Sacrificial anodes, merchant shipping and

Emission estimates for diffuse sources

Netherlands Emission Inventory

Sacrificial anodes, merchant shipping and fisheries

Version dated June 2008

NETHERLANDS NATIONAL WATER BOARD - WATER UNIT in cooperation with DELTARES and TNO

i Anodes, Shipping & Fisheries

Table of Contents

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1 Introduction and scope

2 Description of emission source

2.1

Causes

2.1.1

Passive protection by means of sacrificial anodes

2.1.2

Active protection by means of impressed current

2.1.3

Ballast tanks

2.2

Measures

3 Explanation of calculation method

3.1

Exterior of vessel

3.2

Wet surface area

3.2.1

Calculation of surface areas based on volume

3.2.2

Correction for incomplete draught

3.3

Corrosion rate

3.3.1

Emissions at sail

3.4

Interior of vessel

4 Activity Rates

4.1

Assessment using statistical data

4.2

Interior of vessel

4.3

Time series, 1990-present

4.4

Time series, present-2027

4.5

Annual data setting

5 Description of emission pathways to water

6 Emission factors

6.1

Emission factors

6.2

Application percentages

6.3


6.4

Annual data setting

7 Emissions calculated

7.1

Emission figures 2004

7.2

Emissions 1990-2006

7.3

Emissions forecast, 2009-2027

8 Comments and changes in regard to previous version

8.1

Difference in figures due to mathematical errors

9 Accuracy and indicated subjects for improvement

9.1

Most significant areas for improvement

10 Spatial allocation

10.1

Seagoing vessels and fishing vessels on NCP

10.2

Seagoing vessels in Dutch territory

10.3

Fishing vessels in ports

6–1

6–1

6–2

6–2

6–2

7–1

7–1

7–1

7–3

8–5

8–5

4–1

4–1

4–3

4–4

4–4

4–6

3–1

3–1

3–2

3–4

3–5

3–6

3–8

3–9

5–8

1–1

2–1

2–1

2–1

2–3

2–4

2–5

9–1

9–1

10–1

10–1

10–3

10–4 ii Anodes, Shipping & Fisheries

11 References 11–1 iii Anodes, Shipping & Fisheries

1 Introduction and scope

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The source of the emissions is the anode material placed on the exterior and interior (in the ballast tanks) of seagoing merchant vessels and fishing vessels for the purpose of cathodic protection of metal surfaces.

In the National Emission Inventory, this emission is assigned to the governmental target sector “Transport”. The emissions in question are zinc, aluminium and cadmium. Cadmium is present as a contaminant in the zinc, and is released when zinc anodes decay.

This report is based on a previous quantification of emissions of anodes in shipping and fisheries for the Dutch Continental Shelf (NCP) and in ports conducted for the Traffic and Transport Advisory Service (AVV) under the EMS (Emission Inventory and Monitoring for the Shipping

Sector). The quantification in this report can be considered to be an update of two EMS protocols:

EMS protocol for Emissions by Shipping and Fisheries: Anodes on ships on the NCP (Kuiper, 2003a)

EMS protocol for Emissions by Shipping and Fisheries: Anodes on ships in ports (Kuiper, 2003b)

Here, the quantification of emissions for NCP and ports is integrated into a single report. The method of quantification of the two types of emissions is different, however, and consequently this distinction will be referenced frequently throughout this report.

1–1 Anodes, Shipping & Fisheries

This quantification implements a number of recommendations for improvement of emissions assessment from the protocols listed above, and also incorporates a few new insights. The most significant changes in reference to the protocols are:

Calculation of the Wet Surface Area (WSA) is improved, with a

WSA computed for each individual ship in Dutch waters, taking partial loading of the ship into account;

A traffic and transport database based on the Lloyds traffic file has been created for the NCP, which, in combination of the

WSA per ship, was used to compute the total average WSA present in Dutch waters;

Emissions from floating tank cooling 1 appear to play a much smaller role than described in the protocols. Floating tank cooling is a cooling system used primarily in inland waterway shipping and possibly a few smaller seagoing vessels. Larger seagoing vessels have pipe or plate cooling systems.

Consequently, emissions from floating tank cooling are not reported separately in this report;

Along with historical development in emissions, this report provides a forecast of emissions up to the year 2027;

The emissions are spatially allocated by body of water identified in the Water Framework Directive. This data is provided as a separate database.

1 Cooling system for ship engines involving a steel tank welded to the hull, in contact with the water, and containing a bundle of thin, corrosion-proof pipes. In some versions, the tank is an inverted box on the bottom of the ship with an opening in the bottom. The tank contains a heat exchanger consisting of a package of many thin tubes that come into contact with the outside water on all sides.


2 Description of emission source

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2.1

Causes

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . figure 1 Functioning anode

Ships are coated to prevent corrosion. This protective layer, however, is not sufficient to fully protect the ship from corrosion. For this reason, as well as to protect the uncoated sections of a ship (screw, damage, etc.) and ensure that the ship remains protected as the coating deteriorates, cathodic protection is used.

If two metals are electrically connected in an electrolyte

(such as seawater), the electrons of a base metal will flow to another, more noble metal. This is due to the difference in electrical potential. The more noble metal is referred to as the

"cathode" and the other as the "anode." As the anode supplies electrons to the cathode, it gradually dissolves into ions, with the result that the cathode becomes negatively polarised and thus protected against corrosion. See figure 1. Cathodic protection can be classified as passive or active. This is explained in more detail in the following subsections.

2.1.1

Passive protection by means of sacrificial anodes

Passive cathodic protection of a ship involves the use of "sacrificial anodes". As already indicated, these sacrificial anodes must be of a metal that is less noble (more base) than the metal to be protected. The two metals used as anodes in shipbuilding are zinc and aluminium.

Table 1 shows the various metals in order of nobility. The effectiveness of the anode material in seawater is determined by the composition of the alloy.

Because the anodes dissolve in the seawater, the blocks must be replaced at regular intervals. On average, the blocks are replaced every two to two-and-a-half years, when approximately 15% of the original weight remains. For fishing vessels, the ratios are different. A fishing vessel goes into dry-dock every year, and so the blocks are replaced every year, when some 30% of the original weight remains.


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . table 1

Metals in order of nobility

Nobility of various metals

Metal

Potassium

Sodium

Calcium

Magnesium

Aluminium

Zinc

Iron

Chromium

Nickel

Tin

Lead

Copper

Mercury

Silver

Platinum

Gold

Cr

Ni

Sn

Pb

Cu

Hg

Ag

Pt

Au

Symbol

K

Na

Ca

Mg

Al

Zn

Fe

Zinc anode

The most commonly material used for cathodic protection of seagoing vessels is zinc. The electrical capacity (also indicated by the symbol

ε

, see chapter 4.1) of a zinc anode in seawater is 780 Ah/kg (Ampere per hour per kg of zinc anode). This is a function of the amount of valence electrons that can be moved from the zinc to the less noble metal per hour. If the amount of valence electrons the metal to be protected gives off under the influence of seawater is known, the rate at which the zinc anode dissolves can be calculated.

The zinc anodes installed in ships are generally designed for a lifetime of between 1 and 3 years.

Aluminium anode

Aluminium is being used as an anode material more and more frequently. The electrical capacity of an aluminium anode in seawater is

2,600 Ah/kg. Aluminium anodes perform better than the zinc anodes

(2,600 valence electrons per hour per kilogram versus 780 for zinc), and as such require fewer to achieve the same effect. Although aluminium is a more expensive material than zinc, the end cost of aluminium anodes is less because they require 3.33 times less material.

