District heating needs a green transition – but how can we achieve a cost-efficient tran- sition process? A literature review has shown: There are several scientific approaches to developing theoretical heat strategies. However, when it comes to implementing and operating district heating systems, no systematically developed methodology facilitates the green transition over its lifetime. BOOSTING GREEN DISTRICT HEATING TRANSITION
By Peter Lorenzen, Ph.D. in industrial engineering, waermewerk.eu
As a further result of this research, available methods, technol- ogies, and tools were clustered to these DH scopes. Finally, it was identified that there is no comprehensive methodology for the scope of the organization, design, operational planning, and operation that aligns the related activities so that all facili- tate the green transition.
In Germany and many other European countries, natural gas has been seen as a climate-friendly substitute for coal and oil. But it is neither an emission-free technology nor a low-cost alternative (since February 2022). To achieve the climate tar- gets with large social support, we need a fast green transition in the heating sector, which is economically affordable to all consumers. Although the green transition of district heating systems (DHSs) started years ago, there are still barriers to a beneficial integration of renewable (combustion-free) heat sources. This derives—at least partly—from the existing business logic that is based on the established fossil technologies and their high temperatures. Therefore, the objective of my dissertation was to develop a methodology that facilitates the green transition cost-effi- ciently. The result is a framework that aligns relevant activities in the scopes of design, operative planning, and operation by technical and economic mechanisms. This article presents an overview of the main development and results. Lock-in to high temperatures Established technologies in DHSs are mainly based on the com- bustion of fuels like coal, oil, gas, and non-biomass waste. These combustion processes can produce high supply temperatures. In contrast, most renewable technologies—such as heat pumps, solar-thermal plants, geothermal plants, and surplus heat from industry—are not able or not cost-effective to produce heat at high temperatures. This leads to a lock-in effect of the estab- lished business models at high temperatures (figure 1). Identifying structural challenges in the lifetime of a DHS Structural challenges were analyzed from a systemic perspec- tive to resolve this lock-in effect. To do so, a systematic litera- ture research was carried out to identify the fields of activity. Figure 2 summarizes the specified DH scopes.
There is no incentive for temperature reduction
Conventional (combustion-based) heating plants only marginally benefit from lower supply temperatures
These effects result in a lock-in effect of established businessmodels of conventional heating plants with high temperatures.
Renewable (non-combustion based) heating plants are not competitive at high supply temperatures
Figure 1. The log-in effect of high temperatures The figure illustrates the lock-in effect of high system temperatures. Since conventional plants do not benefit greatly from lower system temperatures, there is no significant incentive to reduce the temperatures in existing DHSs with high temperatures from conventional heating plants. At the same time, the high temperatures impede a cost-effective connection of renewable (combustion-free) heating technologies. And if no renewable heating technologies are connected, there is no direct benefit from reducing temperatures in the existing system.
10 HOTCOOL no.4 2023
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