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Increased demand for fish products has resulted in greater investment in and modernization of the aquaculture sector. These processes have led to higher energy needs of aquaculture farms globally, resulting in their greater environmental impact. Fossil fuel is the main power source in aquaculture, and its combustion generates a large amount of Greenhouse Gases (GHGs) and other emissions. This paper considers the use of renewable energy sources (RESs) in mariculture systems to ensure at the same time cost-effective and environmentally friendly powering options. This paper investigates an alternative solution which relocates the majority of equipment and tasks from a mariculture vessel to a barge to reduce the energy demands of the vessel and to significantly lessen emissions of the system. The solution includes the full electrification of the workboat and the installation of PV cells and a wind turbine onboard the barge, combined with a diesel generator in an integrated power system. A Life-Cycle Assessment (LCA) was performed to evaluate the considered power system configurations from an environmental point of view, while a Life-Cycle Cost Assessment (LCCA) was performed to evaluate the economic performance of the proposed solutions. The results of the implementation of RESs in the mariculture system indicate an emission reduction of about 20% and an increase in capital costs by 0.61%. Feed reduction and the use of electricity in an alternative mariculture farm design in Croatia increase profitability by 4% in most cases. • The integration of RESs is beneficial for mariculture systems. • LCAs and LCCAs of a mariculture system in Croatia are performed. • The influence of fish feed and staff costs on profitability is considered. • Conventional workboat power systems should be replaced with cleaner alternatives. • Electrification of fishing vessels could reduce the CF of fish farming by about 20%. [ABSTRACT FROM AUTHOR]

Abstract: The Energy Strategy of the Republic of Croatia was adopted by the Croatian Parliament in 2009 for the period until 2020 in order to harmonize national energy goals with goals and time framework of strategic documents of the European Union. The adoption of the Energy Strategy Implementation Program with associated measures is still in process. The goal of the Strategy was to create sustainable energy system that will make a balanced contribution to the security of energy supply, competitiveness and environmental protection in Croatia. In this paper an overview of the energy production, final energy consumption and planned development of energy infrastructure is given. The intention of the paper was to research and stress out the abilities and opportunities of Croatian energy system and to give recommendations for Energy Strategy implementation and practical realization of planned energy infrastructure projects for improvement of security of energy supply and competitiveness of energy system of the Republic of Croatia. [Copyright &y& Elsevier]

[Display omitted] • Different multi-vector energy communities are modeled, assessed, and compared. • The analysis examines energy vectors for different geographical locations. • Energy potency indicator for multi-energy communities is introduced. • Results show significant techno-economic and environmental differences. • Results are valuable for energy communities and energy islands. Decarbonization and transformation of the power system go beyond integrating large shares of variable distributed energy sources; it implies understanding the increasing flexibility needs of the power system and breaking barriers in the process of transforming passive users to active participants in future low carbon energy systems. Unlocking the potential of final users and transforming them into distributed flexibility providers requires harmonization of operation through new models such as the association in energy communities. Multi-vector energy communities (MEC) can provide further flexibility options, enable integration of local energy generation and empower energy islands to increase self-sufficiency and resilience to external impacts. In line with this, the paper develops a unified mixed-integer linear programming (MILP) model of a MEC and rigorously assesses techno-economic performances of different combinations of energy sources, vectors and consumers. That way, the potential of different MECs for providing flexibility and increasing the utilization of electricity production from local renewable energy sources is assessed. Based on the results of the MILP models, the paper further proposes novel indicators for estimation of the techno-economic and environmental potential of different multi-energy vectors in decarbonization of energy islands. Case study analysis comprises of eight scenarios with different MEC's setups with realistic data from island Ærø in Denmark and island Vis in Croatia, capturing also geographical specificities. The results show significant differences across different MEC set-ups as well as between the geographical locations, and some of the results that can be highlighted are: demand responsive electric heat pumps and use of battery energy storage systems provide stand-out energy potency and can ensure self-sufficiency with smallest capacity of electricity production from local renewable energy sources, but comes with a growing costs for the increase of storage capacity; use of imported natural gas as a transition fuel could be affordable solution but does not lead to fulfilment of self-sufficiency or environmental goals; hydrogen energy vector has significant potential, especially in cases where seasonal energy storage is needed but the costs are still a main barrier; correlation of production and consumption patterns in island Ærø in Denmark favor wind energy, while the increased capacity and production from solar plants is more favorable in island Vis in Croatia. [ABSTRACT FROM AUTHOR]

