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Estimating GHG emissions of marine ports—the case of Barcelona
Energy Policy 39 (2011) 1363–1368
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Energy Policy journal homepage: www.elsevier.com/locate/enpol
Estimating GHG emissions of marine ports—the case of Barcelona Gara Villalba a,n, Eskinder Demisse Gemechu b,1 a b
Department of Chemical Engineering, Institute of Environmental Science and Technology, Universitat Auto noma de Barcelona, 08193 Bellaterra, Barcelona, Spain Environmental Management and Analysis Group, Department of Chemical Engineering, Universitat Rovira i Virgili, Av. Paı¨sos Catalans 26, 43007 Tarragona, Spain
a r t i c l e in f o
abstract
Article history: Received 27 October 2010 Accepted 1 December 2010 Available online 5 January 2011
In recent years, GHG inventories of cities have expanded to include extra-boundary activities that form part of the city’s urban metabolism and economy. This paper centers on estimating the emissions due to seaports, in such a way that they can be included as part of the city’s inventory or be used by the port itself to monitor their policy and technology improvements for mitigating climate change. We propose the indicators GHG emissions per ton of cargo handled or per passenger and emissions per value of cargo handled as practical measures for policy making and emission prevention measures to be monitored over time. Adapting existing methodologies to the Port of Barcelona, we calculated a total of 331,390 tons of GHG emissions (CO2 equivalents) for the year of 2008, half of which were attributed to vessel movement (sea-based emissions) and the other half to port, land related activities (land-based emissions). The highest polluters were auto carriers with 6 kg of GHG emissions per ton of cargo handled. Knowing the highest emitters, the port can take action to improve the ship’s activities within the port limits, such as maneuvering and hotelling. With these results, the port and the city can also find ways to reduce the land-based emissions. & 2010 Elsevier Ltd. All rights reserved.
Keywords: GHG emissions Ports Sea-based emissions
1. Introduction There are presently many efforts to reach a consensus on how to account for greenhouse gas emissions for individual cities. Indeed this is not a simple task, and confusion arises on many levels. For example, the spatial scale and boundaries that impact how the energy and material flows are allocated are not always clear (Ramaswami et al., 2008). Also, there is the issue of comparability: energy and resource consumption will depend heavily on the city’s geographical location and climate. Is a city with a very harsh winter fairly compared to a city with a much milder climate? Ideally, a measure of the efficiency of energy uses should be included to justly evaluate this discrepancy. Another difference among cities is whether or not they have seaports and airports, the emissions of which can add a significant amount to a city’s inventory. This last issue, however, can be resolved if we consider that the city’s economy depends on these activities. In other words, the city has a carbon dependence on air and marine transportation, and they should thus be included in their account. The objective of this paper is to show how the GHG emissions2 of a seaport can be estimated, addressing the confounding issues described above. We illustrate this using and adapting existing methodologies to account for the emissions of the Port of Barcelona.
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Corresponding author. Tel.: + 34 93 5868372. E-mail addresses: [email protected] (G. Villalba), [email protected] (E.D. Gemechu). 1 Tel.: +34 977 55 8561; fax: + 34 977 55 9621. 2 By GHG emissions the authors refer to the sum of carbon dioxide, nitrous oxide, methane, and fluorinated gases in terms of CO2 equivalents. 0301-4215/$ - see front matter & 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.enpol.2010.12.008
The policy instruments to reduce the vessel-based GHG emissions have been discussed for more than a decade. Since the 1997 Kyoto Protocol, the International Maritime Organization (IMO) was given the obligation to develop and adopt measures for minimizing shipping emissions, but progress has been slow. This task is being carried out by the IMO’s Maritime Environmental Protection Committee (MEPC)—for example, they have estimated GHG emissions due to vessel transport on a global scale from 1990 to 2007 and have shown that shipping is estimated to have emitted 1046 million tons of CO2 in 2007, which corresponds to 3.3% of the global emissions for that year (IMO, 2009). But up to date, and even with the support of the United Nations Framework Convention on Climate Change (UNFCCC) governing climate negotiations, there seems to be no reconciliation or consensus as to whom the emissions should be attributed to (it is important to note that 83% of shipping emissions are due to international shipping). There has been much debate as to the allocation of shipping emissions (country of departure, nationality of transporting company, or where the fuel is sold, to name a few allocation possibilities). It has been suggested that a price on CO2 emissions from international shipping could be imposed based on fuel consumption (Odero, 2009), but it could distort markets due to evasive behavior (buying fuel somewhere else) (McCollum et al., 2009). Faber and colleagues suggest dividing the emissions between the countries of origin and destination (Faber et al., 2007). Wit et al. (2004) explore the potential of how GHG reduction policy in shipping could be brought in line with the Kyoto process by establishing a base line and allowing trading of credits earned from additional abatement. Schemes based on fuel purchased regardless of nationality for high sea transport would be compatible with policy based on the
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emissions attributed to the city the seaport belongs to. In other words, from a policy perspective, it would make GHG accounting transparent and simple if emissions due to maritime shipping are divided into (a)emissions due to port activity that could be included in the city’s inventory and (b) emissions due to transport at high seas. For the latter, there are estimates based on spatially resolved models (Corbett and Kohler, 2003; Corbett et al., 2007; Wang et al., 2007). The former is the objective of our work: to account for the emissions related to the port activity in such a way that the results can be used by both the port authority and the city. We will illustrate this approach by applying it to the Port of Barcelona. Other city seaports have done emission inventories with different approaches such as Los Angeles, Rotterdam, Oslo, and New York, and have even joined forces under the World Ports Climate Initiative (WPCI) (Den Boer and Verbraak, 2010). The main differences are system boundaries and integration of results with city or regional GHG inventories. The city of Barcelona roughly estimated and summed up the emissions due to air and marine transport as 10% of the total annual emissions of the city (ICAEN, 2008). For the year 2006, this estimate was 483,307 tons of GHG emissions. However, GHG emissions from air transport alone was shown to be 2,649,243 tons based on fuel loaded at Barcelona’s main airport for the same year (Kennedy et al., 2009a); so Barcelona’s 10% estimation seems inappropriate or at least questionable. In an effort to correctly account for the city’s emissions, we were able to obtain data in order to calculate the port’s emissions for the years 2007 and 2008.
