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23rd World Gas Conference, Amsterdam 2006


Main author C. Dienst Germany

GREENHOUSE GAS BALANCE OF NATURAL GAS: NEW MEASUREMENTS FOR IMPORT PROCESS CHAIN OF RUSSIAN NATURAL GAS TO EUROPE 1. ABSTRACT During the last decade the role of natural gas in the European energy market has been increasing. In particular regarding GHG emissions, natural gas is seen as an appropriate means of supplementing the climate change policy of increasing energy efficiency and switching to renewable energy sources. The direct GHG emissions from natural gas are far below the ones from other fossil fuels like coal and oil. However, the indirect upstream emissions of the imported energy can have a significant impact on the GHG ranking of energy carriers. Since the early 1990s in particular, there has been speculation about the leakages occurring in Russia’s natural gas industry, which provides 35% of the gas used in Germany and 25% of the amount used in EU-25. Currently a distance of more than 5,000 km has to be covered from the production site in Western Siberia to the user in Mid-Europe. Against that background an extensive discussion about the environmental implications of a fuel switch to natural gas for Europe is still running. However, to date only a limited amount of information about GHG emissions from Russia’s natural gas industry has been published. In response to this, a comprehensive measurement campaign at the Russian Northern and Central export pipelines was carried out by Wuppertal Institute in cooperation with Max-Planck Institute for Chemistry in 2003/2004. The aim of the campaign was to close the existing gaps in available data and to improve the knowledge of the situation in the gas export grid in Russia. Five compressor stations in four different regions were investigated, including around 50 machines of different types and ages, hundreds of valves and adjoining pipelines. Therefore, the data obtained can be assumed to be representative and could be extrapolated for the whole gas export system to Europe. The extrapolation was done using the Monte Carlo method for uncertainty analysis. Using a new approach which differs from older methods, a complete GHG inventory of the gas export system was subsequently established, using the comprehensive Gazprom data set on planned emissions (operation, maintenance, repairs and accidental losses) and energy use for compressor drives. Overall, the new measurements confirmed that the CH4 emissions from the Russian natural gas export network are below 1% of throughput. The emissions during production, processing, transport and storage are somewhat below the level found by previous measurements. In fact around 2/3 of the total GHG emissions (CO2 equivalent) are CO2 emissions from the compressor drives, not methane losses as has often been believed. The emissions from leakages derive mostly from compressor machines and only to a small extent from pipelines. Due to technical and organisational measures the emissions have decreased since the mid-nineties, but there are still a variety of options, and a huge potential, for mitigation. In particular, the improvement of the efficiency of the compressor drives and the implementation of regular emissionmonitoring are possible options – also for JI projects – in the future. This could change the process chain results, as could other developments (increasing part of LNG in the import mix, new gas fields with higher distances from European consumers), not only for the natural gas process chain but for also for oil (e.g. use of unconventional oil sources). It is for this reason that a dynamic comparison is needed for the future.

TABLE OF CONTENTS 1. Abstract 2. Introduction 3. Background 3.1. Export gas network system in Russia 3.2. Previous data and studies 4. New measurement campaign in Russia 4.1. Sites 4.2. Measurements 4.3. Operation-related emissions 4.4. Results of the survey 5. Actual and future development 5.1. Future natural gas supply to Europe 5.2. Development of GHG Emissions (related to natural gas industry) in Russia 5.2.1.Joint implementation 6. Conclusion 7. References 8. List of Tables 9. List of Figures

