Energy content of biofuel (J/kg) or equivalent units. Energy density is the amount of energy stored in a fuel per unit volume, expressed in SI units as joule per litre (J/L) or equivalent units. The table below includes entries for popular substances already used for their energy, or being discussed for such use. The second column shows specific energy, the energy content in megajoules per unit of mass in kilograms, useful in understanding the energy that can be extracted from the fuel. The third column in the table lists energy density, the energy content per liter of volume, which is useful for understanding the
Energy (esotericism) 18th and 19th centuries with Mesmer and the magnetism. They continued to be discussed in the 20th century by some thinkers and practitioners in the modern New Age movement. As biologists studied embryology and developmental biology, particularly before the discovery of genes, a variety of organisational forces were posited to account for their observations. German biologist Hans Driesch (1867–1941), proposed entelechy, an energy which he believed controlled organic processes. However such ideas are discredited and modern science has all but abandoned the attempt to associate additional energetic properties with life. According to Brian Dunning, the scientific term energy is, in