2. The port of Barcelona The Port of Barcelona is the biggest Spanish port for international traffic, seventh in Europe, and 41st in the world, ranked by TEUs (twenty-foot equivalent units, a standardized maritime industry measurement; the PoB had 2.6 million TEUs for 2008)). With its 450 shipping lines, operated by 118 ship owners, the port connects with 850 ports worldwide. It is often considered as the logistic gateway of southern Europe, servicing southern and central Europe and North Africa. Representing 77% of Catalonia’s or 23% of Spain’s foreign maritime trade, the Port of Barcelona (from now on referred to as PoB) plays a significant role in the Catalan’s and the Spanish economy. It is considered to be within city limits, only 8.29 km southeast of downtown Barcelona, occupying 828.9 ha. Economic forecasts suggest that by 2020 the port will account for 6.2% of Catalonia’s GDP, although in 2008 it represented only 1.2% due to the global crisis (between 2003 and 2007 it averaged to 3.3%) (Port of Barcelona, 2009). The PoB is made up of the Port Authority (PA) and the Port Community (PC). The PA is a public administration and it manages and controls all port activities such as vessel movement and cargo handling. It is responsible for the coordination, administration, organization, and management of the port. Its role is also to oversee and manage the use of the port by all the different private companies that operate within it. All these private companies together make up the PC. The activity of these companies varies greatly: from electric cranes that are used to load and unload vessels to industrial processes that make oil and flour out of soy beans.
boundaries based on geographical location, political reasons, or emission inventory objectives. For this study, we have limited the account to the physical demarcation of the Port of Barcelona (north, south, and west borders) and an extension of one nautical mile out to sea (east border), as depicted by Fig. 1. We used 1 nautical mile from the Mediterranean side because this is the distance where vessels stop using their main engines at full speed and start using auxiliary engines to enter the port. A longer distance would lead us to marine transport emissions, which as was established earlier, is not of concern in this study. The Port of Houston, for example, sets its boundary at 45 nautical miles since the vessels travel a long way through channels before arriving to the sea buoy (World Ports Climate Initiative, 2009). Other inventories of US ports use 25 nautical miles (ICF International, 2009). The emissions are divided in two categories, in line with other port inventories (Fig. 2). The vessel-related emissions (also referred to as sea-based emissions) result from ocean going vessels (OGV) arriving and departing from the port, hotelling, and maneuvering. Land-based emissions include all the GHG emissions due to activities carried out in the port by the PA and the PC, which result in the consumption of electricity, fuel, and heating and generation of waste. Categorizing in this manner allowed us to use the same methodology employed in the GHG inventory of Barcelona (Kennedy et al., 2009a, 2009b). The reason we separate the emissions in these two categories is to facilitate an account of the GHG emissions of the city of Barcelona. All the emissions from the land-based category are already accounted for in the GHG inventory of Barcelona: the PoB gets its electricity and natural gas from the city grid; the waste from PoB goes to Barcelona facilities; and emissions from industrial processes are included in the city inventory. In other words, the city of Barcelona would only have to add the emissions due to vessel movement to its GHG inventory and that way there would be no double counting. It is important for this study to include both, however, so the results can also be useful for the PoB to quantify its carbon dependency. The main data sources are categorized as follows:
3.1.1. Port authority data We obtained reliable data in excel format on vessel operations from Barcelona Port Authority. The data from the PA contains information on vessel movements such as vessel name, vessel type, number of calls, date and time of arrival, date and time of departure, estimated time for main activities (aggregated), gross tonnage of cargo, and other information.
3. Method 3.1. System boundaries and data The boundaries can be a very significant source of differences among emissions inventories of seaports. Ports determine their
Fig. 1. Limits to the study of the Port of Barcelona.
G. Villalba, E.D. Gemechu / Energy Policy 39 (2011) 1363–1368
3.1.2. Lloyd’s register data. Lloyd’s Register-Fairplay, Ltd., provides detail information of all ships of 100 gross tonnages and above. Information from Lloyd’s Register basically includes details on registration, ship types, dimensions of ships, tonnages, capacities, construction, classification, communications, ownership, main engine specifications, auxiliaries, special features, cargo gear, and hull types (Lloyd’s Register Fairplay, 2009). This source was mainly used for data on dead weight tonnage (DWT), vessel service speed, and engine power.
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methodology, the emissions inventoried are those attributed to electricity, heating and energy fuels, ground transportation fuels, industrial processes, and waste. The GHG emissions associated with fuels are calculated from a life cycle approach (also referred to as scope 3 by ICLEI (2008)); whereas the rest of emissions are calculated as single process emissions from end-use activities (scope 2).
