Comparative analysis of carbon dioxide emission factors for energy industries in European Union countries

Renewable and Sustainable Energy Reviews 51 (2015) 603–612

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Renewable and Sustainable Energy Reviews journal homepage: www.elsevier.com/locate/rser

Comparative analysis of carbon dioxide emission factors for energy industries in European Union countries Inga Konstantinaviciute a,b,n, Viktorija Bobinaite a a b

Lithuanian Energy Institute, Breslaujos Street 3, LT-44403 Kaunas, Lithuania Kaunas University of Technology, Studentu Street 48, LT-51367 Kaunas, Lithuania

art ic l e i nf o

a b s t r a c t

Article history: Received 22 July 2014 Received in revised form 13 February 2015 Accepted 29 June 2015 Available online 15 July 2015

Strategies for mitigating climate change require accurate estimates of the greenhouse gas (GHG) emissions. Estimates of the amounts of carbon dioxide (CO2) and other GHGs emitted into the atmosphere are crucial for planning and analyzing mitigation efforts. Emissions factors are the fundamental tool in developing national emissions inventories. The quality of GHG inventories has been a long-standing issue among the scientific community and its importance has more recently risen on the policy agenda because national inventories are now the basis of legally-binding commitments. According to the IPCC Good Practice Guidance comparison with the recommended IPCC default values may be informative in establishing the comparability of the country-specificity of the emission factors used. Such comparison may help to identify data outlier where uncertainty ranges do not overlap. The main objective of this article is to assess comparability of CO2 emissions factors between EU countries for energy industries and to evaluate whether the reporting of emissions from energy industries is good enough to monitor progress towards the emission reduction targets set under international agreements according to the quality criteria of transparency, consistency, comparability, completeness and accuracy. Performed analysis of CO2 emission factors showed that almost all EU countries seeking to reduce uncertainty apply country-specific CO2 emission factors for major sources of emissions from energy industries. Application of country-specific emission factors ensures greater accuracy and lower uncertainty of GHG inventory. Comparative analysis showed that country-specific CO2 emission factors applied in EU countries for the main fuels combusted in the energy industries have been established in a comparable way taking into account uncertainty ranges defined in the IPCC Guidelines. Seeking to ensure more accurate estimates of CO2 emissions it is important further improve knowledge on emission factors at individual plant level that allow estimating GHG emissions with lower uncertainty applying higher level tier methods. & 2015 Elsevier Ltd. All rights reserved.

Keywords: GHG emissions inventory Energy industries CO2 emission factor Fossil fuels Accuracy Uncertainty Comparability

Contents 1. 2. 3. 4.

5.

n

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Importance of CO2 emission factors for the preparation of GHG inventories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tendencies of fuel consumption in the energy industries of EU-27 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CO2 emission factors for energy industries applied in EU countries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1. CO2 emission factors of hard coal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2. CO2 emission factors of lignite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3. CO2 emission factor of natural gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4. CO2 emission factor of refinery gas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The impact on CO2 emission estimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Corresponding author at: Lithuanian Energy Institute, Breslaujos Street 3, LT-44403 Kaunas, Lithuania. Tel.: þ 370 37401952; fax: þ370 37351271. E-mail address: [email protected] (I. Konstantinaviciute).

http://dx.doi.org/10.1016/j.rser.2015.06.058 1364-0321/& 2015 Elsevier Ltd. All rights reserved.

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6. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 611 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 612

1. Introduction

0.4% a year since 1995. The global economic recession during 2008– 2009 impacted on a reduction of consumption of various fuels. As a result GHG emissions reduced by 6.1% in 2009. Recovery from the global economic crisis was followed by an increase of GHG emissions. In 2010, GHG emissions increased by 3.1% compared to 2009. As it is evident from Fig. 1, energy industries (they include electricity and heat generation, petroleum refining and manufacturing of solid and other energy industries) are the most important source of GHG emissions that are being generated during the combustion of fossil fuel in Annex I countries. During 1990–2010 GHG emissions from energy industries accounted to about 30% in the structure of total emissions (see Fig. 1). GHG emissions from the energy industries amounted to 5.77 Pg CO2 eq. in 2010 and they had almost been at the same as level as in 1990 (5.80 Pg CO2 eq.). CO2 emissions contribute to about 99% of total GHG emissions CO2 eq. in energy industries of Annex I countries (see Fig. 2) and EU has the second largest contribution of CO2 emissions (29.4% in 1990; 25.1% in 2010). Strategies for mitigating climate change require accurate estimates of the GHG emissions. Estimates of the amounts of CO2 and other GHG emissions emitted into the atmosphere are crucial for planning and analyzing the mitigation efforts and for the development scenarios of future emissions. The quantity and distribution of current emissions as well as the path of future emissions are very important therefore it is critical that estimates of emissions would be accurate and deal with uncertainty in best estimates [12]. Thus, strict requirements for reliable estimations of CO2 emissions when analyzing efficiency of being implemented strategies for climate change mitigation and evaluation of progress towards the CO2 emissions reduction targets; as well considering to the importance of EU energy industries in emitting CO2 induced to concentrate on the issue of quality of CO2 emissions estimations in EU energy industries.

