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The transport sector is the only sector in which there have been no significant renewable energy penetrations and it is heavily dependent on oil with rapid growth in the last decades. Moreover, it is challenging to obviate the oil dependence due to the wide variety of modes and needs in the sector. Nowadays, biofuels are proposed as one of the main options for replacing fossil fuels in the transport sector, along with electricity. The main reasons for avoiding the direct usage of biomass in the transport sector, i.e. producing biomass derived fuels, are land use shortage, limited biomass availability, interference with food supplies, and other impacts on environment and biosphere. Hence, it is essential to do a detailed analysis of the transport sector in order to match the demand and to meet the criteria of a 100% renewable energy system in 2050. The transport sector is the only sector in which there have been no significant renewable energy penetrations and it is heavily dependent on oil with rapid growthin the last decades. Moreover, it is challenging to obviate the oil dependence due to the wide variety of modes and needs in the sector. Nowadays, biofuelsare proposed as one of the main options for replacing fossil fuels in the transport sector, along with electricity. The main reasons for avoiding the directusage of biomass in the transport sector, i.e. producing biomass derived fuels, are land use shortage, limited biomass availability, interference with food supplies,and other impacts on environment and biosphere. Hence, it is essential to do a detailed analysis of the transport sector in order to match the demandand to meet the criteria of a 100% renewable energy system in 2050.

The cement industry is one of the leading producers of the greenhouse gases, where carbon dioxide is the most significant anthropogenic greenhouse gas. There are two thermo-chemical processes involved in cement production which contribute to these emissions. One is the thermal decomposition of limestone, widely known as the calcination process, and the other is the combustion of fossil fuels. Recently, researchers have invested significant effort to improve the energy consumption and pollutant formation of the overall cement manufacturing process. One of these improvements was made by dividing the calcination and clinkering process into two separate furnaces, where the calcination process is performed in a furnace called a calciner, and the clinkering process is performed in a rotary kiln. Because this is a new technology in the cement manufacturing process, cement calciners are still in the research and development phase. The purpose of this paper is to present the first phase of the cement calciner's development, which is the CFD simulation of the cement calciner, with an implemented mathematical model of the calcination process. From the results gained by these simulations, researchers will have an in-depth understanding of all thermo-chemical reactions in a cement calciner. This understanding can be used for the optimization of the calciner's geometry, to have a more efficient production, to lower the pollutant formation and subsequently reduce greenhouse gases emission.

In this paper, an optimization model for incorporating seasonal heat energy storage and biomass trigeneration power plant is presented. Currently in Croatia, overall efficiency of biomass CHP or CCHP has to be above 50% on an annual basis in order to be eligible for a feed-in tariff. Consequently, biomass power plants use the excess heat production for drying biomass which is currently allowed. However, it is expected that it will not be allowed in the future due to inefficient use of heat. Thus, this paper provides a solution for managing excess heat in biomass CHP and CCHP power plants, as well as a way to shave peak energy demand. The objective of the optimization model is to maximize net present value (NPV) using hybrid optimization method. It is a demand driven model, covering real heating and cooling energy need by end-use customers. Optimization model is easy to adopt in different regions and can be used for evaluating economic feasibility of the investment in trigeneration system that covers all heating and cooling energy demand. Two case-studies were done in order to show the impact of minimum allowed overall power plant efficiency on overall economic indicators. Moreover, the financial data for the possible shift from feed-in-tariffs to fixed and variable feed-in-premiums was presented.

The share of energy from renewable energy sources (RES) in the final gross energy consumption in Macedonia is about 14%, mostly due to the electricity produced by large hydro power plants and the use of biomass for heating. Macedonian energy sector is the main emitter of greenhouses gases (GHG) 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 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 (CEEP) 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.

Spatial resolution is often cited as a crucial determinant of results from energy systems models. However, there is no study that comprehensively analyses the effect of spatial resolution. This paper addresses this gap by applying the Heat Infrastructure and Technology heat decarbonisation optimisation model in six UK Local Authorities representing a range of rural/urban areas, at three levels of spatial resolution, in order to systematically compare results. Results show the importance of spatial resolution for optimal allocation of heat supply technologies and infrastructure across different urban/rural areas. Firstly, for the studied cases, differences of up to 30% in heat network uptake were observed when comparing results between different resolutions for a given area. Secondly, for areas that generally exhibit the high and low extremes of linear heat density, results are less dependent on spatial resolution. Also, spatial resolution effects are more significant when there is higher variability of linear heat density throughout zones. Finally, results show that it is important to use finer resolutions when using optimisation models to inform detailed network planning and expansion. Higher spatial resolutions provide more detailed information on zones that act as anchors that can seed network growth and on location of network supply technologies.