Measurement Techniques, Vol. 37, No. 5, 1994

INTERNATIONAL COLLABORATION NATURAL GAS: A R A W M A T E R I A L OR AN ENERGY SOURCE? Yu. I. Aleksandrov and E. N. Korchagina

UDC 541.11:536.626

Topics are raised concerning the imperfections in the conditions of supplying and charging for natural gas in Russia, where emphasis is placed on measuring the volumes and one neglects aspects of monitoring the calorific value of the gaseous fuel. When organizations in fuel and energy supply go over to market economics, particular interest attaches to research and to the use of experience in such organizations abroad. In developed Western countries, there is only about O.1% error in determining the calorific value of natural gas, which is made up of errors in measuring the volume and combustion energy.

The basis for the present paper is the disquiet the authors experienced on considering the conditions under which natural gas is supplied and charged fir in this country. Russia is one of the largest sources of natural gas, and the guiding principle in supply is volume measurement, with the gas literally spoke of not as an energy carrier but as though it were air. Aspects of improving the combustion energy monitoring for the gaseous fuel take second place. However, that aspect of natural gas is of primary interest to all its users. Natural gas at present supplies 15 % of world energy demand. Out of the 2000 billion m3 of world production, 645 billion m 3 come from Russia, and forecasts indicate that the extraction in this country will rise to 735-750 billion m 3 by the year 2000. When fuel and power suppliers go over to market economics, particular interest attaches to research and also to using the experience of such organizations abroad and considering the role of governments in regulating the processes in power engineering [1]. Studies on the gas industry abroad show that the various stages in economic development and correspondingly the various stages in the power supply to Western countries are characterized by differing approaches to energy sources, particularly natural gas, where various uses are made of differing methods of state regulation. In the USA, there are three periods with differing state policies for power supply. The period up to 1973 was characterized by structural unbalance in fuel and power developments, with a gap between the levels of internal and world prices for energy. The period from 1973 to 1980 has a special place in power policy. In 1973, OPEC raised the price of oil by a factor four in connection with the Arab-Israeli war, which was the main reason for the reconsideration of the role of government in energy policy in several leading countries. In that period, there was direct state regulation of the oil price, with the introduction of the law adopted in 1975 on energy policy and energy economy. The Gas Policy Act was adopted in 1978, which laid the basis for a rolling 14-year monitoring system for prices (the gas price had risen by a factor six by that time) (p. 739 of [2]). The period after 1980 was characterized by a reversal of economic policy from excessive state regulation of energy to reliance on market forces. A result of this shift in the government regulation of prices for oil and natural gas was that the internal market for energy in the USA was transformed into a component part of the world capitalist market for fuel. One of the most important points in the above Gas Act was the requirement that every contract to supply gas should contain data on the exactly measured calorific value, which governs the quality. The error in determining the calorific value of natural gas was set at one British thermal unit (1 BTU), which meant that the error in determining the heat of combustion should be 0.1%. The specifications for determining the amount of gas were set at the same level. The charge for natural gas is thus based on two parameters: 1) the amount of gas supplied, which is defined by the volume V, and 2) the quality of the gas, which is defined by its calorific value Q. This is correct because the total energy content of the natural gas H is Translated from Izmeritel'naya Tekhnika, No. 5, pp. 66-68, May, 1994.

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0543-1972/94/3705-0590512.50 9

Plenum Publishing Corporation

H--VO., J.

