What is district energy? District energy is a system for distributing heat generated in a central power plant (steam, hot water) for residential and commercial requirements such as space heating and hot water. The heat carrier is transferred through insulated pipes from the point of generation until the end user. The advantages of this technology are summarised in the following points:
Improved energy efficiency
Reduction of GSHG emissions
Fuel flexibility
High level of control and monitoring
Reliability
Use of consumer diversity
Low maintenance costs
History District energy is not a new concept. The first generation was introduced in USA back in the 1880s. The main characteristic was that it exploited the heat generated from steam. The drawbacks of this generation is that high steam temperatures are achieved by introducing significant heat losses, which means low energy efficiency, poor structural integrity (corrosion) and in some cases accidents due to steam explosions.
The second generation emerged in 1930s and dominated until 1970s. The means of heat transfer was hot water instead of steam in the first generation. The supply temperature was usually over 100°C. The primary aim was to achieve fuel savings and flexibility in the operation of Combined Heat and Power (CHP).
The third generation was introduced in 1970s and it is an established technology until today. The heat carrier is hot water. However, the supply temperatures are below 100°C. This is one of the main benefits as lower temperatures lead to higher energy efficiency. The reason for implementing this generation is to reassure the security of supply deriving from fuels such as coal, biomass and waste which are replacing oil. This technology enables the reduction of operational and investment costs.
Overview of the evolution of district energy
Why 4th generation district energy? Fourth generation district energy networks, also known as smart energy systems, are the most recent. They are a combination of smart electricity, thermal and gas grids used in order to provide an optimum energy supply solution to a community. This concept involves the implementation of sustainable energy systems based on renewable energy in conjunction with better energy efficient buildings. The main advantages of this generation are the following:
Lower distribution temperatures
Higher efficiency
Prefabricated materials which in turn resulted in less man power involvement
