Author: Riga Technical University, Latvia

The goal of this study is to assess environmental impacts of different renewing / modernising scenarios of an existing District Heating (DH) system to a Low Temperature District Heating (LTDH) system. This pilot case study is implemented by Riga Technical University as part of the LowTEMP project.

LTDH can lower energy losses, reduce the operation costs and contribute to renewable share in energy mix. To assess specific environmental impacts like damage to climate change, resources, ecosystem quality and human health created during LTDH construction and operation, this particular case study implements a life cycle analysis approach to provide an assessment on environmental impacts of different DH modernising scenarios of an existing DH system to a LTDH system, which also include solar PV installation. This study shows how life cycle analysis contributes to raising awareness of environmental impacts that can be caused by DH systems. It is an essential tool to cover the knowledge gaps of stakeholders involved in infrastructure planning and reconstruction.

The scope of the study includes four scenarios for DH located in the Eastern part of Latvia:

  • Scenario 1: New DH with supply and return temperatures 60/35°C
  • Scenario 2: New DH with supply and return temperatures 60/35°C and solar PV
  • Scenario 3: New DH with supply and return temperatures 90/60°C
  • Scenario 4: Old DH with supply and return temperatures 90/60°C

As results show, Scenario 1 has the least impact on the environment, while Scenario 4 has the most impact on environment with the highest score in terms of number of equivalent persons affected during one year per unit of emission. Scenario 2 and 3 have the similar single score result, but show different results in damage categories: Scenario 2 has a higher score in climate change and resources category, but Scenario 3 a higher score in the human impact and ecosystem quality category. Overall, the highest impact is for human health for all the scenarios, followed by ecosystem quality category.

In all scenarios, DH operation in terms of heat production and ash treatment showed the highest contribution to environmental impact. This is a proof that more work should be made towards a reduction of fuel consumption of boiler houses form an environmental point of view. In general, the results of this study will contribute to the development of more sustainable action plans for LDTH concepts within the DH management and operation structures.

The results of this study will be turned into a scientific paper and published in the Journal of Environmental and Climate Technologies. Furthermore, RTU will present the case study in the frame of the Conference of Environmental and Climate technologies (CONECT) 2019 in Riga.

Photocredits: Riga Technical University, Lativa