Foto: Schiestlhaus

Manage_GeoCity - Development of a method for the coordinated management of geothermal energy in urban areas

Based on the urban region Graz a method is being developed for the coordinated use and management of shallow geothermal energy for heating and cooling as well as seasonal heat storage in urban regions. Ground water flow, different geologic conditions, heating and cooling demand, heat input from solar collectors and industrial waste heat and the possibilities of seasonal heat storage in the subsurface are considered.

Short Description

Status

ongoing

Summary

Starting point / motivation

Due to the numerous heat sources in urban areas (e.g. underground construction) ground water temperatures and subsurface temperatures increase ('subsurface heat island"). In some cases this temperature increase has negative impacts on the drinking water quality. On the other hand these relatively high subsurface temperatures offer a potential for the use of shallow geothermal energy for heating and cooling. If this heat source is used properly (e.g. heat extraction for heating purposes), a cooling effect of the underground can be achieved. Especially in urban areas the uncoordinated use of underground heat by a lot of small installations could lead to mutual interferences. The energy use might become inefficient and unsustainable. Some cities already discuss the prohibition of the energetic use of groundwater for cooling purposes.

This situation can be improved by a coordinated use and management of different geothermal heat sources, taking into account the thermal preload of the subsurface and framework conditions of water management. Furthermore the coordinated management of geothermal heat sources leads to an efficient and sustainable use of shallow geothermal energy from the subsurface of urban areas.

Contents and goals

The aim of the project is to develop a methodology for the coordinated use and management of shallow geothermal energy for heating and cooling as well as seasonal storage in urban areas. Ground water flow, different geologic conditions, heating and cooling demand, heat input from solar collectors and industrial waste heat and the possibilities of seasonal heat storage in the subsurface are considered.

Methods

The development of the methodology is based on the urban areas of the model region Graz, due to the existing data basis for the subsurface. Favorable subsurface geothermal areas for the use of geothermal energy with and without groundwater will be identified.

Case examples within these favorable subsurface geothermal areas will be selected. For these case examples the heating and cooling demand will be analyzed. The energy demand and the subsurface energy potential will be compared and the possibilities of seasonal storage will be investigated. The case examples will be techno-economically and environmentally evaluated and extrapolated for selected areas.

Simulation will be performed for these selected areas by use of an existing non-steady ground water flow model combined with a heat model. The influence on subsurface temperatures by heat extraction and storage will be analyzed and the influence on the subsurface favorable geothermal areas investigated. Considering the current management of geothermal and water resources, optimization measures and utilization concepts will be developed. Based on the results of the model region Graz the methodology for the coordinated use and management of shallow geothermal energy will be developed. The methodology comprises a procedure for an improved implementation and optimized utilization of shallow geothermal energy projects based on criterions/indicators for the subsurface, for energetic use and framework conditions (e.g. building plans, water quality). The basic systematics will be flexible enough to enable a transfer of the methodology to other urban areas.

In the project advisory board the project results will be discussed and presented to relevant stakeholders (e.g. city planners, energy utilities, administrative authorities).

Expected results

The overall aim of the project is the development of a methodology for a coordinated use and management of shallow geothermal energy for heating and cooling as well as seasonal storage in urban areas, which will be the basis for future use and management plans for cities and urban regions. Results for the model region Graz will be favorable subsurface geothermal areas, case examples and selected areas and simulations of interaction between diverse utilization possibilities of shallow geothermal energy.

Project Partners

Project management

JOANNEUM RESEARCH Forschungsgesellschaft mbH RESOURCES - Institute for Water, Energy and Sustainability

Project or cooperation partners

Grazer Energieagentur GmbH

Contact Address

JOANNEUM RESEARCH Forschungsgesellschaft mbH
RESOURCES - Institute for Water, Energy and Sustainability
Johanna Pucker
Elisabethstrasse 18/II
A-8010 Graz
Tel.: +43 (316) 876 6000
E-mail: Johanna.pucker@joanneum.at
Web: www.joanneum.at

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