Heat supply of development areas through supplementary solar supported near heat nets
In Austria a particular task approaches to net-bound heat supply systems in populous regions. Next to existing district heating systems micro networks are considered as very promising, as shown by a substantial potential investigation in the federal states of Styria and Salzburg, which was then projected to all Austrian federal states. Taking a pessimistic approach, about 17 % of all Austrian municipalities are planning the implementation of new built housing schemes (about 400 municipalities). A number of responsible project managers declare their exceeding interests for net-bound heat supply systems with biomass and the use of solar heat.
In spite of the enormous potential of micro networks in combination with renewable energy sources, they could not be established as a standard heat supply system in Austria in the last few years. In connection with new buildings there are technological, economical and organizational obstructions concerning the implementation of micro networks. In general a new built housing scheme is erected in several construction sections. That means that its heat supply system has to be constructed in a modular structure. In the case of using solar heat decentralized injection points have to be included into the heat supply system.
Based on usual concepts for net-bound heat supply systems in this project special modularly extendable hydraulic concepts were defined, which can be arranged in modules (decentralized load compensation storage, decentralized injection facilities for solar heat, flexible central heating plants) and provide highest efficiency regarding power supply operation temperature and heat losses. The base of the heat supply system consists of a central biomass plant (as required also in a mobile container) and central or non-central collector panels connected with a two-pipe-network, decentralized load compensation storages, flat stations respectively fresh water modules for domestic hot water conditioning and an adequate adapted heat contribution system (max. design temperature 65/40).
Based on the results of the potential assessment three - typically Austrian - new build housing schemes were defined, each consisting of three construction sections (housing scheme "one-family-houses" - 100 kW, multiple family houses - 150 kW, combination of the two housing schemes - 600 kW). For each housing scheme net-bound heat supply plants were designed, simulation-aided variation calculations, cost analyses and dynamic cost analyses were performed.
In comparison with specially defined reference heat supply systems (non-central heating plants, which would have been used instead of the net-bound heat supply system) it could be shown, that a net-bound heat supply system with biomass energy sources and the use of solar heat adapted to each modelled housing scheme was energetically and economically competitive and indeed significantly more cost-effective. The housing scheme "one-family-houses" has a rather low specific heat demand (kWh/mnetwork). For that reason the result of its comparison with the reference housing scheme (with non-central gas-boiler) was, that the same costs arose for both systems. However compared with the reference heat system the net-bound heat supply system causes significant cost advantages for "storey housings" as well as for "combined housings".
This project provides a tool for illustrating and analysing complete heat networks with central and non-central heat sources / heat storages enabling a dynamic simulation on a validated base. The time exposure necessary for illustration and simulation could be considerably reduced within the project works.
About 100 experts participated in a technical meeting organized by the project team, indicating their interests in the technology and the obtained investigation results.
Project or cooperation partner
- BioSol energie Kft, Ungarn
- Stadtwerke Gleisdorf GmbH
- S.O.L.I.D. GmbH
- PEWO Energietechnik GmbH
- INOCAL Wärmetechnik GmbH
- Gemeinnützige Wohn- und Siedlungsgesellschaft Schönere Zukunft GmbH
- Neue Heimat Gemeinnützige Wohnungs- und Siedlungsges. m.b.H.
- KWB - Kraft und Wärme aus Biomasse GmbH
- TU Graz, Institute für Wärmetechnik (Werkvertragspartner)
- TB Kaufmann - Technisches Büro Ing. Harald Kaufmann (Werkvertragspartner)