Most of this heat comes from the burning of fossil fuels such as coal and is responsible for a significant proportion of world pollution. However, to-date we have seen very little progress across the world in cleaning up how we generate heat – despite the existence of more sustainable and cost-effective solutions.
A major reason for this is that the heating systems we have built across much of the world are both costly and troublesome to change, and there are whole piles of government incentives that favour fossil-fuelled alternatives. That said, there are lots of environmental pressures which are forcing change – starting with air quality in cities like Beijing and Delhi, as well as global pressures to decarbonise.
Heat’s complexities begin with its physics. Heat is all about the flow of energy and works in three different ways: by convection, by conduction and by radiation. Heat is also governed by two important scientific laws; the first and second laws of thermodynamics. The first law states that energy cannot be created or destroyed but just goes from one form to another; the second law states that it is impossible to convert one form of energy to another without some form of heat loss. Some of the greatest losses occur when oil and gas are converted from chemical to heat energy to power an internal combustion engine or a turbine. It is thus critical to either reduce the level of waste heat or to capture that heat for other purposes.
There are many ways to reduce waste heat such as building better-insulated buildings or increasing the efficiency of engines. Another way is to capture and use the waste heat for other purposes such as heating hot water, which can then be used locally in a district heating system. Such systems are costly and take time to build – however, the digitalisation of our world is providing us with a massive opportunity to rethink heat, and where we get it from.