2. INTRODUCTION The associated direct CO2 emissions from natural gas usage are lower than those from other fossil fuels. Natural gas, therefore, is seen as a possible measure to supplement the climate change policy of increasing energy efficiency and switching to renewable energy sources. This is why, parallel to the increasing role of natural gas in the European energy market, the question of the indirect GHG emissions has been brought up by critics in the last decade. The emissions that result from the production and transportation of natural gas within, and from, Russia have, in particular, become a topic for discussion about Europe’s energy supply. For Germany and the EU, this question is particularly relevant in the context of a climate protection strategy that favours the increased use of natural gas. If the levels of CO2 and CH4 emissions associated with the transportation of natural gas from Western Siberia are such that they negate the benefits of natural gas with respect to the direct emissions of its use, increased reliance on natural gas in a climate strategy would, at the least, be questionable. To substantially improve knowledge of the emissions situation in the Russian gas export grid and to respond to the points of criticism on previous studies, Ruhrgas AG (now E.ON Ruhrgas AG) commissioned the Wuppertal Institute and the Max Planck Institute for Chemistry to devise and perform new measurements in Russia and to extrapolate the results obtained.

3. BACKGROUND 3.1 Export gas network system in Russia 9 3 The Russian Federation, with verified gas reserves of 47,000 * 10 m , is the world’s largest producer 9 3 9 of natural gas (580 * 10 m /a). Moreover, it is the major gas supplier to the European Union (115 * 10 3 m /a) (1), transporting the gas over a distance of more than 5,000 km from the production site in Western Siberia to the user in Mid-Europe. The Russian market leader Gazprom operates one of the biggest long-distance gas networks with about 153,000 km of gas mains, most of which were installed between the 1970s and 1990s. Most of the Russian gas exported to the West comes from the Western Siberian gas fields around Yamburg and Urengoy. The gas produced here has a high methane content of approximately 97% and so requires only minimal pre-treatment. Two main export corridors, the so-called Central Corridor (CC) and the Northern Corridor (NC), are used to transport the gas to Western Russia and on into Central Europe. The two corridors are operated by different regional gas companies that all belong to the parent group, Gazprom. The corridors cover a distance of 3,075 km (Northern: 4,300 km including transit countries) and 3,376 km (Central: 5,500 km including transit countries) with a total pipeline length of over 34,000 9 3 km, accounting for 22% of Gazprom’s total long-distance gas pipelines. They export some 112 10 m of natural gas to Europe each year. This accounts for roughly 90% of all exports by Gazprom to Europe, and some 20% of all of the gas produced annually in Russia (2; 3).

3.2 Previous data and studies In the mid 1990s most statements on methane emissions from the Russian natural gas export system were based on speculative assumptions. There had been just one approximate worst-case assessment (4) and later more detailed theoretical estimations. To obtain reliable information on emissions, in 1995 Gazprom conducted measurements on its gas transmission network in cooperation with US EPA (1996) and Ruhrgas 1996/97 (6; 7). Both studies had comparable results and put the CH4 emissions from the Russian gas transmission network at approximately 1% of the natural gas produced. The findings suggested significantly lower emissions than had previously been assumed but, on the other hand, they met some criticism (see 7; 8; 9) concerning the small number of sites, a lack of transparency and missing detailed documentation. Therefore, despite these measurement results, some sources still referred to earlier studies (10), while others added their own rough estimates to existing investigations.

4. NEW MEASUREMENT CAMPAIGN IN RUSSIA To close the existing gaps in available data and to improve the knowledge of the situation in the gas export grid in Russia, in 2003 a new comprehensive and independent measurement campaign at the Russian Northern and Central export pipelines was carried out by Wuppertal Institute in cooperation with Max-Planck Institute for Chemistry and with support of Gazprom, E.ON-Ruhrgas and VNIIGAZ Institute (11). The measurement programme, the actual scheme, data extrapolation and error analysis were designed and implemented in accordance with the relevant requirements for GHG inventories (12; 13). A total of three measurement trips to 5 different compressor stations and associated sections of pipeline operated by three subsidiaries of Gazprom were carried out in the spring and autumn of 2003.