Climate change is one of the most challenging issues of our times. Over the past century, human activities have released large amounts of greenhouse gas (GHG) into the atmosphere. Stern [16] found that in order to minimize the most harmful consequences of climate change, concentrations would need to be stabilized below 550 ppm CO2 eq. and any delay in reducing emissions would be costly and dangerous. In order to stabilize the GHG concentration and to reduce global warming, 196 countries in the world agreed to the United Nations Framework Convention on Climate Change [17]. In 1998, a number of countries approved the Kyoto Protocol [18] too. Under the Kyoto Protocol Annex I countries agreed to reduce GHG emissions at least 5% below 1990 levels in the commitment period 2008–2012. The Intergovernmental Panel on Climate Change (IPCC) in the Fourth Assessment Report states, that since 1970, GHG emissions from the energy supply sector have grown by over 145%, while those from the transport sector – by over 120%. As such these two sectors show the largest growth in GHG emissions [9]. Therefore the limitation of GHG emissions in the energy sector represents the highest priority in most of the countries in order to achieve the national commitments for GHG reduction. Under the UNFCC Convention and under the Kyoto Protocol, the Annex I countries are annually reporting their national GHG emissions inventories to the UNFCCC. The estimates of GHG emissions are based on the Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories [6], although the IPCC has already approved the 2006 Guidelines at the 25th session of the IPCC in April 2006 in Mauritius. The new reporting tables based on the 2006 Guidelines will be mandatory from 15 April 2015. Currently GHG emissions inventories are submitted for the years 1990–2010 and are available on the UNFCCC website [20]. The analysis of developments of GHG emissions (see Fig. 1) shows that, although total GHG emissions were decreasing by 1.6% a year during 1990–1994, however, they have started increasing by 20

16 14 12 10 8 6 4 2

Energy industries Transport Fugitive emissions Solvents Waste

Manufacturing Industries & Construction Other Energy Sectors Industrial Processes Agriculture

Fig. 1. Total GHG emissions in Annex I countries, Pg CO2 eq.[20].

2010

2009

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2007

2006

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2004

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GHG emissions, Pg CO2 eq.

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605

7

GHG emissions, Pg CO2 eq.

6 5 4 3 2 1

CO2

CH4

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N2O

Fig. 2. Total GHG emissions from energy industries by type of GHG in Annex I countries [20].

Namely, the main objective of this article is to assess the comparability of CO2 emissions factors between EU countries for energy industries and to compare the CO2 emissions estimates with the guidance provided by the IPCC. The purpose of such analysis is to evaluate whether the reporting of CO2 emissions from energy industries is good enough to monitor progress towards the CO2 emissions reduction targets set under the international agreements according to the quality criteria of transparency, consistency, comparability, completeness and accuracy defined within the UNFCCC GHG emissions reporting guidelines.





2. Importance of CO2 emission factors for the preparation of GHG inventories In general, an emission factor is a representative value that attempts to relate the quantity of a pollutant released to the atmosphere with an activity associated with the release of that pollutant. Emissions factors are the fundamental tool in developing national and international emissions inventories for climate change mitigation strategies. One of the most important uses of emission factors is for the reporting of national GHG inventories under the UNFCCC. The Annex I Parties to the UNFCCC have to annually report their national total GHG emissions in a formalized reporting format. The estimates of GHG emissions are based on the Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories [6]. The IPCC Guidelines allow Parties preparing and periodically updating national inventories in a way that the information provided in the reports was accurate, complete, comparable and transparent. The quality criteria held for estimates of GHG emissions are defined within the UNFCCC GHG emissions reporting guidelines [19] are as follows:

 Transparency means that the assumptions and methodologies



used for an inventory should be clearly explained to facilitate replication and assessment of the inventory by users of the reported information. The transparency of inventories is fundamental to the success of the process for the communication and consideration of information. Consistency means that an inventory should be internally consistent in all its elements with inventories of other years. An inventory is consistent if the same methodologies are used for the base and all subsequent years and if consistent data sets



are used to estimate emissions or removals from sources or sinks. Comparability means that estimates of emissions and removals reported by the Parties in inventories should be comparable among the Parties. For this purpose, parties should use the methodologies and formats agreed by the Conference of the Parties (COP) for estimating and reporting inventories. The allocation of different source/sink categories should follow the split of the IPCC Guidelines, at the level of its summary and sectoral tables. Completeness mean that an inventory covers all sources and sinks, as well as all gases, included in the IPCC Guidelines as well as other existing relevant source/sink categories which are specific to individual Parties and, therefore, may not be included in the IPCC Guidelines. Completeness also means full geographical coverage of sources and in sinks of a Party. Accuracy is a relative measure of the exactness of an emission or removal estimate. Estimates should be accurate in the sense that they are systematically neither over nor under true emissions or removals, as far as can be judged, and that uncertainties are reduced as far as practicable.

The quality of GHG inventories has been a long-standing issue among the scientific community and its importance has more recently risen on the policy agenda. This is because national inventories are now the basis of legally-binding commitments under the UNFCCC. Reliable GHG inventories are essential, both at national and international level. GHG inventories are usable for assessing the efforts to address climate change and progress toward meeting the ultimate objective of the Convention; for evaluating mitigation options; for assessing the effectiveness of policies and measures; for making long-term emission projections, etc. Accuracy of GHG inventory is a very important quality and reliability criteria. Appropriate methodologies conforming to guidance on a good practice should be used to promote accuracy in inventories. An indicator to measure the improved accuracy of the inventories is the reduction of uncertainties of the estimates. The quantification process should be conducted in a manner that minimizes uncertainty. Van Aardenne et al. [10] states that uncertainties in the accuracy of GHG inventories can be subdivided in inaccuracies in the emission inventory structure (structural inaccuracy) and the values of activity data and emission factors (input value inaccuracy). Uncertainty about