Another significant environmental advantage is that the aluminium alloys used do not contain cadmium, unlike the zinc alloys used (and prescribed by standardization; see chapter 3.2).


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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . figure 2

Operation and placement of impressed current system

2.1.2

Active protection by means of impressed current

In addition to passive protection, active cathodic protection is an increasingly common method of protection. The impressed current (IC) system moves potentials to protect the metal.

An IC system uses a transformer, an adjustable rectifier as a power source and inert, or "non-consumable", anodes. The adjustable rectifier can be set so that the connected anode(s) provide exactly the protective current to provide the desired protection potential. See figure 2.

Theoretically, an IC system could be used to protect the entire exterior of a vessel, but in practice this system is often used in combination with passive anodes. The parts of the vessel fitted with passive anodes are the bow thruster tunnel, the screw and the rudder. These parts require a higher level of protection because they use unfinished metal (screw), the coating on these parts has a higher breakdown factor, and the speed of the water that passes along these parts is higher than at other parts of the hull. IC systems are not used in ballast tanks, because the generation of hydrogen gas (H

2

) constitutes a risk of explosion, certainly in combination with the electrical system.

Because IC systems do not release metal ions into the water, this is the most environmentally friendly cathodic protection method. The system also allows online measurement of the state of the coating, and reduces organism growth, thereby contributing to reduced fuel use.


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . figure 3

Placement of sacrificial anodes in ballast tanks

2.1.3

Ballast tanks

Protection of the ballast tank of a vessel is more complex than the protection of the hull, for a number of reasons:

• While the ballast tank may be a tank solely used for ballast water, in many cases the cargo area is also used as a ballast tank, and this causes the anodes to become soiled and no longer function properly

• The ballast tank is not always in ballast

• The ballast tank is difficult to reach and consequently difficult to check;

• The form and structure of a ballast tank (many crossbeams, holes, etc.) require more anode material to keep the less accessible locations (the places not easily reached by cathodic protection) protected

Ballast tanks are constructed primarily of aluminium, presumably due to the longer lifetime of aluminium at the same weight. As indicated above, the anodes in the ballast tank are difficult to replace. See figure 3 for the placement of anodes in the ballast tanks.

For ships with explosive cargo (oil, gas, etc.), ballast tanks are subject to special requirements governing the placement and type of anode material used:

• Aluminium may not be used in ballast tanks for ships transporting flammable cargo. Anodes coming loose and falling can cause sparks;

• Likewise, IC systems cannot be used due to the risk of fire/explosion due to the formation of hydrogen gas (H

2

) in combination with the electrical system.

Consequently, in certain cases zinc is used for the anodes mounted higher in the ballast tank (combining zinc and aluminium anodes is permitted).


The average lifetime of anodes in ballast tanks is calculated at 4-6 years.

2.2

Measures

Government policy is focused on reducing the concentrations of toxic substances to target values. To do this, emissions of many of these substances must be reduced. Between 1985 and 1995, copper impact on surface water had to be reduced 50%, and cadmium 70% (North

Sea Action Plan). These goals were met and exceeded. For cadmium, a priority substance, minimization of discharge is a goal. Zinc, copper and cadmium are of significance for fresh surface water sources, primarily in relation to the contamination of the sediments.

Although cadmium levels in zinc have been lowered in recent years

(0.001-0.005%), this reduction was not and is not in effect for anode material, which uses higher contents (NEN, 1996; DNV, 1993; US-

Military specification, 1987) because of the quality requirements set on the anode material (relating to the composition of the alloy). The issue is that the anodes must corrode evenly, which requires cadmium contents between 0.025 and 0.07 percent. Higher contents may also be found in anodes from less scrupulous suppliers, but there are no figures available on this.

The emission of zinc and cadmium from anodes was addressed in a

1996 OSPAR report (OSPAR, 1992), which recommended monitoring emissions. If an increase in the use of zinc is observed, then supplemental measures should be considered in regard to this cadmium emission.

The fishery sector has seen a large-scale shift towards replacing anodes with IC systems. One important reason behind this is that anodes on the ship's shell increase resistance when sailing, resulting in lower sailing speed and higher fuel consumption. Since 2000, the acquisition of IC systems in the fishery sector has been included in the VAMIL 2 regulations (a financial environmental regulation system mandated by the Ministry of Housing, Spatial Planning & the Environment).

2 VAMIL stands for "voluntary amortization of environmental investment." The VAMIL was established by the Ministry of Housing, Spatial Planning & the Environment.


3 Explanation of calculation method

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The calculation system used is addressed in general terms in the

"method" section. Chapters 5, 6 and 7 cover the activity rates, the emission factors and the emissions.

3.1

Exterior of vessel

This chapter addresses the method of calculation used to arrive at the emission assessment. Emissions are ultimately calculated as the product of an activity rate and an emission factor. emission = activity rate * emission factor

The emission is expressed in tonnes per year.

The activity rate is the wet surface area (WSA) (in m 2 ) on average present in Dutch waters at any given time. The total ship area is the product of the total number of ships found in the NCP and the wet surface of a seagoing vessel, taking type and tonnage into account. The traffic and transport database of the risk model SAMSON (Glansdorp,

Van der Tak, 1993) was used to calculate the number of ships sailing on the NCP and the calculation of the underwater ship area. The basic data for this database were derived from Lloyds for the year 2000. For other years, a comparison with figures from Statistics Netherlands of ship calls at Dutch ports was used.

In the calculations, the activity rate for different years was estimated taking into account the trend in wet surface area and application rates of the various technologies of cathodic protection.

-{}-

AR x,c

= AR y x APP x,c x TREND xy

Where:

AR x,c

= activity rate of technology (t) in year (x)

AR y

APP x,c

= total of activity rates in base year (y)

= application fraction of technology (t) in year (x)

TREND xy

= trend factor of AR in year x in relation to base

year (y)

The emission factor is the leaching rate of aluminium and zinc, expressed here in µ g cm -2 day -1 . These leaching rates used in the calculations are taken from the report Uitloging anodemateriaal van zeeschepen, produced by BECO for RIZA, the Netherlands Centre for

Water Management (Willems, 2003; see chapter 4.4).


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Figure 4

Comparison of the results of different methods of establishing wet ship area for the group bulk carriers

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Table 2 Comparison of the results of different methods of establishing wet ship area

3.2

Wet surface area

If the dimensions of the ship are known, the wet ship area can be calculated by any of several different methods:

•

The Denny-Mumford equation (Man-Diesel, 2002; Kuiper,

2003a,b) was derived by Mumford at the end of the 19th century using tests of ship models in Denny's experimental

(1750 m 3 ) water tank in Scotland. In Denny-Mumford, the wet ship area is calculated from the length, depth and a block coefficient (the ratio of the actual volume of the hull and the product of length x width x depth)

• The Komsi comparison (Koivisto, 2003; OECD, 2005) based on measurements of ships in Finland

•

The Holtrop-Mennen equation (Holtrop, 1977) is the most recent method for determining the wet ship area. This formula is based on the same type of measurements as Denny-

Mumford, factoring in additional insights from hydrological theory. The Holtrop-Mennen coefficients are obtained through regression analysis of MARIN model tests

•

The ratio from Van Hattum et al. (2002) is more of a first order approach to the wet ship area, based on a simplified ship model.

In this study, the methods are compared for the group of Bulk Carriers in the Lloyds register. The results of the comparison are shown in the figure below. The volume of all ship's enclosed spaces is expressed in

GT (gross tonnage) to the power of two-thirds.