3.3. Sea-based emissions 3.1.3. Port community data Data about energy consumption and waste generation is obtained from customer survey performed by the AC. The file from the survey includes about 80% of all consumption of electricity, natural gas, gasoline, diesel oil, and jet fuel (estimate given by the PA based on the companies that responded for the survey), and waste generation sorted by type of waste such as plastic, rubber, paper, batteries, fluorescent, light packaging, wood, and so on. This information is used to determine GHG emissions associated with the use of port facilities including cargo handling (such as electric cranes). 3.2. Land-based emissions The emissions resulting from vessel movement are calculated using the methodology applied to the city of Barcelona (Kennedy et al., 2009b, 2009a), using the data collected via the customer surveys discussed earlier (see first column of Table 1). Based on this
An energy based approach was adapted and used to calculate the emissions based on the power requirements of the vessels. This methodology was proposed by the US EPA (ICF International, 2009), and is also reported by the World Ports Climate Initiative (2009). A vessel has a primary engine, an auxiliary engine, and an auxiliary boiler. How long and to what extent each of these three is used depends on the activity: arrival and departure, maneuvering, and hotelling. To calculate the emissions, we need to know how much of its maximum power the engine is operating at; during these activities within the port, the engines will not be operating at 100%. This can be calculated using the load factor, which is a measure of maximum speed and actual speed. The speed at which a ship enters the port can vary depending on the distance that needs to be covered or the speed limits imposed by the PA. For the PoB, we did not have arrival/departure speeds to calculate load factors for each ship, so we used estimates. Advised by the PoB that arriving and departure speeds are very similar to maneuvering speed, we assumed the same load factor for both of these activities. In our
Emissions from Port of Barcelona
Emissions due to vessels movement (mobile emissions) Ships arriving into the Port Ships departing from the Port Hotelling Maneuvering
Land-based, port related emissions (stationary emissions) Electricity Consumption Heating Fuels Transportation Fuels (Cargo handling, vehicles, trucks, etc.) Waste
Fig. 2. Categories of emissions considered for the study.
Table 1 GHG emissions for land-based port activities for the Port of Barcelona, 2008.
Electricity Natural gas Diesel Gasoline Jet fuel Waste Total a b
Total consumption
Emission factor
GHG Emissions (tons)
%
192.01 GWh 30,426,122 m3 1,4822,522 l 21,704 l 20,000 l 46,705 tons
143 tCO2e/GWha (Baldasano et al., 1999) 61.6 (Baldasano et al., 1999) 82.8 tCO2e/TJ (Kennedy et al., 2009b) 81.9 tCO2e/TJ (Kennedy et al., 2009b) 79.1 tCO2e/TJ (Kennedy et al., 2009b)
27,493 62,750 47,374 56.86 55.57 18,890 156,206
18 40 30 0.04 0.04 12 100
b
a line factor of 1.11 is included. waste is broken up into paper, textile, food waste, wood, and others. Each one of these has its own emission factor; please refer to Kennedy et al. (2009b).
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Table 2 Tons of sea-based GHG emissions for the PoB for 2008. Type of Vessel
Maneuvering, GHG emissions (tons)
Maneuvering time (h)
Hotelling, GHG emissions (tons)
Hotelling time (h)
Total GHG emissions (tons)
Auto carrier General cargo Refrigerated cargo Solid bulk Passenger Liquid tanker Container RO-RO cargo Liquid bulk Ferry Total
6972 2857 402 851 8649 128 32,948 5522 7241 42,364 107,934
1681.4 2810.5 125 476.2 844.7 40.75 5807.1 1638.6 4319.1 8222.0 25,965.4
5452 2560 256 1749 13,529 114 24,693 3571 8380 6769 67,073
7209 18,585.1 478.25 11,131.1 9896.1 264 36,432.5 9832 19,989.4 9681.3 123,499
12,424 5417 658 2600 22,178 242 57,641 9093 15,621 49,133 175,007
case, at 1 nautical mile, we estimated that the ships are entering, maneuvering, and exiting at 40% of the main engine power (also referred to as a load factor of 0.40). Hotelling refers to the time a vessel stays in the port; it is not moving, but it is using fuel (it uses its own engines) or electricity (it is plugged in to the port). For the PoB, vessels use their engines during hotelling, approximated at 20% of main engine power (load factor of 0.20). If we know the power required by each engine for each activity and the time required, we can calculate the total emissions using the following equation: E ¼ PO t LF Ef
ð1Þ
where E is the total emissions per engine, per type of vessel for a certain activity, in grams. PO is the power output, in KW. Since specific data was not available on the power output of each engine for each vessel type, it was calculated as a function of gross tonnage for each type of ship, according to the CORINAIR equations given by the European Environment Agency (2002). t is the time the engine is being used, in hours. The time data available was not disaggregated by activity—it was a lump sum for all three activities. Based on the information given by the PA, we assumed a set time for arrival/departure and maneuvering for each type of ship. Since we estimated the same speed for these activities, the time did not have to be further disaggregated. The time difference was attributed to hotelling. LF is the load factor. As engines are not operating at their maximum tested power, we need to consider load factor calculated based on the propeller law.3 For hotelling and maneuvering, load factors of 0.2 and 0.4 are used, respectively (arrival and departure are included in the maneuvering activity since the speeds are similar). Ef is the emissions factor, in grams per KWh; the GHG included are CO2, CH4, and SOx (these are the combustion gases with global warming potential; other gases such as SOx are important to quantify for air quality control). The following factors were taken from ICF International (2009):
for primary engine at intermediate speed: 677.91 gCO2/KWh; 0.004 g CH4/KWh; 0.031 g NOx/KWh.
for auxiliary engine: 722.54 gCO2/KWh; 0.004 g CH4/KWh; 0.031 g NOx/KWh.
for auxiliary boiler: 970.71 gCO2/KWh; 0.002 g CH4/KWh; 0.080 g NOx/KWh.
3 The propeller law states that the necessary power delivered to the propeller is proportional to the rate of revolutions to the power of three, for intermediate speed.
Once the emissions of CO2, NOx, and CH4 are calculated, they are each multiplied by their respective CO2 equivalent factor (1, 310, and 21, respectively) and summed to give the total GHG emissions.