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structural accuracy is the lack of knowledge of the extent to which the structure of an emission inventory allows for an accurate calculation of the real emission. The equation used to calculate the emission for an inventory of a given structure contains parameters and variables such as emission factors and activity data and hence the emission calculation need input values. Uncertainty about input values accuracy is the lack of knowledge of the values of activity data and emission factors. Errors in the available measurements can lead to inaccurate values of emission factors. Lesiv et al. [11] analyzed the change in the uncertainty of emission estimates which, in general, results from improvement of knowledge and the structural change in emissions. This study showed that increased knowledge of inventory processes has determined the change in total uncertainty in the past and should also be considered as the driving factor in the prospective future. Important cause of the national GHG inventory uncertainty is the use of default emission factors especially if the characteristics of fuels in country vary widely from global average values. In such a case use of default values introduces a larger uncertainty of GHG inventory. Uvarova et al. [21] provided an example to illustrate the impact of improving knowledge. They investigate improvement in accuracy of emissions estimates under a shift of accounting methods: from the production based IPCC Tier 1 to the massbalance-based IPCC Tier 2. The presented comparison showed that estimates in accordance to a higher-tier method resulted in a greater accuracy and a lower relative uncertainty (26% under Tier 2 versus 54% under Tier 1). Authors concluded that this uncertainty could be reduced further by improving the accuracy of parameters, including the use of more geographically explicit emission factors used for the emission estimates. The evaluation in reducing uncertainty in emission estimates reflects improvements in knowledge, e.g. more precisely known emission factors and improvement in activity data. According to the IPCC Guidelines for National Greenhouse Gas Inventories, if an activity is a major source of emissions for a country, it is a good practice to develop and to apply a countryspecific emission factor for that activity. Seeking to increase accuracy and reliability of the GHG inventory it is essential to apply national country-specific CO2 emission factors, which may be more appropriate for different national context. From the theoretical point of view as well based on existing practice one could state that combustion processes are optimized to derive the maximum amount of energy per unit of fuel consumed, hence delivering the maximum amount of CO2 per unit of fuel consumed. This maximum amount of CO2 refers to CO2 emission factor, which is expressed in tCO2/TJ (combustion emissions). If fuel is combusted efficiently, then this ensures oxidation of the maximum amount of carbon available in the fuel. Thus, it could be stated that CO2 emission factors for fuel combustion are 30,000

25,000

Other fuels Biogas Wood & wood waste Derived gases Natural gas Other petroleum products Fuel oil Residual fuel oil Refinery gas and ethane Lignite and derivatives Coke Hard coal

PJ

20,000

15,000

10,000

5,000

0 1990

1995

2000

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2010

Fig. 3. Tendencies of fuel consumption in the energy industries of EU-27, PJ [4].

therefore relatively insensitive to the combustion process itself, but are dependent only on the carbon content of the fuel as it is stated in the IPCC Guidelines for National Greenhouse Gas Inventories. The carbon content varies considerably both among and within primary fuel types on a per mass or per volume basis [8]:

 in the case of natural gas, the carbon content depends on the

 

composition of the gas which, in its delivered state, is primarily methane, but can include small quantities of ethane, propane, butane, and heavier hydrocarbons. Natural gas flared at the production site will usually contain far larger amounts of nonmethane hydrocarbons. The carbon content will be correspondingly different; in case of light refined products, such as gasoline, their carbon content per unit of energy is usually less than for heavier products such as residual fuel oil; in case of coal, its carbon emissions per tonne vary considerably depending on the coal's composition of carbon, hydrogen, sulfur, ash, oxygen, and nitrogen.

Actually, due to inefficiencies in the combustion process, that leave some of the carbon unburned or partly oxidized as soot or ash, incomplete oxidation occurs. This should be taken into account. The oxidation factor is expressed as a fraction of one ant it usually varies in a range of 0.99–1.0, which shows that not oxidized fraction is very small. In the Commission's Decision of 18 July 2007 on Establishing Guidelines for Monitoring and Reporting of Greenhouse Gas Emissions Pursuant to Directive 2007/87/EC of European Parliament and of the Council [22]; as well in IPCC [8] guidelines it is assumed that the fraction of carbon oxidized is equal to 1 and derived default CO2 emission factors are assessed considering to such value of oxidation factor. Saarinen [14] stated that comparability is an essential element in order to evaluate and to ensure emission data reliability. The quality of national GHG inventories could be assessed comparing national, regional and global inventories including estimation methodologies and emission factors. According to the IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories [7] comparison with the recommended IPCC default values and with other available values is informative in establishing the comparability or the countryspecificity of the emission factors used. Such comparison may help to identify data outlier where uncertainty ranges do not overlap. In order to evaluate accuracy of country-specific emission factors applied in EU countries for GHG inventory preparation, it is purposeful to assess comparability of CO2 emission factors taking into account uncertainty ranges defined in the IPCC [6] Guidelines. However, the first step of the analysis is to present the structure of fuels consumed in the energy industries of EU-27. This will allow identifying the fuels which CO2 emissions factors have to be investigated. The issue is discussed in the Section 3 of the paper.

3. Tendencies of fuel consumption in the energy industries of EU-27 Performed analysis of fuel consumption in energy industries of EU countries showed that during the latter two decades a great variety of fuels have been combusted in this sector (see Fig. 3). Historically hard coal was one of the most important fuels for EU countries and made the greatest share (about 35%) in the structure of fuels combusted in the energy industries (see Fig. 3). However, consumption of hard coal was reducing by 2.3% a year during the late twenty years. As a result 6673 PJ of hard coal was combusted in the EU-27 energy industries in 2010 and this made 28.1% of the structure

