CHP & DISTRICT HEATING


Identifying the benefits of a collaborative approach


Sector coupling holds considerable potential for the UK, but harnessing its potential will require forward-thinking and collaboration, says Andrew Harrop.


Andrew Harrop


Global director – regional sales enablement centres for Armstrong Fluid Technology


www.armstrongfluid technology.com


T


he UK has set ambitious targets for district energy schemes as part of a national sustainability


strategy. Currently, around 3% of UK buildings are connected to district energy networks, but the previous government has stated that, by 2050, the figure needs to be 20%. An approach which provides a roadmap for achieving this increase is sector coupling. Already gaining traction in Scandinavia, sector coupling holds considerable potential for the UK, but harnessing its potential will require forward-thinking and collaboration.


Linking energy streams Around 40% of our building energy requirements could be met from the energy that we waste. This could be from data-centre cooling (heat rejection), industry processes, power generation, waste water and numerous other sources. Sector coupling offers enormous potential, by linking energy streams and allowing energy storage in various forms to match changing demands, as well as changing outputs, during a typical 24 hour period. Sector coupling splits energy supply


into four key power grids: electricity, gas (a mix of natural, hydrogen, biogas, etc), district cooling and district heating. The four grids are divided into four areas where the energy is ‘obtained’, stored, converted or used. The source and the use are straightforward, and the more diverse both are, the better. The storage and conversion however, are the two key areas that create flexibility and allow for energy to flow across the four different power grids. The four grids and the four stages


are connected. Even the end users can be consumers or prosumers, taking


EIBI | JULY � AUGUST 2024


How sector coupling could work for a district heating system


or giving energy into the system. Sector coupling can be thought of as a network in which energy travels in all directions across every connection. Energy of all types can move from, or to, the storage, conversion and end use sectors.


Sources of energy The energy sources could include biogas, hydro-electric, nuclear, geothermal, wind, solar, and large scale CHP. Some sources will be available 24 hours a day, every day, such as nuclear for example, whilst the availability of some sources could fluctuate wildly, for example solar or wind. Geothermal, solar and heat pumps could supply energy directly into the district heating network. If renewable energy is in abundance at a particular time, then this excess energy can be stored.


Energy storage Storage is extremely important to increase flexibility of supply. Wind energy could be stored as electrical energy in batteries, can be used to pump water up to high reservoirs and stored as potential energy, ready to be released to produce hydro-electricity via turbines, or the electricity can be used by heat pumps to create heating or cooling. Gas, biogas and hydrogen can be stored using traditional methods, whilst thermal storage allows energy to be stored as LTHW, for example. In a similar way, chilled water can be


stored for cooling networks, possibly even in the same vessels, aquifers or within phase change materials (PCM),


switching from heating to cooling seasonally. However, ‘smart’ sector coupling will also be able to predict peaks in the requirement for certain types of energy. Heating and DHW demand in domestic homes normally peaks early morning and again later in the evening. Knowing this allows the smart network to increase thermal storage ahead of this known peak in demand.


Energy conversion Energy from either the source or from storage can be converted into different types of energy depending on requirements throughout the day. Electrical energy directly from solar or wind, or indirectly from storage batteries in the storage phase, can be used to produce hydrogen or used by heat pumps to create LTHW or chilled water, for example. Consumer waste can be incinerated and turned into LTHW or electricity at waste-to-energy plants. Electrical energy (either directly from source, such as solar or wind, or energy from storage, from batteries or gas powered CHP from the conversion sector) can all be used to pre-charge LTHW thermal stores in the storage sector, ready to meet the predicted district heating peak. The CHP, of course, also produces electricity. Why not use this electrical output to also power heat pumps that can further augment the LTHW store?


End users Depending on the time of day, end users could be consumers or


prosumers. Industry end users often produce heat as a by-product of processes. Very often this heat is wasted. A better approach would be to direct this waste energy back into the district heating system, or to LTHW stores for use at a later time. Typically, electrical power plants send their waste heat to atmosphere, but why not send it to a district heating network instead? Why don’t we capture the heat from wastewater processes for use in the storage, conversion or end use phases?


Harnessing technology Latest generation tools can provide more information than you might think during design and commissioning, to assist in the planning and execution of district energy projects. Digital Twinning for example (which involves the creation of virtual buildings, networks and systems) can map out exactly how efficient the new facilities will be. Armstrong Fluid Technology, for example, has a partnership with Hysopt and is now able to offer customers advanced digital twinning simulations of potential HVAC systems designs. District energy could depend on


sector coupling for its success in achieving ambitious carbon reduction targets. But our industry does not have to take a leap of faith. Harnessing the technology at our disposal, we can measure its potential effectiveness during the design and consultation stages, to speed up district energy implementation collaboratively. ■


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