Bulkers: GT^2/3 vs. oppervlak

35000

30000

25000

20000

15000

10000

5000

0

0 500 1000 1500 2000 grootte^2/3 (GT)

2500 3000 3500

Denny-Mumford

Van Hattum

Komsi

Holtrop-Mennen

Average surface

9072

7735

9250

9223

Denny Mumford

Van Hattum

Komsi

Holtrop-Mennen

% of Holtrop

Mennen

98%

84%

100%

100%


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Equation 1 The Holtrop-Mennen compariso

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Table 3 Coefficients for use in

Holtrop-Mennen equation

For bulk carriers, the results using Denny-Mumford, Holtrop-Mennen and Komsi are very similar. The Van Hattum model produces different results. Because Holtrop-Mennen seems to be the most theoretically sound, the most recent and in keeping with Komsi and Denny-

Mumford, this model is recommended. calculates the wet ship area as follows:

WSA = L(2D+W) x sqrt(C

M

) x (0.530+0.632C

B

-0.360(C

M

-0.5)-

0.00135L/D)

Where:

WSA max

: wet ship area at design draught

D : design draught of the ship

L : length of the ship measured between midship perpendiculars

W : width of ship at widest point

C

M

: surface area coefficient of the largest rib: the transverse section measured at the widest rib of the ship divided by the

C

B surface area defined by W x D at the largest rib

: the block coefficient of the ship: volume of the ship divided by the block defined by L x W x D

Values for C

M

and C

B

for the various vessel types are shown in table 3

(Man-Diesel, 2002).

C

B

C

M

Vessel type

Barge

Bulk carrier

Tanker

General cargo

Container ship

Ferry

0,9

0,85

0,85

0,75

0,7

0,7

0,98

0,98

0,98

0,95

0,95

0,95


3.2.1

Calculation of surface areas based on volume

The current standard of ship measurement is gross tonnage (GT 3 ).

A ship twice as long is generally also approximately twice as wide and twice as deep. The relationship between volume and vessel length is therefore a third exponent. The relationship between surfaces and length is a second exponent. Taken together, all this suggests a relationship between surface and vessel volume to the power of twothirds:

WSA max

~ Volume 2/3

Where WSA max

is the wet surface area at design draught.

Upon further elaboration, this is also shown to apply for most vessel types across a very wide range of vessel sizes. The wet surface can therefore be expressed as a function of ship size in GT:

WSA max

= C GT 2/3

The value of the constant C differs from vessel type to vessel type.

Table 2 presents an overview of the results.

3 Ship size is often expressed in gross tonnage (GT). This gross tonnage is calculated as K * V, where V is the gross volume of the ship and K a correction, calculated as 0.2 + 0.02

10 logV .


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Table 4 calculation of wet ship areas when fully loaded, for each vessel type type no. Vessel types (Samson description

2006)

1 Tankers (single and double-walled)

2

2a

3

4

5

6

6a

7

8, 9, 0

Chemical tankers (single and double-walled)

LPG tankers

LNG tankers

Bulk carriers

Container ships

General dry cargo

Passenger ships and ferryboats

Unitised Ro-ro

Reefers

Other; supply ships; noncommercial ships

Fishing vessels surface area

WSA max

= 9,62

GT 2/3

WSA max

= 9,35

GT 2/3

WSA max

= 7,47

GT 2/3

WSA max

= 9,70

GT 2/3

WSA max

= 8,57

GT 2/3

WSA max

= 8,76

GT 2/3

WSA max

= 5,20

GT 2/3

WSA max

= 6,60

GT 2/3

WSA max

= 10,2

GT 2/3

WSA max

= 8,40

GT 2/3

WSA max

= 8,63

GT 2/3

3.2.2


The wet ship areas above are wet areas when fully loaded, which also puts the ship at design draught. If draught is not full, actual wet area can be calculated from the actual wet area and the percentage draught

(%T) 4 :

4 Derivative; the average ratio of maximum draught (T max

) and vessel width (B) is 1:2.6. The maximum wet area can initially be estimated as

WSA max

= constant * (2T max

+ )B = constant * (2T max

+ 2.6T

max

) = constant * 4.6T

max

. T max

= WSA max

/(constant * 4.6)

In the same way, the actual wet ship area (WSA) is equal to constant *

(2T max

* %T + B) = constant * (2T max

* %T + 2.6T

max

) = constant * T max

(2%T +2.6).

Combining the two comparisons results in WSA = WSA max

(2 * %T

+2.6)/4.6


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Equation 2


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Figure 5

A nodes on the rudder and around the screw

WSA = WSA max

(2 * %T +2,6)/4,6

Estimates of relative draught for the various ship types upon arrival and departure are obtained from MARIN (Van der Tak, 2006).

3.3

Corrosion rate

The draft of the "anode plan" or cathodic protection plan (CB plan) for the ship takes into account factors such as susceptibility to corrosion of the type of vessel and the individual parts of the ship. The areas around the screw and on the rudder, for example, have more anodes placed on them than on the rest of the ship (see figure 5).

The draft assumes recommended electrical current density per m 2 (i c

) to prevent corrosion (Norsok, 1997; DNV, 1993; British Standard, 1991).

The number of anodes to be installed is derived from these current densities. For untreated steel in North Sea water, electrical current density must be approximately 85 mA/m 2 to prevent corrosion. This figure applies at a temperature between 5 o C and 20 o C (fluctuation in

North Sea between 1990 and 1999, with average of 11.8

o C) and a draught between 0 and 30 metres.

The amount of anode material that dissolves in water over a given period of time (such as one year) can be calculated from the voltage density and the electrical capacity of the anode material, using

Dwight's equation. This equation is:


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Equation 2

Dwight's equation for the calculation of the number of anodes required on a ship

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Table 5

Required electrical current density by component of and by type of ship





( (

A

∗ i c

)

/ 1000

)

∗

ε

∗ u t





∗ a m

= m

Where:

Parameter

M

A

Unit

Kg m 2 i c u mA/m t Hours

−{}−ε

Ah/kg

Factor

2

Description

Amount of anode material that corrodes in time t

Wet surface

Required electrical current density

Time spent in water, in hours

Electrical capacity of anode in seawater

Utilization factor; for emission calculations, u=1

Fraction that anode material (zinc or aluminium) used a m

Factor represents in relation to total use of anodes (total of zinc and aluminium anodes)

The electrical capacity of a zinc anode in seawater is 780 Ah/kg

(Ampere-hours per kg of zinc anode) and 2,600 Ah/kg for aluminium anodes. The utilization factor is used to introduce an extra margin for the use of anodes. Assuming a given lifetime of two years, a utilization factor of 0.9 results in a theoretical overcapacity of approximately

10%. For emission calculations, the utilization factor is 1. The factor a m indicates the fraction of zinc or aluminium in relation to the total anode use in shipping or fisheries.

Table 5 shows the required current densities per component and per type of vessel (Willems et al., 2003).

Bulk Carrier

VLCC (Very Large Crude oil

Carrier)

Required current density (mAmp/m 2 )

Hull Screw Rudder Turbine bow thruster

12 700 150 120 700

12 700 150 120 700

Coaster

Ro/Ro Ferries

Fishing

Supply Vessel

Work vessel

Ice class vessel

Container

Reefer

12

12

18

18

40

20

12

12

700

700

1000

1000

1400

1400

1400

700

250

150

250

250

250

250

250

150

120

120

120

120

120

120

120

120

Destroyer

Naval vessel

12

12

700

700

150

150

120

120

700

700

The table above can be used to calculate the leaching of anode material. Because the surface area and number of screws, rudders, turbines and bow thrusters is not known for each vessel type, table 6 is provided to be used for estimates (Willems et al., 2002). This table shows the required current density for the hull including what is necessary to protect the screws, rudders, turbines and bow thrusters.