I. Konstantinaviciute, V. Bobinaite / Renewable and Sustainable Energy Reviews 51 (2015) 603–612

of fuels combusted in the energy industries. Statistical data analysis revealed that 42% of hard coal was domestically produced in 2010 [13]. Poland (58%), Great Britain (14%), Germany (11%), the Czech Republic (8.5%) and Spain (6.2%) were the biggest producers of this type of fuel. They produced about 98% of total domestically produced hard coal in 2010. Historically, hard coal consumption dominated by power sector where 65–70% of hard coal was consumed; followed by coke production, where about 17% of hard coal was consumed during 2006–2010 [13]. The major exporting countries to the EU were Russia (27.3%), Colombia (20.3%), the USA (17.0%), Australia (10.9%), South Africa (10.2%) and Indonesia (5.7%) in 2010. Hard coal export volumes were mainly directed to Germany (22.6%), Great Britain (15.1%), Italy (11.6%), the Netherlands (11.6%), France (9.3%), Spain (7.6%) and Poland (6.4%). Lignite remains a relevant type of coal in EU. EU is recognized as the leading group of countries in the world which produces this type of coal. Nigel Yaxley Ltd. [13] indicates that EU countries are responsible for 40% of lignite production in the world. Germany, Greece, Poland, the Republic Czech, Bulgaria, Romania and Hungary are the largest producers of lignite in EU. They produced about 95% of total domestically produced lignite in 2010, when totally 412.5 Mt (3,733,125 PJ) of lignite were produced in EU. EU consumption of lignite was 414.8 Mt (3,753,940 PJ) in 2010. This shows that domestic supply and demand of lignite are closely matched. The reason why there is little trade in lignite (total EU imports of lignite were 0.7 Mt (6335 PJ) in 2010, only 0.2% of total supply) lies behind the fact that lignite has a low heating value and this result in a high unit transportation cost. Thus, lignite burning power plants are situated close to the mines. Power plants burn about 95% of lignite and the remaining share of lignite (mainly in the form of briquettes) is used for district heating plants and domestic heating. Historical development of lignite consumption shows a reducing trend. Since 1990 consumption of lignite reduced by 34% in EU and its share in fuel structure reduced from 22.6% (1990) to 15.9% (2010). Since 2010 coal consumption shows an increasing trend in EU countries. There can be found several reasons for this, however, financial reasons are the most important. A rapid rise of new drilling techniques for natural gas [1] and discoveries of shale gas [15] led to low prices for natural gas in the USA. This also made a downward competitive pressure on domestically produced coal, which demand declined in USA. Coal, which earlier was widely consumed domestically, started to be exported and EU countries

607

(the Netherlands, Great Britain, Italy, Germany and Spain) became a target markets. There can be segregated several reasons, why coal supplied from USA successfully started penetrate the EU markets. On the one hand the abundance of coal on international markets pushed down its price. Coal price became decoupled from natural gas and oil price developments. As a result competitive position of a coal-firing plant in a merit order improved. On the other hand, global economic recession impacted on a reduced volume of GHG in EU countries, resulting to surplus of emission allowances compared to actual volume of emissions. Due to this, price of emission allowances decreased. From the point of view of companies, it was economically rational to buy emission allowances and produce energy in coal-firing plants. Political decisions of the biggest economies (namely, Germany) to phase out nuclear power plants by 2022 are favorable to develop coal market too. For EU society, where unemployment rate remains high and real wages are relatively low compared to pre-crisis level, energy from coal-firing plants is also an acceptable option despite the fact that this is related to increased damage to environment, health, etc. Natural gas can be established as a second under importance fuels in EU fuel balance after coal [5]. In 2010, it made 28.9% in fuel consumption structure in EU, whereas its share was 10.7% in 1990. Consumption of natural gas had a tendency to increase by 2.2% a year during 2005–2010. This increase was caused by natural gas consumption in power generation (31.7%), households/heating (27.2%), industry (19.4%), and the service sector (10.8%). EU's decision to embark on an ambitious path towards de-carbonizing its energy system influenced on increased consumption of natural gas [5]. As well natural gas is recognized as “bridge fuel” in future, which will expedite transition of EU energy systems to a more sustainable manner and replacement of carbon heavy fuels to lighter ones. Historical data revealed that the largest share of natural gas consumption is covered by its import, whereas its production within EU declines. EU share of imports in European gas consumption has grown from about 50% (2000) to more than 60% (2010) [3]. The EU's largest external sources of natural gas are Russia (24% of total imports), Norway (19%), Algeria (9%) and Qatar (8%) [2]. Refinery gas plays an important role in energy mix of EU countries too. In 2010, 1,056,735 PJ of it was consumed in EU countries and made 4.5% of fuel structure (by 0.8 percentage points more than in 1990).

112 109 107 104 tCO2/TJ

102 99 97 94 92 89

84

AU (1) AU (2) BE BG CZ DK (3) DK (4) EE FI FR DE GR HU IE IT LV LT NL PL(a) PL(b) PL(c) PT RO ES (a) ES (c ) SE Coking coal Anthracite Bituminous…

87

Highest emission factor

Lowest emission factor

Average emission factor

Fig. 4. CO2 emission factors of hard coal applied in EU during 1990–2010. Here: (1) – for power plants and CHP; (2) – for district heating plants; (3) – public heat and electricity production; (4) – other energy industries; (a) – for energy production sector; (b) – for petroleum refining; (c) – for other energy industries; gray color shows that the same value of CO2 emission factor of hard coal was applied during 1990–2010; crossed gray color shows that CO2 emission factor of hard coal was reducing during 1990– 2010; diamond black color shows that CO2 emission factor of hard coal was increasing during 1990–2010.