4. Results and discussion 4.1. Land-based emissions Based on the methodology above described, the results obtained are given in Table 1. A high percentage of emissions due to natural gas is the result of several companies in the port that use natural gas for their production processes, such as heating tanks and regasification. There is a very small amount of gasoline consumed, since diesel is the fuel of preference for most of the machinery and road transport. 4.2. Vessel movement emissions The total GHG emissions for each type of OGV are given in Table 2 for 2008 according to the methodology described above (results for 2007 are included in the Supporting Information). The highest emitters are the container vessels, followed by the ferries. The total GHG sea-based emissions for 2008 were 175,184 tons. A different method based on fuel consumption was used to corroborate the results from the energy-based approach. We used a modified version of the methodology developed by the EU project MEET (methodologies for estimating air pollutant emissions from transport) (Trozzi and Vaccaro, 1998). Although this methodology is not as precise as the one presented in this paper (i.e. the same emissions factor is applied to all engine types and modes of operation), it did serve to confirm the order of magnitude of the results. The total emissions were about 30% higher, for 2007 we calculated 225,821 and for 2008 235,327 tons of GHG emissions. One possible reason for this is that the fuel based approach does not differentiate among fuel consumption rate of different engines (primary, auxiliary, and boiler). Based on average fuel consumption rates could lead to an overestimation for typical operations in ports that require less fuel. For a description of the fuel-based approach, please see the Supporting Information. The number of ships that enter and exit the port (also referred to as a ‘‘call’’) is not an adequate figure to compare the emissions, since the gross tonnage of each ship can vary greatly. However, what can serve as an indicator is the total cargo handled and passengers arriving, departing, and in transit. Table 3 shows the total tons of cargo handled and the total amount of emissions for each type of ship for 2008 (results for 2007 are in the Supporting Information). Port activity remained more or less constant between 2007 and 2008, which is coherent with similar emissions for those years.
G. Villalba, E.D. Gemechu / Energy Policy 39 (2011) 1363–1368
Table 3 GHG emissions per cargo handled and per passengers for 2008. GHG emissions per ton of cargo handled (kg)
Type of ship
Cargo (tons)
GHG emissions (tons)
Auto carrier General cargo Refrigerated cargo Solid bulk Liquid tanker Container RO-RO cargo Liquid bulk
1,518,289 8,608,127
9086 6278
5.98 0.73
780,721
452
0.58
6,634,408 5,086,331
3297 116
0.50 0.02
17,998,646 3,932,876 5,985,735
58,068 8506 15,373
3.23 2.16 2.57
Passengers
GHG emissions (tons)
Ferry Passenger Total
1,162,422 2,074,554
44,333 21,305 175,184
GHG emissions per passenger (arrival, departure, and in transit) (kg) 38.14 10.27
Using this indicator, high polluters are the car carriers followed by container vessels. By far, however, the highest emitters are the passenger vessels. For passenger vessels, the ferries emit GHG emissions at four times the rate of the regular passenger vessels (mostly cruise ships). The measure we have chosen of emissions per ton of cargo handled is a useful indicator on several accounts. It can serve as an indicator to evaluate if mitigation policies are successful (or not) in decoupling economic activity from accumulation of GHG emissions. This metric is helpful for the port to establish a base line and to monitor emissions over time. It is also useful for comparison with other ports, although careful consideration must be made since the system boundaries of different ports can vary. Having this indicator further divided by ship type, plans of action can be prioritized for high polluters such as the car carriers and the ferries. Although this metric is helpful on several accounts, it could be further improved. Energy efficiency measures that could reduce hotelling power requirements, for example, are not captured by this indicator. However, this could be solved with a few more calculations. The load factor used in Eq. (1) would have to be corrected: instead of the 0.2 now associated with hotelling, a lower one that reflects a lower energy requirement should be used. In general, using average load factors is a limitation that could be further improved given enough data. An additional measure of emissions per value of cargo handled would complement the emissions per weight indicator. For 2008, the volume of cargo handled in the PoB was 73,150 million h or 4.5 tons of CO2 per million h (summing up both sea-based and landbased totals). On the same basis, we can calculate 127 tons of CO2 per thousand TEUs. These indicators together capture two main mechanisms by which economic growth could delink from the generation of CO2 emissions in seaports: increasing value and improving technologies.
5. Conclusions There are different ways GHG emissions can be allocated. For example: all emissions due to vessel transportation could be attributed to the shipping company, or all emissions could be attributed to the port/city receiving the cargo. In this paper we suggest that the emissions be attributed to the port once the OGVs
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are not in their cruise speed and are approaching the port using auxiliary engines. Furthermore, we divide the emissions between land-based and sea-based. This approach is beneficial in several ways. Firstly, it is compatible with existing city inventories. The city of Barcelona can use this inventory to quantify and benchmark its carbon dependence on the economic activity provided by the port without double counting. Having emissions disaggregated into land and sea-based, the port can monitor how policy measures can help reduce its impact. Here, emissions per ton of cargo handled is proposed as an indicator to pin point high polluting vessels—a measure independent of the city the port belongs to. Secondly, the consequences of GHG emissions might be more than global scale climate change. A recent study has found that urban CO2 domes enhance local air pollution, making it all the more important to quantify emissions on a local level (Jacobson, 2010). There are some limitations to this study. The emissions due to industrial processes that take place right in the port were not taken into consideration. For these processes, we only accounted for the emissions due to electricity and fuel consumption. All the emissions are calculated as single process emissions and the study could be further improved by calculating life cycle emissions. Only for fuel consumption for land-based activities, we were able to estimate the life cycle emissions, as was shown in Table 1. The data collected for land-based emissions came from surveys responded by 80% of the port community; so the results are not 100% representative of the port. The load factors used to calculate energy requirement were estimates based on US reports (ICF International, 2009) because of data limitations. It would be best to calculate load factors based on the speed of ships entering and leaving the Port of Barcelona. Up to now the PoB has not taken any direct measures for GHG emissions reduction. We hope that this work will serve to find ways of lowering this impact. However, although possible solutions come to mind such as having shorter hotelling times, we lack the knowledge and experience to see the viability of such actions. Thus we have limited ourselves to exposing the results in a transparent manner, not only for the PoB and the city of Barcelona to take appropriate action, but also other cities and ports can follow suit.
Acknowledgements This work has been possible, thanks to the cooperation of the Port of Barcelona, namely Dolors Carrascal and Joaquim Cortes, and the funding from the European Commission of an Erasmus Mundus scholarship for a Joint European Masters in Environmental Studies (JEMES program).
