Innovated Model REPAS for Calculation of CO 2 Emission from Passenger Cars in Developing Ccountries

Transcription

1 EnviroInfo 2007 (Warschau) Environmental Informatics and Systems Research Innovated Model REPAS for Calculation of CO 2 Emission from Passenger Cars in Developing Ccountries Radoje Vujadinovi 1, Danilo Nikoli 1 Abstract Motor vehicles, as fossil fuels consumers, contribute in a large scale to emission of carbon dioxide, CO 2. It is very important to quantify the volume of the gas emitted into the atmosphere. This paper introduces innovative model REPAS for calculation of CO 2 emission from passenger cars, taking into account certain specific features not included by other models, proper to transition countries. Based on this model, software REPAS 1.1 was developed, for calculation of total emission of CO 2 as well as specific emission of CO 2, involving data for fuel use according to manufacturer declaration for 1620 vehicle types by various manufacturers. In the paper model REPAS was implemented on passenger car fleet in the Republic of Montenegro. The results of applying the model have been compared to those obtained through the application of the models COPERT III and REMODIO, revealing considerable aberrations. Very important segment in the area of modelling of CO 2 emission represents the prediction of emission parameters for the certain period in the future. The conception of REPAS model enables, not only the calculation of emitted quantity of CO 2, and specific CO 2 emission, but also the prediction of these parameters in the future as well. This is to be achieved through prediction of the trend of change of individual parameters used in the model REPAS. Wording below presents the prediction of CO 2 emission for Montenegro by the year Two scenarios are presented, named optimistic (OPTIMIST) and pessimistic (PESSIMIST). 1. Introduction Although carbon dioxide emitted by motor vehicles is not a noxious compound it is undesirable as it contributes to the global warming. However, this gas provides life, because without it a temperature would tend to be at least for 30 C lower from today's level. Until industrial revolution, some 150 years ago, greenhouse effect was only natural phenomenon. From that time, as a result of large industry growth, emission of greenhouse gasses arose significantly due to fossil fuel combustion, which has increased greenhouse effect and as a consequence mean temperature on the Earth, which has already made many anomalies in climate. Motor vehicles are significant contributors to the greenhouse effect. This fact makes very important calculations of CO 2 emission from this source. The aim of this paper was to make quantitative analysis of CO 2 emission from passenger cars on selected geographic area. For this purpose, an innovative model REPAS was developed. A number of computer based models are available for the prediction of vehicle air pollution particularly in the public domain. For example COPERT III is accepted from all EU members and recommended to candidate members. Among other things, the software determines average annual emission of greenhouse gasses from motor vehicles in selected countries. However, each geographical area has a number of specific features regarding the traffic of motor vehicles, as well as a number of factors impacting CO 2 emission which have been taken into account only partially and in general terms. That is why the authors decided to elaborate the REPAS model, taking into account specific features proper to transition countries with older vehicles fleet. Based on several years of experimental research of motor vehicles in use (5249 tested vehicles), it was concluded that the values indicated by manufacturers, when it comes to exhaust emission pa- 1 University of Montenegro, Faculty of Mechanical Engineering, Cetinjski put bb, Podgorica, Montenegro radojev@cg.yu, internet: 229

2 rameters, after several years of unfavourable exploitation conditions, become considerably degraded. The degradation moves towards increased concentration of noxious CO combustion products (around 70%), and decreased concentration of CO 2 (by around 20%) [6]. In other words, carbon from fuel turns considerably to CO and HC, instead of its complete transformation into CO 2. This reduced concentration of CO 2 has been considerable during measurements, which is why the authors have built the results of the research into the model, which has not been the case in other models so far. 2. Model REPAS Model REPAS envisages reduction of the emitted CO 2 volume due to incomplete combustion, inefficiency of the system for the