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94.6 t/TJ (2005) to 97.9 t/TJ (2010), from 93.3 t/TJ (1990) to 94.2 (2010) and from 94.95 t/TJ (2005) to 94.97 t/TJ (2010), respectively. CO2 emission factors were reduced in Ireland, Italy, Poland (in other sector), Denmark, Finland and the Netherlands. Ireland reduced CO2 emission factor of hard coal by 2.1% from 94.99 t/TJ (2001) to 92.99 t/TJ (2010) and currently it is one of the lowest in EU countries after Belgium (92.7 t/TJ in 2010) and Portugal (92.0 t/TJ in 2010). Spain applied the highest CO2 emissions factors for assessment of GHG emissions in electricity and heat production industries as well manufacturing of solid fuel and other energy industries. It was set at 101 t/TJ for energy production industries, whereas it was at 112 t/TJ for manufacturing of solid fuel and other energy industries. Poland applied different time series of CO2 emission factor for various energy industries. For electricity and heat production industries it applied time varying CO2 emission factor, which was reduced from 95.25 t/TJ (1990) to 94.97 t/TJ (2010). For petroleum refining industry values of CO2 emission factors were by 0.4% lower than in electricity and heat production industries. CO2 emission factor for manufacturing of solid fuel and other energy industries was variable: 94.70 t/TJ (1990), 94.86 t/TJ (1995) and in later years CO2 emission factor was reduced from 94.54 t/TJ (2001) to 94.34 t/ TJ (2005). In 2010, 94.67 t/TJ CO2 emission factor was applied in manufacturing solid fuel and other energy industries. The comparative analysis of country-specific CO2 emission factors of hard coal revealed that CO2 emission factors in the largest EU hard coal importers (namely, Germany, Italy, the Netherlands, France, Spain and Poland) are less compatible with a default CO2 emission factor. This observation was made considering to the calculated standard deviation indicator, which is 7.03 for the largest hard coal importers and 1.60 for the remaining EU countries. Nonetheless, CO2 emission factors of hard coal is within the uncertainty ranges of a default CO2 emission factor in these countries (except in Spain and Latvia). Thus far CO2 emission factor of hard coal combusted in Spanish energy producing industries reaches the upper bounds of default CO2 emission factors of anthracite and bituminous coal, therefore GHG emissions in this sector is not overestimated. However, GHG emissions could be overestimated in Spanish other energy industries, since applied CO2 emission factor exceeds the upper bounds of all types of hard coal default values. For the estimation of GHG emissions in 1990–2000, Latvia applied CO2 emission factor which was lower than the lower bound of a default CO2 emission factor. Currently, CO2 emission factor applied in Latvia is within the uncertainty ranges of a default CO2 emission factor.

Due to EU policy directed towards reduction of GHG emissions and increase in consumption of renewable energy sources by 20% in 2020, wood and wood waste as well biogas found a sound place in EU fuel balance too. Since 1990 wood and wood waste consumption increased by 8 times and they made 4.2% in the structure of fuel consumed in 2010. Consumption of biogas increased from 14,211 PJ (1990) to 403,420 PJ (2010). In 2010, biogas made 1.7% in EU fuel consumption structure. The role of residual fuel oil reduces rapidly due to its negative impact on the environment. EU data revealed that during the last two decades residual fuel consumption reduced by 4 times till 757,480 PJ in 2010. Thus, by summarizing what was discussed it could be concluded that hard coal, lignite, natural gas and refinery gas are the most relevant fuels consumed in energy industries of EU-27. These are fossil fuels an increasing consumption of which contributes to increase in GHG emissions and cause climate change. Due to this reason it was decided to investigate CO2 emission factors of these fuels.

4. CO2 emission factors for energy industries applied in EU countries All CO2 emission factors presented are based upon net calorific values. The emission factors presented assume complete oxidation of carbon in the fuel during combustion. 4.1. CO2 emission factors of hard coal In many EU countries hard coal (anthracite, coking coal and other bituminous coal) is an indigenous fuel and one of the widest used fuels in energy industries. Chemical composition of this type of fuel is different in various countries. As a result countries apply different values of country-specific CO2 emission factor of hard coal. It is important to point out that countries rarely provide different CO2 emission factors for various types of hard coal. Instead CO2 emission factor for the category “hard coal” is set. CO2 emission factors of hard coal applied in EU countries during 1990–2010 are presented in Fig. 4. As it is seen from Fig. 4, most of the countries used the same value of CO2 emission factor of hard coal during 1990–2010. However, Greece, Ireland, Italy, Latvia, Poland, Denmark, Finland, Germany, Romania and the Netherlands applied time series of CO2 emission factors of hard coal. The peculiarity of time series of CO2 emission factors of hard coal in Latvia, Greece, Germany and Polish public heat and electricity production – they were increased from 86.87 t/TJ (2001) to 94.08 (2005), from 130 126 122

tCO2/TJ

118 114 110 106 102 98 94

Average emission factor

ES (3)

ES (2)

SI

ES (1)

SK

RO (2)

PT

RO (1)

PL (2)

NL

PL (1)

HU

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GR (1)

DE (5)

DE (6)

DE (4)

Lowest emission factor

IPCC (1996)

Highest emission factor

DE (3)

DE (2)

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DE (1)

BE

BG

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AU (1)

90

Fig. 5. CO2 emission factors of lignite applied in EU during 1990–2010. Here: gray color shows the average CO2 emission factor of lignite during 1990–2010; diamond black color shows that CO2 emission factor of lignite was increasing during 1990–2010; circle gray color shows that CO2 emission factor of lignite was reducing during 1990–2010.

