Supplementary Materials for

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1 Supplementary Materials for Understanding China s non fossil energy targets Joanna I. Lewis,* David G. Fridley, Lynn K. Price, Hongyou Lu, John P. Romankiewicz This PDF file includes Materials and Methods Tables S1 to S17 References Database caption S1 *Corresponding author. joanna.lewis@georgetown.edu Published 27 November 2015, Science 350, 1034 (2015) DOI: /science.aad1084 Other Supplementary Material for this manuscript includes the following: (available at Datafile S1. MIT Study calculations as an Excel file.

2 Materials and Methods In order to compare China s power plant coal consumption (PPCC) method-derived values for estimating the contribution of non-fossil energy to others used internationally, we relied on published China energy balances expressed both in physical units (tonnes, m 3, TWh) and in standard energy terms (tonnes of coal equivalent or tce). China s energy balance in standard energy terms provides two total columns: one calculated based on the sum of the calorific energy values (i.e. direct equivalent in each row and the second based on China s PPCC method values. The values of primary electricity in the energy balance are expressed in calorific energy values only. In order to calculate primary electricity using the PPCC method, the physical values of primary electricity generation from the energy balance table (in TWh) were each divided into the corresponding PPCC method total value (in tce) to determine the multiplier compared to the calorific energy value. In the 2010 China energy balance, the PPCC method value for primary electricity was kgce/kwh, compared to its calorific value of kgce/kwh, a factor of 2.6 difference. China s PPCC method is the basis for calculating China s targets for non-fossil energy penetration, but the corresponding primary electricity values must first be expressed in PPCC method terms to be able to calculate the penetration rate based on the total energy value provided in PPCC method terms. For this calculation for 2010, the standard energy values of primary electricity in tce are multiplied by 2.6 to convert them from a calorific to PPCC method basis, and the total of these numbers can then be used to divide into the total energy value to calculate the share of non-fossil primary electricity using the PPCC method. Non-fossil electricity accounts for nearly all of China's non-fossil energy production, as detailed below. Data sources The primary Chinese energy data used for this analysis are from the 2010 national energy balance of the China Energy Statistical Yearbook 2011 published by China s National Bureau of Statistics (NBS) (13), also available for download in the China Energy Databook (17). These official data cover Mainland China only, and exclude household biomass energy and solar water heating but include a non-standard category of recovered energy referring to waste-heat recovery in industrial facilities. China s energy balances provide values of Total Primary Energy Supply (TPES), which is the sum of energy supplied for transformation of primary energy to other energy forms (e.g. through electricity generation, coking, petroleum refining, and gasification), final consumption by end-use sectors, losses, and any statistical discrepancy that arises between supply and consumption accounting. Because transformation consumption is by Chinese convention reported as a negative, the identity is: TPES = Transformation + Final Consumption + Losses + Statistical Difference When converted into Chinese standard energy units (e.g. tonnes of coal equivalent or tce), China s national energy accounts are reported in two formats. The first uses the Power Plant Coal Consumption Method ( 发电煤耗计算法 ) in which: (i) all energy used in thermal power generation is allocated to final consumption sectors by proportion of each sector s use of electricity (and thus power generation appears as zero in the Total Energy column); and (ii) all primary electricity (hydropower, wind, solar, geothermal, other renewables, and nuclear) is converted to coal equivalent at the average heat rate (in kgce/kwh) of coal fired power plants in that year. The second format uses the calorific value calculation method ( 电热当量计算法 ), 1

