Classifications for the energy transition E RE N-RE ES www.irena.org

Table of Contents

• Contents 3
• Figures 5
• Figure 1 Main structure of the energy taxonomy for (total) energy and its components 10
• Figure 2 IRENA classification of non-renewable energy 12
• Figure 3 SIEC classification of coal with IRENA coding and additional products 14
• Figure 4 SIEC classification of peat and peat products with IRENA coding and additional products 17
• Figure 5 SIEC classification of natural gas with IRENA coding and additional products 19
• Figure 6 SIEC classification of oil with IRENA coding and additional products 21
• Figure 7 IRENA classification of renewable energy 26
• Figure 8 IRENA classification of renewable hydropower 27
• Figure 9 Example of capacity and generation statistics showcasing mixed hydropower for Croatia, 2020-2022 30
• Figure 10 IRENA classification of marine energy 31
• Figure 11 IRENA classification of wind energy 34
• Figure 12 IRENA classification of solar energy 36
• Figure 13 IRENA classification of geothermal energy 47
• Figure 14 IRENA classification of bioenergy 49
• Figure 15 IRENA classification of solid biofuels. 51
• Figure 17 Traditional generational classifications of biofuels 62
• Figure 16 IRENA classification of liquid biofuels 62
• Figure 18 Pathways to produce biomethanol 63
• Figure 19 Transesterification of triglycerides with methanol and sodium hydroxide catalyst to produce biodiesel and glycerol 67
• Figure 20 Pretreatment of oils to optimise the yield of biodiesel through transesterification 67
• Figure 21 Synthesis pathway to produce hydrogenated vegetable oil diesel 69
• Figure 22 IRENA classification of gas biofuels 71
• Figure 23 Anaerobic digestion process 73
• Figure 24 Common biomass thermochemical processes to produce biogas/syngas 75
• Figure 25 Synthesis pathways to produce biological hydrogen 78
• Figure 26 Synthesis pathways to produce biothermal hydrogen 79
• Figure 27 IRENA classification of non-bio renewable fuels 82
• Figure 28 Water electrolysis with a proton exchange membrane 85
• Figure 29 Photoelectrochemical hydrogen production with a photoelectrode panel 86
• Figure 30 IRENA classification of other renewable energy 88
• Figure 31 IRENA classification of energy storage 92
• Figure 32 Process for ammonia energy storage without cooling 102
• Figure 33 Special grouping for hydropower 103
• Figure 34 Special grouping for hydrogen 104
• Figure 35 Special grouping for ammonia 105
• Tables 6
• Table 1 Hard and brown coal classification based on vitrinite mean random reflectance (VMRR) and gross calorific value (GCV) on a moist, ash-free basis 15
• Table 2 Technical aspects of concentrated solar power technologies 42
• Table 3 Pyrolysis conditions for different physical states 76
• Table 4 Energy taxonomy 116
• Boxes 6
• Box 1 Correspondence with Food and Agriculture Organization of the United Nations (FAO) Classification of Forest Products 2022 53
• Box 2 Anaerobic digestion step by step 73
• Box 3 Overview of the lithium-ion battery 94
• Equations 6
• Equation 1 Main hydrolysis reaction within anaerobic digestion 73
• Equation 2 Main acidogenesis reactions within anaerobic digestion 73
• Equation 3 Main acetogenesis reactions within anaerobic digestion 73
• Equation 4 Main methanogenesis reactions within anaerobic digestion 74
• Equation 5 Simplified combustion reactions of biomass 76
• Equation 6 Redox reactions of a typical lithium-ion cell 94
• Equation 7 Latent heat transfer equation 98
• Equation 8 Sensible heat transfer equation 99
• Why do we need an energy taxonomy? 7
• Energy taxonomy 10
• 100000 Non-renewable energy 12
•  110000 Fossil fuels 13
•  120000 Nuclear energy 24
•  130000 Non-renewable waste 24
•  140000 Other non-renewable energy 25
• 200000 Renewable energy 26
•  210000 Renewable hydropower 27
•  220000 Marine energy 31
•  230000 Wind energy 34
•  240000 Solar energy 35
•  250000 Geothermal energy 47
•  260000 Bioenergy 49
•  270000 Non-bio renewable fuels 82
•  280000 Multiple renewables 88
•  290000 Other renewable energy 88
• 300000 Energy Storage 91
•  310000 Electric storage 93
•  320000 Electrochemical storage 93
•  330000 Electromagnetic storage 95
•  340000 Mechanical storage 95
•  350000 Thermal storage 98
•  360000 Chemical fuels storage 99
• Special groupings 103
• Hydropower 103
• Hydrogen 104
• Ammonia 105
• References 106
• Appendix A. Taxonomy table 116
• Appendix B. Taxonomy diagram 123