Renewable energy

Location of building: Turu 16a, Tartu.

Tartu city centre’s cooling station is a district cooling station whose purpose is to produce and supply cooling for commercial buildings, shopping centres, hotels, etc. District cooling has several advantages over traditional cooling, primarily in energy efficiency. Tartu’s district cooling station produces cooling using traditional industrial equipment as well as cold river water.

Tartu’s city centre contains a variety of public buildings, including a water park, a theatre, four shopping centres, a science centre, and numerous office buildings. The buildings have different energy consumption peaks, which allows for energy consumption optimisation. The cold water of the Emajõgi River can be used as a free cooling source (energy from nature) from October to April. When water from the Emajõgi cools the water in the cooling network to the appropriate temperature (6 °C), there is no need to use industrial cooling equipment. When the water of the Emajõgi warms up, cooling production also requires the use of the industrial equipment.

Tartu’s city centre meets several criteria for successful district cooling:

• The city centre is sufficiently densely populated;
• It will become even more densely populated in the future;
• New buildings guarantee a high energy density: ca 7 kW/m (the average being 1.8-5.5 kW/m);
• Fortum is the owner of riverside property;
• River water can be used for general cooling in autumn, winter and spring and for cooling turbocompressors in summer.

District cooling is estimated to reduce traditional cooling energy costs by roughly 90%, and compared to a traditional cooling system, Tartu’s CO₂ emissions will fall by 70%.

As part of the SmartEnCity project, the district cooling station was fitted with solar panels to produce electricity for the station.

The power of the district cooling station is 13 MW and the current span of the district cooling network is 1.6 km.

Contact information:
Turu 18, 51013 Tartu
Phone: +372 733 7100
Fax: +372 733 7108
[email protected]
fortumtartu.ee

The cooling station’s environmental impact survey shows that the station’s environmental impact is low. As the Emajõgi is a hospitable environment for the common carp, external impact on the Emajõgi is strictly regulated:

• The water temperature in the system’s outflow must not rise by more than 3 °C;
• The water temperature in the system’s outflow must not exceed 20 °C;
• The water temperature during spawning season must not exceed 10 °C.

The results of the survey show that:

• The temperature of the water returned to the river is on average 4.4 °C warmer than that of the incoming water;
• The water use of the district cooling system is ca 0.18%, i.e. 436 m³/h;
• At worst, the water temperature in the outflow area rises by 0.09 °C;
• In order to reduce environmental impact, the outlet pipe should be located in a faster-flowing part of the river.

Location: Lohkva, Luunja Parish

Type of building: Tartu Power Station is a cogeneration plant which generates electricity and heat at the same time. The electricity produced is transmitted to the electricity grid and sold on the power market of Nord Pool AS, while heat is directed to Tartu’s district heating network, which heats the city’s homes, shopping centres, commercial buildings, municipal and state agencies, nursery schools, schools, hospitals, cultural institutions, etc.

In electrical and thermal energy production, the type of fuel used is very important. Tartu Power Station only uses local fuels: 80% renewable biomass (woodchips – low-value wood, logging waste) and 20% peat (which is not considered a renewable energy source, but is local). Using local fuels improves the local living conditions and economy and provides employment. Using renewable energy is environmentally friendly and reduces exhaust gas emissions. The CO₂ emissions from burning woodchips and timber industry waste, for example, can be written off, as the CO₂ released when burning biofuels is reabsorbed by plants through photosynthesis, which means the greenhouse effect does not increase.

The energy efficiency of cogeneration comes from the fact that a certain amount of fuel simultaneously produces both electricity and heat. Producing the same amount of heat and electricity in separate stations would require 40% more fuel. The general operating principle of an electricity and heat cogeneration plant is the maximum use of fuel energy through the cogeneration process to achieve the highest possible total efficiency.

The reasons for using woodchips are explained in more detail on Fortum Tartu’s website.

Building energy figures: The heat capacity of Tartu Power Station is 50 MW and the power capacity is 25 MW.

Energy from renewable sources: Tartu’s district heating network is one of a kind in Estonia: although the majority of the heat is produced at Tartu Power Station and boiler houses using biofuels, Fortum Tartu has also launched an open district heating project with the printing company Kroonpress. This means that the extra heat generated in the printer’s production process which is not used by Kroonpress is directed to Tartu’s district heating network. This network also receives extra heat from district cooling – the heat returned from district cooling consumers is directed via a heat pump to the district heating network to heat buildings and water. The job of today’s energy companies is to offer customers products they need, based on smart solutions, while using all the energy produced in the process without wasting it.

For more information about the power station, visit Fortum Tartu’s website.

Read more (in Estonian)