Goran Krajačić

Increasing the renewable energy sources absorption capacity of the Macedonian energy system

Macedonian energy sector is the main emitter of greenhouse gases with share of about 70% in the total annual emissions. Also, 70%–75% of emissions are associated with the electricity generation due to the predominant role of the lignite fuelled power plants. Recently, the government has adopted a strategy for the use of renewable energy sources (RES) which identifies a target of 21% of final energy consumption from RES by 2020. In this paper, analyses are conducted in order to investigate to which extent and in which way the absorption capacity of the power system for RES electricity can be improved. For this purpose, combining various conventional and RES technologies, including pump storage hydro power plant and revitalisation of the existing lignite power plants six scenarios for the power system expansion are developed by making use of EnergyPLAN model. Critical excess of electricity analyses are conducted in order to identify the maximal penetration of wind electricity. The results have shown that in the exiting capacities maximal penetration of wind electricity in 2020 is 13% of total electricity consumption. The revitalization of the existing lignite power plants and building of pump storage power plant would increase the wind penetration. Furthermore, the developed scenarios are comparatively assessed in terms of the associated greenhouse gases emissions and import of electricity.

The Potential of GHG Emissions Reduction in Macedonia by Renewable Electricity

The energy sector in Macedonia is the main emitter of greenhouses gases (GHG) with share of about 70 % in the total annual emissions (12 – 14.5 Mt CO2-eq). Furthermore, within the energy sector, 70-75 % of emissions are associated with the electricity generation due to the predominant role of the lignite fuelled power plants. This makes the electricity sector the most significant key source and, at the same time, the main target for GHG emissions reduction. The main goal of this paper is to assess the potential for GHG emissions reduction by increasing the use of renewable energy sources (RES) for electricity generation. For this purpose a RES scenario for the power system expansion is developed by making use of EnergyPLAN model. The maximal penetration of wind and solar energy results in reduction of the GHG emissions from the reference scenario for 8.26 %. Total investment needed for realization of this option is estimated to 800 M€. Furthermore, the RES technologies are analyzed from economic aspect and combined in a form of emission reduction cost curve, displaying the total marginal cost of the GHG emissions reduction by renewable electricity.

Energy Storage in Islands - Modelling Porto Santo’ s Hydrogen System

Most islands depend mainly on the importation of fossil fuels for energy production. This causes economic and environmental problems. But generally, islands present a considerable potential in renewable energies. Islands that have energy sources such as hydro or geothermal energy, can easily integrate them into the power system, but those with mainly intermittent renewable energy sources (wind, solar) have to tackle the need of energy storage. In these cases, advanced energy planning should be used, The present paper intends to demonstrate the urging need of planning energy storage systems for small islands and the results of a case-study carried out in a Portuguese island. The need to store intermittent energy is an important issue in the island of Porto Santo, since it is a small and isolated network. H2RES was used to model the energy storage scenarios for this island. One scenario was chosen to evaluate the potential of hydrogen as an energy storage vector and a pilot system of two 5kW fuel cells, one electrolyser of 13 kW, and a 55 m3 storage tank was built. The main objective of this system is to produce hydrogen from electricity from wind mills that otherwise would be wasted, and to use this hydrogen for electricity during peak time.

New Energy Planning Software for Analysis of Island Energy Systems and Microgrid Operations - H2RES Software as a Tool to 100% Renewable Energy System

Abstract H2RES energy planning software was created for optimization of microgrid components sizing. Requirements taken into the account during optimization are: local loads, the level of microgrid autonomy from the utility grid, technical characteristics and cost of components, lifetime of equipment, available area and space, impact on the environment. The optimization resides on the past meteorological data for the specific location (wind speed and solar insulation). Procedures for selecting, dimensioning and placing of renewable energy systems (RES) for location-specific microgrids in urban environments are assessed with weather forecasting. The problem of storage systems is the increase in cost of distributed RES, making them, in market terms, less economically viable. This storage characteristic is even more highlighted in microgrids that need sophisticated and costly power electronics and communication systems to manage power flows from various sources to different controllable and uncontrollable loads. It is essential for further deployment of microgrids to ensure its optimal planning and sizing in order to avoid unnecessary costs on one side and on the other to ensure acceptable level of energy supply autonomy.

Integrating the flexibility of the average Serbian consumer as a virtual storage option into the planning of energy systems

With the integration of more variable renewable energy, the need for storage is growing. Rather than utility scale storage, smart grid technology (not restricted, but mainly involving bidirectional communication between the supply and demand side and dynamic pricing) enables flexible consumption to be a virtual storage alternative for moderation of the production of variable renewable energy sources on the micro grid level. Study, motivated with energy loss allocation, electric demand and the legal framework that is characteristic for the average Serbian household, was performed using the HOMER software tool. The decision to shift or build deferrable load rather than sell on site generated energy from variable renewable energy sources to the grid was based on the consumers net present cost minimization. Based on decreasing the grid sales hours of the micro grid system to the transmission grid from 3, 498 to 2, 009, it was shown that the demand response could be included in long-term planning of the virtual storage option. Demand responsive actions that could be interpreted as storage investment costs were quantified to 12 €/year in this article.