Geothermal energy is a widely available renewable energy source. In Croatia geological data have been indicating promising potential, especially in the North-Eastern part of the country with a geothermal gradient higher than 49 °C/km and terrestrial heat flux of 76 mW/m 2 . Nonetheless, despite this potential, this resource is not highly exploited to date. Efficient use of geothermal energy can contribute on reducing Croatia’s energy dependence. In this paper, a methodology of a possible integration of geothermal energy within residential, commercial and industrial systems was attempted. Pinch analysis was used to find the best ways to fulfil the energy system requirements in an efficient, clean and cost-effective way. The used approach gives a good overall picture of energy targets for process, site and utility levels. The recommendation for cost-effective integration of geothermal energy into regional energy network is considered by use of Pinch Analysis. Additional attention was paid to geothermal energy utilisation in low enthalpy sedimentary environments. The obtained results can be used for integration of geothermal energy in different cases and “countries”. It gives general recommendation for geothermal sources placement as well as for energy planning and regional sustainability. [ABSTRACT FROM AUTHOR]

In this paper, the energy potential of biomass from growing short rotation coppice on unused agricultural land in the Republic of Croatia is used to investigate the feasibility of Combined Heat and Power (CHP) facilities fueled by such biomass. Large areas of agricultural land that remain unused for food crops, represent significant potential for growing biomass that could be used for energy. This biomass could be used to supply power plants of up to 15 MW e in accordance with heat demands of the chosen locations. The methodology for regional energy potential assessment was elaborated in previous work and is now used to investigate the conditions in which such energy facilities could be feasible. The overall potential of biomass from short rotation coppice cultivated on unused agricultural land in the scenarios with 30% of the area is up to 10 PJ/year. The added value of fruit trees pruning biomass represents an incentive for the development of fruit production on such agricultural land. Sensitivity analysis was conducted for several parameters: cost of biomass, investment costs in CHP systems and combined change in biomass and technology cost. [ABSTRACT FROM AUTHOR]

• District heating and cooling play a vital role in the EU's decarbonisation effort. • The H2RES tool has been upgraded to including district cooling. • Power to heat is a valuable demand response tool. • Wind and PV could cover up to 73% of Croatia's electricity demand in some scenarios. • District cooling has a significant positive impact on the reduction of curtailment. Europe's decarbonisation ambitions can't be achieved without the full and rapid decarbonisation of its buildings which represent over 36% of its greenhouse gas emissions, the majority of which are linked to space heating and domestic hot water preparation. District heating, and in recent times, cooling must play a large role in satisfying this demand, especially in densely populated urban areas which already hold over half of the World's population. Besides the decarbonisation potential linked to heating and cooling production, these systems hold a strong potential for increased flexibility in the power sector using power to heat technologies thus increasing the potential for the utilization of intermittent renewables such as wind and solar. The goal of this research is to demonstrate the impact district heating and cooling can have on the potential for the utilization of intermittent renewable electricity sources in mild and Mediterranean climates, which traditionally have lower shares of district energy systems. Additionally, this paper presents the newly implemented capabilities of the H2RES linear optimization tool to model district cooling systems alongside the existing capacity to model district heating systems. The results demonstrate a significant capacity of district heating and cooling systems to act as demand response tools thus greatly increasing the potential for the utilization of wind and PV for electricity generation. In some scenarios, up to 73% of the total electricity demand could be covered with wind and PV and a production of excess electricity of only 5% on an annual basis. The Republic of Croatia has been used as a case study for this research. [ABSTRACT FROM AUTHOR]

In the past 15 years worlds and Croatian economy is faced with the transition from classic primary energy sources to renewable energy sources. It is widely assumed that renewable energy can be stored in the form of hydrogen. Hence, world is faced with roll out of the commercial generation hydrogen fuel cell electric vehicles on the road. Anticipating estimated development there is a question when and how will Croatia keep along with this global scenario?! One of the possible answers, derived from Croatia position as EU country that draws 13% of its GDP mostly from tourists flooding during two summer months, was discussed in this paper. The number of hydrogen fuel cell electric vehicles that could be running by foreign tourists in Croatia up to 2030 was estimated. It was proposed hydrogen infrastructure based on photovoltaic technology of solar energy conversion and water electrolysis as adopted hydrogen production technology. Installed hydrogen infrastructure should be incorporated into national grid power system as renewable energy production, energy consumption, and energy storage subsystem. [ABSTRACT FROM AUTHOR]

Croatia has enormous renewable energy potential, particularly solar, but it is underperforming with regard to its use both for electricity production and heating. Paper focuses on the reasons therefor by analyzing the policy with regard to environment, subsidies, the role of international financial institutions, monopoly dimension of power utility companies, as well as social dimension. The author presents proposals for changing the status quo in order for Croatia to catch up with regard to securing reasonable solar and other renewable energy share in its energy supply. Apart from the state as regulator which has various instruments at its disposal to implement thoroughly the renewable energy use, local authorities should assume central role and responsibility for solarizing their territories and generating the energy locally from other renewable energy sources available on their territory. Municipal utility companies would thus add electricity production to their regular activities and could provide installation and maintenance services for individual energy generating systems within the territory of their competence. [ABSTRACT FROM AUTHOR]

