Heat and the Energy Transition

The use of heat makes up around half of the world’s energy use and causes around half of the world’s CO2 emissions. Heating is therefore a hugely important, but often underlooked, part of the challenge of energy system decarbonization and the wider transition towards global sustainability. This chapter investigates the issue of heat in its broadest sense. It first considers the physics of what heat is before considering how the use of heat by humans has developed. The chapter then considers the geographical nature of heat, considering heat use across the world, exploring what heat is currently used for and how it is produced, highlighting the complex and heterogeneous nature of heat systems. Looking to the future, the chapter considers how heating practices and technologies need to change if climate change and sustainable development goals are to be met. Thankfully, sustainable heating technologies exist today and these technologies can be scaled up. However, the speed at which the heat (and wider energy) transition need to happen is challenging, and powerful interests and societal norms and expectations mean that incumbency and lock-in risk slowing down or derailing the journey. The journey towards a sustainable heat system could deliver significant co-benefits and build on existing energy system momentum around renewables. However, to achieve a sustainable heat system in a timely manner will require a rapid reform of energy systems around the world.