after-treatment of exhaust gases and a number of other parameters causing reduction. Totally emitted CO 2 per one year (ECO 2 ) from passenger cars in model REPAS is determined with the next equation: E CO2 N l i = i r j K n m tons g ECE g K z K j ECE ns i i i i= 1 j= 1 year where are: i number of vehicle categories (i=1,, 32). N i number of registered vehicles in the observed category i [vehicles/year], l i average annual mileage of category i [km/vehicle, year], j number of types per category i (j=1,,m). g ECEj manufacturer ECE test specific fuel consumption of PC model "j" of category i [l fuel/100 km], r j share of type j in category i, Kg ECEi worsening degree of the manufacturer-indicated fuel consumption of vehicle category i, Kz i emission factor of vehicle category i [kg CO 2 /liters of fuel], Kns i incomplete combustion coefficient of vehicles category i. All parameters featuring in equation (2.1), have the author s recommendation for setting and adoption. Thus, the number of categories (i) into which total number of registered vehicles is distributed is defined according to the type of used fuel (gasoline, diesel), as well according to legal regulations referring to exhaust emission-for corresponding categories of the engine volume. The number of the registered vehicles per individual categories (N i ) can be determined from the database of the Ministry of Interior Affairs. Average annual mileage of a vehicle from category (l i ) is established on the basis of servicing records or software, based on service intervals and the mileage, revealing mileage on the annual basis. An extremely important property of the model REPAS is the manner of defining of an average specific fuel consumption by a vehicle from the specific category. The model envisages a detailed analysis of the vehicle fleet structure of the country for which the calculation is being made. For the purpose of a detailed calculation of this important property, software REPAS 1.1 has been elaborated, including manufacturerindicated fuel consumption for 1620 types of vehicles, proper to the territory of Montenegro. By inputting the number of vehicles of individual represented type into the software multiplying their declared fuel consumption (g ECE ) j with their share in the observed category (r j ), one comes up with the total average fuel consumption of the vehicles from the observed category. Coefficient of increasing manufacturer-indicated value of fuel consumption (Kg ECE ) is set on the basis of driver s poll by investigation of real specific consumption in a given area, taking into account as many (2.1) 230

3 relevant parameters leading to the increase of manufacturer-indicated specific fuel consumption as possible. Emission factor of CO 2, i.e. factor of forming CO 2 in the engine of passenger cars (tested e.g. after combined cycle) (K z ) is, according to definition, the ratio between specific emission of CO 2 e CO2 [gco 2 /km] and specific fuel consumption G [l/100 km]: eco K z = G 2 kgco lgor (2.2) Recently, car manufacturers have started to publish within technical properties of the vehicle (engine) values for specific emission of CO 2. Coefficient of incomplete combustion (K ns ) is determined experimentally and later has been quantified aberration of real value of CO 2 concentration in exhaust emission from theoretical value (manufacturer test data for manufacturer test data concentration). This aberration is usually manifested as reduction of CO 2 concentration in exhaust gases, resulting from incomplete combustion, deficiencies in the operation of the exhaust gases after-treatment system, and increased concentration of carbon monoxide and unburned hydrocarbons. This coefficient is determined by the following equation: m CO CO K = + F ns (2.3) j= CO 1 2F j where are: CO 2 - measured concentration of carbon dioxide in the exhaust gases of motor vehicles from the observed category CO 2F - manufacturer test data for the concentration of carbon dioxide in the exhaust gases of motor vehicles for individual models Thus, engine operating in the area of rich mixture creates high concentration of incomplete combustion products such as CO and HC, and low concentration of CO 2. This fact directly impacts the final outcome of the totally emitted volume of CO 2 in the observed area, which is why it is necessary to take it into account while calculating by correction coefficient K ns. The value of the coefficient ranges within the interval from 0,65 to around 1, with lower values corresponding to older vehicle categories. Taking this into account, the application of the coefficient is particularly stressed in the areas with older vehicle fleet, lower fuel and maintenance quality, caused by lower living standard of the population. Unlike the model COPERT III, capable of precisely determining only the output parameters, the concept of model REPAS offers the possibility of prediction of carbon dioxide emission parameters for a future, based on prediction of trend of changing the value of individual parameters, encompassed by the model. 