Energy planning relies on potential assessments where the role of each energy source in the energy balance will correspond to the attributed potential. Biogas is a gaseous renewable energy fuel derived from biomass. It origins from numerous substrates and provides all useful energy forms which makes biogas potential assessment challenging. Biogas production and utilization has also side-effects from which a country could both benefit, and, if not properly addressed, suffer. Practice proves that a demand based approach to agricultural biogas potential assessment is not providing the value(s) to which either energy or rural development policy planning can work with. The problem stems from three main challenges: (a) biogas rarely occurs in monodigestion, (b) co-digestion has to compete with other non-food sectors for co-substrates, (c) biogas production needs constant inputs. Paper provides methodology to assess the technical and economical on-farm biogas potential of a geographic region. Technical potential assessment links resource based, statistical data with spatial data of single farms to detect farms with plausible biogas production. Return on investment is used to trim the technical to economic potential. Results provide sufficient data for developing on-farm biogas production and its conversion to useful energy forms in energy planning. The methodology is applied to Croatia as a case study. The results indicate discrepancy between the existing biogas supporting measures and features of the Croatian livestock sector. In addition, the results suggest that biogas potential is underestimated which is potentially loss in public money dedicated for development of renewable energy sector. [ABSTRACT FROM AUTHOR]

Croatian energy system is currently highly import-dependent and integration of a high share of renewable energy sources needs to be considered. This paper studies eight scenarios; three proposed by the Croatian Energy Strategy, one proposed by the Indicative medium-term development plan of Croatia’s Transmission System Operator, and four alternative scenarios that propose extensive construction of hydro, wind and solar power plants in Croatia. Calculations have been conducted in the EnergyPLAN model based on modeled long term energy demand projections in the NeD model, with 2009 as the base year and a scope ranging until the year 2030. Each of the eight proposed scenarios is observed through different hydrological conditions while analyzing import dependency, economic costs and CO 2 emissions. After the initial calculations, additional analysis of intensive wind power penetration has been conducted. The Results show that energy systems with a larger share of conventional and nonflexible power plants have more difficulty adjusting to wind power plants production. In case of a high share penetration of wind in a system based upon such power plants, the feasibility of investing in new large combustion plants that will spend most of the time working on minimum capacity is brought into question. [ABSTRACT FROM AUTHOR]

Abstract: This paper analyses potential supporting schemes for pumped hydro storage (PHS) facilities in Croatia, which would guarantee recovery of the investment cost, with feed-in tariffs – for instance – which would guarantee payment for discharging wind-originated power as a reward for boosting the integration of renewable energy sources (RESs). The payment level acts as a floor basis for the PHS operator during the decision-making process to contract fixed payments for wind support or to act market-free on other market segments, through price arbitrage and reserve provision. The market share required for the efficient operation of a PHS facility and the levels of feed-in tariff (FIT) are set mathematically. Main findings put the level of FIT for an applied project in Croatia in the range 42–265€/MWh for an average load factor of 20%, depending on particular local conditions, such as the level of wind power curtailment in the system, the power price for charging the storage and the number of pumps and penstocks, which could lower the capital cost. It is claimed that not all services that PHS provides to the electricity system are adequately rewarded by the electricity market, and thus there is a serious uncertainty as to how investment costs in energy storage would be recovered. Other elements, outside the market, are likely to influence the operation of PHS, such as the regulated level of a desirable rate of curtailment of RES power excess, the adequate level of energy security and the reserve margins which PHS could help to ensure. [Copyright &y& Elsevier]

Abstract: A dominant share of Croatian cogeneration capacity and future cogeneration potential belongs to district heating systems currently operating in almost all bigger mainland and coastal towns. Since public cogeneration and public heating plants cover only 10% of heating requirements of households and services sectors it is reasonable to assume that in future energy supply district heating could take a bigger relative and absolute share even in conditions of reduced heat demand imposed by implementation of Energy Performance of Buildings Directive. However, development of future district heating projects will inevitably depend on capability to bridge financing barriers usually manifesting in large investment costs and long pay-back time. The public involvement will be necessary either at state or/and at municipal level since private companies are focused on short-term profitability. In this paper comparison of various concepts of district and individual buildings heating has been performed with respect to efficiency and environmental indicators. Taking a midsize town as an example profitability of operation of both biomass and of natural gas fired district heating cogeneration plants have been analysed. Calculated results indicate levels of financial support required for sustainability of district heating projects in specific conditions of Croatian energy market. [Copyright &y& Elsevier]

Following a strategic orientation towards sustainable development, the Government of the Republic of Croatia has changed its energy legislation and has put forward a framework for the systematic development and increased use of renewable energy sources and cogeneration. This paper focuses on changes in the regulatory context relevant to the cogeneration sector and also analyses the impact of energy market transition on cogeneration viability in municipal district heating, industry, services and the residential sector. Particular attention has been paid to the expected changes of heat, electricity and gas prices. We present a simple model for quantitative prediction of the cogeneration system profitability at different power levels under given national circumstances. Our findings support a need for a strong institutional support for initial penetration of the micro-cogeneration technologies into the Croatian energy system. [Copyright &y& Elsevier]