700

700

700

700

700

700

700

700


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 6

Average required electrical current density for hull, stern and bow thrusters, by type of vessel

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Equation 3

Equation for the calculation of the corrosion rate of anodes

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 7

Current densities and corrosion rates for anodes on sea vessels

Required current density (mAmp/m 2 )

Type of vessel

OBO carrier

Tankers

Bulk Carrier

Container

Ro-ro

General Cargo

Reefer

Passenger

Work vessels

Supply

Fishing

Hull

15

15

15

15

20

20

15

20

35

22

24

Equation 2 (Dwight's equation) in combination with the recommended voltage densities allows calculation of both the number of anodes and the corrosion rate. Dwight's equation can be used to directly derive the formula for the corrosion rate in µ g/cm 2 -day, which is:





 i c

∗

2400

ε





= corrosion rate

3.3.1

Emissions at sail

For corrosion rate, the emission estimate distinguishes between seagoing vessels, Ro-ro, passenger/ferryboats and fishing vessels

(current density 25 mA/m 2 ). See table 7 (EPA, 1996).

Type of vessel

Tankers, bulk carriers, container ships

Current density and corrosion rate, vessel exterior

Current density corrosion rate in

µµµµ g/cm

2

/day i c

in mA/m

2 zinc aluminium

15 46 13,3

Ro-ro, supply, passenger, ferry

Fishing vessels

20

25

61,5

77

17,8

22,2

3.3.2 Emissions in ports

The literature shows that the corrosion rate in port is less than at sail by a factor of 3-5 (EPA, 12). For this reason, the calculation of the corrosion rate in ports uses an emission factor reduced by a factor of 4 in comparison to the emission factor at sail. The results of this exercise are shown in table 8 (EPA, 1996; Kuiper 2003a,b).


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 8

Current densities and corrosion rates for anodes on sea vessels in port

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 9

Activity rate factor, exterior of ships, at any moment, for year 2000

Type of vessel

Seagoing vessels

Fishing vessels

3.4

Interior of vessel

Current density i c

in mA/m

2

3,8

6,3 corrosion rate in

µµµµ g/cm

2

/day zinc aluminium

11,5 3,3

19,3 5,6

For the ballast tanks, the same approach is used as for the exterior of the ship. To do this, the surface area of the interior of the ballast tanks is estimated, as well as the corrosion rate and the exposure time of the ballast water. Ballast water is changed offshore, in part to prevent contamination by exotic organisms. For this reason, the emission takes place primarily on the NCP.

The total number of ship tonnage on the NCP is known from the

SAMSON database. Table 9 shows the maximum ballast capacity in

Deadweight Tonnage (DWT) (Willems et al., 2003). This allows a maximum ballast capacity to be calculated, in m 3 , for each type of vessel. From this, the internal surface area of the ballast tanks can be estimated by multiplying the volume by a factor. This factor depends on the shape of the ballast tank, and varies from 1 to 5. This report uses an average factor of 2.5.

Type of vessel

OBO carriers

Tankers > 80.000

Tankers > 80.000

Chemical tankers

LNG/LPG tankers

Bulk carriers

Container

Ro-ro

Reefer

General Cargo

Passengers

Work vessels

Supply

Fishing vessel

Ballast water capacity in % of DWT

30

30

20

20

25 – 30

20

30

20 – 25

10 - 15

10 – 15

10 -15

10 -15

10 -15

10 -15

The corrosion rate in

µ g/cm 2 -dag can be calculated using equation 3.

According to a statement in the BECO report, an average current density of 90 mA/m 2 can be maintained for i c

(this varies from 86 to

120 mA/m 2 , depending on the type and shape of the ballast tank). For the anodes in the ballast tanks, the corrosion rate is:


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 10

Corrosion rate of anodes in ballast tanks

Current density i c

in mA/m

2

Corrosion rate in

µµµµ g/cm

2

/day zinc aluminium

All vessels 90 276 79,8

For the fraction of the time that ballast water is in the ballast tank,

BECO estimates a factor of 0.35. An estimate of the discharge on the

NCP is made as follows. In practice, not all ships will change ballast water on the NCP. It is assumed that of all ships on the NCP, a maximum of

50% sail to ports in the Netherlands, while the other half sailed from

Dutch ports. A few will not call in the Netherlands at all. Consequently, it is assumed that a maximum of 50% of the ships change their ballast water on the NCP (these being the ships that sailed to Dutch ports in ballast to pick up cargo).


4 Activity Rates

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 11

Activity rate (AR) for Seagoing Vessels and Fishing Vessels on North Sea

4.1

Assessment using statistical data

The method for assessment of the activity rates is taken directly from the previous versions of this protocol (Kuiper, 2003). This means that the wet surfaces are estimated by means of the number of vessels according to the Statistics Netherlands, multiplied by the average surface per ship. The wet surface area in 2004 was calculated in detail from the geographic files. See chapter 10 for the derivation of this figure. The result is considered determinated for the base year in question. This means that all other emissions are scaled against this result. Here, too, the number of vessels is taken from Statistics

Netherlands. This revealed that minor changes in the files have been introduced since 2003.

Year NCP

Seagoing vessels

2004 = 735709

NCP

Fishing vessels

2000 = 65551

Number AR(m 2 ) Trend Number AR(m 2 ) Trend

1990

1995

2000

2004

2005

2006

45920 766976 1.04

44056 735843 1.00

42087 702955 0.96

44048 735709 1.00

43189 721362 0.98

44011 735091 1.00

639

563

546

473

441

440

76716

67592

65551

56787

52945

52825

1.17

1.03

1.00

0.87

0.81

0.81


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 12

Activity rate (AR) for Seagoing Vessels and Fishing Vessels on North Sea

Year NCP

Seagoing vessels

2004 = 735709

Number AR(m 2 ) Trend

NCP

Fishing vessels

2000 = 65551

Number AR(m 2 ) Trend

1990

1995

2000

2004

2005

2006

45920 157792 632284

44056 151387 606618

42087 144621 579506

44048 151360 606508

43189 148408 594680

44011 151232 605998

1,04 639 173677 1,35

1,00 563 153021 1,19

0,96 546 148400 1,15

1,00 473 128559 1,00

0,98 441 119862 0,93

0,99 440 119590 0,93

The figures above are compiled from the totals of the figures for Dutch seaports. This total is higher than the annual total figure published by

Statistics Netherlands, because a ship may call at multiple ports. The figures above include all calls. The data goes back to the year 1996. For years prior to 1996 Statistics Netherlands does not publish online statistics, so these figures are estimates.

The following ports are included: Amsterdam, Delfzijl en Eemshaven,

Dordrecht, Harlingen, IJmuiden, Klundert, Moerdijk, Rotterdam,

Scheveningen, Terneuzen, Vlaardingen, Vlissingen, Zevenbergen and

Zaanstad.


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 13

Activity rate for seagoing vessels and fishing vessels from ballast tanks in

2004

4.2

Interior of vessel

The activity rate factor for the ballast tanks is the internal surface area of the tanks in the ships present on the NCP on average permanently.

The calculation of this surface area assumes that 50% of ships are transporting ballast water, and change this ballast water on the NCP.

The calculation of the wet surface of ballast tanks is directly related to the wet surface of the ships.

Vessel type

Anchored vessel

Bulker

Chemical

Container

General Dry Cargo

Gas tanker

(LPG/LNG)

Miscellaneous

Ore/Bulk/Oil

Oil

Pass./Ferry

Roll-on/Roll-off (roro)

Tug/supply

Floating workstation

Fishery

Total

AR

(m 2 )

150421

79728

67290

107886

131388

14763

7191

5574

73725

13153

70749

3416

10423

56787

Factor

%

10

20

20

25

10

25

10

25

25

10

20

10

10

18

WSA ballast

(m 2 )

15042

15946

13458

26971

13139

3691

719

1394

18431

1315

14150

342

1042

10222


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 14

Activity rates for ballast tanks for the years 1990-2006

4.3


The table below shows the time series for the activity rates for the internal surface area of the ballast tanks.