3. Application of model REPAS Application of model REPAS on the vehicle fleet in Montenegro constituted an ideal opportunity to test the model, because in its elaboration an attempt was made to encompass as much as possible local exploitation conditions proper to the area. Properties of the vehicle fleet and road traffic in Montenegro are as follows: high average age of the vehicles, considerable percentage of vehicles with conventional systems for engine fuel supply, irregular and unprofessional servicing outdated legal regulations in the area of exhaust emission control, untested quality of fuels and lubricants, irregular oil fill intervals, aggressive driving technique, undeveloped traf- 231

4 fic infrastructure, unfavorable terrain configuration (for driving), inadequate signalization (traffic lights), as well as a number of other facts bearing a negative impact on fuel consumption and emission parameters. All the above parameters lead to aberrations of theoretical values of consumption and theoretical values of CO 2 concentration, and hence also totally emitted volume. It is interesting that, on the one hand, there is an increase of emitted CO 2 volume due to increased consumption with regard to manufacturer test data values, whereas on the other, there is a reduction of CO 2 volume due to incomplete combustion, malfunction in the operation of the exhaust gases after-treatment system, etc. This has been substantiated by a number of individual results of passenger car exhaust emission measurements on the field. Since the model has been defined in some detail in the previous chapter, here we shall list only the main segments and the final results of applying the model on passenger cars registered in Montenegro. For the model, a software application REPAS 1.1 has been elaborated, whose final form encompasses 32 vehicle categories with the 1620 vehicle types with manufacturer test data on fuel consumption. After inputting data on the number of vehicles per individual categories, the software calculates average fuel consumption for the vehicle categories. To the set categories after were added corresponding lengths of the average annual mileage covered. The number of registered vehicles in Montenegro on 31/12/2003 was supplied by the Ministry of Interior Affairs of the Government of Montenegro. Average annual mileage covered by the vehicles was determined based on the data from service software in the licensed services of the following manufacturers: Volkswagen, Audi, Renault, Peugeot, Seat, Skoda and Kia. The software, apart from data on servicing interventions, also include the daily mileage covered, offering the possibility of calculating the annual vehicle mileage covered. Coefficient of increasing manufacturer test data on fuel consumption (KgECE) has been set based on several years of investigation of real specific consumption and polling drivers, while the correction coefficient of the emitted CO 2 volume was, due to a number of previously described factors (Kns), obtained on the basis of results of individual measurements of exhaust emission of 5249 passenger cars, which makes about 5% of all registered vehicles in Montenegro. According to the input data, software REPAS 1.1 calculates the emitted volume of CO 2 from passenger cars registered in Montenegro in Comparative analysis of the results upon application of three models REMODIO - COPERT III - REPAS After the presentation of calculation according to the prescribed procedure of model REPAS, provided shall be only the results of applying by models REMODIO, COPERT III for comparative analysis. The results obtained through the application of all three models are, for better comparison, provided in Table1. Table 1: Presentation of results of applying three models on calculations of emitted volume of CO 2 Gasoline consumption [t] Diesel fuel consumption [t] Total fuel consumption [t] ECO 2 [t] eco 2 [g/km] REMODIO ,3 COPERT III ,3 REPAS Regarding fuel consumption, good match was obtained between the results of models REMODIO and REPAS. Data on fuel consumption are about 6% lower than those obtained from Jugopetrol, company 232

