Integration of renewable energy sources for district heating in cities

Urban energy supply systems with a comparatively high demand density are usually forced to either transport the energy carriers required by the local population over huge distances or to utilise local energy sources.

In the frame of this project the questions were treated, if the future installation of new technologies in the existing district heating systems of the cities of Vienna and Sankt Pölten for covering the energy demand for space heating and cooling in a reasonable economic framework is possible, if these technologies may contribute to a reduction of the emission of greenhouse gases, which technologies these are and which energy carriers they require.

During project preparation a new methodology for technology assessment in a given economic framework has been developed. The standard of valuation used in this study is the output-specific annuity of the net present value of total cost including the cost for possibly necessary CO2-certificates. The technologies are presented in a mean-variance-portfolio of this benchmark.

In a brainstorming workshop with experts a list of possible technologies has been elaborated and assessed subsequently. Thus, a set of technologies has been identified, which are state of science (i.e. which are new options) and which contribute to the project aim of a sustainable development of urban district heating systems to multi-functional energy supply systems according to expert opinion.

The study resulted in 3 groups of technologies, which are of major interest for this development. These are:

1. Renewable energies - liquid renewable fuels by pyrolysis
   The integration of renewable energy sources into the energy mix of urban areas usually faces on the one hand the problem of a low volumetric energy content of common forms of renewable energy sources and high energy demand densities on the other hand. By transformation of bulk solid biomass into a liquid fuel by modern pyrolysis technologies (flash-pyrolysis) an increase of the volumetric energy density by a factor of approximately 10 is possible. This is an economic short term to medium term energy supply option.
2. Fossil fuels - Carbon Capture and Storage
   The implementation of measures that go beyond improvement of the energy efficiency of the energy supply chain is necessary, because the Austrian greenhouse gas emissions exceed the targets of the Kyoto protocol by far and because those large plants for heat and power supply, which will be built over the next decade and which will be in operation over several decades thereafter will most probably be fuelled by fossil fuels. Carbon Capture and Storage (CCS) could be one of these measures. Problems with this option arise because of the low public acceptance of CCS and because of missing environmental assessments.
3. Multi functional energy supply - air conditioning by district heating
   Air conditioning by means of district heat is an ecologic and economic attractive alternative to common systems based on compressor chillers. The positive effect of chilling by district heating on the CO2-emission of the energy sector has already been proven in other studies.

A project pipeline of 10 projects together with an action plan has been developed as starting point for the implementation of the recommendations of this study.

Projectleader

DI Karl Gruber
KWI Management Consultants & Auditors GmbH

Projectpartner

• DI Eva Hamann
  TU Wien, Institut für Wirtschaftsmathematik, Abteilung für Ökonometrie
• DI Martin Hammer
  KWI Management Consultants & Auditors GmbH
• DI Andreas Karner
  KWI Management Consultants & Auditors GmbH
• Mag. Birgit Schretzmayer
  KWI Management Consultants & Auditors GmbH
• DI Klaus Sehling
  KWI Management Consultants & Auditors GmbH
• Mag. Manfred Stockmayer
  KWI Management Consultants & Auditors GmbH

DI Karl Gruber
KWI Management Consultants & Auditors GmbH
Fuhrmannsgasse 3-7
A-3100 St. Pölten
Tel.: +43 (2742) 350 - 41
Fax: +43 (2742) 350 - 66
E-Mail: gr@kwi.at
Internet: www.kwi.at