Nothing to do with feet, “toe” in energy is the unit “tonnes of oil equivalent”. Like boe (barrels of oil equivalent) it’s a measure most often seen in datasets and charts looking at country-scale energy mixes where different energy sources and types are converted to a single common unit. It represents the amount of energy you’d get out of burning a tonne of crude oil. As with boe, it is defined by convention, since different grades of oil can contain different amounts of energy in the same weight or volume. The IEA define 1 toe as 11.63 MWh.