Red-giant branch the star when it reaches the horizontal branch, so the properties of red-clump stars can be used to determine the mass difference before and after the helium flash. Mass lost from red giants also determines the mass and properties of the white dwarfs that form subsequently. Estimates of total mass loss for stars that reach the tip of the red-giant branch are around . Most of this is lost within the final million years before the helium flash. Mass lost by more-massive stars that leave the red-giant branch before the helium flash is more difficult to measure directly. The current
Power-to-gas reaction, or biological methanation resulting in an extra energy conversion loss of 8%. The methane /SNG may then be fed into the natural gas grid or further converted in to LPG by synthesising SNG with partial reverse hydrogenation at high pressure and low temperature. LPG in turn can be converted into alkylate which is a premium gasoline blending stock because it has exceptional antiknock properties and gives clean burning. The third method uses the output gas of a wood gas generator or a biogas plant, after the biogas upgrader is mixed with the produced hydrogen from the electrolyzer, to upgrade