 | | 20.00 Energy , Renewable energies, Household energy |
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| | 20.01 Energy and power (general works) incl. energy per country, energy savings, and publications covering several sources of energy, rural energy |
| | 20.02 Transformation, distribution and storage of energy and electricity |
| | 20.03 Conventional energy resources (oil, petroleum, coal, natural gas, peat, nuclear energy) |
| | 20.04 Renewable energy resources |
| | 20.05 Wood and charcoal (incl. kilns and activated charcoal) |
| | 20.06 Solid fuels from agricultural wastes and other organic material (pellets, eco- bricks, briquets) |
| | 20.07 Biogas (incl. biogas equipment) |
| | 20.08 Cookstoves, Fuel-saving cookstoves, Household Energy |
 | | Untitled |
| | 20.10 Alcohol and other liquid fuels |
| | 20.11 Solar energy, photovoltaic energy |
| | 20.12 Wind energy |
| | 20.13 Hydropower |
| | 20.14 New Energy technology and research, Planetary Association for Clean Energy publications |
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