Appendix A. Supplementary material Supplementary data associated with this article can be found in the online version at doi:10.1016/j.enpol.2010.12.008.
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Energy Policy journal homepage: www.elsevier.com/locate/enpol
Estimating GHG emissions of marine ports—the case of Barcelona Gara Villalba a,n, Eskinder Demisse Gemechu b,1 a b
Department of Chemical Engineering, Institute of Environmental Science and Technology, Universitat Auto noma de Barcelona, 08193 Bellaterra, Barcelona, Spain Environmental Management and Analysis Group, Department of Chemical Engineering, Universitat Rovira i Virgili, Av. Paı¨sos Catalans 26, 43007 Tarragona, Spain
a r t i c l e in f o
abstract
Article history: Received 27 October 2010 Accepted 1 December 2010 Available online 5 January 2011
In recent years, GHG inventories of cities have expanded to include extra-boundary activities that form part of the city’s urban metabolism and economy. This paper centers on estimating the emissions due to seaports, in such a way that they can be included as part of the city’s inventory or be used by the port itself to monitor their policy and technology improvements for mitigating climate change. We propose the indicators GHG emissions per ton of cargo handled or per passenger and emissions per value of cargo handled as practical measures for policy making and emission prevention measures to be monitored over time. Adapting existing methodologies to the Port of Barcelona, we calculated a total of 331,390 tons of GHG emissions (CO2 equivalents) for the year of 2008, half of which were attributed to vessel movement (sea-based emissions) and the other half to port, land related activities (land-based emissions). The highest polluters were auto carriers with 6 kg of GHG emissions per ton of cargo handled. Knowing the highest emitters, the port can take action to improve the ship’s activities within the port limits, such as maneuvering and hotelling. With these results, the port and the city can also find ways to reduce the land-based emissions. & 2010 Elsevier Ltd. All rights reserved.
Keywords: GHG emissions Ports Sea-based emissions
1. Introduction There are presently many efforts to reach a consensus on how to account for greenhouse gas emissions for individual cities. Indeed this is not a simple task, and confusion arises on many levels. For example, the spatial scale and boundaries that impact how the energy and material flows are allocated are not always clear (Ramaswami et al., 2008). Also, there is the issue of comparability: energy and resource consumption will depend heavily on the city’s geographical location and climate. Is a city with a very harsh winter fairly compared to a city with a much milder climate? Ideally, a measure of the efficiency of energy uses should be included to justly evaluate this discrepancy. Another difference among cities is whether or not they have seaports and airports, the emissions of which can add a significant amount to a city’s inventory. This last issue, however, can be resolved if we consider that the city’s economy depends on these activities. In other words, the city has a carbon dependence on air and marine transportation, and they should thus be included in their account. The objective of this paper is to show how the GHG emissions2 of a seaport can be estimated, addressing the confounding issues described above. We illustrate this using and adapting existing methodologies to account for the emissions of the Port of Barcelona.
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Corresponding author. Tel.: + 34 93 5868372. E-mail addresses: [email protected] (G. Villalba), [email protected] (E.D. Gemechu). 1 Tel.: +34 977 55 8561; fax: + 34 977 55 9621. 2 By GHG emissions the authors refer to the sum of carbon dioxide, nitrous oxide, methane, and fluorinated gases in terms of CO2 equivalents. 0301-4215/$ - see front matter & 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.enpol.2010.12.008
The policy instruments to reduce the vessel-based GHG emissions have been discussed for more than a decade. Since the 1997 Kyoto Protocol, the International Maritime Organization (IMO) was given the obligation to develop and adopt measures for minimizing shipping emissions, but progress has been slow. This task is being carried out by the IMO’s Maritime Environmental Protection Committee (MEPC)—for example, they have estimated GHG emissions due to vessel transport on a global scale from 1990 to 2007 and have shown that shipping is estimated to have emitted 1046 million tons of CO2 in 2007, which corresponds to 3.3% of the global emissions for that year (IMO, 2009). But up to date, and even with the support of the United Nations Framework Convention on Climate Change (UNFCCC) governing climate negotiations, there seems to be no reconciliation or consensus as to whom the emissions should be attributed to (it is important to note that 83% of shipping emissions are due to international shipping). There has been much debate as to the allocation of shipping emissions (country of departure, nationality of transporting company, or where the fuel is sold, to name a few allocation possibilities). It has been suggested that a price on CO2 emissions from international shipping could be imposed based on fuel consumption (Odero, 2009), but it could distort markets due to evasive behavior (buying fuel somewhere else) (McCollum et al., 2009). Faber and colleagues suggest dividing the emissions between the countries of origin and destination (Faber et al., 2007). Wit et al. (2004) explore the potential of how GHG reduction policy in shipping could be brought in line with the Kyoto process by establishing a base line and allowing trading of credits earned from additional abatement. Schemes based on fuel purchased regardless of nationality for high sea transport would be compatible with policy based on the
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emissions attributed to the city the seaport belongs to. In other words, from a policy perspective, it would make GHG accounting transparent and simple if emissions due to maritime shipping are divided into (a)emissions due to port activity that could be included in the city’s inventory and (b) emissions due to transport at high seas. For the latter, there are estimates based on spatially resolved models (Corbett and Kohler, 2003; Corbett et al., 2007; Wang et al., 2007). The former is the objective of our work: to account for the emissions related to the port activity in such a way that the results can be used by both the port authority and the city. We will illustrate this approach by applying it to the Port of Barcelona. Other city seaports have done emission inventories with different approaches such as Los Angeles, Rotterdam, Oslo, and New York, and have even joined forces under the World Ports Climate Initiative (WPCI) (Den Boer and Verbraak, 2010). The main differences are system boundaries and integration of results with city or regional GHG inventories. The city of Barcelona roughly estimated and summed up the emissions due to air and marine transport as 10% of the total annual emissions of the city (ICAEN, 2008). For the year 2006, this estimate was 483,307 tons of GHG emissions. However, GHG emissions from air transport alone was shown to be 2,649,243 tons based on fuel loaded at Barcelona’s main airport for the same year (Kennedy et al., 2009a); so Barcelona’s 10% estimation seems inappropriate or at least questionable. In an effort to correctly account for the city’s emissions, we were able to obtain data in order to calculate the port’s emissions for the years 2007 and 2008.