3 also called the Direct Equivalent Method, in which all primary electricity is summed as the heat value of electricity (3.6 MJ or kgce/kwh). Calculating China s non-fossil primary electricity generation: Power Plant Coal Consumption Method China has established a target of increasing non-fossil energy in its energy mix to 11.4% in 2015 and 15% in 2020 primarily by increasing the proportion of primary electricity in its power mix. This target is calculated based on China s power plant coal consumption method, which converts primary electricity to standard energy units based on the average heat rate of coal fired power plants in that year. It is a variation of the substitution method described below. Table S2 shows how the data in China s national energy balance are used to calculate the power plant coal consumption coefficient for Using the energy balance table reported in standard units (tonnes of coal equivalent, tce), dividing the value for hydro, nuclear, and wind power into total energy reported using the power plant coal consumption method gives a coefficient of kgce/kwh, compared to the calorific energy value of primary electricity of kgce/kwh used in the direct equivalent method. To calculate the proportion of primary electricity in total energy using the power plant coal consumption method, the reported electricity values in calorific terms are multiplied by (the factor difference between the calorific value of electricity of and the power plant coal consumption value of in 2010 shown in Table S1) then divided into total primary energy expressed in the power plant coal consumption value. The 2010 share of non-fossil primary energy in China s primary energy supply is 8.4% using the Chinese power plant coal consumption method based on values shown in Table S2. Calculating China s non-fossil primary electricity generation: Direct Equivalent Method China also reports primary energy values using a calorific value calculation consistent with the internationally used direct equivalent method. Table S2 shows that when using this method, the 2010 share of non-fossil generation in China s primary electricity is 3.4%. Specifically, dividing the total indigenous production of primary electricity (reported in the energy balance table in calorific terms) into the calorific value of total primary energy supply (TPES) gives a 3.4% penetration rate of non-fossil primary electricity in the energy system. The 4% difference between total indigenous production of electricity and the sum of hydro, nuclear, and wind power includes the electricity generated from solar, geothermal and tidal plants. This calculation is an estimate, since it is not clear how the National Bureau of Statistics treats electricity imports and exports, which are also considered primary electricity but are not necessarily of non-fossil origin. If net exports (or some portion thereof) are deducted from the primary electricity total (as shown in the TPES row), then the percentage contribution would be lower. Further, China s target is expressed in terms of all non-fossil energy, which would also include biomass power generation, ethanol for gasoline blending (counted as non-fossil, but requiring an equivalent amount of fossil energy to produce), and biodiesel, which together contributed approximately 10% to China s overall non-fossil energy production in 2010 (18), but none is accounted for in the published energy statistics, and biomass is omitted altogether. Consequently, though primary electricity is the major source of non-fossil energy supply, its contribution alone slightly understates that of all non-fossil energy. 2

4 Calculating China s non-fossil primary electricity generation: Substitution Method Calculating China s non-fossil energy share using the substitution method (as used by the U.S. EIA) increases the percentage contribution because of the differing factors used for converting primary electricity into standard energy units (5). China s published energy balances details only the production of hydro, nuclear, and wind power as part of the total primary electricity total. To estimate the contribution of other primary electricity forms, such as solar PV, geothermal energy, and tidal energy, we allocated the balance according to the shares of other renewable energy generation as reported by the China National Renewable Energy Center (19). In 2010, the share of solar electricity in other renewables was 83%, and geothermal/tidal energy accounted for 17%. By applying the U.S. EIA conversion factors for each non-fossil electricity source, the estimated total non-fossil primary electricity supply in 2010 was about 316 Mtce. Because of the different method for converting primary electricity into standard units, China s TPES value needs to be recalculated as well in order to derive the contribution percentage of primary electricity to the total. For this calculation, it is assumed that imported and exported electricity has an average power generation efficiency of 33%, consistent with the U.S. EIA approach. Thus, by adding the previously estimated indigenous production of primary electricity to imported and exported electricity, total primary energy supply of electricity was approximately 304 Mtce in Total primary energy supply of other energy sources (that are not supplied in the form of electricity) is estimated by subtracting the calorific energy value of electricity from the calorific energy value of total energy. Although both the U.S. EIA and China s NBS calculate the heat content of fuels as volume (weight) multiplied by unit energy content, China s convention of using Low Heating Value (LHV) has been retained here instead of using the U.S. EIA s High Heating Value (HHV) standard. Thus the total primary energy supply of energy sources other than electricity is 3,052 Mtce. Adding the two components of TPES gives a total TPES of 3,356 Mtce, which approximates the total primary energy supply of China in 2010 using the substitution method for primary electricity accounting. Dividing total non-fossil primary electricity into TPES results in a 9.2% share of non-fossil energy in total consumption in 2010 using this conversion method (Table S3). Calculating China s non-fossil primary electricity generation: Physical Energy Content Method The IEA uses the physical energy content method when converting primary energy electricity into standard energy units in which a 33% efficiency rate is applied for nuclear and solar thermal electricity, a 100% efficiency rate is used for hydro, solar PV, and wind, and a 10% efficiency rate is used for geothermal energy (8). Using this method, total primary electricity in 2010 was 132 Mtce, with the total primary energy supply estimated to have been 3,179 Mtce, resulting in a primary electricity contribution of 4.2% (Table S4). Estimating China s 2030 non-fossil energy goal China s recently announced goal of a 20% share of non-fossil energy in total energy by 2030 was calculated using the PPCC method. If the direct equivalent method had been used, the share would have been different. To demonstrate, we use the forecast electricity generation composition and total energy consumption of the Continuous Effort scenario of a recent modeling forecast study by Tsinghua University and Massachusetts Institute of Technology (14). In this example calculation, we assume an average China coal power plant heat rate of kgce/kwh in This heat rate represents a 3.1% improvement over 2010 and is derived as the 3

