This table provides wide informations on the technological facets of various sources of primary energy. One of the outstanding features of this table is that it exposes and compares various technological problems involved in the energy conversion processes. The primary energy sources treated here are the solar energy (heat and light are treated separately), the geothermal energy, coal (gasification and liquefaction are treated separately), oil, natural gas, oceano-energy (tidal energy, temperature difference, and wave energy are treated separately), organic wastes, oil shale, tar sand, hydraulic power, wind power, biomass, uranium, thorium, and deuterium and lithium. On the other hand, the comparisons are made in three major items, i.e. charactersitics as natural resources, conversion or refinement to secondary energy sources, and economical characteristics. The first item includes the estimated and recognized amount of deposits, easiness of mining, storage, and transportation, and cleanliness and safety. As for conversion characteristics, the easiness, controlability, efficiency, cleanliness, and safety of various conversion processes are compared. Finally, as for economical problems, cost comparisons are made for gathering or mining those resources, including required energy input, man power, required facilities, and site conditions.