Year Trend Seagoing vessels

AR(m 2 )

Trend Fishing vessels

AR(m 2 )

1990

1995

2000

2004

2005

2006

1,04

1,00

0,96

1,00

0,98

0,99

128874

123643

118117

123620

121210

123516

1,35

1,19

1,15

1,00

0,93

0,93

11963

10540

10222

8855

8256

8237

The 2004 figures for the above table were determined using the spatial allocation database. The other figures were determined based on the trends in number of seagoing vessels and fishing vessels.

4.4

Time series, present-2027

The trend in the activity rate (wet ship area) is dependent on two factors:

trends in ship activities

trends in ship size

Ship activities

A forecast for trends in ship movements can be based on CPB scenarios. The scenario document Welvaart en leefomgeving (CPB et al., 2006) outlines a trend in the quantity of goods stored in the ports.

The trend in ship movement (in tonne-km) is assumed to be directly related to this stored quantity of goods.

The Global Economy scenario is selected, which entails the assumption that during the period from 2002 to 2040, shipping activities will more than double (2% growth per year).

In the same period, the fisheries sector is expected to shrink 50% (2% per year until 2040).

Trend in vessel size

Trends in vessel size are important for tracking the development of emissions from anodes. Growth in average vessel size means a decrease in total wet surface (at equal total tonnage), because larger ships have relatively less surface area than smaller ships. The development of vessel size per vessel type is based on trends in average vessel size over the past 20 years. Looking at these trends reveals that for a number of vessel types, there has been no growth in this period, while others have grown by 20-30%.

Vessel types that have seen no significant growth are: Tankers for chemicals and oil products, bulk carriers, reefers and


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 15

Activity rates for the years 2004 through 2007 miscellaneous, non-merchant. For these vessel types, no growth will be assumed for the coming 20 years.

Vessel types that have seen growth are: oil tankers, OBO, container ships, general dry cargo ships, ferryboats, passenger ships/ro-ros and fishing vessels. For these vessel types, a 20% growth in vessel size will be assumed for the coming twenty years.

Trends in wet ship surface:

Combination of the growth in vessel activities and average vessel size results in the index figures as compared to 2004 shown in the table below. The result of growth in average vessel size is that ultimately, the growth in WSA will be curtailed somewhat. This is because larger ships have slightly less surface area per unit of cargo capacity than smaller ships.

Year Index figure WSA vessels with no significant vessel growth 1

2004

2009

2015

100

110

124

Index figure WSA vessels with significant vessel growth 2

100

107

116

Index figure WSA fishing vessels

100

88

76

2021

2027

139

156

125

135

65

56

1) Tankers for chemicals and oil products, bulk carriers, reefers and miscellaneous, non-merchant.

2) Oil tankers, OBO, container ships, general dry cargo ships, ferryboats, passenger ships/ro-ros and fishing vessels.


4.5

Annual data setting

Source for annual updating of data

The assumed data on the number of calling ships and the size of the fishery fleet are updated annually against actual figures from Statistics

Netherlands.

The emissions calculated can be easily updated based on recent annual figures of the number of calls of seagoing and fishing vessels. These figures are published annually by Statistics Netherlands.

Description of data supply pathway

The data can be obtained from Statistics Netherlands in two ways. The first is with the assistance of Statistics Netherlands help desk, which is available to take questions on any published figures by phone and email. The second method is to use Statistics Netherlands's StatLine database, which can be accessed via the internet. The data required are found under the main group Bedrijfsleven ("Industry") by selecting the sub-groups Verkeer, vervoer en communicatie ("Traffic, transport and communication" and then Personen- en goererenvervoer ("Passenger and goods transport"). Under this group, select zeevaart ("sea transport") and then zeevaart, kwartaalcijfers ("sea transport, quarterly figures"). To obtain the correct figures, under the Periodes ("Periods") tab select the annual totals from 1996 through 2006, and under the

Belangrijkste Nederlandse havens ("Biggest Dutch ports") tab, select all afzonderlijke zeehavens ("individual seaports"). Do not select

Nederland totaal (All Netherlands) under the "Biggest Dutch ports" tab

(this would exclude duplicate records).

For the fishery fleet , select the main group Bedrijfsleven ("Industry") and then the group Landbouw en visserij ("Agriculture and fisheries").

Then select Visserij ("Fisheries"). Under this group, select Zee- en kustvisserij ("Sea and coastal fisheries"). To obtain the correct figures, under the tab Onderwerpen ("Subjects"), select Vloot ("Fleet") and then Aantal schepen ("Number of ships"). All types must be selected.

Under the Periodes ("Periods") tab, select the desired years.

Use of this database and the help desk is free. StatLine does not include any figures for sea transport and traffic from before 1996. Older figures may be requested from the information desk.


Sources for updating of spatial distribution data

If the spatial allocation must be updated, two data sources are required:

1.

2.

For the Dutch shipping lanes and ports, the database for calculation of air emissions must be used.

To update spatial distribution data on the NCP, the MARIN traffic and transport database must be used.

Both of these functions will most likely require specialist assistance.

For the calculation of the underwater surface area on the NCP, the traffic and transport database from the risk model SAMSON is the source for periodic updating against actual figures.

Calculation of the wet surface area of the ships relies on the data from the SAMSON traffic and transport database. The basic data for the traffic and transport database over the year 2004 were derived from

Lloyds. In view of their high cost, these basic data will only be purchased periodically. Updating of the Lloyds database does not result in major changes in wet ship area. MARIN converts the Lloyds data into a traffic and transport database. In the future, this database will be based on AIS data (whether or not this data will still have to be acquired from Lloyds is uncertain). The traffic and transport database is available from MARIN or the Traffic and Transport Advisory Service

AVV (E. Bolt). Up to now, the Lloyds database has been used to create a new traffic and transport database approximately once in four years.


5 Description of emission pathways to water

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The anodes emissions source has the spatial character of a diffuse source. As a whole, the emission source can be essentially considered a line source along the seaways on the NCP, with the strength proportional to the annual wet ship area travelling those pathways annually. The fisheries sector is an additional diffuse source. Depending on size, the ports can be considered a point source (small ports) or an area source (large ports).


6 Emission factors

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 16

Emission factors for anodes on the exterior and interior of the vessel

Table 17

Emission factors for anodes on sea vessels in port

6.1

Emission factors

For the ship’s shell and ballast tanks, the emission factor is compiled from the corrosion rate of the anode material and the factors exposure time and level of application of the anode material in question (zinc or aluminium).

The emission factors for the various components are shown in table 16.