This formula is the basis for thermal calculations on natural gas used in Germany and many other countries [3, 4]. The high level of the specifications for measuring the energy content is due to the enormous losses that would be borne by gas suppliers and users if there were inaccurate charging for the amount and quality of natural gas. For example, the data show that the extraction of natural gas in 1984 in the USA was 18 quadrillion British thermal units, which in terms of the prices in that year was equivalent to 83 billion dollars. An error in determining the energy content at the level of 0.1% implies a loss of 83 million dollars (p. 739 of [2]). Similar loss calculations have been performed in the countries of the European Union [5]. For example, on the 1993 data, the cost of the natural gas in the annual turnover in Union countries in the 1990s was estimated as 40 billion ECU. In contrasts operative in the Union, a discrepancy of 0.1% is usually permitted in the values of the calorific value between supplier and user, which nevertheless is accompanied by a loss of 40 million ECU per annum. Publications show that 0.1% error in measuring calorific value for natural gas defines the present level of world specifications in this area. The ISO working commission (ISO/TC 193/SC- 1) has been concerned amongst other matters with defining the norms (specifications) for measuring the energy content of flowing natural gas on gas transmission through national borders, and it bases its work on this level of specification for the error in measuring the calorific value [6]. On the whole, over the period 1976-1986, the average price for gas in the USA rose by a factor 12 (p. 135 of [7]). High natural gas prices will persist in the future, and the forecast is for a rise from 2.1-2.9 dollars/GJ in 1982 to 3.1 dollars/GJ in 1995, so the gas industry is under ongoing pressure to raise the accuracy in measuring gas quality and quantity (p 703 of [2]). Data from Pacific Gas and Electric PGE, which operates with volumes of natural gas of 24.3 billion m 3 a year, indicate that the amount of gas unaccounted for in 1987 was 3.77 million m 3, i.e., 1.61% [8]. Of this, losses due solely to imperfect flow-rate measurement constituted 237-8 million m 3 (1.01%), while escapes and leaks constituted only 31.5 million m 3, i.e., 0.13%. We now consider natural gas as an energy source and the tight specifications that have been put forward for accuracy in measuring the parameters determining the amount and quality of the gas, which have led to radical changes in the measurement and metrological principles used in the gas industry. Firstly, there has been complete abandonment of the gas calorimeters formerly employed there, whose error in the mid-70s was 1.5-2%, which exceeds the new specifications (0.1%) by more than an order of magnitude, and they have been replaced by gas chromatographs. This due to the advances in gas chromatography as a method of determining calorific value. This involved a simultaneous transfer from direct calorimetric measurement of the heat of combustion to calculations based on composition analysis. At present, the corresponding standardization documents of national type [9] and international ones [10] have been fully developed, although work on upgrading them will be continued. On the other hand, direct calorimetry remains the basic method of determining the calorific value for users and particularly for power engineers. However, here again the approach to natural gas as an energy source has not remained without consequences. The outdated less accurate calorimeters (of Rainike, Juncalor, and Junkers types) have been replaced. The main gas calorimeter now used is the upgraded C a t l e r - H a m m e r one, whose error of measurement for the combustion energy of natural gas is not more than 0.5 %. Recently, there have been papers on new instruments of either measuring the energy flux from natural gas directly or the energy of combustion with an error of not more than 0,3% (p. 123 of [7], p. 12 of [2], and [11]). An important if not decisive link in providing the necessary accuracy in measuring combustion energy is the provision of metrological facilities with elevated accuracy together with systems for unifying measurements (traceability) as regards the calorific value and the concentrations of the components. Recent experience has shown that a decisive conditions for resolving disagreements between suppliers and users on account of discrepancies in the calorific value is provided by a link to national standards (p. 55 of [7]) when one side uses a method of measurement differing from that used by the other. The main method of determining calorific value in gas corporations is calculation, while users mainly employ direct calorimetric methods, which is due to the specific features of supporting reliable measurements for the combustion energy. A reflection of this is seen in the production of standard specimens, which are artificial mixtures approximating in composition to natural gas and certified with 0.1% error not only for component concentrations but also for calorific value. The American Gas Association was the initiator of programs for setting up the necessary metrological basis in the USA; it was the source of the first program and all subsequent ones. The same may be said of the gas associations in other countries. At

