According to the United Nations, cities globally are responsible for 60-80% of total energy consumption and 75% of CO2 emissions. As communities continue to grow, these numbers are also increasing, making energy efficiency in cities one of the most effective ways to mitigate the climate crisis. Karol Juszczak from Alfa Laval emphasizes that this transformation does not have to require significant financial outlays. Starting with the effective use of the resources we already have is essential. He points out that waste heat is a still untapped resource in cities. This lost energy, from sewage treatment plants, data centers or industrial plants, could be successfully used in different ways.
“In Polish cities, we already see a number of investments – both in public transport and in infrastructure – aimed at improving their energy efficiency. These include the thermal modernization of buildings and investments aimed at utilizing waste heat, to maximize efficiency and minimize energy losses,” says Karol Juszczak, Head of the Energy Department at Alfa Laval Polska.
Despite occupying only about 3% of the Earth’s surface, cities house around 3.5 billion people, nearly half of the global population. Projections estimate that by 2030, this number will increase to around 5 billion, meaning that roughly six in ten people will be city residents. This advancing urbanization implies that the impact of urban areas on the environment and climate will continue to grow. On the other hand, they are also where numerous negative phenomena, such as air pollution, are concentrated.
“City goals increasingly aim for sustainable development. This involves ensuring the best living conditions for residents and minimizing their environmental impact,” Alfa Laval expert explains. It includes effective energy management in both production processes and buildings, utilizing resources available in the present, responsible water resources management, designing liveable spaces, creating new modes of sustainable transportation, recycling as broadly understood, resource recovery and education, fostering awareness among residents about the importance of resource management.
According to Juszczak, considering the growing emissions, energy efficiency in cities may prove to be one of the most effective ways to tackle the climate crisis. The conclusions from COP28 specify that efforts in this area should double by 2030 to fulfill the objectives of the 2015 Paris Agreement. To achieve this, large-scale actions are necessary.
“City transformation doesn’t necessarily have to be expensive,” asserts Juszczak.”For example, Poland has a powerful district heating network, so it’s a matter of modernizing it and embracing new technologies. In the case of office buildings or large apartment complexes, a comprehensive approach involving thermal upgrades and provision of affordable, clean energy can generate savings of up to 30–50% of their annual operating costs.”
Waste heat from sewer plants can be used to boost temperatures in heating networks. Furthermore, data centers produce enough heat, which can potentially be used for city hot water systems. According to Alfa Laval experts, 90% of electrical energy consumed in a data center is converted into heat. If waste heat from servers was fully utilized for heating purposes, 3000 TWh could be saved annually. That’s enough to heat 300 million European households.
Alfa Laval cites an example of implementation in Hamburg, where they managed to generate savings of 160,000 MWh per year using heat from chemical plants – reducing CO2 emissions by 20,000 tons and water consumption by 12 million m³. This heat supplies around 3,500 buildings.
To manage energy and resources more efficiently within a city, broad cross-sector cooperation and integration of various entities and industries are necessary, for example sewage treatment plants, server rooms, industrial plants, and energy companies.
Juszczak concludes: “In cities, we have a wide range of possibilities for transformation. We can start by utilizing the resources we already have available, and simply connect plants that have an excess of heat with users who need it daily. This can improve parameters, generally lower operating costs and electricity bills.”
