| Most of any fuel used for motive power ends up as waste heat simply due to the inherent (in)efficiencies of the Carnot cycle: <https://en.wikipedia.org/wiki/Carnot_cycle>. Where liquid hydrocarbons (not necessarily petroleum, but also biofuels and synfuels) have clear wins are: - Overall energy density. By both mass and volume, little short of nuclear power exceeds this. Battery storage is roughly 1/10th the density of liquid hydrocarbons by mass. - Handling ease. Liquid hydrocarbons, particularly kerosene (jet aviation fuel), diesel, and fuel oil are quite mild-mannered. Even the rather more rambunctious petrol is safe enough for ordinary civilians to dispense, store, and handle, for the most part. Liquid hydrocarbons can be stored at ambient conditions in simple containers, are largely non-toxic, and can be piped or flowed readily between locations. - Storage stability. There are very few energy options which are as stable in storage for days to years or more. - Ease of utilisation. Electric motors are arguably simpler, but other options, including direct (as in on-board) nuclear are not. Again, untrained civilians can use small to large internal combustion engines readily. In particular, there are usage modes, most notably air, marine, and mobile / remote-location applications, where liquid fuels are quite difficult to substitute for. Ground-based and inland-waterway transport can be electrified, but long-distance freight and passenger travel whether by sea or air not so much. Efficiency considerations pale next to the handling and utilisation characteristics. I'm not defending fossil fuels, and again the arguments apply equally to liquid hydrocarbons of any origin. But given the properties, prevalence, and low cost (however illusory that may be) of petroleum-derived hydrocarbon fuels, they're not trivially substituted for in all applications. |