City direction: energy efficiency and lower costs

In Germany, the use of district heating is not quite that widespread, compared to some other EU countries. One example of widespread use, however, is Hamburg, which has a vast district heating network supplying 19% of all households with district heating. A superlative city development named HafenCity has been at the heart of the city’s plans.

Since becoming Europe’s largest inner-city development project covering 155 hectares of harbor area in the early 2010s, it is setting standards throughout Europe with its mix of apartments, offices, recreational facilities, retail trade and culture. This is also true of its energy supply, as city planners chose the most sustainable and economically advantageous long-term solution: all buildings are supplied with district heating.

The goal for HafenCity was to develop an energy supply concept that fulfilled the strictest economic and environmental requirements. In essence, the concept is based on the combination of the existing, well-proven Hamburg district heating system with decentralized, local heating distribution units.

The district heating supply in HafenCity is a cost-effective and sustainable solution. Hamburg’s prestigious project is a model for successful city development and not just for architectural reasons. The energy concept also sets standards. The control equipment installed in a wide range of buildings for the distribution of district heating ensures that every single kilowatt of energy is used as efficiently as possible, to the benefit of house owners, tenants and the energy supplier.

Located in the North-eastern part of Bosnia and Herzegovina, the historic city of Tuzla enjoys a continental climate with cold winters and hot summers. To meet the heating demand of the city, surplus heat from the large, municipal coal-fired power plant is used to supply district heating to a large number of homes and other buildings within the metropolitan area.

The available flow capacity of the existing, 30-year-old system was 2,300 m³/hour, whereas the required flow to fulfill the heating demand of the connected homes, public and commercial buildings and other facilities was closer to 2,800 m³/hour.

The shortcomings of the system were especially felt in the mornings, when the inhabitants got up to cold rooms during the winter months. In order to maximize system efficiency, raise the level of end-user satisfaction and improve the stability of the system, the local Heating Company TPP Tuzla decided to carry out a complete renovation of the system. It has carried out a major renovation of the city’s comprehensive district heating network, providing reliability of supplies, improved comfort as well as energy and cost savings. Based on thorough analysis and a long-term strategic approach, the old system has been gradually transformed into a modern and smart energy system.

What were the results achieved by reengineering the Tuzla district energy system? 30% energy savings compared to old system before retrofit and capacity expanded by 36%.

Moving back north-west across Europe, there is another strong example emphasising the benefits of implementing a new system into the city. In Silkeborg, Denmark, the world’s largest solar heating plant harnesses energy to heat the homes and workplaces of 40,000 citizens. After helping to achieve a fascinating 30% cost reduction in 1st year, it currently supplies 18-20% of the annual heat consumption which has an ambitious target of CO₂ neutrality in heat production by the year 2030.

The government in Denmark is furthermore reducing subsidies to traditional power sources to motivate utility companies to transfer to green energy sources. Silkeborg District Heating plant had installed the new solar heating plant in advance of just such a reduction in subsidies which came into effect in January 2019.

Solar water heating was chosen since it allows storage of solar energy harvested in daylight for use at night time or in a different time of year. This extends the added value of the sun and makes solar solutions even more profitable. The Silkeborg plant is a shining example of a cost and energy effective solution. Designed for a lifetime of 25 years (and containing 22 km of piping linking together 12,436 solar heating panels, equivalent to the area of 20 football fields), it is 4-6 times more effective than residential solar water heating systems installed typically on rooftops of private homes.

As both percentage and number of people living in cities is projected to grow significantly by 2050, the impact on cities, their energy consumption and costs will be even bigger than today. It is precisely because of this that examples set by Istanbul, Hamburg, Tuzla or Silkeborg should be followed to create a cleaner, greener and less expensive future.