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4.2. CO2 emission factors of lignite Various country-specific CO2 emission factors of lignite are applied in EU countries for the assessment of GHG emissions from energy industries. Fig. 5 presents the CO2 emission factors applied in EU countries and a default value during 1990–2010. Fig. 5 shows that EU countries mostly applied the same value of CO2 emission factor of lignite in energy industries during 1990– 2010. Greece, Hungary, Poland and Slovenia applied time serious of CO2 emission factor of lignite combusted in energy industries. It can be seen that there is no clear tendency how these CO2 emission factors developed in time. In Hungary CO2 emission factor had a tendency to increase from 108.8 t/TJ (2005) to 110.9 t/TJ (2010). Since 2001 CO2 emission factor was decreasing in Slovenia and 104.52 t/TJ CO2 emission factor was applied in 2010. Poland applied different time varying values of CO2 emission factors of lignite in different industries. Historically, Poland used fluctuating CO2 emission factor of lignite combusted in electricity and heat generating industries. However, since 2005 value of CO2 emission factor applied for assessment of GHG emissions in these industries was increasing and 108.62 t/TJ was applied in 2010. Time varying CO2 emission factor was also used in manufacture of solid fuels and other energy industries in Poland. Since 2001 emission factor was increased by 3% from 105.5 t/TJ (2001) to 108.60 t/TJ (2010). Several other countries (Austria, Greece, Spain and Germany) applied differentiated CO2 emission factors of lignite too. Austria differentiated its CO2 emission factor of lignite under 2 criteria. They are: capacity of plant and mode of energy generation. For plants, which installed capacity is less than 50 MWth it applied low CO2 emission factor (97.0 t/TJ in 2010, see AU (1) in Fig. 5), but for plants with installed capacity that exceeds 50 MWth 11–13% higher CO2 emission factors were set. For example, 108 t/TJ CO2 emission factor was applied if lignite was combusted in district heating plants (AU (2) in Fig. 5) and 110 t/TJ (AU (3) in Fig. 5) if lignite was combusted in power and CHPs plants. Spain used CO2 emission factor differentiated according to the type of lignite. For lignite briquettes it set 98 t/TJ (ES (3) in Fig. 5); for black lignite – 99.42 t/TJ (ES (1) in Fig. 5) and 100.2 t/ TJ (ES (2) in Fig. 5) for brown coal. Germany differentiated CO2 emission factor of lignite in the following way. For the combustion of raw lignite in the public sector power stations, the district-specific values for CO2 emission factors were applied. If raw lignite was combusted in power stations of Helmstedt district, then 99.0 t/TJ (DE (2)) CO2 emission factor was applied. In the case raw lignite was combusted in Mitteldeutschland district, then – 104 t/TJ (DE (1)) CO2 emission factor was applied. The highest CO2 emission factors were

609

set for raw lignite combustion in power stations in Lausitz (113 t/TJ, DE (4)) and Rheinland (114 t/TJ, DE (5)). It can be mentioned that a mixed (one) value, which covers the different relevant districts (Rheinland, Lausitz, Mitteldeutschland, Helmstedt, Hessen), was applied for raw lignite combusted in district heating stations. In 2010, 112.2 t/TJ (DE (6)) CO2 emission factor was set for lignite combusted in this type plants. Germany applied weighted (lignite production and imports were considered) CO2 emission factors of raw lignite combusted in industry, commercial/institutional sectors. They were differentiated under the criteria “old and new German Länder” and “for Germany as a whole”. For the period 1990–1994, for which separate fuel balances of the old and the new German Länder were prepared, weighted CO2 emission factors were differentiated according to “old and new German Länder” criteria. Later, one CO2 emission factor for raw lignite combusted in industry, commercial / institutional sectors was set (110 t/TJ in 2010, DE (3) in Fig. 5). In almost all countries value of CO2 emission factor was higher than the default CO2 emission factor of lignite recommended in 1996 IPCC Guidelines for National Greenhouse Gas Inventories. However, almost all country-specific CO2 emission factors of lignite fell into the uncertainty ranges of a default value, except CO2 emission factor of lignite combusted in power and CHP plants in Austria (AU (3)); in electricity production sector in Greece (GR (1)); in German commercial/institutional sector (DE (3)), power stations in Lansitz (DE (4)) and Rheinland (DE (5), as well in district heating stations (DE (6)) in Germany; Hungary and Poland. It can be observed that all countries applied higher than an upper bound CO2 emission factor of lignite. Thus, it could be argued that GHG emissions could be overestimated in these countries.

4.3. CO2 emission factor of natural gas A default value of CO2 emission factor for natural gas combusted in energy industries set in 1996 IPCC Guidelines for National Greenhouse Gas Inventories is 56.10 t/TJ, taking into account that uncertainty range is 52.17–60.03 t/TJ. CO2 emission factors of natural gas combustion in EU countries are presented in Fig. 6. It was observed that the Republic of Czech, Hungary, Portugal and Romania applied IPCC [6] default CO2 emission factors of natural gas and in other countries country-specific CO2 emission factors were set. Austria, Belgium, Bulgaria, Estonia, Finland, Germany, Greece, Italy, Latvia, Poland, Slovakia and Spain applied countries countryspecific CO2 emission factors, which were by 0.2–2.1% lower than a default CO2 emission factor. Slovenia and Finland applied the lowest CO2 emission factors of natural gas. Slovenia, where historically one–

62 60

tCO2/TJ

58 56 54 52

AU BE (1) BE (2) BG CZ DK (1) DK (2) EE FI DE GR (1) GR (2) GR (3) GR (4) HU IE IT LV LT LU NL PL PT (1) PT (2) RO (1) RO (2) SK SI ES (1) ES (2) SE IPCC (1996)

50

Highest emission factor

Lowest emission factor

Average emission factor

Fig. 6. CO2 emission factors of natural gas applied in EU during 1990–2010. Here: gray color shows the average CO2 emission factor of natural gas during 1990–2010; circle gray color shows that CO2 emission factor of natural gas was increasing during 1990–2010; diamond black color shows that CO2 emission factor of lignite was reducing during 1990–2010.

