The district heating plant represents the heart of any district heating system, pumping energy, as such, its optimum design and efficiency shouldn’t be underestimated.
Recent advances and developments regarding district heating plant design respond to the growing interest in the advantages of district heating. In fact, there are many factors leading to the prevalence of the district heating system today, including a perfect mix between increasing heating energy demand from urban city districts, as well as the need to transition from fossil-fuel heating to renewable energy sources, as well as models that employ waste heat and other circular economy potentialities.
A district heating system can, in fact, incorporate all such benefits, which is the main reason why both private operators and governmental actors are favoring this model today. In fact, as the IEA reports, in 2021 district heating was already meeting 8% of the global final heating demand in both building complexes and industrial contexts. This percentage represented a 3% increase from the previous year, a growth guided by these networks “great potential for efficient, cost-effective and flexible large-scale integration of low-carbon energy sources”.
However, not all district heating networks are the same, and steps must be taken to ensure they reach their maximum potential in terms of sustainability and efficiency, including the move towards renewable energy sources.
As such, we want to provide a brief guide about the design principles that should guide a district heating plant project today. Keep reading to find out.
District heating plant: a definition
The analogy of a district heating plant being the heart of a district heating system works well because, in fact, it stands at the center of this heat distribution model.
The district heating plant can thus be defined as the infrastructure that, within a district heating system, is in charge of generating heat that will be then distributed from this centralized location.
As such, it works in sync with the rest of the elements in these structures, including the distribution piping network, the energy transfer stations, and integrated control systems.
The role of design in enhancing a district heating plant
As the adoption of the district heating system continues growing, heating technologies are facing the challenge of achieving two goals:
- Increase the equipment’s efficiency
- Extend the share of renewable energy sources used in heat supply
Design concerning heating technologies stands at the center of this. As such, correct design initiatives will take into account the following good practices:
- Incorporate an end-to-end approach: professionals should be able to offer services that take a project’s full life cycle, from consulting to design, manufacture and implementation, all with a personalized approach.
- Prioritize efficiency: a district heating plant can incorporate a wide range of technologies for its operation. In this context, professionals should make efficiency a priority during design considerations, including sealing and insulation options, as well as the incorporation of thermal storage technologies.
- Maximize sustainability: citizens, public administrators and private actors are coalescing in the quest for maximizing sustainability. The possibility of a district heating plant to incorporate sustainable, local and non-fuel heat sources pushes these efforts a step further.
Tips to maximize performance in a district heating plant
As more and more design initiatives look for an optimal performance in district heating, different formulas are devised and experimented.
It must be noted that, when it comes to designing a district heating plant, each design enterprise must take into account the needs of each specific project. However, there are certain procedures that have been proven successful which can be applied to a majority of cases.
This is the case of research that confirmed two elements are typically involved in the generation of an efficient district heating system: leveraging the role of the prosumer and Thermal Storage solutions.
Let us go through these and other current possibilities to enhance a district heating plant efficiency today:
1. Picking the right heat pump
Large-scale heat pumps are allowing district heating to make the shift from burning fossil fuels to using electricity to generate substantial heat, even if it originates from low-grade sources.
This is because this equipment’s unmatched efficiency ratios, which are measured by the coefficient of performance (COP). This calculation measures the ratio between the heating energy that is generated and the electricity that is consumed. The result for industrial heat pumps is an outstanding COP of between 3 to 6 units (that is, delivering between 3 to 6 times more heat output than the input). The US Energy department has provided solid support to these efficiency figures: when conducting their own research, they found ducted air-source heat pumps can reduce electricity use by 50%; while geothermal heat pumps can reduce energy use by 30%-60%.
In other words, heat pumps are able to provide heating energy from renewable sources in an efficient manner and incurring low operational costs.
2. Make the most of energy ‘prosumers’
The prosumer stands out as a new player in the field of energy generation that is enabled by district heating design. Due to the outstanding energy efficiencies we’ve mentioned above, this model recognises certain buildings are able to generate heating surpluses.
A well-designed network will then stimulate the leverage of these heating surpluses in a circular model that understands sharing as a source of abundance which can lead cities to increased sustainability.
As such, different sectors and buildings aren’t restricted to a passive role, as they not only receive heating energy but are also able to produce it. This approach has been recognized by different organizations as a winning formula, including the ‘EU Strategy for Energy System Integration’, part of the European Green Deal, which mentions the need to promote local-based, ‘multi-directional’ heating networks that integrate heat surpluses.
3. Understanding and choosing the right heating sources
The choice of heating sources plays a key role in a district heating plant efficiency, but also in its environmental impact.
The IEA report we mentioned at the beginning of this article is extremely confident about the potential for district heating to revolutionize the heating energy industry. However, the organization is also cautious when it mentions that fossil fuels still dominate most district network supplies, being responsible for about 90% of total heat production today, particularly in certain geographical locations that represent the two largest markets (China and Russia).
However, the same report is particularly ambitious considering the “large potential for the integration of renewable sources” in district heating solutions. In fact, heating sources for a district heating plant are varied and include a wide number of renewable energy sources such as:
- Large-scale thermo solar
- Heat storage
- Biogas conversion
- Centralized heat pump
- Industry surplus
- CHP waste incineration
- Service buildings
Many initiatives are already making the most of this possibility, with certain European countries leading this integration: the report cites countries such as Sweden, Denmark, Austria, Estonia, Lithuania, Latvia and Iceland as locations where more than 50% of district heat originates in renewable sources.
The use of renewable heating sources will not be a choice in the short and mid-term: initiatives such as the European Green Deal are already pushing operators to cut fossil-fuel emissions by 40% or reach the use of renewable energy sources in percentages that are beyond 30%.
In this context, the potential for adequate district heating plant models to incorporate locally-available and renewable energy sources (even those considered “low-grade” sources) represents a promising option for present and future sustainability efforts.
4. Paired with thermal storage solutions
As we’ve mentioned above, district heating formulas are increasingly incorporating Thermal Storage solutions as an answer to increase heating efficiency. The way these systems work is they accumulate thermal energy during off-peak hours to be used in peak hours or when its production is more expensive. This means solutions like TES tanks are an ideal ally to increase district heating plant efficiencies, allowing the infrastructure to deal with energy peaks and lows as well as their impact on costs and energy consumption.
Want to learn more about current district heating plant design considerations and how to have access to the efficient and sustainable heating technologies your project needs?