LCA of Low-temperature District Heating Network Components

Abstract: Following the development of new materials and the continuous technical progress made in the construction and energy industries, district heating as a concept finds itself on the brink of a generational shift. One of the pioneering projects leading the way is the creation of Brunnshög, an modern and sustainable district under construction in the north-eastern end of the city of Lund, Sweden. The area boasts a brand new low-temperature district heating network that is made up of both conventional steel district heating pipes but also recently developed ones where the steel has been replaced with temperature resistant plastic. Kraftringen, the energy company in charge of the network, are interested in the environmental profile of the new additions to the district heating market and how they compare to the standard pipe units. A life cycle assessment, or LCA for short, in the shape of a master's thesis is carried out to try to provide an answer. The study examines a specific scenario and part of the district heating grid at Brunnshög where both pipe options could be installed and used. By establishing the number of pipes and additional components needed to create that particular branch of the network, the life cycles of both structures are mapped out and evaluated. The result of the assessment is divided into four distinct categories, each representing a specific environmental issue. The plastic system, referred to as PE-RT in the report, is according to the study the slightly worse alternative in three out of four categories. The major culprit is the lower thermal insulation capacity in the studied PE-RT pipes which indirectly lead to an increased output of emissions from heat generation in power plants and similar production units. Ignoring this particular feature, the conventional steel district heating pipes are the poorer alternative in every part of the life cycle and each environmental category. The production of steel is especially hefty in the perspective of global warming. All things considered, both options perform similarly well and the small difference in the result makes for reasonable plausibility that another LCA investigating the same topic would yield a set of different conclusions. The report also aims to act as a comprehensible introduction to the field of life cycle assessment, providing an extensive theory chapter and a general report structure emphasizing accessibility. This master's thesis concerns a case study and any result provided is first and foremost applicable to the investigated scenario. Any attempt to apply the findings on other similar contexts or the district heating industry in general should be done cautiously and only if there is an sufficient resemblance to the presented scenario.