The nature of the "liquid sunlight"

Today, the term “liquid sunlight” refers to a green fuel obtained by means of a process inspired by the natural photosynthesis. The method to have this fuel is based on the combination of compatible inorganic and biological components to transform light, water, and carbon dioxide to methane. A similar term, “sunlight-to-liquid” or “sun-to-liquid”, exists for a recently proposed synthesis of a gas, which is further processed to obtain kerosene. Here we will show that in the past the term “liquid sunlight” was used for the petroleum. Actually, the meaning of the term, today and in the past, is the same: conversion of the sunlight energy into a fuel.