5 which in 2003 supplied nearly 100% of all fuel in the market. Aberration of 6% is quite realistic and may be justified by increased consumption in the tourist (summer) season. A considerable higher aberration was obtained through the application of software COPERT III: over 25%. This is justified by the fact that software COPERT III, based on entered number of vehicles produced in one of the categories, assumes that all vehicles from that age category were meeting then valid emission standard, i.e. based on the year of production without going into the structure of the registered vehicles manufacturer. A more detailed analysis of the vehicle fleet in Montenegro has revealed a large number of vehicles by eastern manufacturers (Lada, Zastava, etc). Their share and manufacturers test data on fuel consumption have, by applying model REPAS, resulted in obtaining an approximately realistic consumption matching statistical data. The model COPERT III has provided a much lower calculated volume of (leaded) fuel consumption, the said fuel being already phased out from the European Union. In Montenegro, there is a large number of such vehicles, which were confirmed by applying models REMODIO and REPAS, involving a more detailed analysis of the vehicle fleet structure. The results of calculating totally emitted volume of CO 2 obtained by applying the model REPAS show the lowest values. The results obtained by model COPERT III are about for 10% higher, and those obtained by model REMODIO as high as 28%, which is certainly a considerable aberration. The testing of exhaust gases ECO TEST performed in Croatia has show that in 2003 there were 30% of improperly operating catalyzed vehicles, and around 63% unanalyzed ones. If we take into account that Croatia has nearly the same average age of vehicle fleet as Montenegro, this fact substantiates the application of model REPAS. Thus, as it takes into account the most specific character of the observed area, one may consider this value to be the closest to the real one. This makes the model in question suitable for use in all transition countries, with a similar vehicle fleet and exploitation conditions. Particularly, it is significant to clear out the issue of lower CO 2 emission from vehicles in such countries. From the aspect of causing greenhouse effect, reduction of total CO 2 emission may be considered as a positive phenomenon, but much hazardous for both human health and nature is the increase of the emission of incomplete combustion products (CO, HC, soot, NOx, ). Bearing all this in mind, the optimal direction of reducing both total and specific CO 2 emission is considered to be reduction of the specific fuel consumption Prediction of CO 2 emission from passenger cars in Republic of Montenegro using model REPAS Very important segment in the area of modeling of CO 2 emission represents the prediction of emission parameters for the certain period in the future. The conception of REPAS model enables, not only the calculation of emitted quantity of CO 2, and specific CO 2 emission, but also the prediction of these parameters in future as well. This is to be achieved through prediction of the trend of change of individual parameters used in the model REPAS. Especially important parameter is the fuel consumption i.e. its prediction of the values thereof, since the limited quantities of the fossil fuel on the planet Earth make the problem of global energy efficiency actual. Prediction results serve to regulation bodies to adopt appropriate legal provisions and measures so that the CO 2 emission would be kept under control and ease the consequences of excessive emission. WORDING BELOW PRESENTS THE PREDICTION OF CO 2 EMISSION FOR MONTENEGRO BY THE YEAR 2020 UNDER THE REPAS MODEL. TWO SCENARIOS ARE PRESENTED, NAMED OPTIMISTIC (OPTIMIST) AND PESSIMISTIC (PESSIMIST). THE INITIAL YEAR IS 2003 FOR WHICH WAS PREVIOUSLY PERFORMED THE DETAIL CALCULATION OF CO 2 EMISSION. 233

6 Scenario OPTIMIST According to this scenario, the favorable movement of happenings is foreseen which will, despite the increased number of cars, cause the reduction of both the total and specific CO 2 emission. The first thing foreseen by this scenario is the considerable increase of the number of cars (for about 3.8 times) as a result of increase of living standards of the population i.e. the increase in the motorization degree up to the level achieved in the developed countries in Europe. At the same time, it is foreseen the greater number of new cars to have the diesel engine, which are energetically more efficient, and because of the better fuel economy, they bring reduction of specific CO 2 emission. It is