4.1 Sites Based on information about the different compressor types and pipelines a representative selection of compressor stations and their associated pipelines in both export corridors was identified in cooperation with the involved partners. The requirement was to select a representative sample of compressor types and age, taking into account different geographical and infrastructural factors and different subsidiary companies. As the size of the Gazprom export gas network makes it impossible to investigate all of the stations and sections of pipeline in detail in one campaign, we tried to represent the status of the whole export gas network as accurately as possible in the choice of sites (see table 1). The first phase of the measurement campaign was carried out in May 2003 on the Central Corridor, with the gas transmission company Mostransgaz, at the compressor stations and pipelines in Davidovskaya and Kursk, south of Moscow. In June, the second phase of the campaign took place in Northern Russia at the two stations of Uchta and Njukzeniza operated by Severgazprom. Finally, in October 2003, the third phase of the campaign was conducted at the Kazym station (Tyumentransgaz) in Western Siberia (cf. Fig. 1). Figure 1: Measurement campaigns on the Russian natural gas export pipelines

4.2 Measurements The scope of the extensive campaign is shown in table 1. In all, 50 compressors of different types and ages, as well as 25 pipeline intersections, were investigated. Approx. 2,380 km of pipeline was surveyed from the air by helicopter. A systematic inspection and survey of individual plant sections, such as compressors, dust filters, gas driers, gas coolers, etc., was carried out at the compressor stations. This examination included several steps beginning with the identification and listing of all units at the compressor stations, including valve knots at adjoining pipeline sections. The next step involved a thorough screening at the identified locations with sensitive CH4 detectors, followed by documenting and marking places found to have elevated methane levels and taking methane leakage rate measurements by the flux method. Various

vents installed on machines, fittings and fuel gas supplies for the controlled discharge of gas were subjected to direct volumetric measurements (see figure 2 and 3). Pipeline

Regional branch


Shops measured

Machines No. / power



1 (electr.)

7x12.5 MW



1 (gas)



1 (gas)


3 (gas)



2 (gas)


5 Stations

8 Shops

6x10.0 MW 2x16.0 MW 5x6.0 MW 13x10.0 MW 2x16.0 MW 6x6 MW 6x10.0 MW 50 Machines (534 MW)



km Overflight 300

valve nodes 1





1982 2001 1986 77-88 2001 1972 1977













Source: 9

Table 1: Overview of the measurement campaign 2003 Pipeline sections of adjoining compressor stations were screened for elevated methane concentrations with the ‘Aeropoisk III‘ laser leak detector installed on a helicopter. By using this 3 method it was possible to reliably detect leaks of the order of approximately 200 – 500 m /d and more. Valve knots on the pipeline sections were investigated by using the same scheme as used for elements of compressor stations, namely by screening and using the flux method. The quality of the campaign was assured through a comprehensive quality control concept that included various aspects before and during the campaigns as well as in the archiving of the data and the calculations and extrapolations afterwards.

Figure 2 and 3: Vent screening. Davidovskaja, May, 2003; Valve screening with GfG-unit 4.3 Operation-related emissions In addition to the unplanned emissions resulting from leaks and the possible technical problems that were surveyed in the measurements, operations-related discharges and breakdowns were also considered in this survey. For the analysis a comprehensive data set on the internal operational data for both export corridors was prepared by VNIIGAZ/Gazprom (2004) with information on the plant and equipment installed on the export corridors, machine operating hours, characteristic emission values, repairs and maintenance, breakdowns etc. These emissions include the releases of gas (CH4) on machine start-up and shutdown, releases from venting of machines, from maintenance of pipelines and repair purposes as well as from the cleaning

of dust filters and traps. In addition, CO2 emissions from the turbines as operation-related emissions were included. The data is given for the year 2003 and contains specific information for every machine-hall of all stations and for every pipeline section of both corridors. A significant proportion of the data could be verified with information collected at the sites during each measurement campaign in liaison with the station managers and the engineers responsible. By comparing the operational data provided by Gazprom, collected in situ, and data from literature, other surveys and plausibility checks, it was possible to arrive at typical emission parameters for all operations-related emissions from the Russian export network and to extrapolate the emissions on both export corridors (see table 2). Source Unit per year Mean value1) Compressor stations Start-up/shutdown emissions m3 CH4 per compressor 15,4002) 3 Shop venting m CH4/shop 105,000 Filter cleaning m3 CH4/shop 44,359 Long distance pipelines Maintenance and repairs m3 CH4/km 3,750 Breakdowns m3 CH4/km 2843) 1) Specific emission factors based on this with ranges were used for the calculation. 2) Detailed data was used for each machine type for all shops in the northern and central corridors; the emissions range from approx. 200 to 3,900 m3 per start-up/shutdown cycle depending on type. 3) only CH4 not ignited Source: 9

