Mission Green Sofia: Ways to Decarbonize District Heating

We talk to Mariana Iteva, Deputy Regional Director of Veolia Bulgaria, about the important sector of district heating in cities.

От МOVE.BG, публикувана на 5 април 2024

As part of MOVE.BG's "Mission Green Sofia" initiative, we continue to look for ways for a successful green transition of Bulgarian municipalities. Today, we are focusing on an important topic - centralized heat supply and possible solutions for the decarbonization of this sector. On this topic, we are talking to Ms. Mariana Iteva, who is Deputy Regional Director of Veolia for Bulgaria

District Heating

The largest company of this type in Bulgaria is “Toplofikacia Sofia” - the district heating (DHN) company of Sofia Municipality that is responsible for 70% of all users of district heating in Bulgaria. Currently, the company is owned by Sofia Municipality, and the municipal authority will retain control after the Ministry of Energy buys the BGN 1.6 billion debt of  “Toplofikacia Sofia” to the state-owned Bulgarian Energy Holding (BEH), according to a recent decision of the outgoing government.

The transformation of the Sofia district heating company is one of the unsolved tasks not only for Sofia Municipality but also for our country due to the scale and the effects of the “Toplofikacia Sofia”'s impact. Therefore, this topic was among the issues discussed during our event "World Cafe Mission Green Sofia: Ready for the Future", dedicated to developing recommendations for a successful green transformation of Sofia and other municipalities in Bulgaria. The initiative has brought together 55 leading experts from various fields - representatives of the private sector, the financial sector, scientists, and NGOs, as well as representatives of the Sofia Municipality and the Bulgarian government. In April, MOVE.BG will present the experts' ideas in a special report with over 150 recommendations for a successful green transition in Sofia and other municipalities in Bulgaria

One of the participants in "World Cafe Mission Green Sofia: ready for the future" is Ms. Mariana Iteva, with whom we are talking about the ways to decarbonize the district heating sector and about Veolia's experience in this field, both from Bulgaria and abroad. Veolia operates on five continents and in 2023, the group served 113 million people with drinking water and 103 million with wastewater services, produced 42 terawatt-hours of energy, and recovered 63 million metric tons of waste. Among “Veolia”s assets in Bulgaria are “Sofiyska Voda”, which provides full water cycle management services to the capital Sofia, “Veolia Energy Varna” EAD, which operates the district heating in the second largest city in Bulgaria - Varna, and Veolia Solutions Bulgaria, which is among the leading companies in providing on-site services to industrial customers as well as energy efficiency services for buildings.

Ms. Iteva, why are the sector of district heating and its decarbonization important topics?

Climate change is challenging our economic system, forcing us to review our needs and analyze what energy to conserve so that its impact is as planet-friendly as possible. Developing the capacity to generate energy from different renewable sources locally provides strategic autonomy, which is an indispensable advantage in the energy transition

District heating systems are one of the best ways to tackle so-called low emissions - fine particulate air pollution in small and large towns where boilers running on low-quality fuel with high hydrocarbon emissions (e.g. coal and household waste) are used to heat homes. An additional advantage in favor of the development of this sector is the fact that CHP technology, which ensures the simultaneous production of electricity and heat in a single process, is the most efficient way of producing energy. However, it should not be forgotten that the process itself does not prove that the solution is environmentally friendly. The key to reducing emissions is fuels, circular economy solutions, and a range of energy efficiency measures. 

What are the possible solutions for the decarbonization of the district heating sector, based on the experience of Veolia?

Nowadays, you cannot rely on one solution or one type of fuel. A combination of several solutions is needed for a truly sustainable transformation and development.  

It is of utmost importance for all district heating companies to develop local sources of decarbonized energy as soon as possible in order to achieve fuel diversification.  This will increase the efficiency of the companies and strengthen their strategic autonomy.  

Natural gas should be seen as a transitional fuel. This is due to the fact that it is associated with less carbon dioxide (CO2) emissions and the possibility of using it with environmentally friendly and decarbonized gases such as biomethane and green hydrogen in the future. 

District heating systems are based on a district heating network which, as it develops, will provide the opportunity to implement a model integrating different decentralized renewable energy sources using heat pumps to recover energy that is wasted today, for example from wastewater, server rooms, or industrial processes.

Under European Union regulations, some waste cannot be landfilled, making it appropriate to recover energy and heat from it. The market advantages of such a solution are to reduce dependence on imported fuels and to valorize waste streams. There are more than 500 clean waste-to-energy plants in Europe that are operating in full compliance with environmental requirements and bring value to society.

It is also necessary to look for synergies. What is considered waste today can be used in different ways. The concept of a circular economy should therefore guide initiatives in the areas of energy, water, and waste. The synergy between wastewater management and district heating also provides an opportunity to diversify fuel for Sofia district heating. 