Type of vessel corrosion rate in

µ g/cm 2 /day zinc aluminium

Exposure

Days/year

Application factor zinc aluminium

Emission factor kg/m 2 -year zinc aluminium

Exterior of vessel

Tankers, bulk carriers, container ships

Ro-ro, supply, passenger, ferry

Fishing vessels

Ballast tanks

46

61,5

77

13,3

17,8

22,2

365

365

365

0.7

0,7

0,2

0.125

0,125

0,1

0,1175

0,1571

0,1967

0,0607

0,0812

0,1013

All vessels 276 79,8 128 0,1 0,3 0,0353 0,0306

Type of vessel

Seagoing vessels

Fishing vessels corrosion rate in

µ g/cm 2 /day zinc aluminium

11,5

19,3

3,3

5,6

Exposure

Days/year

( ~ 1,5)

*

(~ 160) * application factor Emission factor g/m 2 /year zinc aluminium zinc aluminium

0,7 0,125 0,12 0,0062

0,2 0,1 6,16 0,88

*) See chapter 10


6.2

Application percentages

In practice, zinc and aluminium anodes are used. Additionally, IC systems are used, and these systems cause no emissions. Percentages used on the exterior of seagoing vessels are as follows (Willems et al.,

2003):

• 70.0% zinc anodes

• 12.5% aluminium anodes

• 17.5% ICCP systems

The proportion of cathodic protection systems in use by fishing vessels is different than that of other seagoing vessels. IC systems are used in

70% of cases. For fishing vessels, the percentages are (Willems et al.,

2003):

• 20% zinc anodes

• 10% aluminium anodes

• 70% ICCP systems

Not all ships use anodes in their ballast tanks. 40% of ballast tanks are equipped with anodes, while the other 60% use only coating protection. Of the ballast tanks equipped with anodes, some are coated and some are not. No information is available on percentages. The percentages of anode materials in ballast tanks are (Willems et al.,

2003):

• 60% no anodes

• 30% aluminium anodes

• 10% zinc anodes

6.3


Ascertaining trends in application percentages will require further research, mainly in the degree of use of materials. Such research could be carried out by means of a survey among ships. This would require considerable effort. So far, figures for the years from 1990 to the present have been based on an assumption of the emission factors in tables 16 and 17.

6.4

Annual data setting

There are no other estimates for the emission of zinc originating from the corrosion of anode material on vessels for the NCP. In the coming years, attention can be devoted to the trend in the application of the type of cathodic protection (zinc, aluminium, IC systems) as well as methods of handling ballast water.


7 Emissions calculated

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7.1

Emission figures 2004

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 18

Emission by anodes on the exterior and interior of the vessel in 2004 (kg/year)

Emissions for 2004 for the ships of the spatial distribution database are as follows:

Process description

Anodes on exterior of seagoing vessels sailing on NCP

Anodes on ballast tanks of seagoing vessels sailing on NCP

Anodes on exterior of seagoing vessels sailing from/to/in ports

Anodes on exterior of seagoing vessels in port

Subtotal, seagoing vessels

Anodes on exterior of fishing vessels sailing on NCP

Anodes on ballast tanks of fishing vessels sailing on NCP

Anodes on exterior of fishing vessels in port

Subtotal, fishing vessels

Zinc

90625

4367

18269

17831

131093

3193

361

1811

5204

Cadmium

45

2

9

9

66

2

0,2

1

3

Aluminium

4680

3788

943

910

10321

460

313

263

897

7.2

Emissions 1990-2006

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 19

Emission of zinc by anodes on the exterior and interior of the vessel since 1990 (kg/year)

Tables 19, 20 and 21 show emissions by the anodes on the exterior and interior of the vessel for the years 1990 through 2006.

1990 1995 2000 2005 2006 Process description





94477

4553

19045

18589

90642

4368

18272

17835

86591

4173

17456

17037

88858

4282

17913

17484

90549

4364

18253

17816

136664 131117 125257 128536 130983 Subtotal, seagoing vessels

Anodes on exterior of fishing vessels sailing on NCP 4313 3800 3685 2977 1685


. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 20

Emission of cadmium by anodes on the exterior and interior of the vessel since 1990 (kg/year)




Process description










488

2447

7031

430

2156

6195

417

2091

6008

337 291

1689 2573

4852 4549

1990

47

2

10

9

68

2,2

0,2

1,2

3,5

1995

45

2

9

9

66

1,9

0,2

1,1

3,1

2000

43

2

9

9

63

1,8

0,2

1,0

3,0

2005

44

2

9

9

64

1,5

0,2

0,8

2,4

2006

45

2

9

9

65

1,3

0,1

0,8

2,3


. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 21

Emission of aluminium by anodes on the exterior and interior of the vessel since 1990 (kg/year)

Process description










1990

4879

3949

983

1995

4681

3789

943

948 910

10760 10323

622

423

355

1212

548

373

313

1068

7.3

Emissions forecast, 2009-2027

2000

4471

3619

901

869 892 909

9862 10120 10312

531

362

303

1035

2005

4589

3714

925

429

292

245

836

2006

4676

3785

943

370

252

244

868

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 22

Emission of zinc by anodes on the exterior and interior of the vessel for 2009 through 2027

(kg/year)

Tables 22, 23 and 24 show the forecasts for emissions by the anodes on the exterior and interior of the vessel for the years 2009 through

2027.

2009 2015 2021 2027 Process description

Anodes on exterior of seagoing vessels sailing on

NCP





97797

4703

19870

19224

141595

2813

107187

5142

21984

21046

155359

2416

117513

5623

24331

23047

170513

2075

128873

6151

26937

25246

187206

1783 Anodes on exterior of fishing vessels sailing on NCP

Anodes on ballast tanks of fishing vessels sailing on

NCP



318

1596

4585

273

1371

3939

235

1177

3383

202

1011

2906


. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 23

E mission of cadmium by anodes on the exterior and interior of the vessel for 2009 through

2027 (kg/year)

Process description


NCP







NCP



. . . .

. . . . . . . . . . . . . . . . . . . . . . . . .

Table 24

E mission of aluminium by anodes on the exterior and interior of the vessel for 2009 through 2027 (kg/year)

Process description


NCP







NCP



2009

49

2

10

10

71

1,4

0,2

0,8

2,3

2015

54

3

11

11

78

1,2

0,1

0,7

2,0

2021

59

3

12

12

85

1,0

0,1

0,6

1,7

2009

5050

2015

5535

4080 4460

1026

981

1135

1074

11137 12204

405 348

276

232

790

237

199

679

2021

6068

4877

1256

1176

13378

299

204

171

583

2027

6655

5335

1391

1288

14669

257

175

147

501

2027

64

3

13

13

94

0,9

0,1

0,5

1,5


8 Comments and changes in regard to previous version

The methodology for determining the emissions is the same as the previous version of the fact sheets (Kuiper, 2003a and 2003b). A few mathematical errors in the calculation of the emissions from the ballast tanks and fishing vessels were corrected. Additionally, the emissions from ships sailing from/to/in Dutch ports were added, applying the same emission factors as applied on the NCP. The emissions from floating tank cooling were removed, because the floating tank cooling system is not in general use.

No changes in the methodology were made for the 2008 emission round.

8.1

Difference in figures due to mathematical errors

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 19

Emission of zinc by anodes on the exterior and interior of the vessel since 1990 (tonnes/year)

Process description

The tables below show the differences in figures for the years 1999 and

2000. Principally, the differences can be traced back to mathematical errors in the derivation and/or application of the emission factors presented in the previous version. This version uses the same corrosion rates as the previous version.

This addresses the mathematical errors referred to in section 7.4.