foreseen to change the structure of vehicle so much that, up to 2020, in accordance with predictions of the Institute Ricardo, there will be equal number of vehicles with diesel and gasoline engines. This ratio for the year 2003 in Montenegro was 68:32 in favor to vehicles having gasoline engines. In the year 2004, as a result of liberalization of import of used vehicles, an increase of the number of vehicles with diesel engines for about 20 % was noted comparing with the previous year, and vehicles with gasoline engines for about 10 %. In the year 2005, it is expected that the increase will be of 15 % for diesel engine vehicles and 10 % for the vehicles having the gasoline engine. From the year, 2006 to 2016 it is expected increase of 10 % for diesel and of 5 % for gasoline. After the year 2015, when it is expected Montenegro to enter the European Union, it is predicted that the given percentage will be enlarging for 5 % each year. Regarding the mileage, it envisages that trough the introduction of set of measures, the average annual mileage increase will be very small. The predicted degree of increase is 1 % until the year From 2010 to 2015 it is predicted that the given percentage will be enlarged for 0,5 % each year. After the year 2015 it is envisaged that the measures for reduction CO 2 emission shall be represented in such amount that the annual mileage shall be kept constant. Previously stated assumptions understand the permanent replacement of old vehicles by new, more efficient, ones. This will result in continuing reduction in average annual fuel consumption from 1 % to 2 %, which will be especially expressed after the year 2015, so that the noted reduction for the year 2020 is 3 % in relation to the initial year. The coefficient Kg ECE which is used to enlarge the manufacturer declared values of fuel consumption is foreseen to decrease annually for 0,5 % as a result of the renewal of passenger car fleet, improved quality of maintenance, more qualitative fuel usage, more developed infrastructure and all other parameters. Index 100 = 2003 KNr_b KNr_d Klr Kglr KECO2 KeCO Year Figure 1: Overview of relevant parameters of CO 2 exhaust emission for Montenegro according scenario OPTIMIST 234

7 The coefficient Kns, that takes into account the irregularities regarding the combustion process, out of order of the after-treatment system and similarly, increases for 0,01 annually, along with suppression of the causes for appearance of the events that quantify this coefficient, so it is predicted that this coefficient reaches value of 0,95 in the year These effects have led to the moderate increase of total emitted CO 2 quantity regardless the enormous number of cars. As a result of decrease of average consumptions, the specific emission of CO 2 (eco 2 ) will be reduced as well. All coefficients are brought to initial year Figure 1 clearly shows that in spite of extremely high expressed increase in the number of vehicles, especially those having the diesel engine (for about 6.2 times), the total emitted quantity of CO 2 increased only for about 3.5 times. This moderate increase of total emitted quantity of CO 2 is a result of smaller increase of the annual mileage, which has not changed over the period due to the measures taken for the past years of the observed period, as well as lowering down the average manufacturers declared consumption (for 31 %). As a result of change with other parameters it is obtained that the specific CO 2 emission will be reduced for 24 % Scenario PESSIMIST Another event development, related to the area of CO 2 emission, predicts unfavorable values of the CO 2 emission, represents the second scenario called PESSIMIST (because of the character of prediction). This scenario predicts substantially smaller increase of the number of vehicles (about 2.2 times) in relation to the previous scenario; predicted annual increase of 8 % for diesel engine vehicles and 4 % for the gasoline engine vehicles. Smaller increase of motorization rate is foreseen as a result of insufficiently fast economic recovery and non-satisfactory living standard of citizens. The average annual mileage shall be greater each year since there shall not be measures introduced that would reduce the necessity of citizens of Montenegro to use this kind of transport, as well as a series of other measures previously described. Foreseen rate of increase of the average annual mileage is 2.5 % by the year From 2010 to 2015 this rate is 2 % and by the year 2020 it will be Since the replacement of old cars by new ones will not be performed in the sufficient extent, neither average manufacturers declared fuel consumptions shall be reduced at the rate like in the previous scenario. 500 KNr_b KNr_d Klr Kglr KECO2 KeCO Index 100= Year Figure 2: Overview of relevant parameters of CO 2 exhaust emission for Montenegro according scenario PESIMIST 235

