns.
For more details or any clarification required, do not hesitate to contact us.
NOTE 1: in photo a big number of jellyfish is shown, in Tersan Shipyard, Yalova, Turkey.
NOTE 2: A “Step-by-step Guide to Ballast Water Treatment” is developed by BIMCO and FATHOM and will be launched in December 2013. For more details, please visit the following web site: http://www.ballastwaterguide.com/