5 level that results in a 20% penetration of non-fossil electricity in total energy consumption using the PPCC method. To calculate the penetration using the direct equivalent (IPCC) method, the non-fossil electricity share was expressed in standard energy units using the IPCC conversion, and the difference between the PPCC and IPCC conversion results subtracted from the energy total. Under this scenario, the share of non-fossil electricity in total energy in 2030 using the direct equivalent method falls to 9%, compared with 20% using the PPCC method. Details of the calculation can be found in the accompanying Excel spreadsheet. 4

6 Table S1. Methods for converting primary electricity into standard energy units. Primary Conversion Method Power Plant Coal Consumption Direct Equivalent Substitution Physical Energy Content Adopted by: China IPCC U.S. EIA, BP,* World Energy Council OECD, IEA, Eurostat source: Nuclear energy Hydropower Renewable electricity (solar PV, solar thermal, and wind) Geothermal energy Conversion to standard units based on the average heat rate (kgce/kwh) of coal fired plants in that year. 1 kwh = 9.4 MJ = kgce in 2010 Assumes 1 kwh = 3.6 MJ = kgce Assumes 32.6% efficiency 1 kwh = MJ =0.376 kgce (2010: varies by year) Assumes 35% efficiency: 1 kwh = 10.3MJ = kgce (2010: varies by year) Assumes 35% efficiency: 1 kwh = 10.3 MJ = kgce (2010: varies by year) Assumes 35% efficiency: 1 kwh = 10.3 MJ = kgce (2010: varies by year) Assumes 33% efficiency: 1 kwh = 10.9 MJ = kgce Assumes 100% efficiency: 1 kwh = 3.6 MJ = kgce Assumes 100% efficiency (solar PV, wind): 1 kwh = 3.6 MJ = kgce Assumes 33% efficiency (solar thermal): 1 kwh = 10.9 MJ = kgce Assumes 10% efficiency: 1 kwh = 36 MJ = kgce *BP also uses the Substitution Method but assumes a 38% conversion efficiency for all forms of renewable electricity. 5

7 Table S2. Estimation of China s share of non-fossil electricity in primary energy in 2010 using the power plant coal consumption and direct equivalent methods. China s TPES calculation includes the non-standard categories of Chinese bunkering overseas (treated as an import) and foreign bunkering in China (treated as an export). Data in columns 1, 2 and 4 are reported by China s National Bureau of Statistics in the national energy balance (12); columns 3, 5 and 6 are the authors calculations. Item Total energy (power plant coal consumption Total energy (direct equivalent (direct equivalent (10,000 tce) Total primary energy supply* 332, , , (power plant coal consumption Primary electricity as % total energy (direct equivalent Primary electricity as % total energy (power plant coal consumption Indigenous production 296, , , , Hydro power 23, , , , Nuclear power 2, , Wind power 1, , Recovery of energy 5, , Import 54, , Domestic airplanes & ships refueling in abroad Export (-) -7, , Oversea airplanes & ships refueling in China -1, , Stock change -16, ,

8 Table S3. Estimation of China s share of non-fossil electricity in primary energy in 2010 using the substitution method. Data in column 1 are reported by China s National Bureau of Statistics in the national energy balance (12); the remaining columns are the authors calculations based on the values in Table S1. Physical units Calorific value EIA conversion rate EIA method primary electricity production Total Energy - EIA method Energy sources other than electricity TWh Mtce kgce/kwh Mtce Mtce Mtce Mtce Total Primary Energy Supply , , Total Primary electricity as % total energy Indigenous Production , , Hydro power Nuclear power Wind power Other renewables PV Geothermal/ Tidal energy Import Domestic airplanes and ships refueling abroad Export (-) Oversea airplanes and ships refueling in China Stock Change

9 Table S4. Estimation of China s share of non-fossil electricity in primary energy in 2010 using the physical energy content method. Data in column 1 are reported by China s National Bureau of Statistics in the national energy balance (12); the remaining columns are the authors calculations based on the values in Table S1. Physical units Calorific value IEA conversion rate IEA method primary electricity production Total Energy - IEA method Energy sources other than electricity TWh Mtce kgce/kwh Mtce Mtce Mtce Mtce Total Primary Energy Supply , , Total Primary as % Total Energy Indigenous Production , , % Hydro power Nuclear power Wind power Other renewables PV Geothermal/ Tidal energy Import Domestic airplanes and ships refueling abroad Export (-) Oversea airplanes and ships refueling in China Stock change Data file S1. MIT Study calculations as an Excel file. 8

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