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78 74

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70 66 62 58 54

ES

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NL

IT

IE

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IPCC (1996)

Highest emission factor

FR

FI

DK

BG

BE (1)

AU

50

Fig. 7. CO2 emission factors of refinery gas applied in EU during 1990–2010. Here: gray color shows the average CO2 emission factor of refinery gas during 1990–2010; diamond black color shows that CO2 emission factor of refinery gas was increasing during 1990–2010; circle gray color shows that CO2 emission factor of refinery gas was reducing during 1990–2010.

third of natural gas was imported from Algeria, applied 55.02 t/TJ CO2 emission factor. Till 1996 country used CO2 emission factor of natural gas which was typical for a particular year. However, since 1996 it uses a unified CO2 emission factor for all the following years. The motivation for such a decision was that chemical composition of natural gas changed few, therefore there was no need to use timevarying CO2 emission factor. Several countries (Denmark, Greece, Ireland, Lithuania, Luxembourg, the Netherlands, Portugal and Sweden) applied higher than IPCC [6] default CO2 emission factors. The highest CO2 emission factor was set in Greece (58.56 t/TJ). This value was set for natural gas that was domestically produced. For imported natural gas 55.59 t/TJ CO2 emission factor was applied in Greece. CO2 emission factor of natural gas in Ireland was increasing because the contribution of imported gas, which is more carbon intensive, increased in the national energy balance. Estonia applied CO2 emission factor of natural gas the same as it was in Russia (55.30 t/TJ). Other countries, which import natural gas from Russia, used similar CO2 emission factors as it was in Russia. For example, Finland applied 55.04 t/TJ CO2 emission factor. This CO2 emission factor was derived considering to the observation of monthly data. During 2005–2010 monthly values of CO2 emission factor changed in the interval of 54.98–55.22 t/TJ. Since it was noticed that value of CO2 emission factor changed few, thus, it was decided to use a unified CO2 emission factor for the following years. Nonetheless, the results of analysis of CO2 emission factors of natural gas combusted in EU energy industries show that they all are within the uncertainty ranges of IPCC default value.

4.4. CO2 emission factor of refinery gas Refinery gas is a mixture of gases generated during refinery processes which are used to process crude oil into various petroleum products. The composition of this gas varies, depending on the composition of the crude it originates from and the processes it has been subjected to. General components include butanes, butylenes, methane, ethane and ethylene. Some products found in refinery gas are subject to controls as a result of programs which are designed to address climate change. Refinery gas can be packaged and sold as a final product on the open market, it can also be used as a fuel or be used as feedstock for other processes in the refinery. CO2 emission factors of refinery gas applied in EU countries for GHG inventories are presented in Fig. 7.

The comparison of IPCC default CO2 emission factor and emission factors provided in Fig. 7 shows that all countries set country-specific CO2 emission factor of refinery gas. Austria, Finland, Greece, Ireland and Italy used time varying CO2 emission factors. Volatility of value of CO2 emission factor in Austria was the highest. Because of changes in refinery gas composition it was increased from 51.60 t/TJ (1990) to 74.10 t/TJ (2005). In 2010, GHG emissions from refinery gas were calculated considering to 63.00 t/TJ CO2 emission factor. Finland used plant specific CO2 emission factors for assessment of GHG emissions, which values were reduced from 65.0–71.4 t/TJ (2005) to 53.0–71.4 t/TJ (2010). Greece applied time varying CO2 emission factor of refinery gas, i.e. since 2005 value was reduced by 18% till 56.65 t/TJ (2010). Reduction trend of CO2 emission factor of refinery gas is also seen in Ireland and Italy, where CO2 emission factors were reduced till 53.51 t/TJ and 57.80 t/TJ in 2010, respectively. In 2010, values of country-specific CO2 emission factor fell into the uncertainty ranges of IPCC default value in Belgium, Denmark, Finland, France, Germany, Greece, Italy, the Netherlands, Poland, Romania (RO (2)) and Spain. Meanwhile CO2 emission factors of refinery gas was lower than the lower bound of IPCC [6] default value only in Ireland in 2010. Therefore GHG emissions could be underestimated in Italy. GHG emissions could be overestimated in Austria, Bulgaria, Finland, Romania (RO (1)) and Slovakia.

5. The impact on CO2 emission estimates Performed analysis of CO2 emission factors used for reporting of national GHG inventories under the UNFCCC showed that almost all EU countries seeking to reduce uncertainty applying country-specific CO2 emission factors for a major sources of emissions from energy industries. The IPCC [6] Guidelines suggest an overall uncertainty value of 7% for the default CO2 emissions factor of energy sector. Country-specific CO2 emission factors are reported with significantly lower uncertainty value. In some cases uncertainty values are lower by 60% in comparison to the default value. Application of country-specific CO2 emission factors ensures greater accuracy and lower uncertainty of GHG inventory. The different country-specific emission factors applied in EU countries represent different carbon contents of fuels and are more appropriate for different national context. This section of the paper analyze how application of country-specific CO2 emission factors instead of IPCC default values influence CO2 emission

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611

16 14 12 10 8 6 4 2

Lignite

Hard coal

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

2000

1999

1998

1996

1995

1997

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1990-2010

Refinery gas

1994

1993

1992

-2

1991

0 1990

Overestimate (+) / underestimate (-) of CO2 emissions, %

18

Fig. 8. The impact of country-specific emission factors on CO2 emission estimates in energy industries (own work).

estimates. The aim of such analysis is to disclosure an accuracy of emission estimates between EU countries. The analysis was performed considering to fuel consumption data provided by Eurostat. Fuels consumed in energy sector and transformed in various energy industries were taken from fuel balances of EU countries during 1990–2010. For this part of analysis were considered only countries, which CO2 emission factors were identified from the National GHG Inventory Reports and were discussed in previous sections. Calculations were done taken into account the following assumption: when there were no possibilities to break down fuel consumption in accordance to the differentiation criteria of CO2 emission factor, then an average value of CO2 emission factor of fuel was taken. In all other cases total CO2 emissions from combustion of a specific fuel in a particular year in EU were calculated based on Eq. (1): CO2EU;m ¼

