The aim of this paper is to discuss the needs for investment in electricity interconnectors in Europe by 2025. We evaluate the impact of cross-border transmission capacity on dispatch costs, ...curtailment needs for renewable energy sources (RES), on CO2 emissions, on hydro storage utilisation and on security of supply (in terms of energy not served). The analysis is performed with EUPowerDispatch, a minimum-cost dispatch model. For the evolution of the electricity generation portfolio and electricity consumption we use the latest Scenario Outlook and Adequacy Forecast of the European Network of Transmission System Operators for Electricity (ENTSO-E). The model results show that the planned additional cross-border transmission capacity between 2010 and 2025 will reduce annual dispatch costs, will have limited impact on the security of supply and will not be a significant cause of variable RES curtailment. However, in case of more RES, it will reduce dispatch costs to a larger extent and will considerably reduce RES curtailment needs, and, if demand grows at the historical rate of 2%, it will be needed to maintain the current level of security of supply. Moreover, our study shows that hydro pumping and storage and cross-border transmission are partly complementary technologies.
•A model for assessing the benefits of cross-border transmission capacity in Europe.•Current cross-border transmission: not an important constraint for RES by 2025.•CO2 emissions from electricity generation decrease by 17% (2010–2025).•Transmission investment necessary if demand is slightly higher than projected.•Storage and transmission are at least partly complementary technologies.
The present article proposes an optimal battery system management model in distribution grids for stationary applications. The main purpose of the management model is to maximise the utilisation of ...distributed renewable energy resources in distribution grids, preventing situations of reverse power flow in the distribution transformer. Secondly, battery management ensures efficient battery utilisation: charging at off-peak prices and discharging at peak prices when possible. This gives the battery system a shorter payback time. Management of the system requires predictions of residual distribution grid demand (i.e. demand minus renewable energy generation) and electricity price curves (e.g. for 24 h in advance).
Results of a hypothetical study in Great Britain in 2020 show that the battery can contribute significantly to storing renewable energy surplus in distribution grids while being highly utilised. In a distribution grid with 25 households and an installed 8.9 kW wind turbine, a battery system with rated power of 8.9 kW and battery capacity of 100 kWh can store 7 MWh of 8 MWh wind energy surplus annually. Annual battery utilisation reaches 235 cycles in per unit values, where one unit is a full charge-depleting cycle depth of a new battery (80% of 100 kWh).
•A battery management model is developed for stationary battery applications.•The model is tested in a hypothetical case study in Great Britain in 2020.•Battery usage ensures high wind energy surplus compensation in the distribution grid.•Efficient battery utilisation is achieved.•The battery contributes to residual demand smoothing at electricity market level.
Due to historical and geographical reasons, the Baltic States are strongly interconnected to power transmission grids of Russia and Belarus. Current energy security policies and electricity ...interconnection targets in the EU trigger the need for studying and implementing alternative electricity supply options and power system configuration schemes for the Baltic countries.
In order to provide a supporting analysis for the energy policy making, with a special focus on electricity, a framework with methodologies is proposed in this paper to assess the electricity independence of the Baltic States. To comprehensively assess the electricity independence, we provided three indices: “adequacy”, “security” and “economic factor”. The proposed framework and methodologies are applied for assessing the electricity independence of the Baltic States in the present (2014) and future scenarios: mid-term (2020), and long-term (2030) time frame.
The analysis results show that the planned generation capacities are adequate to cover future electricity demand in the Baltic States in 2020 and 2030. Under the current electricity grid planning, power distribution in some local areas is limited in the future scenarios. Additional grid investments are necessary to keep high security level of power supply in 2020/30.
Nuclear power currently supports the goals of the European Union low-carbon society by being a dependable source of energy, while emitting no CO2. In the future, more flexible nuclear systems could ...enable wind to achieve a 50% share of the renewable contribution to the energy mix. Small and medium-sized reactors (SMRs) could provide firming power generation to back-up the supply from renewable resources and follow-load. This study involves the hypothetical combination of an off-shore wind farm and a SMR, operated together as a virtual power plant (VPP). Results using wind data from the North Sea indicate that the combination results in 80% less wind power variation to the grid, effectively creating a virtual baseload power plant. This gain comes at the loss of 30% SMR capacity utilization. The research identified that the reduction of 1000MW off-shore wind farm variability was best achieved with 700MW SMRs using 100MW modules. In demand-following mode the VPP could maneuver output to improve synchronization with demand by 60–70% over a wind-only system. Power variability was indifferent to the SMR module size. The VPP could not reduce 100% of the wind variation, as additional balancing measures (e.g., smart grid, storage, and hybrid-nuclear systems) are still needed.
►A VPP with wind+nuclear produced 80% less wind power variation to grid. ►The virtual plant improved demand-following by 60–70% over wind-only. ►Power variability was indifferent to the nuclear reactor module size. ►Reactors using multiple modules can share the stress from power excursions. ►The reduction in wind power variability is offset by lower reactor utilization.