2. The port of Barcelona The Port of Barcelona is the biggest Spanish port for international traffic, seventh in Europe, and 41st in the world, ranked by TEUs (twenty-foot equivalent units, a standardized maritime industry measurement; the PoB had 2.6 million TEUs for 2008)). With its 450 shipping lines, operated by 118 ship owners, the port connects with 850 ports worldwide. It is often considered as the logistic gateway of southern Europe, servicing southern and central Europe and North Africa. Representing 77% of Catalonia’s or 23% of Spain’s foreign maritime trade, the Port of Barcelona (from now on referred to as PoB) plays a significant role in the Catalan’s and the Spanish economy. It is considered to be within city limits, only 8.29 km southeast of downtown Barcelona, occupying 828.9 ha. Economic forecasts suggest that by 2020 the port will account for 6.2% of Catalonia’s GDP, although in 2008 it represented only 1.2% due to the global crisis (between 2003 and 2007 it averaged to 3.3%) (Port of Barcelona, 2009). The PoB is made up of the Port Authority (PA) and the Port Community (PC). The PA is a public administration and it manages and controls all port activities such as vessel movement and cargo handling. It is responsible for the coordination, administration, organization, and management of the port. Its role is also to oversee and manage the use of the port by all the different private companies that operate within it. All these private companies together make up the PC. The activity of these companies varies greatly: from electric cranes that are used to load and unload vessels to industrial processes that make oil and flour out of soy beans.
boundaries based on geographical location, political reasons, or emission inventory objectives. For this study, we have limited the account to the physical demarcation of the Port of Barcelona (north, south, and west borders) and an extension of one nautical mile out to sea (east border), as depicted by Fig. 1. We used 1 nautical mile from the Mediterranean side because this is the distance where vessels stop using their main engines at full speed and start using auxiliary engines to enter the port. A longer distance would lead us to marine transport emissions, which as was established earlier, is not of concern in this study. The Port of Houston, for example, sets its boundary at 45 nautical miles since the vessels travel a long way through channels before arriving to the sea buoy (World Ports Climate Initiative, 2009). Other inventories of US ports use 25 nautical miles (ICF International, 2009). The emissions are divided in two categories, in line with other port inventories (Fig. 2). The vessel-related emissions (also referred to as sea-based emissions) result from ocean going vessels (OGV) arriving and departing from the port, hotelling, and maneuvering. Land-based emissions include all the GHG emissions due to activities carried out in the port by the PA and the PC, which result in the consumption of electricity, fuel, and heating and generation of waste. Categorizing in this manner allowed us to use the same methodology employed in the GHG inventory of Barcelona (Kennedy et al., 2009a, 2009b). The reason we separate the emissions in these two categories is to facilitate an account of the GHG emissions of the city of Barcelona. All the emissions from the land-based category are already accounted for in the GHG inventory of Barcelona: the PoB gets its electricity and natural gas from the city grid; the waste from PoB goes to Barcelona facilities; and emissions from industrial processes are included in the city inventory. In other words, the city of Barcelona would only have to add the emissions due to vessel movement to its GHG inventory and that way there would be no double counting. It is important for this study to include both, however, so the results can also be useful for the PoB to quantify its carbon dependency. The main data sources are categorized as follows:
3.1.1. Port authority data We obtained reliable data in excel format on vessel operations from Barcelona Port Authority. The data from the PA contains information on vessel movements such as vessel name, vessel type, number of calls, date and time of arrival, date and time of departure, estimated time for main activities (aggregated), gross tonnage of cargo, and other information.
3. Method 3.1. System boundaries and data The boundaries can be a very significant source of differences among emissions inventories of seaports. Ports determine their
Fig. 1. Limits to the study of the Port of Barcelona.
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3.1.2. Lloyd’s register data. Lloyd’s Register-Fairplay, Ltd., provides detail information of all ships of 100 gross tonnages and above. Information from Lloyd’s Register basically includes details on registration, ship types, dimensions of ships, tonnages, capacities, construction, classification, communications, ownership, main engine specifications, auxiliaries, special features, cargo gear, and hull types (Lloyd’s Register Fairplay, 2009). This source was mainly used for data on dead weight tonnage (DWT), vessel service speed, and engine power.
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methodology, the emissions inventoried are those attributed to electricity, heating and energy fuels, ground transportation fuels, industrial processes, and waste. The GHG emissions associated with fuels are calculated from a life cycle approach (also referred to as scope 3 by ICLEI (2008)); whereas the rest of emissions are calculated as single process emissions from end-use activities (scope 2).