1990 old

1990 new

2000 old

2000 new


NCP







NCP



100,8

17,0

-

24,6

142,4

4,5

2,5

17,4

24,4

94,5

4,6

19,0

18,6

136,7

4,3

0,5

2,4

7,2

95,3

16,1

-

23,2

134,6

3,7

2,3

14,4

20,4

86,6

4,2

17,5

17,0

125,3

3,9

0,4

2,1

6,4


. . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

Table 20

Emission of cadmium by anodes on the exterior and interior of the vessel since 1990 (kg/year)

Process description


NCP





Anodes on exterior of fishing vessels sailing on

NCP




1990 old

2,6

1,2

9

12,8

50

8

-

12

70

1990 new

47

2

10

9

68

2,2

0,2

1,2

4,1

2000 old

2

1,1

7

10,1

48

8

-

12

68

2000 new

43

2

9

9

63

1,8

0,2

1,1

3,5


. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 21

Emission of aluminium by anodes on the exterior and interior of the vessel since 1990 (kg/year)

Process description 1990 old

1990 new

2000 old

2000 new


NCP


Anodes on exterior of seagoing vessels from/to/in ports





NCP



5,4

14,8

-

1,3

21,5

0,7

4,9

3,9

0,9

0,9

10,6

0,6

5,2

14,2

-

1,3

20,7

0,6

2,1

1,6

4,4

0,4

0,4

1,4

2,0

1,4

4

There are also known studies for other areas. These studies usually assume the estimated amount of anodes on a ship, the estimated lifetime of the anodes and the amount of anode material still present at the end of the lifetime (or at time of replacement). Comparison with an

American study (EPA, 1996) by this method reveals results very much similar results compared to the emission findings of this report. Based on the previous version of this protocol, an estimate was made of emissions on the entire North Sea (Walraven, 2006) using the number of seagoing vessels calling in other countries. For the year 2000, the emissions of zinc in the entire North Sea were estimated at just under

1,800 tonnes. In view of the intensity of shipping traffic on the NCP and the ratio of the areas of the entire NCP and the entire North Sea, this estimate on the part of Walraven appears to be too high. This apparent overestimate is most likely due to the very high total number of seagoing vessels calling at Danish and English seaports. The size of vessels and time spent in port were not accounted for in that study.

4,7

3,8

0,9

0,9

10,3

0,5

0,4

0,3

1,2


9 Accuracy and indicated subjects for improvement

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The above can be expressed in the classification system used in the

Emissieregistratie publication series (Van Harmelen, A.K., 2001). This method is based on the CORINAIR (CORe emission INventories AIR) methodology.

CORINAIR uses the following quality classifications:

A: a value based on a large number of measurements from representative sources

B: a value based on a number of measurements from some of the sources that are representative of the sector

C: a value based on a limited number of measurements, together with estimates based on technical knowledge of the process

D: a value based on a small number of measurements, together with estimates based on assumptions

E: a value based on a technical calculation on the basis of a number of assumptions

The number of seagoing and fishing vessels on the NCP is carefully tracked, which means a classification of A for that component of the activity rate. The wet surface of the ships on the NCP is derived from model-based estimates. In total, this results in a classification of B for the activity rate.

The emission factors are based on recommendations drafted based on technical knowledge and experience from practice. This means that we can classify the emission factors in category C.

As far as the distribution of emissions among individual compartments and emission pathways to water is concerned, it is clear that all the emissions directly enter the surface water, so category A applies here. Spatial allocation is further explained in chapter 10. Because this is fairly detailed, it can be classified as category B.

Element of emission calculation Classification

Activity rates

Emission factors

Distribution among compartments

Emission pathway to water

Spatial allocation

B

C (E for ballast water)

A

A

B


The number of ships on the NCP in this study is established for the year

2004. So as to also be able to present figures for the years 1990 through 2006, this figure was compared to the Statistics Netherlands annual figures for the total number of seagoing vessels calling at Dutch ports. Both the figures of the Statistics Netherlands and Lloyds were considered reliable, but a linear relationship between the number of ships on the NCP and the number of ships calling at Dutch ports is not assured.

There are no good data available on trends in the application of the various alternatives for cathodic protection (choice of zinc, aluminium or IC). The precise degree to which ballast water is changed on the

NCP is not known.

Information on the number of vessels on the NCP and their underwater surface area is only known for the year 2004, and this data comes from the Lloyds database. So as to still be able to present figures for the years 1990 through 2006, a constant average surface (that for the year

2004) per ship was assumed.

Both the figures of the Statistics Netherlands and Lloyds were considered reliable, but whether the data on the ships on the NCP can be directly projected onto the ships in port is uncertain.

9.1

Most significant areas for improvement

Simply based on the above, the most significant areas for improvement can be identified as follows (in order of importance):

In a subsequent year, a study can be set up to establish trends in the use of the various different types of cathodic protection over time;

An attempt can be made to obtain a better picture of the exchange of ballast water on the NCP and the use of zinc and aluminium anodes.


10 Spatial allocation

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10.1

Seagoing vessels and fishing vessels on NCP

The emissions per 5x5 km map square are determined using the wet surface area (WSA) calculated per vessel type by MARIN using the

Lloyds traffic and transport database for the year 2004.

The traffic types this includes are:

Route-specific shipping transport

Ships at anchor

Fishing vessels

Work ships

For every ship sailing on the Dutch Continental Shelf (NCP), the maximum wet surface area is calculated using the vessel dimensions known from the Lloyds ship register. Where possible, this calculation was based on the Mennen-Holtrop equation (equation 1); where this was not possible due to the lack of data, calculation was based on the derived method for determining WSA based on ship size in GT

(equation 2). The actual wet ship area was obtained after correction for actual cargo using equation 3. MARIN then applied this data to the traffic and transport database after first averaging across the SAMSON vessel types and SAMSON vessel size classes. Next, a determination of the location of each kilometre square (in which water body defined in the Water Framework Directive the square is situated) was made. The emissions were then calculated for each Water Framework Directive water body.


Figures 7 through 11 below show the wet ship area of the four types of shipping traffic in spatial terms.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 7

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 8

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

.

Figure 9

Distribution of the total wet underwater Distribution of the wet underwater surface area of ships on the Dutch

Continental Shelf (NCP). surface area of route-specific ships on the Dutch Continental Shelf (NCP).

Distribution of the wet underwater surface area of ships at anchor on the

Dutch Continental Shelf (NCP).

. . . . . . . . . . . . . . . . . . . .

Figure 10

Distribution of the total wet underwater surface area of fishing vessels on the Dutch Continental

Shelf (NCP).


. . . . . . . . . . . . . . . . . . . . .

Figure 11

Distribution of the total wet underwater surface area of work ships on the

Dutch Continental Shelf

(NCP).

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 22

Conversion factors for ships in port, manoeuvring and at sail, by wet surface

10.2

Seagoing vessels in Dutch territory

Spatial allocation of the shipping emissions calculated was performed based on the data on seagoing vessels calling at the major seaports.

In this calculation, a distinction is made by vessel type and the phase the ship is in: sailing in, manoeuvring and in port. All basic data are drawn from the EMS models for the calculation of air emissions. The activity rates from the air module are expressed for these phases in GTkm for sailing in, GT-hours for manoeuvring and GT for in port. These quantities are assigned per port and per phase to shipping lane segments from the database “Nationaal Wegenbestand” (NWB, a publication of the Traffic and Transport Advisory Service, an agency of the Ministry of Public Works & Water Management). The activities are assigned to each port in proportion to the length of the shipping lane segments traversed.

For each phase that the vessels sail in Dutch territory, a different formula is used for the calculation of the average wet ship area (WSA) present.

The formula for conversion of ships in port is:

GT * WSA/GT * Time in port / 8760

The GT of ships in port is derived from the file supplied by AVV for the calculation of air emissions.

The formula for conversion of ships at sail is:

GT-km / Speed * WSA/GT / 8760

The GT-km of sailing ships is calculated using the model with which the air emissions of sailing ships are calculated.

The formula for conversion of manoeuvring ships is:

GT-hours * WSA/GT / 8760

The GT-hours of manoeuvring ships is calculated using the model with which the air emissions of manoeuvring ships are calculated.

Table 22 shows the factors used for conversion from GT to WSA.

