Energy accounting

An explainer about methods for accounting of the supply and consumption of energy.

A country’s energy system can be represented by figure 1.1 2 3

Figure 1. Schematic of a country’s energy system.

Measures of interest are Total Primary Energy Supply (TPES), and Total Final Consumption (TFC).

TPES provides a means to evaluate the energy supplied to an energy system from all fuel types. It accounts for energy supplied in its primary form, prior to any conversions such as coal to electricity.

TFC (also known as final energy) accounts for energy consumed by a country in its final form. For example, accounting for gas burned to produce heat separately from that burned to produce electricity. TFC data is only available from the IEA dataset, and so is at least two years old.

Primary energy supplied by non-combustibles (i.e. renewable and nuclear fuels) can’t be directly compared with that supplied by combustibles because non-combustibles have natural forms of primary energy (e.g. sun, wind, uranium etc). To overcome this, an equivalent TPES quantity can be calculated for each non-combustible, using a method of ‘primary energy equivalence’. The method applied to IEA data4 on this site, and that used by BP,5 is the ‘substitution method’.6

The substitution method is performed by calculating the quantity of primary energy required to be input to a thermal power station of average efficiency, in order to generate an amount of electricity or heat equivalent to that generated by each non-combustible. TPES values for non-combustibles are therefore the equivalent quantity of thermal generation they’ve supplanted.

Values of efficiency applied to IEA data on this site are those used by the IPCC:7 38% for electricity and 85% for heat. Therefore to calculate equivalents, non-combustible quantities of electricity are multiplied by 2.63 (i.e. 1/0.38), and heat by 1.18 (i.e. 1/0.85), as shown in figure 2 below.

BP data inherently uses the substitution method with yearly-dependant efficiency values ranging from 36% to 40%, due to efficiency improvements. Therefore this site does not apply further processing to BP data.

Figure 2. Calculation of TPES, showing the substitution method for non-combustible sources.

A shortcoming of TPES is that the total TPES value of an energy system is excessive relative to that needed in an energy system solely fuelled by non-combustibles. The total energy currently supplied by combustion of fossil fuels wouldn’t be required to be generated by non-combustibles, because the inefficiency of thermal generation wouldn’t exist.

The pursuit of a solely non-combustible fuelled national energy system is not policy of any country, and future carbon-free energy systems may continue to include substantial quantities of thermal generation, and emissions reduced using carbon capture and storage (CCS), and the remainder offset by atmospheric carbon dioxide removal (CDR).

Total Final Consumption (TFC) (i.e. final energy) could be used instead of TPES, but the TFC of combustibles (e.g. fossil fuels burned for heat by residences and industry) are also excessive relative to that needed to do the same work in a fully non-combustible energy system. And recent TFC data is unavailable.

The table below shows the calculation of TPES by applying the above method in figure 2 to IEA data, and compared to that from the IPCC. Both rely on IEA data for year 2010 and compare favourably (they are not exactly the same because the IEA annually applies quality control methods to historical data, and the IPCC used IEA data published in 2012, whereas this site used IEA data published in 2017).

Table 1. World energy system (TPES), year 2010, substitution method of primary energy equivalency, comparison of this website’s results with those from the IPCC.8

Commonly used metric prefixes for the large numbers used on this site are listed in table 2(a) below, and units in (b).

Table 2. Explanation of (a) Prefixes, and (b) Units.

Footnotes
  1. J.M.K.C. Donev et al. (2017). Energy Education – Total primary energy supply [Online]. Available: https://energyeducation.ca/encyclopedia/Total_primary_energy_supply [Accessed: February 20, 2019].()
  2. The International Energy Agency (IEA) statistics overview, http://www.iea.org/media/training/presentations/statisticsmarch/balances_overview.pdf()
  3. Macknick, Jordan. “Energy and CO2 emission data uncertainties.” Carbon Management 2, no. 2 (2011): 189-205. http://www.iiasa.ac.at/web/home/research/researchPrograms/TransitionstoNewTechnologies/macknick_ene_co2_uncertainties_CM_2011.pdf()
  4. https://www.iea.org/statistics/()
  5. https://www.bp.com/en/global/corporate/energy-economics/statistical-review-of-world-energy/downloads.html()
  6. There are two other methods of primary energy equivalency: the ‘direct method’ and the ‘physical energy content method’. The direct method directly compares quantities of energy from combustible and non-combustible sources without any account for the efficiency of thermal generation. This is only useful for future energy scenarios where the supplies of non-combustible fuels are high. The physical energy content method is used by the IEA for their TPES values, which enlarges the contribution of nuclear energy and diminishes that from other non-combustibles. This method applies the following weights to non-combustible energy supplies: Nuclear = 33%, Geothermal heat = 50%, Geothermal electricity = 10%, Solar thermal heat = 100%, Solar thermal electricity = 33%, Hydro, wind, marine and solarPV = 100%. For further information see section A.II.4, Krey V., O. Masera, G. Blanford, T. Bruckner, R. Cooke, K. Fisher-Vanden, H. Haberl, E. Hertwich, E. Kriegler, D. Mueller, S. Paltsev, L. Price, S. Schlömer, D. Ürge-Vorsatz, D. van Vuuren, and T. Zwickel, 2014: Annex II: Metrics & Methodology. In: Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Edenhofer, O., R. Pichs-Madruga, Y. Sokona, E. Farahani, S. Kadner, K. Seyboth, A. Adler, I. Baum, S. Brunner, P. Eickemeier, B. Kriemann, J. Savolainen, S. Schlömer, C. von Stechow, T. Zwickel and J.C. Minx (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_annex-ii.pdf()
  7. Footnote of table A.II.10, p. 1294, Krey V., O. Masera, G. Blanford, T. Bruckner, R. Cooke, K. Fisher-Vanden, H. Haberl, E. Hertwich, E. Kriegler, D. Mueller, S. Paltsev, L. Price, S. Schlömer, D. Ürge-Vorsatz, D. van Vuuren, and T. Zwickel, 2014: Annex II: Metrics & Methodology. In: Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Edenhofer, O., R. Pichs-Madruga, Y. Sokona, E. Farahani, S. Kadner, K. Seyboth, A. Adler, I. Baum, S. Brunner, P. Eickemeier, B. Kriemann, J. Savolainen, S. Schlömer, C. von Stechow, T. Zwickel and J.C. Minx (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_annex-ii.pdf()
  8. table A.II.10, p. 1294, Krey V., O. Masera, G. Blanford, T. Bruckner, R. Cooke, K. Fisher-Vanden, H. Haberl, E. Hertwich, E. Kriegler, D. Mueller, S. Paltsev, L. Price, S. Schlömer, D. Ürge-Vorsatz, D. van Vuuren, and T. Zwickel, 2014: Annex II: Metrics & Methodology. In: Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Edenhofer, O., R. Pichs-Madruga, Y. Sokona, E. Farahani, S. Kadner, K. Seyboth, A. Adler, I. Baum, S. Brunner, P. Eickemeier, B. Kriemann, J. Savolainen, S. Schlömer, C. von Stechow, T. Zwickel and J.C. Minx (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_annex-ii.pdf()