The cooling process is done at night
At Carlsberg City the water in the tanks is chilled through a process that draws cool air from outside or through compression cooling – or a combination of the two. The cooling process is usually done at night, because the air is generally cooler, and because more renewable electricity for the compressor is available at a lower cost. The fact that so many consumers are connected to the storage tanks also produces economies of scale that thus drive the cost per unit down, and the cooling process is not only cheaper but also more environmentally and climate friendly.
At the next stage of the project, a heat pump will even enable the cooling system to generate surplus heat for the district heating system. By exploiting the full potential of district cooling, Denmark can reduce heating and cooling costs by almost EUR 1.5 billion, shows a strategic study by Ramboll.
Other advantages for users include far fewer technical complications and economic risks, no on-site chemicals handling, better use of space and less noise.
And as Lars Riemann, Group Market Director at Ramboll Buildings explains, district cooling does not require a big piping system running from a power plant to the area where the cooling is used – as district heating usually does.
“All it takes is a storage tank. It’s easy to install and can be used in small areas, for example a block in Manhattan with a tank just three storeys high,” he points out.
However, district cooling can also be used at a much larger scale. Ramboll is participating in one of the world’s biggest projects, a 500-MW district cooling system in Makkah, Saudi Arabia.
In the Middle East 70% of electricity production region is used for air conditioning even though district cooling is 50% more efficient than individual chillers. So district cooling could make life a lot greener in arid climates too.
Facts: District energy and storage in the EU
The EU countries can save at least EUR 100 billion annually – and cut carbon dramatically – by making district heating and cooling a key factor, and the EU’s Energy Efficiency Directive requires all member states to conduct a comprehensive assessment of the national potential.
District energy is closely related to energy storage, and in a working paper the EU Commission states that “energy storage will play a key role in enabling the EU to develop a low-carbon electricity system” because it can supply more flexibility, improve efficiency and reduce costs.
Batteries and thermal storage are the most important types of renewable energy storage. The use of renewables in the transport system requires batteries, which are becoming more efficient but remain quite expensive. Thermal storage is the cheapest storage means, but can only be used when connected to district heating or cooling.
Sources: Heat Roadmap Europe and others.