Table 2: Typical emission factors for operations-related discharges and breakdown-related losses

4.4 Results of the survey The results of the measurements and of the analysis of the technological discharges have been extrapolated to the North and Central export corridors. By means of a Monte Carlo simulation the uncertainty has been included in the calculations (as documented in 11). An extrapolation for the Russian long-distance natural gas pipeline grid as a whole has also been calculated (as documented in 14). Around 68% of GHG emissions from gas transportation along the export corridors in 2003 were CO2 emissions. Primarily, the exhaust from the gas turbines used to drive the compressors and the CO2 emissions from Russian power generation attributable to the electric motors used for compressors are the main sources (see table 3). Compared to these sources, CO2 emissions from ignited gas from breakdowns or damages are of almost no relevance. The same is true of N2O, which comes from the turbine exhausts or the power supply, and accounts for only 1% of GHG emissions along the export corridors. Just under 31% of GHG emissions at the export corridors are due to the release of CH4. Of this, a good two-thirds were due to leakages from machine fittings, compressor stations and valve nodes on the pipelines. Another significant proportion is due to the venting (i.e. the discharging of gas to atmosphere) of shop and pipelines for maintenance and repair purposes; taking the worst-case assumptions that were made, venting accounts for around 5% of GHG emissions along the export corridors. Other operations-related emissions are mainly due to gas-regulated fittings and compressor seal oil systems (shaft seals). CH4 losses are also to find at the storage facilities or are due to power supply. CH4 losses can also be due to breakdowns, and here again a worst-case estimate was used which – for reasons of safety – is well above the detailed data we have about the actual breakdown/damagerelated emissions in 2002 and 2003. Emissions from the storage facilities were allocated pro-rata to the central export corridor and to the use of power. Compared to the export corridors, in the emission characteristics of the Russian long-distance gas system (given in 14) CO2 emissions from traction energy per unit of gas transported are less important because of the lower average transportation distances. Specific emissions of CH4 are somewhat higher due to lower load factor of the whole grid compared to the export corridors. Overall, the new measurements and calculations confirmed that the CH4 emissions from the Russian natural gas export network stand at approximately 0.7% of the natural gas arriving at the Russian western border (with a range from 0.4 to 1.6 %of the gas exported) and about 1% arriving at Germany’s eastern border (with a range from 0.6 to 2.4%).

Emissions by plant section/mode

106 t CO2 equivalent


CO2 Turbine exhaust Power supply (for electric drives) Breakdowns (ignited) Total CO2 N2O CH4 Leaks from fittings and vents Leaks from compressors Other leaks from compressor stations Leaks from pipelines Operational (measured) including: Fuel gas. start-up gas and pulse gas supply Seal oil systems (shaft seals) Operational (calculated) Compressor start-up/shutdown Methane in turbine waste gas Maintenance/repairs to stations Maintenance/repairs to pipelines CH4 from Breakdowns CH4 from underground storage (pro rata) CH4 from power supply Total CH4 Total of greenhouse gas emissions overall Source: 9

37,27 3,03 0,03 40.33 0,58

63,0% 5,1% 0,1% 68,2% 1,0%

12,42 11,07 0,04 1,31 1,32 0,57 0,75 3,48 0,37 0,09 1,05 1,97 0,15 0,36 0,48 18,21 59,12

21,0% 18,7% 0,1% 2,2% 2,2% 0,9% 1,3% 5,9% 0,6% 0,2% 1,8% 3,3% 0,3% 0,6% 0,8% 30,8% 100,0%

Table 3: Greenhouse gas emissions from the Russian North and Central export corridors (2003)

5. ACTUAL AND FUTURE DEVELOPMENT The results of the measurement campaign only reflect the current situation of the emissions that derive from the Russian gas export transport system to Western Europe. Future changes relating to indirect emissions depend on future trends in the origin of the natural gas used in Europe and improvements in technology and infrastructure, as well as overall developments in the international gas supply structure. In particular, the possible developments that may take place over the next 25 years are discussed in the following chapter.

