Marija Macenić

• PostDoc Position at University of Zagreb Faculty of Mining Geology and Petroleum Engineering

With ambitious targets set by the EU for the reduction of emissions from the energy sector by 2030, there is a need to design and develop more building projects using renewable energy sources. Even though in Europe, heating and cooling share from renewable resources is increasing, and in 2021, the total share in this sector in Croatia was at 38%, t...

Aquifer Thermal Energy Storage (ATES) systems are a promising solution for sustainable energy storage, leveraging underground aquifers to store and retrieve thermal energy for heating and cooling. As the global energy sector faces rising energy demands, climate change, and the depletion of fossil fuels, transitioning to renewable energy sources is...

The increased interest in geothermal energy is seen, along with exploitation of traditional hydrothermal systems, in increased research and projects developing around reuse of already drilled oil, gas and exploration wells. The Republic of Croatia has around 4000 wells, however, due to long period of time since most these wells were drilled and com...

Storage of thermal energy in the ground is a method of balancing uneven energy consumption for heating during the year. The principle is based on the storage of thermal energy during the summer months so that during the winter months this energy can be used for heating purposes in buildings. Different forms of thermal energy storage can be designed...

In this work the feasibility of using the coaxial borehole heat exchangers (BHE) in multiple arrangements for production of heating and cooling energy has been investigated. Theoretical case studies are given for a few locations in City of Zagreb that use different conventional forms of heating and cooling. Multi-apartment buildings or households a...

In the last decade, due to climate change concerns and new environmental regulations in the EU, there was a tremendous rise in installed heat pump systems in new homes and buildings. The majority of these installed units are related to air-source heat pumps, as they offer a good trade-off between capital and operating expenses. However, when analys...

Dear Colleagues, With the rise of the low-carbon energy demand geothermal energy exploitation is gaining more visibility as a sustainable, renewable and clean energy resource. Along with project development from classic hydrothermal systems, increased interest is seen in developing projects which use existing oil & gas well assets as well as the d...

Geothermal energy will certainly be one of the most important renewable energy sources in the future. Unlike other forms of renewable sources (e.g., wind energy, solar energy, wave energy), geothermal energy is a stable energy source, which can cover base loads. This paper determines the possibilities of exploitation of geothermal water from geothe...

The Pannonian Basin, partly located in Croatia, is well known for its higher-than-average geothermal gradient with good potential for geothermal energy exploitation. Most of the currently known geothermal potential locations in the Croatian part of the Pannonian Basin (CPB) were discovered during the oil and gas exploration and exploitation from th...

The paper analyzes the technical solutions, economic feasibility and institutional aspects of geothermal energy use in a district heating system by retrofitting wells on a mature oil field based on the case study. The objective is to describe institutional procedures for brine production from the mature oil field. The research methodology includes...

In this work the feasibility of using the coaxial borehole heat exchanger (cxBHE) of deep geothermal wells for simultaneous production of heat and electricity is investigated. Coaxial borehole heat exchangers have advantage for being the single well-system and disadvantage for having lower heat transfer efficiencies when compared to conventional de...

Kindergarten Grdelin in the city of Buzet, Istria, Croatia, was chosen to undergo a deep retrofit of the current thermo-technical system, as a part of the HORIZON 2020 HAPPEN project 1. The existing shallow spiral heat exchanger field is insufficient to cover heating loads of the building. Therefore, additional BHEs were drilled and completed to de...

In the last decade there is an increase of interest to retrofit and exploit dry and abandoned oil and gas wells for geothermal power and heating. Current research focus is based upon a deep coaxial heat exchanger system. The heat energy is extracted by circulating working fluid with inflow through inner pipe, or tubing, and outflow through the annu...