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present, in the USA alone., there are over 4000 cylinders in circulation containing gas mixtures certified at the Gas Technology Institute in Chicago, which is the principal organization for checking gas calorimeters and gas chromatographs used to determine natural-gas calorific value (p. 703 of [2]). The Standard Specimens Bureau (BCR) of the European Union is an important coordinating body in Europe. Against this background of major changes in evaluating natural gas quantity and quality in developed Western countries, Russia, which at present supplies gas in cubic meters, appears as an under-developed country that heedlessly and carelessly consumes its riches. This was economically justified when 1000 m 3 of natural gas cost from 15 to 30 rubles (1990), while the price of Dutch gas in Europe was 60-70 dollars for the same 1000 m 3. However, with the onset of transfer to market economics, the behavior of prices for natural gas in Russia showed substantial changes, with large rises, which attained 11,000 rubles or 11 dollars per 1000 m 3 in September 1993. As that price is till well below the world level (60 dollars per 1000 m3), it is clear that the analogy with the second stage in the USA means that the difference will be reduced to zero in power engineering in the next year o r two. This is also indicated by the intention of the government to raise the prices for oil and gas to world levels in the near future. It is clear that our country is entering a period in which natural gas is evaluated as an energy source, with all its consequences, which particularly considerably tightening in the measurement accuracy specifications for the amount and quality of gas. Are the Russian fuel and power industries ready to meet these requirements? One can say quite definitely that they are not. The basis is that the metrological level of the measuring instruments now used to determine gas amount and quality are inadequate, as are the standardization documents dealing with the requirements for the measurement errors. It is not our purpose here to analyze the metrological features of measurement facilities used to determine the amount of natural gas, but it is clear that there is an essential relationship between the specifications for the errors in measuring volume and calorific value when one determines energy flows for natural gas. Such a relationship exists in the evaluation of natural gas as an energy source, but when one considers it as a raw material, which is evaluated by volume, there is no such relationship. That situation can be demonstrated from the corresponding Russian documentation. Also, in the basic GOST 554287, there are no specifications for errors of measurement for the calorific value of natural gas [12]. The possible error in measuring the calorific value can be estimated only indirectly, and that only very roughly from the documentation on the methods of measurement [13-15]. One determines the calorific value with a gas calorimeter (usually either the completely outdated Junkers calorimeters long withdrawn from manufacture or the somewhat better Juncalor calorimeters, but which have also been withdrawn), which is done in accordance with GOST 27193-86 and is accompanied by an error of + 1% (permissible deviation of three parallel determinations form the mean). To calculate the calorific value in accordance with GOST 22667-87 [15], one is not given the possible systematic errors, although they are more than likely, while the random errors are entirely governed by the error in the chromatographic analysis (GOST 23781-87). The permissible deviations between two determinations are laid down by that standard at the + 1% level. We can use another approach to estimate that error. In contracts for supplying natural gas, there is an indirect statement of the need to measure the calorific value. However, the error is not laid down in explicit form and can be identified only from an analysis of the pricing. Annual option prices for industry are established for calculating combustion energy (base value Q) of 33,080 _ 420 ld/m 3. In the actual calorific value deviates from the base one by more than 420 Kj/m 3, a conversion is performed by the supplier and user on the basis of: PQ,I, P.,I.= 33080 ' in which P~ is the actual price for the gas, P the price in the price list, and Q~the actual calorific value in ld/m 3. The maximum permissible error is thus +420 kJ/m 3, which corresponds to + 1.3%. The two approaches thus give essentially coincident estimates of 1-1.3%. What are the losses of the gas-extraction and gas-using organizations at that level of accuracy in measuring the calorific value with the current price (11,000 rubles for 1000 m3)? The production volume is 645 billion m 3 and the total cost of the gas at the prices in September 1993 was 7.095 trillion rubles, while when the world price level is attained, the cost will rise by at least a factor five and constitute not less than 35 trillion roubles. This means that with a measurement error of 1%, the annual losses will be 70 billion rubles (70 million dollars), which in the next year or two will rise to 350 billion roubles. Is Russia rich enough not to notice such losses? 592

