Picking the right heating sources for a district heating project is often decisive on that system’s efficiency in terms of economic and environmental impact.
To begin with, a district heating system approach stands out as a more sustainable and cost-efficient option, helping optimize urban heating solutions and leading decarbonizing efforts in cities around the world.
However, it’s important for district heating structures to be guided by appropriate heating sources that further the possibilities in cost cutting and sustainability.
Find out about the top heating sources available today and how to pick the right one for your district heating project.
It may interest you: District heating energy systems: all about the heating process
What are the current heating sources in district heating systems
At the center of a district heating system and its functioning lies the central production plant, in charge of generating energy.
A common heating solution throughout the 20th century, they have typically used fossil fuels (including carbon, diesel or gas) to create heat and warm water. In fact, most district heating structures still employ fossil fuels today, according to stats published by Irena.
Because of this, the traditional approach to energy production in these plants is now outdated: high fuel and gas prices and restrictions in carbon emissions mean burning fossil fuels is no longer an option.
As diverse national and international legislations are establishing new greenhouse gas emission reduction targets, heating structures must be adjusted to meet them.
For instance, a look at the European Green Deal delineates current international efforts for sustainability. This program is putting in place a number of measures to achieve targets such as a 40% cut in greenhouse gas emissions, a 32% share for renewable energies and a 32.5% improvement in energy efficiency.
These goals have a direct effect on heating system choices today in Europe, confronting inefficient and polluting structures and facilitating the incorporation of more sustainable systems.
However, the truth is that the possibilities in heating sources for district heating systems are multiple. In fact, some of them represent a more sustainable choice than other heating alternatives. Energy generation in these central energy plants can come from sources such as:
- Large-scale thermo solar
- Heat storage
- Biogas conversion
- Centralized heat pump
- Industry surplus
- CHP waste incineration
- Service buildings
Taking these options into account, district heating systems have passed the test of time and now stand out as a sustainable and cost-efficient opportunity guiding cities’ efforts to reduce their environmental impact.
Why and how make district heating sources electric
In order to make district heating systems cost-efficient and sustainable, the first step is to shift from a fossil fuel burning paradigm to one that is guided by electricity. As a consequence, electricity is in charge of heat generation.
There are two options to do so: opting for an electrical boiler or picking an industrial heat pump (- as known as large scale heat pump).
In terms of efficiency, industrial heat pumps stand out as the best system for district heating projects. This is calculated by looking at each system’s coefficient of performance (or COP). This measures the ratio between how much heating energy a system is able to generate against how much electrical energy it consumes.
While electrical boilers present a COP that equals 1, industrial heat pumps provide a COP that varies between 3 to 6 units. In other words, a well-adjusted heat pump can deliver between 3 and 6 times more heat output than the equivalent of the electric input it uses. In light of such figures, the choice of a large scale heating pump remains the most efficient and sustainable.
Other data confirms this preference for heat pump systems: for instance, the US Energy department calculates that ducted air-source heat pumps can reduce electricity use for heating by approximately 50% compared to other structures.
All in all, analyzed from a full life-cycle perspective that includes both operational and maintenance processes, heat pump heating stands out as the wisest choice in heating technologies today.
How to pick the best heating sources for an industrial heat pump
But a reduction in energy consumption is not the only environmental and economical benefit that heat pumps can bring about: these systems can also incorporate renewable and economical energy sources into the equation, further improving their performance and sustainability.
Explained briefly, heat pumps work by absorbing heat from an external source and delivering it at a sink. These external energy and heating sources for a heat pump are multiple. The current available sustainable heating technologies include:
- Geothermal sources: capturing heat from underground water
- Sewage water: makes the most of recovering waste heat
- Residual heat from industries: it can be recycled and incorporated into heat pump systems
- River and seawater: although this source typically presents lower temperatures
- Combined heat and power plants: these use residual heat from burning fossil fuels in order to obtain energy in a process also known as cogeneration (they generate both electricity and heat).
- Biomass: they employ energy from the burning of natural and renewable elements (from trees to agricultural waste).
- Solar heating technologies: converting sunlight into electricity by using solar cells
- Wind-powered technologies: they employ energy from the wind.
- Biodiesel heating technologies: a cleaner and renewable alternative to burning fossil fuels
The choice amongst these heating sources must be aligned with each project’s needs and capacities. The following criteria can guide the decision when choosing the best heating sources:
- Availability: some locations may have easy access to sewage water sources; others will easily employ geothermal energy; others can make the most out of residual industrial heat; and so on.
- Cost benefit criteria: project managers must also look at current carbon regulations, potential taxes and or tax-exemptions and electricity costs
- Efficiency: each of these possibilities presents different performance levels, which should be taken into account when considering what is the most convenient option for a particular heating system.
- Reliability: heating sources should also be chosen taking into account their potential reliability. This includes their current price stability and other social and economical issues that could potentially interfere with a heating system’s functioning.
The truth is the multiple energy sources available for heat pumps in district heating make them an all-around system that brings about multiple benefits. Those projects that have taken the step to move to heat pump DH structures report the following advantages:
- Local and sustainable energies can be incorporated, having a positive economic impact on communities while reducing external dependencies.
- The incorporation of these alternative, local energies also means communities are less dependent on constant fluctuations on gas prices.
- The possibility of incorporating industrial energy waste or sewage water energy as a heating source is synonymous with generating synergies between supply and production. As a consequence, circular economy models are generated, further extending these systems' claims for sustainability.
- An adequate approach and design of district heating systems may also mean projects can have access from governmental economic support aimed at cutting CO2 emissions.
- Cost reduction may also come from these system’s enhanced heat storage possibilities, as well as from the incorporation of automated technologies that are based on use patterns and weather prediction parameters.
All in all, in order to build adequate district heating systems, it’s crucial to rely on trusted experts and suppliers in heating technologies.
The design and implementation of sustainable and efficient district heating systems, as well as the choice of the right heating sources, will then be in good hands, in charge of picking the most sustainable, cost-effective solution for each project.
Learn more about heating sources and district heating models by downloading our free guide ebook ‘District Heating’ where you’ll find the current heating technologies that are being implemented to achieve decarbonization, energy efficiency and cost reductions.