5.1 Future natural gas supply to Europe Currently around 25% of the natural gas supply to EU-25 comes from Russia, with the share of the import differing enormously between the different countries. In Northern and Central Europe some countries depend on Russia for 100% of their gas, while other Western and Central European countries buy 30 – 70% of their gas from Russia. Some Western countries, e.g. United Kingdom and Ireland, do not obtain any of their gas from Russia (cf. 15). Other important producers are Norway, The Netherlands, Denmark, United Kingdom and Germany, with around 11% also coming from Algeria. According to current projections, the dependency of EU-25 on gas imports is going to increase significantly until 2030. From a level of around 50% of imports at the beginning of this century, the percentage is expected to rise to around 80-90% in 2030 (16). The main suppliers will remain Russia and Norway, but also the import options of LNG will be used much more intensively than today. By 2010 the amount of LNG traded on the worldwide market is predicted to more than double. In addition to the increase in import dependency the absolute European demand for natural gas is expected to more or less double, and new countries will enter the market on the demand side and on the supply side (17). Together with increasing imports diversification will take place, in infrastructure as well as on the supply side (UN ECE 2003), with the specific goals of securing the supply, fulfilling the growing demand and obtaining a good position in the competitive market. Parallel the gas industry and

governments will need to rise to enormous challenges and will face the need to invest in order to maintain and improve the existing infrastructure, as well as to develop new production areas and new transport paths. These developments imply significant changes for indirect energy use and emissions related to the natural gas supply of the EU, which will be addressed in the following section. The focus will be on the situation of Russia in its role as the most important external supplier of natural gas to the EU, both currently and for the foreseeable future. 5.2 Possible Future Trends of GHG Emissions (related to the natural gas industry) in Russia What developments might take place in the Russian gas market and what might be the consequences for levels of methane and carbon dioxide emissions? First of all, there is a huge potential for optimisation and, thereby, for the mitigation of the emissions. By taking further steps to improve the management and retrofitting of existing equipment in the Russian natural gas industry, a significant reduction of energy consumption and CH4 emissions from the existing infrastructure could be achieved. Many cost-effective emission-reduction practices have been highlighted and demonstrated in the Natural Gas Star Program for the US (18). They range from the installation of flare systems and green completions at wells, the replacement of high bleed pneumatics with low bleed systems, the introduction of directed inspection and maintenance at compressor stations, to the retrofitting of fuel gas recovery for blow-down valves and composite wrap repairs for pipeline tubes. Estimates on CH4 mitigation options for the Russian natural gas industry, carried out by US EPA, project a decrease of around 31% (19). In addition to this optimisation, reinvestment is urgently needed over the next two decades, in particular to replace old compressors that are still in current operation. A high proportion of the fugitive emissions measured at the Russian transportation system come from old machines with less than 10 MW, which were installed before 1980. Reinvestment will significantly increase fuel-efficiency and reduce the emissions. Other developments in Russia can equally influence the future emission basis, such as the projected development of new transport systems, e.g. the new transport corridors like Jamal-Europe, the Northern European Gas Pipeline (NEGP) or LNG systems, which will change the amount of transport energy needed and parallel the quantity and quality of possible emission sources. The new pipelines will feature international best available technology and thus further reduce the emissions. On the other hand, the putting into operation of new production sites and the associated intensified exploitation of declining fields might result in an increase of technological expenditure, longer transportation distances to cover and the possibility of resultant increased emissions. 5.2.1 JI-projects A possibility for financing the optimisation can be seen in the flexible Kyoto mechanism of Joint Implementation (JI). Notable examples already exist in Russia. For instance the “Rusagas Carbon Offset Project”, which was carried out between TransCanada and Gazprom as a test for possible JIprojects, resulted in emission reductions of about 50%, achieved by directed inspection and maintenance at two Russian compressor stations (20). Regarding the CO2 emissions from energy use, E.ON-Ruhrgas and Gazprom have carried out a JI-pilot project where they attained 1.5 * 109 kWh reduction of gas consumption for turbines by computer-based load optimisation. They are currently planning to expand the project to the whole Gazprom system where emission reductions of about 4.5 * 106 t of CO2 are expected. Overall it is recognised that, by optimising the Russian production and transport gas system, it could be possible to reduce the current emission level by a remarkable 30-60%. But of course there are still several unanswered questions relating to future developments, such as how much will be invested in the optimisation of the middle and low-pressure inner Russian gas system. Other unknown quantities include the possible development and change of the production areas and transport paths over the next 20 years. And of course energy supply, export and import are strictly dependant on the international political situation and degree of co-operation.