It is now economically inevitable that we transfer to evaluating natural gas as an energy source and tighten considerably the specifications for accuracy in measuring gas amount and quality. The Russian fuel and power industries are not ready to transfer to contemporary world requirements on accounting for the amount and quality of natural gas. Metrological support is decisive here, in order for us to meet that level of requirements, so one naturally raises the question as to whether Russian metrology is ready to transfer to evaluating natural gas. Until very recently, that area of measurement, at least as regards the measurement of calorific value, was not the subject of detailed attention from metrologists. One reason appears to be that there was a raw-material approach to natural gas from the extraction industry and from users. It is clear that everybody was satisfied with the level of accuracy in measuring the calorific value that we have, although in fact it is below the world level by an order of magnitude. Only this can explain why there was no action to improve the metrological facilities such as was undertaken by the American Gas Association, and none is still being taken. Under these conditions, it is not surprising that the two methods of determining calorific value have developed independently. This is bound to be reflected in the metrological support to calorific-value measurements on gas fuel. In the present test scheme (GOST 8.026-79), there is no provision for comparing the results from the two methods. In the draft for the new test scheme, that deficiency has been eliminated. Also, to eliminate disagreements between natural-gas users and suppliers due to differences in their methods, the Mendeleev All-Union Metrology Research Institute has developed M12262-93 [16]. The expert checking is based on a special metrological facility in the form of cylinders containing natural gas certified for calorific value by direct calorimetry with an error of 0.3 %. Although that accuracy level at present meets the requirements, it is inferior to the world level by a factor three. Therefore, to provide future development in metrological support, one must take prompt action to set up a special primary standard in the area of gas calorimetry together with substandard metrological facilities for measuring natural-gas calorific value at the world level. It is inevitable to make the transition from evaluating natural gas as a raw material to a major energy source. As was done in the developed countries in the 1970s, in the near future we will have to devise a suitable policy for the gas industry. Essential elements will be to organize exact charging for natural gas energy flows based on exact measurements of gas amount and quality, which include the following: 1) investment in the design and routine production of the latest automated gas calorimeters and gas chromatographs to meet the specifications for measuring calorific value; 2) ongoing development of means for metrological support to the exact measurement of natural-gas amount and quality at all stages in extraction, transportation, and distribution; 3) development of standardization documentation laying down contemporary world specifications for errors of measurement for calorific value and amount of natural gas, with the specifications consistent one with another and with the specifications for error in determining the total energy content, which is dictated by trends in pricing policy; and 4) the need for measuring calorific value with the established accuracy by the supplier and the user, which is recorded as an essential condition in contracts for supply. As the entire economic mechanism in Russia is being reformed, it is a particularly favorable time for incorporating world experience and making major changes in the gas industry policy. Each year lost involves enormous irrecoverable losses.

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E. R. Govsievich and A. A. Chepenko, I~lektriecheskie Stantsii, No. 5, 5 (1993). Gas Quality, G. I. Rossum (ed.), Proc. Cong. Gas Quality Specification and Measurement of Physical Properties of Natural Gas, Groningen, 22-26 April, 1986. Elsevier, Amsterdam (1986). Arbeitsblatt G-685: Technische Regeln: Durchfuhrung der thermischen Abrechnung yon Gasmengen. DUGW Regelwerk. H. Dienelt, Gwf - Gas/Erdgas, 122, No. 1, 20 (1981). Determination of the Gross Calorific Value of Natural Gas. Results of a BCR Intercomparison, Report EUR 14439/EN, Commission on the European Communities, Brussels (1993). Bundesanstalt fur Materialforschung un Prfifung (BAM), Jahnresbericht (1991), p. 101. Natural Gas Energy Measurement, edited by A. Attary and D. L. Klass (eds.), Elsevier Applied Science Publishers, Institute of Gas Tectmology, London (1987), No. 8, 18 (1991). D. Greenstead and R. Cowhill, Neft', Gaz i Neftekhimiya za Rubzhom, No. 8, 18 (1991).

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Index of Russian Standardization Documents and International and Foreign Standards: Liquid and Gaseous Fuel [in Russian], Gosstandart, VNIIKI, Moscow (1984), Issue 5. ISO 6976-89: Natural Gas: Calculation of Calorific Value, Density and Relative Density. L. Howard, Neft', Gaz Neftekhimiya Rubezhom, No. 12, 62 (1988). All-Union State Standard 5542-87; Natural Combustible Gases for Industrial and Domestic Use: Technical Specifications [in Russian]. All-Union State Standard 27193-86: Natural Combustible Gases: Method of Determining Heat of Combustion with a Water Calorimeter [in Russian]. All-Union State Standard 10062-75: Natural Combustible Gases: Method of Determining Specific Heat of Combustion [in Russian]. All-Union State Standard 22667-87: Natural Combustible Gases: Calculation Method of Determining Heat of Combustion, Relative Density, and Wobbe Number [in Russian]. MI 2262-93: The State System of Measurements: Measurement of Natural-Gas Combustion Energy: Sequence for Matching Measurement Results from Combustion Calorimeters and Gas Chromatographs [in Russian].