N X

EFCO2 ;i;N;m  Q i;N;m

ð1Þ

i¼1

Here: CO2EU – total CO2 emissions in all analyzed EU countries; m – year; EFCO2 – CO2 emission factor; Q i – fuel consumption; i – type of fuel; N – EU country. Seeking to compare CO2 emissions, two cases were analyzed. The first case it was based on IPCC default values of a particular fuel to assess CO2 emissions. In the second case CO2 emissions were calculated considering to country-specific CO2 emission factors. Conclusions about underestimates ( ) / overestimates (þ ) of CO2 emissions were drawn by calculating relative difference between CO2 emissions based on country-specific CO2 emission factors and CO2 emissions based on a IPCC default value. Results of calculations for analyzed types of fuels are provided in Fig. 8. Information provided in Fig. 8 showed that calculated and reported CO2 emissions based on a country-specific CO2 emission factor of refinery gas were higher by 5.2% than whose which were assessed based on IPCC default values during 1990–2010. CO2 emissions from combustion of lignite were higher by almost 15% during 1990–2010. CO2 emissions from combustion of natural gas were underestimated by 0.8% in comparison with IPCC default value. CO2 emissions from combustion of hard coal in energy industries were slightly underestimated, i.e. by 0.2% during 1990–2010. These differences confirm that lignite and refinery gas countryspecific CO2 emissions factors differ in the wide range from the IPCC default values. CO2 emission factor of coal vary with the carbon content which is influenced by the type of coal and the geographical location of

the mine. CO2 emission factor of refinery gas depends on the composition of this gas and it varies significantly between EU countries. Performed comparative analysis showed that country-specific CO2 emission factors applied in EU countries for the main fuels combusted in the energy industries have been established in a comparable way taking into account uncertainty ranges defined in the IPCC Guidelines. Consistent applications of country-specific emission factors ensures a fair estimate in CO2 emissions trend and provide accurate monitoring of the EU countries compliance with set targets of GHG reduction.

6. Conclusions Importance of accurate estimates of the GHG emissions is growing as a new emission reduction targets are set up and linked with existing ones. Therefore it is critical that estimates of emissions would be based on more precisely known and comparable emission factors. Comparability is an important element of quality of CO2 emission factor in order to evaluate whether the reporting of emission from energy sector is good enough to monitor progress towards the emission reduction target. Consequently in order to evaluate accuracy of country-specific CO2 emission factors applied in EU countries for GHG inventory preparation a comparative analysis of CO2 emission factors taking into account uncertainty ranges defined in the IPCC Guidelines is purposeful. The analysis of CO2 emission factors of hard coal showed that mainly country-specific CO2 emission factors are applied in EU countries. These values fell into the uncertainty ranges of default emission factors of category hard coal, except in Spain and Latvia. Almost all country-specific CO2 emission factors of lignite are within the uncertainty ranges of a default value, except CO2 emission factor of lignite combusted in Hungary and Poland, in power and CHP plants in Austria, in electricity production sector in Greece, in German commercial/institutional sector, power stations in Lansitz and Rheinland, as well in district heating stations in Germany. It can be observed that all countries applied higher than an upper bound CO2 emission factor of lignite. The performed analysis showed that the Republic of Czech, Hungary, Portugal and Romania applied IPCC [6] default CO2 emission factors of natural gas and other countries set countryspecific CO2 emission factors. Seeking to increase accuracy of reported GHG emissions it is essential to develop and apply

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country-specific emission factors in all EU countries. Currently applied country-specific CO2 emission factors of natural gas fell into the uncertainty ranges of a default value. The analysis of CO2 emission factors of refinery gas showed that EU countries set country-specific CO2 emission factor. Since chemical composition of refinery gas varies between countries, therefore time-varying values of CO2 emission factors differs significantly between countries. In 2010, values of countryspecific CO2 emission factors were within the uncertainty ranges of IPCC [6] default value in almost all analyzed countries, except in Ireland, Austria, Bulgaria, Finland, Romania and Slovakia. Performed analysis showed that country-specific CO2 emission factors applied in EU countries for the main fuels combusted in the energy industries have been established in a comparable way and provide accurate monitoring of GHG emissions for assessing the efforts to address climate change according to the quality criteria defined within UNFCCC GHG emissions reporting guidelines. Seeking to ensure more accurate estimates of CO2 emissions it is important further improve knowledge on emission factors at individual plant level, i.e. plant-specific emissions factors, that allow estimating GHG emissions with lower uncertainty by applying higher level tier methods. References [1] Birnbaum M. Europe consuming more coal. Available at 〈http://www.washing tonpost.com/world/europe-consuming-more-coal/2013/02/07/ec21026a-6b fe-11e2-bd36-c0fe61a205f6_story.html〉; 2013. [2] Eurogas. Statistical Report 2012. Brussels; 2012. [3] Eurostat. Energy production and imports. Brussels; 2012. [4] Eurostat database on fuels consumption in EU countries. Available at 〈http:// epp.eurostat.ec.europa.eu/portal/page/portal/statistics/search_database〉. [5] Goldthau A.The politics of natural gas development in the European Union. Available at 〈http://belfercenter.hks.harvard.edu/files/MO-CES-pub-GeoGa sEU-102513.pdf〉; 2013. [6] IPCC. The Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories. Available at 〈http://www.ipcc-nggip.iges.or.jp/public/gl/invs1.html〉; 1996. [7] IPCC. Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories. Available at 〈http://www.ipcc-nggip.iges.or.jp/ public/gp/english/〉; 2000.

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