Helsinki Energy: Text and photograph by Tero Tuisku strength in innovative methods of heat and cooling production Helsinki Energy relies on the efficiency of CHP, also known as cogeneration. At present, CHP accounts for more than 90 per cent of the company’s total district heat production. 20
energy efficiency in CHP is over 90 per cent, while “The in conventional condensing power production the efficiency typically remains at approximately 40 per cent,” says Marko Riipinen, who heads the district heating business of Helsinki Energy. The main fuels in the company’s power plants are natural gas (60 per cent) and coal (35 per cent). Marko Riipinen points out that the use of coal at a fuel efficiency of 86 per cent in CHP plants is also ecologically efficient. According to him, CHP is “We are not confined to combined heat and power production, but we also integrate district cooling to the service offering. This is why we prefer to talk about the three lines of production,” says Marko Riipinen, who heads the district heating business of Helsinki Energy. well justified and rational whenever there is sensible use for the heat, either in a district heating network or in an industrial process, for example. “Helsinki is the coldest capital in Europe, so there is an obvious need for heating in the winter. District heat is also used in Finland for producing hot service water; it accounts for about 30 per cent of the total sales of district heat. The need for heat is the smallest in warm summer days, when this need is approx. 200 megawatts.” The volume of district heat produced by Helsinki Energy varies from one year to another, primarily as determined by weather. In 2010, Helsinki Energy produced 7,850 gigawatt hours of district heat, which is a new record. Advantage: comprehensive district heating network The City of Helsinki has a very comprehensive district heating network. The heating network of approximately 1,250 kilometres has contributed to the possibility to connect the best available production methods located in different parts of Helsinki to the system. One example is the Katri Vala heat pump plant, which utilises purified warm waste water in energy production. Previously, this water was discharged into the sea. “The first calculations of whether or not it is profitable to build a heat pump plant that exploits waste water in energy production were made in Helsinki in the early 1970s. It was concluded then and over the following decades that a heat pump plant would be unprofitable. However, the situation changed in early 2000s, when we set out to develop a new business area of district cooling. The new calculations indicated that a heat pump plant would actually be viable. After all, the same heat pump plant can also produce district cooling using versatile production alternatives.” The Katri Vala heat pump plant was completed in 2006. Since then, its five units have produced district heat at a total power of 90 megawatts. Similarly, district cooling can be produced at a power of 60 megawatts. “To our knowledge, we have the world’s largest heat pump plant which uses the heat of purified waste water as the heat source and which produces both district heat and district cooling. The overall package has worked very well in every respect in the past five years,” says Marko Riipinen. Cutting edge expertise According to Marko Riipinen, Helsinki Energy’s district cooling expertise represents the cutting edge in the world. “Helsinki Energy integrates the production and use of district heating and district cooling in a unique manner. The need for cooling has increased rapidly in Helsinki in recent years. It is supplied to office buildings, shopping malls, computer rooms and even some apartment buildings. As an example, computer rooms create much waste heat in all seasons of the year, and cooling is needed. This is why district cooling is produced in the winter by means of free cooling from the cold sea water, and in the summer by means of absorption refrigerating machines and heat pumps. In absorption, the energy is derived from the heat obtained from CHP. In the heat pump arrangement, the excess heat collected from the cooling customers is recovered and used in district heating.” “The waste heat recovered by cooling is utilised eco-efficiently whenever possible.” In the winter, for about six months annually, all district cooling produced by Helsinki Energy is obtained from the sea. According to Marko Riipinen, the sea provides efficient and inexpensive cooling in an environmentally benign manner. The winter period accounts for as much as one third of the annual sales of district cooling by Helsinki Energy. Marko Riipinen points out that a traditional refrigeration machine using a compressor does not represent modern technology in areas provided with district cooling. “Compressor production uses much electricity, requires frequent maintenance, uses refrigerants, and is noisy. This is not at all smart in terms of the environment,” Marko Riipinen stresses. zx 21
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