Vessel type

Other Tankers (Juice,

Chemical)

WSA/GT

(m 2 /GT)

0,43

Time in port

(hours)

28

24

Speed

(km/hour)

17,3

Conv. General Cargo 0,54

Reefers 0,51

Other Ships 0,5

52

21

25

24

31

46

19,2

20

20,2

20,2

23,1

24,8

26,3


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 12 :

Seagoing vessels en route to ports and in Dutch ports and Emden

The red lines 5 on the map below (figure 12) indicate which line segments from the NWB are linked to the emissions from seagoing vessels in port. GIS was used to determine what portion of a given shipping lane segment falls within a given Water Framework Directive water body. These segments were used to assign the emission to a

Water Framework Directive water body.

10.3

Fishing vessels in ports

The underwater surface area of fishing vessels in fishing ports is determined using the LEI's VIRIS system, which records all fishing vessel movements at sea. VIRIS does not record the number of days in port directly. The number of days in port is 365.25 days (number of days in the year) minus the number of sailing days. A ship may call at multiple ports in the course of a year. The number of days in a specified port is computed by multiplying the ratio of total number of journeys per year to number of journeys from the port in question by the number of days in port as calculated above. The number of days in a port is multiplied by 24 to obtain the number of hours in that port.

The number of hours in a port is multiplied by 1.0*GT of ship to obtain the underwater surface area. The underwater surface area is then aggregated per port and divided by 8760 (hours per year).

5 The protruding line segments at Scheveningen and Goeree-

Overflakkee were left out of the database.


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 23

Average wet surface of fishing vessels present in fishing ports in 2005, (m 2 )

Table 23 shows the underwater surface area per fishery port in 2005, and figure 13 shows the locations of the ports. The Water Framework

Directive area of each port is known. Not all ports are located in Water

Framework Directive areas that are classified as saline.

Port WSA 6

Oostburg - Breskens

Schouwen Duiveland

Delfzijl

Harlingen

Den Helder

Hemelumer-Oldeferd (municipality of Nyefurd)

IJmuiden

Katwijk

Ulrum - Lauwersoog

Terneuzen

Scheveningen - Den Haag

Goedereede - Stellendam

Stavoren (municipality of Nyefurd)

Terschelling

Texel

Urk

Vlissingen

Wonseradeel

Wieringen

Yerseke

Zierikzee

98

158

4320

253

10309

116

2522

385

10

952

51

1770

19569

9199

20

52300

3

5559

19

14577

6369

128559

6 Corrected for calls of foreign fishing vessels (approx. 30 percent)


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 13:

Location of Fishing Ports


11 References

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

British Standard, (1991) BS 7361 Cathodic Protection, Part.1 Code of practice for land and marine applications

Centraal Bureau voor de Statistiek. (2003) Elektronische database

Statline. Internetapplicatie.

CPB, MNP, RPB (2006), Welvaart en leefomgeving, een scenariodocument voor Nederland in 2040, Centraal Planbureau,

Milieu- en Natuurplanbureau en Ruimtelijk Planbureau, ISBN-13: 978-

90-6960-149-6

Det Norske Veritas (1993) DNV RP B401 Recommended Practice

Cathodic Protection Design

Environmental Protection Agency. (1996) Nature of discharge report

“Cathodic Protection

Glansdorp, C.C., Tak, C. van der. (1993) Modellering van de functie

"scheepvaart"in het MANS-project. MARAN&MSCN.

Harmelen, A.K. van et al. November 2001. Emissiemonitor, jaarcijfers

1999 en ramingen 2000 voor emissies en afval. Rapportage reeks milieumonitor nr. 2.

Hattum, B. van, Baart, A.C., Boon, J.G. (2002) Computer model to generate predicted environmental concentrations (PECs) for antifouling in the marine environment, 2 nd edition accompanying the release of

Mam-Pec version 1.4. rapportnr. E-02-04 / Z3117. IVM, Amsterdam 

WL, Delft.

Holtrop J., A (1977) Statistical Analysis of Performance Test Results.

International Shipbuilding Progress, 1977, Vol 24, No. 270.

Kuiper, P.J.C. (2003a) EMS-protocol Emissies door Zeevaart en Visserij,

Anodes op schepenop het NCP. RIZA-werkdocument nr. 2003.153X.

Kuiper P.J.C. (2003b), EMS-protocol Emissies door Zeevaart en Visserij,

Anodes op schepen in havens. RIZA-werkdocument nr. 2003.153X.

Koivisto, S. (2003), Proposal for Finnish exposure scenarios for antifouling products, Finnish Environment Institute, 2003

Man-Diesel (2002) Basic principles of ship propulsion, Man-Diesel document P-254-04-04; http://www.manbw.com/article_003859.html


Nederlands Normalisatie-instituut (1996). NEN-EN 12496

“ Opofferingsanodes voor kathodische bescherming in zeewater”,

Norsok. (1997) Norsok Standard M-503 Cathodic protection

OECD (2005) Emission scenario document on antifouling products,

OECD Environmental Health and Safety Publications Series on Emission

Scenario Documents No. 13, Environment Directorate Organisation for

Economic Co-operation and Development, Paris, France

OSPAR (1992). Zinc inputs to the environment from sacrificial anodes used offshore and inland.

Roovaart, J.C. van den. (2002) Uitloging zeeschepen in havens. RIZAwerkdocument nr. 2001.088X, volgnr. 3.

Tak, K van der (2006), personal communication, MARIN, Wageningen.

U.S. Military Specification (1987). MIL-A-18001J “Anodes, Corrosion

Preventive, Zinc; Slab, Disc and Rod Shaped”

Walraven, N., Assessing the input of various sources (riverine, direct discharge, atmospheric and sea shipping) of Cu, Zn, Cd, TBT and biocides to the Greater North Sea, Annex 1 of INPUT 06/4/1-

E(L),OSPAR (January,31-February,2, 2006)

Willems, M. et al. (2003) Uitloging van anodemateriaal van zeeschepen. BECO Groep BV, Rotterdam.

Willemsen P.R., Ferrari, G.M. (1992) Emissies van organotin naar

Nederlandse oppervlaktewateren. TNO-rapport, rapportnr. C 92.1003.

Wulffraat, K.J. et al (1993). De belasting van de Noordzee met verontreinigende stoffen 1980 – 1990. Rapport DGW 93-037.


Sacrificial anodes, merchant shipping and

Emission estimates for diffuse sources

Netherlands Emission Inventory

Sacrificial anodes, merchant shipping and fisheries

Version dated June 2008

NETHERLANDS NATIONAL WATER BOARD - WATER UNIT in cooperation with DELTARES and TNO

Table of Contents

1 Introduction and scope

2 Description of emission source

2.1

Causes

2.2

Measures

3 Explanation of calculation method

3.1

Exterior of vessel

3.2

Wet surface area

3.3

Corrosion rate

ε

ε

3.4

Interior of vessel

4 Activity Rates

4.1

Assessment using statistical data

4.2

Interior of vessel

4.3

Time series, 1990-present

4.4

Time series, present-2027

4.5

Annual data setting

5 Description of emission pathways to water

6 Emission factors

6.1

Emission factors

6.2

Application percentages

6.3

Time series, 1990-present

6.4

Annual data setting

7 Emissions calculated

7.1

Emission figures 2004

7.2

Emissions 1990-2006

7.3

Emissions forecast, 2009-2027

8 Comments and changes in regard to previous version

8.1

Difference in figures due to mathematical errors

9 Accuracy and indicated subjects for improvement

9.1

Most significant areas for improvement

10 Spatial allocation

10.1

Seagoing vessels and fishing vessels on NCP

10.2

Seagoing vessels in Dutch territory

10.3

Fishing vessels in ports

11 References

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