The present paper focuses on FACTS (Flexible Alternating Current Transmission System) and HVDC (High Voltage Direct Current) transmission technologies. Particular attention is paid to different ...specific technical, economic and environmental features of these power electronics-based devices. Final aim of the paper is the investigation of the role that FACTS and HVDC may play towards the development of the future pan-European transmission system. (8 pages)
This paper contributes to the investigations related to the development of the future transmission system in Europe. Focus is on some specific long-term (2040) analyses in a pan-European perspective. ...The studies have been conducted by extending a pan-European zonal model. After the build-up of a suitable long-term scenario framework for the pan-European system, an optimization tool is applied. Some effects of extending the geographical coverage of the pan-European zonal model are assessed. This evolution can be considered as a crucial stage towards the development of the northern part of a potential global power grid.
Differences of Latvia’s silver birch (Betula pendula Roth.) provenances Gailis, A., Latvian State Forest Research Inst. Silava, Salaspils (Latvia); Augustovs, J., Latvian State Forest Research Inst. Silava, Salaspils (Latvia); Purvins, A., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) ...
Mezzinatne (Latvia),
(2012), Letnik:
25, Številka:
58
Journal Article
Recenzirano
Birch is one of the most widespread tree species in Latvia (30% from the area). During the past century it was not viewed as valuable tree species in most of the countries around the Baltic Sea, ...therefore limited number of experiments were carried out. In Latvia, intensive breeding process of the species was started from the year 1995 with selection of candidate stands, their inventories and selection of plus trees for establishment of seed orchards and progeny trials. Currently these two seed orchards cover almost all the demand for birch seeds that has been constantly growing mainly due to afforestation of former arable lands and, in recent years, also planting in forest. Established progeny trials can provide information not only for selection of new set of tested seed orchard clones, but also general trends in comparison of provenances across Latvia. Aim of the study is to analyze the differences and geographical patterns of provenances. Material was collected from plus trees and good quality trees from 37 stands representing all regions of Latvia. In 3 trials altogether 921 open-pollinated family was used, majority of them were represented in two (331) or all three (316) trials, but portion (274) only in one trial. Therefore number of families per site ranges from 613 to 653. Design was either large block plots (32 trees) in 4 replications or single tree plots. All trials were established on abandoned agricultural land with initial spacing 2×2 m or 2×2.5 m using one-year-old container plants. For the analysis only 6 or 10 highest trees per block-plot or family were used. Results reveal that average tree height in different test sites reaches 6.3 m to 7.6 m, diameter of the thickest branch up to two meters height is on average 10mm and branch angle in the middle part of the green crown 45°. Frequency of trees with spike knots varies greatly among trials due to both genetic and environmental reasons: from 14% up to 38%.
Influence of hydrogen fuel cell stack output current ripple caused by a one phase voltage-fed inverter system on efficiency of the fuel cell stack is investigated experimentally. The system includes ...hydrogen canister, 1.2 kW hydrogen fuel cell module, DC/DC step-up converter and PWM inverter. The system has two DC voltage stages: relatively low and variable voltage on the fuel cell output and stabilized high voltage on the input of the PWM inverter. The electrically isolated voltage-fed push-pull DC/DC step-up power converter with high frequency transformer is found as appropriate for this system from the conventional converters by the following criteria - high efficiency and high power density.
Hydrogen as a clean energy carrier Purvins, A., Latvia; Ribickis, L., Riga Technical Univ. (Latvia). Faculty of Power and Electrical Engineering. Inst. of Industrial Electronics and Electrotechnology
Energija un Pasaule (Latvia),
(2007)
2
Journal Article
One of the perspective forms of future renewable energy resources is hydrogen (H2) energy. In the article have been viewed one of energy transformation cycle, were hydrogen used as a compiler of ...electric energy. Research on properties of high power density of proton exchange membrane fuel cells has been carried out at the Department of Industrial Electronics and Electro-technology of the Riga Technical University.
•A Europe-wide electricity system model with 35 interconnected countries.•Validation of the model against historical records of 2016.•Modelling results closely follow observed electricity generation ...and cross-border trade.•Modelled wholesale electricity prices replicate well daily and weekly dynamics.•Annual modelled load-weighted wholesale price in Europe is 35.41€/MWh – 3€ less than historical.
This article presents and validates a Europe-wide electricity system model for techno-economic analysis. It is a zonal model in which 35 countries are modelled as individual bidding zones. Validation of the model is performed via comparing modelling results with historical records of 2016. The model replicates historical electricity system behaviour well in terms of electricity production and cross-border trading. Modelled hourly prices follow historical variations. The model results in an average annual load weighted electricity price of 35.41€/MWh, which is 3€ less than the historical value. The presented validation exercise provides a simple and fast way to improve modelling accuracy through adjusting input data and modelling assumptions. This article also shows how to set up a complete Europe-wide electricity system model from open-source data.
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