3.3. Sea-based emissions 3.1.3. Port community data Data about energy consumption and waste generation is obtained from customer survey performed by the AC. The file from the survey includes about 80% of all consumption of electricity, natural gas, gasoline, diesel oil, and jet fuel (estimate given by the PA based on the companies that responded for the survey), and waste generation sorted by type of waste such as plastic, rubber, paper, batteries, fluorescent, light packaging, wood, and so on. This information is used to determine GHG emissions associated with the use of port facilities including cargo handling (such as electric cranes). 3.2. Land-based emissions The emissions resulting from vessel movement are calculated using the methodology applied to the city of Barcelona (Kennedy et al., 2009b, 2009a), using the data collected via the customer surveys discussed earlier (see first column of Table 1). Based on this
An energy based approach was adapted and used to calculate the emissions based on the power requirements of the vessels. This methodology was proposed by the US EPA (ICF International, 2009), and is also reported by the World Ports Climate Initiative (2009). A vessel has a primary engine, an auxiliary engine, and an auxiliary boiler. How long and to what extent each of these three is used depends on the activity: arrival and departure, maneuvering, and hotelling. To calculate the emissions, we need to know how much of its maximum power the engine is operating at; during these activities within the port, the engines will not be operating at 100%. This can be calculated using the load factor, which is a measure of maximum speed and actual speed. The speed at which a ship enters the port can vary depending on the distance that needs to be covered or the speed limits imposed by the PA. For the PoB, we did not have arrival/departure speeds to calculate load factors for each ship, so we used estimates. Advised by the PoB that arriving and departure speeds are very similar to maneuvering speed, we assumed the same load factor for both of these activities. In our
Emissions from Port of Barcelona
Emissions due to vessels movement (mobile emissions) Ships arriving into the Port Ships departing from the Port Hotelling Maneuvering
Land-based, port related emissions (stationary emissions) Electricity Consumption Heating Fuels Transportation Fuels (Cargo handling, vehicles, trucks, etc.) Waste
Fig. 2. Categories of emissions considered for the study.
Table 1 GHG emissions for land-based port activities for the Port of Barcelona, 2008.
Electricity Natural gas Diesel Gasoline Jet fuel Waste Total a b
Total consumption
Emission factor
GHG Emissions (tons)
%
192.01 GWh 30,426,122 m3 1,4822,522 l 21,704 l 20,000 l 46,705 tons
143 tCO2e/GWha (Baldasano et al., 1999) 61.6 (Baldasano et al., 1999) 82.8 tCO2e/TJ (Kennedy et al., 2009b) 81.9 tCO2e/TJ (Kennedy et al., 2009b) 79.1 tCO2e/TJ (Kennedy et al., 2009b)
27,493 62,750 47,374 56.86 55.57 18,890 156,206
18 40 30 0.04 0.04 12 100
b
a line factor of 1.11 is included. waste is broken up into paper, textile, food waste, wood, and others. Each one of these has its own emission factor; please refer to Kennedy et al. (2009b).
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Table 2 Tons of sea-based GHG emissions for the PoB for 2008. Type of Vessel
Maneuvering, GHG emissions (tons)
Maneuvering time (h)
Hotelling, GHG emissions (tons)
Hotelling time (h)
Total GHG emissions (tons)
Auto carrier General cargo Refrigerated cargo Solid bulk Passenger Liquid tanker Container RO-RO cargo Liquid bulk Ferry Total
6972 2857 402 851 8649 128 32,948 5522 7241 42,364 107,934
1681.4 2810.5 125 476.2 844.7 40.75 5807.1 1638.6 4319.1 8222.0 25,965.4
5452 2560 256 1749 13,529 114 24,693 3571 8380 6769 67,073
7209 18,585.1 478.25 11,131.1 9896.1 264 36,432.5 9832 19,989.4 9681.3 123,499
12,424 5417 658 2600 22,178 242 57,641 9093 15,621 49,133 175,007
case, at 1 nautical mile, we estimated that the ships are entering, maneuvering, and exiting at 40% of the main engine power (also referred to as a load factor of 0.40). Hotelling refers to the time a vessel stays in the port; it is not moving, but it is using fuel (it uses its own engines) or electricity (it is plugged in to the port). For the PoB, vessels use their engines during hotelling, approximated at 20% of main engine power (load factor of 0.20). If we know the power required by each engine for each activity and the time required, we can calculate the total emissions using the following equation: E ¼ PO t LF Ef
ð1Þ
where E is the total emissions per engine, per type of vessel for a certain activity, in grams. PO is the power output, in KW. Since specific data was not available on the power output of each engine for each vessel type, it was calculated as a function of gross tonnage for each type of ship, according to the CORINAIR equations given by the European Environment Agency (2002). t is the time the engine is being used, in hours. The time data available was not disaggregated by activity—it was a lump sum for all three activities. Based on the information given by the PA, we assumed a set time for arrival/departure and maneuvering for each type of ship. Since we estimated the same speed for these activities, the time did not have to be further disaggregated. The time difference was attributed to hotelling. LF is the load factor. As engines are not operating at their maximum tested power, we need to consider load factor calculated based on the propeller law.3 For hotelling and maneuvering, load factors of 0.2 and 0.4 are used, respectively (arrival and departure are included in the maneuvering activity since the speeds are similar). Ef is the emissions factor, in grams per KWh; the GHG included are CO2, CH4, and SOx (these are the combustion gases with global warming potential; other gases such as SOx are important to quantify for air quality control). The following factors were taken from ICF International (2009):
for primary engine at intermediate speed: 677.91 gCO2/KWh; 0.004 g CH4/KWh; 0.031 g NOx/KWh.
for auxiliary engine: 722.54 gCO2/KWh; 0.004 g CH4/KWh; 0.031 g NOx/KWh.
for auxiliary boiler: 970.71 gCO2/KWh; 0.002 g CH4/KWh; 0.080 g NOx/KWh.
3 The propeller law states that the necessary power delivered to the propeller is proportional to the rate of revolutions to the power of three, for intermediate speed.
Once the emissions of CO2, NOx, and CH4 are calculated, they are each multiplied by their respective CO2 equivalent factor (1, 310, and 21, respectively) and summed to give the total GHG emissions.