Smart Energy Storages for Integration of Renewables in 100% Independent Energy Systems

Primary energy import dependence of the European Union is currently around 53%, and it is expected that in the next 20-30 years it will reach or surpass 70%. The situation in Croatia is similar. In 2007 import dependence was 53.1%, while for 2030 it is predicted to reach 72%. Such import dependence leads to decreased security of energy supply, due to current geopolitical situation in which main sources of fossil fuels are in unstable regions and in which the competition for those resources from developing countries is growing. EU energy strategy, and a compatible Croatian strategy, is focused on policies and measures that will bring increase of share of renewable and distributed energy sources, increase in energy efficiency and energy savings and decrease in green house gas emissions. The results of previous research has shown that in order to increase efficiency and viability, there is need for energy storage, in the primary or secondary form, in order to transfer energy surplus form period of excess to the period when there is a lack. The problem of storage systems is that they increase the cost of already expensive distributed and renewable energy sources, making them, in market circumstances, even less economically viable. Although there are a number of storage technologies, as chemical, potential or heat energy, not all those technologies are optimal for each energy system. The paper shows results of energy planning and several cases where use of smart energy storage system could help with integration of the energy flows, the transformations and energy demand at the location of the energy enduse or close to it.

Campus and Community Micro Grids Integration of Building Integrated Photovoltaic Renewable Energy Sources - Case Study of Split 3 Area, Croatia - Part A

Micro grids interconnect loads and distributed energy resources as a single con-trollable entity. New installations of renewable energy sources in urban areas, such as building integrated photovoltaic, provide opportunities to increase ener-gy independence and diversify energy sources in the energy system. This paper explores the integration of renewable energy sources into two case study commu-nities in an urban agglomeration to provide optimal conditions to meet a share of the electrical loads. Energy planning case studies for decentralized generation of renewable energy are conducted in highways 2 renewable systems energy plan-ning software for hourly energy balances. The results indicate that building inte-grated photovoltaic and photovoltaic in the case study communities can cover about 17% of the recorded electrical demand of both areas. On a yearly basis, there will be a 0.025 GWh surplus of photovoltaic production with a maximum value of 1.25 MWh in one hour of operation unless grid storage is used. This amounts to a total investment cost of 13.36 million EUR. The results are useful for proposing future directions for the various case study communities targeting sustainable development.

Integration of Desalination and Renewables, a Demonstration of the Desalination Module in the H2RES Model: Case Study for Jordan

Water scarcity and the dependence on fossil fuels as a primary source of energy are crucial problems for a number of arid countries. The integration of energy and water systems presents a possible solution for both issues. The flexibility of a desalination system can increase the possibility for the penetration of intermittent renewable energy sources and thus provide both fresh water and the potential for the local production of clean energy. Jordan is the fourth most water deprived country in the world and is also highly dependent on energy import. Almost all of its primary energy comes from imported fossil fuels, mostly from natural gas. It is a country rich in wind and solar energy but unfortunately, almost no utilization of that potential. The integration of desalination systems and renewable energy sources is a possible solution both for Jordan’s water and energy supply. The goal of this paper is to demonstrate the desalination module in the H2RES model using Jordan as a case study. H2RES is a flexible energy modelling tool used for the balancing of energy supply and demand on an hourly basis. It is capable of demonstrating the benefits of water and energy integration for the purpose of increasing the penetration of intermittent renewables and the reduction of CO2 emissions. For this purpose, four scenarios have been created. The first one is a business as usual scenario with no desalination, a desalination scenario and two desalination scenarios that utilize the produced brine as energy storage in pump hydro plants. The results will show that the utilization of desalination, especially in the case where desalination is combined with pump storage, can help increase the penetration of renewable energy sources into the electrical grid and thus help decrease the dependence on energy import and reduce the CO2 emissions of the energy system.

Waste heat utilisation of Croatian cement industry accounting Total Site demands

Abstract The cement industry sector as an energy intensive industrial sector, where energy cost represents approximately 40% of the total production cost per one ton of cement, and one of the highest greenhouse gases - GHG emitting industrial sectors, accounts for around 5% of global anthropogenic GHG emissions as reported (Mikulcic et al, 2015). Considering that, the cement is the most widely used material for construction needs, this paper analyses the potential of energy efficiency improvement of the cement production for a particular cement plant in Croatia. The heat recovery potential was determined and an amount of waste heat available for utilisation accounting site wide demands are identified with use of Process Integration technique. The results show huge potential for energy saving of cement production. Different scenarios for utilization of low potential heat are proposed accounting different site demands and energy prices. Implementation of paper results helps to the cement plant’s profitability and reduces environmental impact of the cement industry.

Cost Minimisation for Total Site Heat Recovery

In this paper minimisation of total cost for retrofit of Total Site heat recovery system is proposed. It based on analysis of balanced Total Site Profiles and includes procedure for calculation of heat transfer area. Heat transfer area is calculated for different regions with use of intermediate utility and direct heating and cooling. Minimal temperature difference between Total Site Profiles is analysed. Global minimum of heat transfer area for Total Site recovery is calculated for array of minimal temperature differences. It is analysed with utility consumption, numbers of units and material of equipment. Selection of minimum total cost for retrofit project of site recovery system is proposed.