Veolia is the operator of Sofiyska voda. Are there good solutions from the management of water and sewerage services that can be used to decarbonize district heating?

There are many things in common in the management of water services and district heating regarding decarbonization, including the recovery of heat from wastewater and the possibility of producing biogas from the sludge from wastewater treatment, which can then be converted into biomethane. 

Biogas can be used locally in a cogeneration system (this is already being done at the Sofia wastewater treatment plant in Kubratovo) and to provide green heat for the district heating network or it can be converted into biomethane, which is then fed into the gas grid. 

The potential for energy recovery from wastewater should be seen as an element worth considering in the efforts to develop sustainable energy and heating. Similar projects have already been implemented in Hungary, Poland, and France just to name a few of them. The solution can be combined with a heat pump-based installation and an additional CHP system. 

"Sofiyska Voda", the operator of the water and sewerage system on the territory of the Sofia Municipality, is already in the process of assessing the potential in Sofia for wastewater heat recovery and is on its way to becoming the first water and sewerage company in the region to achieve full energy neutrality thanks to the production of green electricity and heat from wastewater treatment. 

Another possible local energy source is biogas from landfills, which can be captured (recovered), processed into biomethane, and fed (injected) into the district heating systems.  

Similarly, waste heat from the industrial production process can be recovered and fed to the district heating network. 

The benefits of such projects primarily include reducing CO2 emissions to the atmosphere and providing recovered (decarbonized) heat energy. They also have the advantage of contributing to affordable energy sources which are untapped at the moment.

During the event "World Cafe Mission Green Sofia: Ready for the Future", in which you also participated, geothermal and solar energy was mentioned as an important part of the solutions for the decarbonization of district heating. What is your opinion? 

Another way to decarbonise district heating systems is to use geothermal energy as a fuel which is perceived as one of the most efficient solutions. The use of this type of energy is mainly determined at the local level - an analysis of suitable geological parameters such as depth and volume of the source, as well as suitable water parameters, e.g. temperature, on which the heat energy potential directly depends. The analysis of these parameters is important because they affect the capital expenditure costs, the profitability of the investment itself, and the competitiveness of the heat prices offered. 

Veolia operates geothermal heating networks in France (where over 87% of geothermal energy is used for heating) and Hungary, and we are also developing a similar project in Poland with a very promising capacity of 100 MWh for heating purposes.

Solar thermal energy is another source with significant potential in district heating systems, especially in the context of the sector's transformation process. This is also consistent with the model of district heating networks integrating different decentralized renewable energy sources. 

The key to using solar panels on an appropriate scale is seasonal energy and, therefore, thermal storage technologies - technologies that collect and store excess energy and thus provide power at times when sunlight is weak. Renewable energy sources of this kind are therefore a good complement to a district heating system while increasing its efficient operation. The use of this technology is widespread in the Nordic countries. We have already implemented the first project of this kind in Poland.  

Flexibility is also important due to a number of factors - the market is constantly changing, new trends, technologies, and regulations are emerging, the geopolitical situation is changing, as is customer awareness. All of these factors are crucial for the green transition, and especially in the energy business. Their constant monitoring, as well as the demand for innovation, allows for the continuous adaptation and change of plans and strategies, as a result of which they can not only remain competitive but above all continue to develop.

The approach at the European level is for diversification and decarbonization measures to go hand in hand and in sync with energy efficiency measures. What is your opinion?

At Veolia, we call energy efficiency our "first choice of fuel", because the cheapest energy is the energy that is not consumed. Today, some of the electrical and thermal energy is simply wasted.

At Veolia, energy efficiency measures are implemented in a comprehensive manner and can be divided into several categories. The first of these is the efficiency of energy production sources. This category includes, for example, the development of energy storage systems - thermal batteries - which allow us to increase source flexibility and at the same time reduce the amount of fuel used in production processes. 

The second category is related to the network itself. Here, innovations and technologies based on big data and artificial intelligence are used to optimize the performance of the entire network, thereby reducing the amount of energy needed to heat homes while maintaining the same thermal comfort. 

The last category is directly related to customers and their apartments. This category includes investments in thermal insulation, as well as changes in habits, even seemingly minor changes in consumer behavior that avoid excessive heating of homes.

The energy transformation of district heating systems requires integrated solutions that address the energy transition in its entirety and include simultaneous decarbonization measures through the development of local, decentralized renewable sources and the implementation of energy efficiency measures.

Mission Green Sofia

An initiative of MOVE.BG in support of the successful green transformation of Sofia and its becoming a model for green development of other municipalities in Bulgaria.

Mission Green Sofia: Sofia can be a place for a happy life.

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