6. CONCLUSION The new measurements conducted in 2003 confirmed that the methane emissions from the Russian natural gas export network are approximately 0.7% of the gas arriving at the Russian Western border and around 1% of the gas delivered to the German border (9). By far most of the of the greenhouse gas emissions from gas transportation along the Russian export corridors – around two-third – are CO2. A representative sample of 5 compressor stations and their associated pipelines sections, in conjunction with a detailed data set on the Russian main export corridors made it possible to perform a detailed calculation on the GHG emissions related to the transport chain. By using the Monte Carlo method to determine the confidence interval for the CH4 emission value, it found that emissions fall within the range of 0.4 to 1.6% of the exported gas with 95% certainty. This is far below the speculative assumptions made in elder studies and even somewhat below the emission levels gained from previous measurements. Due to numerous technical and organisational measures taken by Gazprom since the mid-nineties, some emission sources have clearly decreased. In other areas there is still the potential to further reduce emissions. The main sources of emissions are primarily leaks or discharges from machines and valves at compressor stations and – to a lesser extent – leaks from pipeline valves. Gas venting for maintenance and repairs and emissions as a result of breakdowns are of lesser importance. However, these results only reflect the current situation in the Russian gas industry where there is still a significant potential for reducing greenhouse gas emissions. Future changes to the indirect emissions depend on future trends in the origin of the natural gas used in Europe and improvements in technology and infrastructure, as well as overall developments in the international gas supply structure. Regarding CH4 in particular, there are cost-effective mitigation options available that have not yet been fully implemented by Gazprom. E.g. drive energy reduction and the huge distribution system offer further significant potential for mitigation. On the other hand, other trends, like new production sites and pipelines, might change the preconditions and lead to a possible increase of emissions in the future. All in all the possibility of a remarkable reduction of the current emission level deriving from the optimisation of the Russian production and transport gas system can already be seen.

7. REFERENCES 1. British Petroleum (2004), Statistical review of world energy 2004 ‹› London, 2004 2. Gazprom/VNIIGAZ (2004): Technical Bulletin on the operational data as part of Project B8 „Determining Methane Emissions“. Signed by the Deputy Head of the Department for Gas Transmission, Underground Storage and Gas Usage of OAO Gazprom, W.M. Dedeshko 3.6.2004-0609. Unpublished data. 3. Dedeshko (OAO Gazprom) (2001): Complex diagnostics and repair of gas pipelines as a basis for enhancing the safety of the Russian integrated network. – 11th International Working Party „Diagnostics-2001“, Tunisia, April 2001. Vol. 1. pp. 9 – 20. Moscow 2001. 4. Rabchuk et al., (1991); A study of methane leakage in the Soviet natural gas supply system, Prepared for Battelle Pacific Northwest Laboratory, Siberian Energy Institute, Irkutsk 1991. 5. Dedikov et al. (1999): Estimating Methane Releases from Natural Gas Production and Transmission in Russia, Atmospheric Environment, 1999 6. Kobzev, Yu.V.; Akopova, G.S.; Gladkaja, N.G. (1997): Assessment of methane emissions into atmosphere by the Gazprom’s facilities. Moscow, “Gazovaya promyshlennost”, №10, 1997. 7. Popov, I. (2001): Estimating Methane Emissions From the Russian Natural Gas Sector. Advanced International Studies Unit, PNNL operated by Batelle. Prepared with support from the U.S. DOE PNNL-1342. 8. Lechtenböhmer, S., et al. (2003): GHG emissions of the natural gas life cycle compared to other fossil fuels (in Europe). In: 3rd International Methane & Nitrous Oxide Mitigation Conference, Beijing, China, November 17th-21th 2003. - Beijing, 2003, pp. 790-798. 9. Lechtenböhmer, S. et al. (2005): Greenhouse Gas Emissions from the Russian Natural Gas Export Pipeline System, Results and Extrapolation of Measurements and Surveys in Russia, A Project on behalf of E.ON Ruhrgas AG, Wuppertal & Mainz,

