District heating and cooling (DHC) networks distribute heat and cooling to consumers. This can come from combined heat and power (CHP), conventional boilers or waste heat from industry. It can power industrial processes, heat buildings, or provide cooling via an absorption chiller.
DHC networks can serve a variety of consumers. Peaks and troughs in the heat required by individual consumers or consumer types can be smoothed by serving multiple demand profiles, such as the differing requirements of residents or businesses. This can create a consistent base-level demand for the DHC network, which is ideally suited to CHP’s ability to achieve maximum operational efficiency when meeting a constant demand.
The combination is scalable and equally suitable for individual sites and community networks. CHP/DHC is a proven technology that provides heating to homes, businesses and industrial premises. Climate change, pollution and rising energy costs have driven demand for new installations. In the UK there are now over 17,000 DHC networks.
Below, we take a look at how you can manage the typical applications of district heating networks and CHP, from optimisation right through to management.
Local DHC networks typically use a concentrated generation model. Boilers and CHP systems are housed in a strategically located plant room connected to consumers through a network of heavily insulated pipes. This approach minimises the expenditure on generation equipment infrastructure, including fuel supplies, plant housing, network connections, exhaust management and security. However, it introduces a single point of failure where a catastrophic event, such as a plant room fire, could disable the whole network.
Community DHC networks typically use a distributed model of generating heat on-site at the individual developments served. Distributed generation adds resilience and reduces transmission heat loss. However, distributed generation increases the total heat network cost because multiple plant rooms are needed, each with their own fuel supplies, network connections, waste management and security.
Many sites, including hospitals, distribution centres and ports. have 24/7 heating or cooling requirements suited to CHP/DHC. Sites where demand shifts through the day are also suitable. For example, a university sees demand focused on the teaching facilities, laboratories and offices during daytime, but this migrates to the campus accommodation in the evening, creating a constant demand for most of each day.
CHP is efficient when serving a constant demand for heat and power. The longer it is operational, the greater the savings and environmental benefits. To maximise returns, CHP is sized to meet the base-level demand for heating and cooling. Additional demand for heat is met by boilers, and for electricity by generators or the grid connection.
The electricity generated by a CHP can be used to power plant room systems and help meet local site demand. The savings of self-generating low cost power can be set against the CHP running costs and can provide resilience for the DHC network in the event of an interruption to the grid electricity supply.
DHC networks can also scale easily. Hot water created from capturing the waste heat of CHP generation, or reclaimed from industrial processes, can be integrated into an existing network. New consumers can be connected by adding distribution pipes and demand growth can be met by adding new CHP or boiler systems.
DHC comes with an inherent risk. It serves many consumers, so a loss of service will have a significant impact and risks reputational damage for the operator. The risk is mitigated through the network design. CHP and on-demand boilers reduce the severity of single equipment failure. The risk is also mitigated by real-time remote monitoring and scheduled maintenance to identify and rectify problems before they become critical. The equipment supplier/installer must be experienced and have sufficient capacity to maintain the system and rapidly respond to failures.
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