8 All of these will result in the larger increase of the total emitted CO 2 quantity and higher specific CO 2 emission in relation to the scenario OPTIMIST. Figure 2 show that this scenario forecasts the increase of number of vehicles with diesel engine for about 4.4 times, while the mileage rise of about 41 %. There was obtained the total reduction of the average fuel consumption for about 21 %. This is a result of reduction of 1 % by 2010, then 1.5 % by 2015 and 2 % by the year As a result, there was obtained an increase of total emitted quantity of CO 2 for about 3.7 times, and the reduction of the specific CO 2 emission for only 17 %. Observing non-corrected values of CO 2 emission, there was obtained an increase of the total emitted CO 2 for only 3.2 times (E(CO 2 ) bk ), while specific emission of CO 2 (e(co 2 ) bk ) decreased for 27 % Prediction scenarios comparison For better comparison of two scenarios stated, the basic parameters of CO 2 emission are shown in the Figure KECO2_OPT KeCO2_OPT KECO2_PES KeCO2_PES Index 100= Year Figure 3: Overview of relevant parameters of CO 2 exhaust emission according described scenarios As presented in the Figure 3 a great difference in the forecasting values is obtained according to these scenarios. This is of a greater importance when emphasize that according to the scenario OPTIMIST the forecasted percentage on the increased number of vehicles is higher for about 23 % than by the other scenario, and still obtained values are smaller of both total emitted CO 2 quantity (for 17 %) and specific CO 2 emission (for 7 %). Prediction scenario PESSIMIST obtained an average specific fuel consumption for 10 % greater in relation to the scenario optimist, which from the point of energy efficiency aspect would have large negative effect. 4. Conclusions 1. Road transport is a sector, due to its huge role in emission of greenhouse gasses of over 20%, which requires special attention within the program of reduction of the exhaust emission. 236

9 2. In the system of monitoring of atmospheric emission and concentration of the carbon dioxide, extremely significant is the segment referring to the application of an adequate model quantifying the emission of the CO Experimentally, on a large sample, proven and presented through model REPAS was the anomaly of reducing the concentration of carbon dioxide in the exhaust gases of motor vehicles in use, as a result of deteriorated combustion process, deficiencies of the system for the after-treatment of exhaust gases, as well as a number of other factors mentioned in the paper. This results in a considerable reduction of the totally emitted carbon dioxide volume. Model COPERT III has provided about 10% higher emission of carbon dioxide, while model REMODIO came up with about 28% higher value. 4. The concept of the REPAS model offers possibilities of prediction of carbon dioxide, CO 2, emission parameters for the future time period on the basis of prediction of the trend of changing values of individual parameters encompassed by the model itself. It is especially important the possibility of the prediction of specific fuel consumption as a parameter of special importance because of the more and more actual theme regarding energetic efficiency and the presence of fossil fuel on the Earth in the limited quantities. Bibliography Vujadinovic, R. (2005): Modelling of CO 2 emission from passenger cars, Doctor Dissertation, University of Belgrade, Faculty of Mechanical engineering, Serbia and Montenegro Kouridis, C., Ntziachristos, L., Samaras, Z. (2000): Technical report No 50: COPERT III-Computer programme to calculate emissions from road transport; User manual (Version 2.1) November 2000 Nikolic, B., Vujadinovic, R., Nikolic, D., Pajkovic, V., Simovic, S. (2001): Exhaust emission analysis from in-use vehicles in Republic of Montenegro, Power Source and Transfer (IPS) Conference, Becici, Serbia and Montenegro. Nikoli, B., Nikoli, D., Vujadinovi, R. (2002): Exhaust emission from vehicles in Montenegro, FISITA 2002, Helsinki Vujadinovi, R. (2003): State of exhaust emission from in-use vehicles, Master degree thesis, University of Belgrade, Faculty of Mechanical engineering, Serbia and Montenegro Vujadinovic, R., Nikolic, D., Nikolic, B. (2005): Exhaust emission from in use vehicles equipped with gasoline engines, Clean Air Conference, Lisbon, Portugal