10. DGMK (1992): Deutsche Wissenschaftliche Gesellschaft für Erdgas, Erdöl, Kohle ee. V. (DGMK), Ansatzpunkte und Potenziale zur Minderung des Treibhauseffektes aus Sicht der fossilen Energieträger, Research Report 448-2, DGMK, Hamburg. 11. Lechtenböhmer, S., Dienst, C. et al. (2005): GHG-emissions of Russian natural gas industry by gas export to Europe, Non-CO2 Greenhouse Gases (NCGG-4), coordinated by A. van Amstel © 2005 Millpress, Rotterdam, ISBN 90 5966 043 9, P. 209 – 216. 12. IPCC (2000): IPCC-Good Practice Guidance and Uncertainty Management in National Greenhouse Inventories. 13. GRI/US EPA (1996): Methane Emissions from the natural gas industry. GRI/US EPA, Report No. EPA-600/R-96-080. 14. Lelieveld, J. et al. (2005): Low methane leakage from gas pipelines A switch from coal or oil to natural gas could mitigate climate effects in the short term. NATURE, Vol. 434, 14 April 2005, p 841f. 15. E.ON Ruhrgas (2005): Erdgasimportabhängigkeit in der EU-25, 16. UNECE Gas Centre (2003): Report on security of natural gas supply in the European part of the Venugopal, S. (2003): Potential Methane Emissions Reductions and Carbon Offset Opportunities in Russia. In: 3rd International Methane & Nitrous Oxide Mitigation Conference, Beijing, 2003, S. 906913. 17. Verberg, G. (2004): The growing role of natural gas in the global energy supply. Natural Gas Day 11-11-2004 at the Finnish National Gas Association. 18. Fernandez, R., Lieberman, D., Robinson, D. (2004): U.S. Natural Gas STAR Program Success th Points to Global Opportunities to Cut Methane Emissions Cost-Effectively. In: Oil & Gas Journal 12 July 2004. 19. Robinson, D. R., Fernandez, R., Kantamaneni, R. K. (2003): Methane Emissions Mitigation Options in the Global Oil and Natural Gas Industries. In: 3rd International Methane & Nitrous Oxide Mitigation Conference, Beijing, China November 17th-21st 2003. Beijing, 2003, p. 923-933. Ruhrgas 20. Venugopal, S. (2003): Potential Methane Emissions Reductions and Carbon Offset Opportunities in Russia, In: 3rd International Methane & Nitrous Oxide Mitigation Conference, Beijing, 2003, S. 906913.

8. LIST OF TABLES Table 1: Overview of measurement campaign 2003 Table 2: Typical emission factors for operations-related discharges and breakdown-related losses Table 3: Greenhouse gas emissions from the Russian North and Central export corridors (2003)

9. LIST OF FIGURES Figure 1: Measurement campaigns on the Russian natural gas export pipelines Figure 2: Vent screening. Davidovskaja, May, 2003 Figure 3: Valve screening with GfG-unit

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