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Chapter 4 - Measurement units and conversion factors

Chapter 4 - Measurement units and conversion factors. Leonardo Souza United Nations Statistics Division The 4 th meeting of the Oslo Group on energy statistics Ottawa, Canada, 2-6 February 2009. General. One of the first IRES chapters to be posted on the forum

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Chapter 4 - Measurement units and conversion factors

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  1. Chapter 4 - Measurement units and conversion factors Leonardo Souza United Nations Statistics Division The 4th meeting of the Oslo Group on energy statistics Ottawa, Canada, 2-6 February 2009

  2. General • One of the first IRES chapters to be posted on the forum • Preliminary text for the chapter. • It presents: • the recommendations from UN Manual F.29 • points raised during last OG meeting. • comments provided in the online forum • (some of them already addressed in the revised text)

  3. Structure A. Introduction B. Measurement units 1. Original units 2. Common units C. Calorific values 1. Gross and net calorific/ heating values 2. Standard vs specific calorific values [3. Efficiencies/useful energy?] D. Recommendations

  4. B. Measurement units • Original units: • Simplest, more suited to measure the fuel in its current physical state • Mass (weight), volume, energy • Common units • Common energy units. Allows, e.g.: • inter-fuel comparison* • estimate efficiencies*

  5. C. Calorific values • Allow conversion from original to energy units • Gross and net calorific/ heating values • Difference: heat content lost in released vapor • Standard vs specific calorific values • Default x country-specific values • OG to agree on standard values (see proposals)

  6. Recommendations (from F29)(review and amend, if applicable) • (Rec. 5) National and international statistical offices, and bodies that advise them or undertake work for them, should always define clearly the accounting units or presentation units employed in published analyses. The conversion factors and the route used to convert original physical units into the chosen common accounting unit or units should also be stated, or readily available published sources where they may be found should be cited. It should also be made clear whether energy units are defined on a gross or net calorific basis (para.48; see also (19) and (20), below). • (19) When expressing the energy content of primary and secondary fossil energy sources in terms of a common energy accounting unit, net calorific values (NCV) should be used in preference to gross calorific values (GCV). If and when recuperation of a significant part of the difference between GCV and NCV from exhaust gases becomes a practical possibility and seems likely to become a reality, this recommended basis may need to be reconsidered (para. 135).

  7. Recommendations (from F29)(review and amend, if applicable) • (20) Given that the joule, and multiples of it by raising it to powers of 103, is the only energy unit in the SI, international and national statistical offices should consider adopting the joule (1 joule = 0.239 calorie) as the rigorous accounting unit for energy balances. The TOE (1 TOE = 107 kcal NCV) and/or TCE (l TCE= 7 x 106 kcal NCV) may be used as supplementary presentation units. Whenever they are used, they should be clearly defined in terms of the joule, and the route used for converting original data to TOE or TCE should be clearly described (para. 157). • (Rec. 25) Energy balances should contain in the column headings for each energy source the average conversion factor (appropriate for expressing the original units in (or underlying) that column in terms of the common accounting unit as shown in the balance). Such average factors should be complemented in foot-notes, or accompanying text; with clear descriptions of the routes and stages followed in any conversions that are not adequately defined by the average factors (para. 268).

  8. D. Recommendations (discussion) • The text suggests recommendations on units of data collection • Can units be recommended for data collection? • Only to international data compilation or also to national statistics data collection and/or dissemination? • For all products or might there be exceptions (e.g., waste)?* • Do we need to give guidance on the conversion of TOE and TCE to TJ? ** • The text (from UN handbooks) recommends the use of the SI • Should the SI be recommended? • It may be useful to have a section describing how to calculate average (specific) calorific values. • Do you agree with having such a section in IRES? ***

  9. Questions • OG invited to provide comments on the general structure and coverage of the chapter • Does it cover the relevant aspects related to measurement units and conversion factors? • Are there additional topics that should be covered in this chapter? • Which recommendations are to be contained in IRES?

  10. Questions (continued) • Tables with conversion factors might render the chapter rather lengthy • Would it be better to send them to an Annex? • Which ones? All tables? • Part on efficiencies/useful energy may fit better in Chapter 7 • move it to Chapter 7?*

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