Sažetak U sklopu projekta, analizom različitih tehnoloških rješenja, utvrđena je mogućnost eksploatacije geoter-malne vode kao stabilan obnovljiv energetski izvor za potrebe grijanja, ali i hlađenja zgrada javne namjene na području Grada Ivanić-Grada u sklopu kojih se nalaze Specijalna bolnica za medicinsku rehabilitaciju Naftalan, Dom zdravlja Iva...

When considering implementation of shallow geothermal energy as a renewable source for heating and cooling of buildings, special care should be taken in the hydraulic design of the borehole heat exchanger system. Laminar flow can occur in pipes due to the usage of glycol mixtures at low temperature or inadequate flow rates. This can lead to lower h...

When considering implementation of shallow geothermal energy as a renewable source for heating and cooling of the building, special care should be taken in hydraulic design of borehole heat exchanger system. Laminar flow can occur in pipes due to usage of glycol mixture at low temperature or inadequate flow rate. This can lead to lower heat extract...

Carbon capture and storage (CCS) technology is a beneficial greenhouse gas mitigating strategy carried out in the last 20 years. Depleted gas reservoirs are promising candidates for the storage of carbon dioxide (CO2). Therefore, a depleted gas reservoir in the Upper Miocene sandstone located in Northern Croatia was taken as an example. The purpose...

Based on the statistical analysis of the time series of data, the influence of the change of the Sava River temperature on the changes of the groundwater temperature of the Zagreb and Samobor-Zaprešić aquifers is described. In the analysis, data was used from daily measurements of the Sava River temperature and from the quarterly measurements of th...

The utilization of shallow geothermal energy is well known in several European countries. Even though large parts of the Republic of Croatia show significant potential for its use, the installation of ground source heat pump systems (heat pump and heat exchangers) is slowly progressing. Therefore, a short overview of research published thus far con...

Wider Zagreb city area, capital city of Republic of Croatia, has significant potential for major implementation of geothermal heat pump systems in not just the residential sector, but in commercial sector as well. Geothermal heat pumps often cumulatively describe different earth energy heat exchanger installations, from groundwater up to shallow gr...

Aim of our research is to present evaluation of using abandoned deep hydrocarbon reservoirs and dry wells in Croatian part of Pannonian Basin as geothermal energy source. Croatia has been exploring and exploiting hydrocarbon reserves in Pannonian Basin from mid 20th century. Therefore, many oil and gas wells are reaching the end of their production...

Total CO2 storage capacities are estimated in numerous studies, but there is lack of research of possible injection rates at a particular site. We performed compositional simulation with permeability variation (based on log-normal distribution parameters of measured data from similar formations in an oil field above the aquifer) in order to include...

Quality cementation of a borehole heat exchanger is often considered to be important parameter when analysing long-term heat pump efficiency. Implementing low conductivity grout leads to an increase of borehole thermal resistance and poor heat transfer. This paper analyses one real retrofit project which comprises of 16 borehole heat exchangers wit...

In certain engineering tasks of preliminary nature there is a need for an estimation of important physical and mechanical properties such as uniaxial compressive and tensile strength. This paper analyzes the problems related to the assessment of uniaxial compressive and tensile strength of rock material in the deposit of gypsum in the Knin area. It...

In a last decade, there is a tremendous growth in geothermal and aero-thermal heat pump market. Reason for this growth is commitment to highly energy-efficient, low-carbon EU economy. Trends in installation of heat pumps in Croatia are similar to global scale of EU, but somewhat slower. Climate of northern part of Croatia classifies as Dfb, by Köpp...

Undisturbed ground temperature is one of the most crucial thermogeological parameters needed for shallow geothermal resources assessment. Energy considered to be geothermal is energy stored in the ground at depths where solar radiation has no effect. At depth where undisturbed ground temperature occurs there is no influence of seasonal variations i...

Deep geological disposal is internationally recognized as the safest and most sustainable option for the long-term management of high-level radioactive waste. Mainly, clay rock, salt rock and crystalline rock are being considered as possible host rocks. Different geological environment in different countries led to the various repository concepts....