4. Results and discussion 4.1. Land-based emissions Based on the methodology above described, the results obtained are given in Table 1. A high percentage of emissions due to natural gas is the result of several companies in the port that use natural gas for their production processes, such as heating tanks and regasification. There is a very small amount of gasoline consumed, since diesel is the fuel of preference for most of the machinery and road transport. 4.2. Vessel movement emissions The total GHG emissions for each type of OGV are given in Table 2 for 2008 according to the methodology described above (results for 2007 are included in the Supporting Information). The highest emitters are the container vessels, followed by the ferries. The total GHG sea-based emissions for 2008 were 175,184 tons. A different method based on fuel consumption was used to corroborate the results from the energy-based approach. We used a modified version of the methodology developed by the EU project MEET (methodologies for estimating air pollutant emissions from transport) (Trozzi and Vaccaro, 1998). Although this methodology is not as precise as the one presented in this paper (i.e. the same emissions factor is applied to all engine types and modes of operation), it did serve to confirm the order of magnitude of the results. The total emissions were about 30% higher, for 2007 we calculated 225,821 and for 2008 235,327 tons of GHG emissions. One possible reason for this is that the fuel based approach does not differentiate among fuel consumption rate of different engines (primary, auxiliary, and boiler). Based on average fuel consumption rates could lead to an overestimation for typical operations in ports that require less fuel. For a description of the fuel-based approach, please see the Supporting Information. The number of ships that enter and exit the port (also referred to as a ‘‘call’’) is not an adequate figure to compare the emissions, since the gross tonnage of each ship can vary greatly. However, what can serve as an indicator is the total cargo handled and passengers arriving, departing, and in transit. Table 3 shows the total tons of cargo handled and the total amount of emissions for each type of ship for 2008 (results for 2007 are in the Supporting Information). Port activity remained more or less constant between 2007 and 2008, which is coherent with similar emissions for those years.
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Table 3 GHG emissions per cargo handled and per passengers for 2008. GHG emissions per ton of cargo handled (kg)
Type of ship
Cargo (tons)
GHG emissions (tons)
Auto carrier General cargo Refrigerated cargo Solid bulk Liquid tanker Container RO-RO cargo Liquid bulk
1,518,289 8,608,127
9086 6278
5.98 0.73
780,721
452
0.58
6,634,408 5,086,331
3297 116
0.50 0.02
17,998,646 3,932,876 5,985,735
58,068 8506 15,373
3.23 2.16 2.57
Passengers
GHG emissions (tons)
Ferry Passenger Total
1,162,422 2,074,554
44,333 21,305 175,184
GHG emissions per passenger (arrival, departure, and in transit) (kg) 38.14 10.27
Using this indicator, high polluters are the car carriers followed by container vessels. By far, however, the highest emitters are the passenger vessels. For passenger vessels, the ferries emit GHG emissions at four times the rate of the regular passenger vessels (mostly cruise ships). The measure we have chosen of emissions per ton of cargo handled is a useful indicator on several accounts. It can serve as an indicator to evaluate if mitigation policies are successful (or not) in decoupling economic activity from accumulation of GHG emissions. This metric is helpful for the port to establish a base line and to monitor emissions over time. It is also useful for comparison with other ports, although careful consideration must be made since the system boundaries of different ports can vary. Having this indicator further divided by ship type, plans of action can be prioritized for high polluters such as the car carriers and the ferries. Although this metric is helpful on several accounts, it could be further improved. Energy efficiency measures that could reduce hotelling power requirements, for example, are not captured by this indicator. However, this could be solved with a few more calculations. The load factor used in Eq. (1) would have to be corrected: instead of the 0.2 now associated with hotelling, a lower one that reflects a lower energy requirement should be used. In general, using average load factors is a limitation that could be further improved given enough data. An additional measure of emissions per value of cargo handled would complement the emissions per weight indicator. For 2008, the volume of cargo handled in the PoB was 73,150 million h or 4.5 tons of CO2 per million h (summing up both sea-based and landbased totals). On the same basis, we can calculate 127 tons of CO2 per thousand TEUs. These indicators together capture two main mechanisms by which economic growth could delink from the generation of CO2 emissions in seaports: increasing value and improving technologies.
5. Conclusions There are different ways GHG emissions can be allocated. For example: all emissions due to vessel transportation could be attributed to the shipping company, or all emissions could be attributed to the port/city receiving the cargo. In this paper we suggest that the emissions be attributed to the port once the OGVs
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are not in their cruise speed and are approaching the port using auxiliary engines. Furthermore, we divide the emissions between land-based and sea-based. This approach is beneficial in several ways. Firstly, it is compatible with existing city inventories. The city of Barcelona can use this inventory to quantify and benchmark its carbon dependence on the economic activity provided by the port without double counting. Having emissions disaggregated into land and sea-based, the port can monitor how policy measures can help reduce its impact. Here, emissions per ton of cargo handled is proposed as an indicator to pin point high polluting vessels—a measure independent of the city the port belongs to. Secondly, the consequences of GHG emissions might be more than global scale climate change. A recent study has found that urban CO2 domes enhance local air pollution, making it all the more important to quantify emissions on a local level (Jacobson, 2010). There are some limitations to this study. The emissions due to industrial processes that take place right in the port were not taken into consideration. For these processes, we only accounted for the emissions due to electricity and fuel consumption. All the emissions are calculated as single process emissions and the study could be further improved by calculating life cycle emissions. Only for fuel consumption for land-based activities, we were able to estimate the life cycle emissions, as was shown in Table 1. The data collected for land-based emissions came from surveys responded by 80% of the port community; so the results are not 100% representative of the port. The load factors used to calculate energy requirement were estimates based on US reports (ICF International, 2009) because of data limitations. It would be best to calculate load factors based on the speed of ships entering and leaving the Port of Barcelona. Up to now the PoB has not taken any direct measures for GHG emissions reduction. We hope that this work will serve to find ways of lowering this impact. However, although possible solutions come to mind such as having shorter hotelling times, we lack the knowledge and experience to see the viability of such actions. Thus we have limited ourselves to exposing the results in a transparent manner, not only for the PoB and the city of Barcelona to take appropriate action, but also other cities and ports can follow suit.
Acknowledgements This work has been possible, thanks to the cooperation of the Port of Barcelona, namely Dolors Carrascal and Joaquim Cortes, and the funding from the European Commission of an Erasmus Mundus scholarship for a Joint European Masters in Environmental Studies (JEMES program).
Appendix A. Supplementary material Supplementary data associated with this article can be found in the online version at doi:10.1016/j.enpol.2010.12.008.
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