Climate and Sustainability

The Energy and Liquids Production and Distribution Company “ENERGETIKA” Kragujevac is a state-owned enterprise whose main business area is steam supply and air conditioning. In addition to this core activity, the company is also involved in the following areas:

• Conversion and distribution of electricity
• Production and distribution of demineralized water (DM).

Following the restructuring of the Zastava Group on December 31 of the year 2000, Energetika became an independent business entity based on the founding agreement. In 2021, coal-fired boilers were replaced with gas-fired boilers, and the new plant is expected to be operational during the 2022/2023 heating season. This project has significantly reduced the pollution caused by the heating plant.

The goal of the project is to use the waste heat from a data center and feed it into the district heating network using a heat pump. The data center is planned in two phases, with the first phase having been operational for less than two years. The total usable area of the data center is 15,000m². The internal temperature for the IT systems is set at 21°C and is cooled by electrically powered chillers. The data center is located near the Aerodrom Boiler Plant.

The current cooling capacity of the two modules is 4.4MW. With the planned expansion of the data center to four modules, the cooling capacity is expected to double in the coming years. The cooling system is designed for redundant operation. Decentralized air-cooled chillers with integrated heat exchangers are used. In total, about 32 units will be installed, with 16 already in place, providing approximately 275 kW of cooling capacity per unit. The supply and return temperatures of the cooling water for the chillers are designed to be 5/10°C.

The heat from the chillers can generally be utilized in two ways:

• Heat recovery from the condensation heat
• Heat recovery from the cooling water

Both methods should generally be possible, but using the cooling water cycle would be the simplest, as no modifications to the chillers are required. Two rooms are hydraulically connected to two chillers. In this case, an additional heat exchanger can be used for two rooms, meaning that a total of 16 heat exchangers will be required (8 for each module).

The average heat output from the server rooms is currently about 1,920kW, and it is expected to double in the second phase of expansion. Based on the current situation, the rated capacity of the heat pump is up to 2MW. In full operation, the heat pump can provide up to 4MW of heating power. In this case, it is possible to split the load between two machines, which brings many advantages (backup, stable operation, partial load, etc.). This evaluation considers the full expansion.It is planned to integrate the heat pumps into the return circuit to increase efficiency. The electrical savings of the data center were calculated based on an average heat output of 700 kW per module (2,800 kW in total). The waste heat potential of the data center can reach up to 6.3 MW in full operation, which increases the heat pump capacity and electricity savings, thereby improving the economic parameters of the project. The effects on the system and the equipment will be examined in the feasibility study.

District heating is an effective way to optimize the use of available heat sources, reduce the carbon intensity of heat, and lower fuel costs. In the long term, the city of Kragujevac has a clear role in addressing the challenges of climate change by already beginning the decarbonization of its district heating system. According to the Republic of Serbia’s energy sector, development strategies, until 2035 the reduction of greenhouse gas emissions, adaptation to the impacts of climate change, and reaffirmation of low-carbon references will be the next phase of Kragujevac’s transition to a low-carbon future. The strategy has set clear goals for the district heating sector, which the city administration will pursue, such as:

• Providing heat for the secure supply of households and industry, while strictly adhering to environmental protection standards.
• Increasing energy efficiency in generation, transportation, distribution, and heat usage.
• Strengthening the use of renewable energy sources.
• Ensuring sustainable operation of the heat generators.

To achieve these goals, the following key measures must be taken:

• Continuous modernization of existing district heating systems.
• Introduction and application of a unified tariff system for heat generation, distribution, and supply.
• Institutional linking of the systems.
• Expansion of the existing district heating system.

The city of Kragujevac must play a clear role in addressing the challenges of climate change by already beginning the decarbonization process of its heating system. As a transitional step, the city has implemented the project to modernize the hot water system—constructing 5 new boilers with a total capacity of 110 MW and switching from coal to natural gas in the “Main Site” boiler plant. In the long term, further efforts are needed to utilize renewable energy sources (RES), and energy efficiency measures must be significantly enhanced. However, these efforts must be measured and quantified to understand whether the promised goals can be achieved. The main tasks in planning and implementing district heating projects are to generate district heat as cost-effectively as possible, achieve a high energy standard for as many people and businesses as possible, and ensure sustainable development.