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Geothermal Energy Utilisation Potential in Croatia

Resource assessment • Križevci Geothermal potential is confirmed with one exploration well near the city. It would be of great interest to evaluate the well capacity for supply of hot water for heating of the public buildings and the swimming pool in the immediate area that should be beneficial and feasible for Križevci community. • Varaždinske Toplice This health, rehabilitation and spa centre also appears to have a good geothermal resource potential. There is obviously a long-term tradition for using the geothermal water for house heating, spa and swimming pools. The Varaždinske Toplice area overflows hot geothermal water and there are additional wells that could provide heating of the planned new extension of the hotel and other buildings. • Krapinske Toplice There is a tradition of over 150 years of harnessing geothermal water for heating households, hotel/spa, and agriculture. Recently, a water park using geothermal fluid was constructed and opened. The confirmed geothermal area is giving 40°C hot water but further exploration, and drilled well found water with temperature of 56-60°C. This promising result should be an incentive for further evaluation of data and exploration. • Karlovac The Karlovac area has at least two wells, Ka-2 and Ka-3, with a confirmed temperature over 140°C and 50 kg/s flow which indicates a good geothermal resource that can support a combined electrical generation unit (ORC) and a district heating system with 90°C water for heating or as a discharge from the power generation process. The geothermal area around wells is around 8-10 km from the city and is favourable for utilisation of the geothermal water for district heating system for house heating, hotel and spa systems, green houses, fish farming or other industries. • Vukovar A geothermal potential has been confirmed with seven wells drilled near the city, with indication of water with temperatures ranging from 60-80°C. The temperature gradient of the wells varied from 33.5-43.3°C/km, highest gradient in Vu-4 and lowest in Vu-3. However, these wells were drilled decades ago for oil and gas exploration and their condition is unknown. Main Recommendation Karlovac • The district heating system at Karlovac is heated with fossil fuel today but the available resource data indicate the possibility to use renewable geothermal water for heating instead of fossil fuel. • Current district heating system at Karlovac is well past its lifetime, needs expensive refurbishments and lacks efficiency. Therefore, it is highly recommended that a new district heating system is installed. • Karlovac needs to establish a working group that will focus on energy efficiency to save fossil fuel in the heat central with the future goal to change over from fossil fuel to renewable energy (geothermal hot water). • The geothermal field is in nearby area and therefore feasible to establish a district heating system. • The quality and amount of available geological data gathered in the course of drilling of the wells, as well as obtained data on geothermal water in the reservoir has put Karlovac in the most favourable position for further development. • Conservative approach for utilisation of the geothermal resource at Karlovac with a relatively low risk is to build up the geothermal system in stages. • Recommendations for the first stage of the utilisation of the geothermal resource is to establish the geothermal energy for district heating and connect it to Karlovac. Next stages, if the first stage is a success, is to expand the geothermal heating district system by drilling more wells and reinjection wells with connection pipelines to it. Production of electricity is a possibility, in the latter stages. Recommendations for the first stage is to divide it into two different phases as follows:  Recommendations for phase 1 is to do a test investigation of the geothermal area by re-enter either well Ka-2 or Ka-3 with a drilling rig to clean out the well before inserting a deep well pump.  Phase 2, if phase 1 is a success, will involve construction of the connection pipelines to the heat central in Karlovac. Recommendations for other stages are not included in this report as the success of the first stage decides whether it is feasible to continue with the expansion of the geothermal heating system. Recommendations for Utilisation of Geothermal Resources in Croatia The geothermal resources in Croatia should be examined in the light of the following criteria: 1. A policy based on professional and scientific assessment and conditions in Croatia. 2. Support Schemes for the geothermal development. 3. A properly structured policy system, is critical for success for each location. a. Priority 1 – Education capacity building, networking and awareness raising. b. Priority 2 – Evaluation of geothermal resources and district heating opportunities. c. Priority 3 – Promotion of geothermal district heating and power generation. d. Priority 4 – Development of framework conditions. e. Priority 5 – International cooperation based on geothermal and financial expertise.

geothermal energy, district heating, regulatory framework

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