Entropy is both a property of matter and a device for selecting probability distributions in light of data. Hence it's an enormously useful tool that should  be widely understood. The book explains how entropy gives insight into several aspects of the energy transition, and even had an impact on the course of the 1914-18 war. As a key tool of data processing, its importance is increasing as the world digitises.

Politicians speak of energy as a single, undifferentiated thing: electricity and gas are both sold by the kilowatt hour. But electricity is more valuable than gas because it is energy that is free of entropy. Vast quantities of energy are contained in the Earth's atmosphere and oceans, but this energy is unsaleable because it's heavily polluted with entropy. A heat pump is a device for increasing the quality of free, heavily polluted energy by adding entropy-free energy drawn from the electricity grid. The heat engines found in power stations, cars and aeroplanes produce entropy-free energy from energy that's moderately polluted with entropy by disposing of the undesired entropy in `waste heat'. Carnot already determined the minimum amount of heat that must be discarded to deliver a unit of pure energy. Real engines discard more than this minimum but over the nearly two centuries since Carnot, engineers have edged steadily closer to Carnot's minimum. A solar cell is ultimately a heat engine and subject to Carnot waste-heat formula.

We import an increasing fraction of our natural gas in liquid form. This trade involves pumping most of the entropy out of the gas before it's shipped, and then putting the entropy back in when the ship arrives. These steps are expensive, and Carnot's work tells us that a big opportunity is lost when current plants return the entropy.