Role of cooling
Cooling has long been under-represented in energy policy, compared to heat, power and transport. The European Commission has recognised this and took a first step with the launch of its Heating and Cooling Strategy in February 2016. Nevertheless there is still far too little joined-up thinking on the cooling side of the debate.
Regarding cooling demands, the report presenting the results of the First Stakeholder Round Table on Cooling summarises:
Even in temperate European countries, cooling is everywhere, and vital to many aspects of modern life: food, medicine, energy, data, industry and comfort. The food supply relies overwhelmingly on a seamless ‘cold chain’ of refrigerated warehouses and vehicles that stretch from the farm gate – which could be in Asia, Africa or Latin America – to the supermarket display cabinet. 70% of foods are chilled or frozen when produced, and 50% are retailed using refrigerated display, and increasing amounts delivered to the customer’s doorstep by refrigerated home delivery vans. Domestic refrigeration is the biggest single cooling energy load – in the UK it consumes 13TWh per year or 4% of all electricity.
Cold chains are also vital for the safe supply of vaccines and other medicines – including the world’s biggest selling medicine, the anti-cholesterol drug Lipitor. MRI scanners could not work without the extreme cold of liquid helium.
Data centres are a relatively recent but fast growing source of demand for cooling; almost half a data centre’s electricity goes on cooling, without which the internet would quickly collapse. In Britain, data centres consume 2-3% of the electricity supply. Global data centre power consumption almost quadrupled between 2007 and 2013 to 43GW, roughly the generating capacity of South Africa. At this growth rate, by 2030 the additional cooling load would require another 35GW of generating capacity, or more than that of Poland.
Cooling is essential for producing chemicals, plastics, industrial gas production for steelmaking and other metallurgical processes. Cooling is a fundamental step in the Haber-Bosch process that converts atmospheric nitrogen into ammonia fertilizer, credited with producing the food to feed 3 billion people – almost half the world’s population. Put another way, this process provides all the food eaten every second day.
Cooling is also important for comfort and productivity particularly in large buildings; skyscrapers would be uninhabitable without air conditioning. Demand is rising steeply in the EU, where the Commission expects building cooling demand to rise 70% by 2030. Worldwide energy demand for space cooling will overtake space heating by 2060, and outstrip it by 60% at the end of the century.
At the same time, a broad variety of supply options exist. Depending on the application, natural cooling, electrical chilling, the use of surplus heat or recovered cold from other processes is an option. These technologies are mostly available and range from high to low temperature, individual applications and grid-based systems such as District Cooling. Most cold production/transfer technologies can be applied on all levels from small to large.
When deciding on the technologies for a certain cooling need, not just the size and the temperature level play a role but also the location, the availability of resources, the annual and daily consumption pattern, the potential recovery options, and energy system around. An integrated approach to the cold chain, or more generally to the thermal demand chain and the application of the best available technologies, is key to the decarbonisation not just of the cold sector but of the thermal sector as a whole as well as to a more efficient and balanced electricity sector. The combination of heat and cold demands and linking them through heat recovery systems and reversible/simultaneous supply/production systems on the individual or district level are key. The cooling demand for one can cover the heating demand for someone else.