Seawater cools down buildings in Copenhagen

Cooling of buildings with district cooling may save the climate large quantities of greenhouse gases by exploiting seawater all-year round. In Copenhagen, two district cooling centres have been established and more are on the way. (Updated)

• Warmer climate increases cooling needs

  At the prospect of longer and warmer summers, the need for cooling in buildings where people live, work, etc. will be greater in future. This includes buildings such as shopping centres, banks, hotels, office buildings, hospitals and museums. Today, many buildings of this kind have their own cooling systems. A majority of these systems run on CFC gases which degrade the ozone layer and contribute to global warming. They also use large volumes of electricity, particularly if the plants are old and ineffective. Furthermore, they are noisy and take up a lot of often rather expensive building space. These are obvious problems which may be solved by connecting to a district cooling distribution system.

• Three ways to produce cooling

  HOFOR's first district cooling centre was ready in 2010 in the old factory buildings Turbinehaller on Adelgade in the heart of Copenhagen, and yet another centre was ready at Tietgensgade near the City Hall Square in 2013.

   

  

  The Tietgensgade centre from the outside.

  
  These plants can produce cooling centrally in three different ways:

   

  Seawater. In the winter months, cooling is solely produced by means of seawater which is led into the cooling centre through a pipe between the harbour and the centre. This type of production is completely carbon-free and is called 'free cooling'. However, a small volume of electricity is used when the cold water is pumped out to customers. The rest of the year, seawater is used to enhance the efficiency of other installations, as the seawater is used to cool for example cooling compressors.

   

  Steam. In summer months, steam is bought from CHP production, as heating consumption in the summer is very low. Here, waste incineration represents a large part of the steam production, and therefore carbon emissions are low for cooling production based on steam in the summer. This method is called absorption cooling.

   

  Electricity. Electricity compressors are used in the summer months; seawater is used to remove surplus heat from the compressor machines. A number of different capacity electricity compressors are available on the market. This mean there is always a machine which fits the cooling consumption. Thus, efficiency is significantly increased for electricity compressors compared with the compressors which buildings might alternatively have installed to cover their cooling needs.

   

  In future, district cooling centres will be expanded in the rest of the capital. At the moment, HOFOR is assessing possibilities in seven other areas in Copenhagen. The plan is to establish district cooling in Nordhavn, Kalvebod Brygge, Islands Brygge and Sydhavn, among other places.

• District cooling generates less carbon emissions

  There is a great demand for district cooling in Copenhagen. Space-savings, the price of district cooling, and the environmental advantages have motivated many enterprises and public buildings to change to district cooling.

  The head of district cooling in HOFOR, Henrik Bøgeskov, hopes that the 36 service agreements now entered into will encourage even more players to see the benefits of district cooling.

  
  "Fortunately, many customers are attracted to this solution, but there is still a long way to go before we can exploit the full potential of our two cooling centres. It is encouraging that district cooling is spreading so quickly as we know that each new customer who joins the solution reduces carbon emissions by up to 70%. Customers also save up to 40% in costs. Therefore, at the moment, many property owners, administrators and advisors are choosing district cooling for new as well as old properties".

  
  The grid system in Copenhagen is constantly being expanded as customers join the district cooling centre. This way, customers decide the areas in which HOFOR will be establishing district cooling in the future.

   

  

  The red cooling machine in Tietgensgade (also known as the Ferrari) is one of five machines which are to produce a total of 25 megawatt cooling in the centre when it is fully expanded.

• Facts about district cooling

  District cooling is the distribution of cold water through pipes from a centre to the customer where the water, through a transformer, cools the air in the customer's air conditioning units.

  
  Customers who choose district cooling may achieve economic savings of 40% compared with traditional cooling systems and reduce their carbon emissions by up to 70%.

  
  HOFOR produces carbon-free cooling most of the year using cold water from the harbour that is a natural and sustainable resource.

  
  At the end of 2012, HOFOR invested DKK 138 million in the expansion of district cooling.

   

  The need for cooling is assessed to increase by 50% at European level up until 2020.