• Energy Research
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Considering the targets of the Paris agreement, rapid decarbonisation of the power system is needed. In order to study cost-optimal and reliable zero and negative carbon power systems, a power system model of Western Europe for 2050 is developed. Realistic future technology costs, demand levels and generator flexibility constraints are considered. The optimised portfolios are tested for both favourable and unfavourable future weather conditions using results from a global climate model, accounting for the potential impacts of climate change on Europe's weather. The cost optimal mix for zero or negative carbon power systems consists of firm low-carbon capacity, intermittent renewable energy sources and flexibility capacity. In most scenarios, the amount of low-carbon firm capacity is around 75% of peak load, providing roughly 65% of the electricity demand. Furthermore, it is found that with a high penetration of intermittent renewable energy sources, a high dependence on cross border transmission, batteries and a shift to new types of ancillary services is required to maintain a reliable power system. Despite relatively small changes in the total generation from intermittent renewable energy sources between favourable and unfavourable weather years of 6%, emissions differ up to 70 MtCO2 yr−1 and variable systems costs up to 25%. In a highly interconnected power system with significant flexible capacity in the portfolio and minimal curtailment of intermittent renewables, the potential role of green hydrogen as a means of electricity storage appears to be limited.

Worldwide, the utilization of Renewable Energies (REs) for electricity generation is growing rapidly driven by the increasing fears of fossil fuels depletion, the price volatility of these fuels and the necessity of reducing the Green House Gas (GHG) emissions to preserve the environment. On the other hand, REs especially the Variable Renewable Energies (VREs) like wind and solar power suffer from intermittency in its output generation. This intermittency can introduce severe technical and economic problems for the power systems with high penetration from these energies. This intermittency should be mitigated not only during the system operation phase but also during power system planning phase. For this purpose, the classical power system planning methodologies and models should be upgraded to account for this intermittency in a way to find the optimum solutions to mitigate it. In this regard, this paper will focus on developing a new Generation Expansion Planning (GEP) model to find the optimum mix of dispatchable generation technologies that can allow the integration of VREs into the power system while mitigating the technical and economic impacts of its intermittency. In addition, a number of new concepts related to generation mix flexibility, VREs capacity credit and role of system operating reserve in integrating VREs will be revisited. Then, the developed GEP model will be applied to a case study handling the future expansion scenarios of VREs in the Egyptian grid. Results obtained show that, increasing the share of VREs in the grid will shift the mix of new generation capacities from the least cost and low flexibility options into more expensive and flexible generation options.

Abstract In the face of ever more ambitious global energy challenges, the European Union has set striving climate targets for 2030, planning to increase renewable energy penetration in the electricity generation as a key measure towards a clean energy transition. To respond to the challenge of keeping the increase in power sector costs, that inevitably arises when a profound reconfiguration of the electricity generation sector is expected, to the lowest possible, this paper aims to quantify the economic burden associated with the reduction of direct CO2 emissions through a comparative assessment of various alternatives proposed for 2030 ranked in terms of their cost-effectiveness. A sensitivity analysis is also applied to the main economic and energy parameters that make up CO2 mitigation costs to include those uncertainties that characterise future projections. The impact of electricity generation shares on CO2 mitigation costs is assessed thus providing a basis for the definition of alternative configurations for the Italian electricity sector capable to achieve the desired environmental performance with a limited economic impact. Finally, results reveal that those scenarios based largely on natural gas and solar source are characterized by high mitigation costs, while energy efficiency is essential for a virtuous and clean electricity sector along with the use of all available sources in appropriate shares, both renewable and non-renewable, to pursue the highest environmental objectives in a cost-effective manner. Although related to the Italian case, the methodology provided in this study can be applied to any other electricity sector to ultimately evaluate the economic burden arising from possible different configurations.

Abstract Traditionally, the decision criteria when analyzing hydropower plants projects, has been based mostly on technical and economical analyses focused on the electric production aspects. Nowadays a broader approach is necessary, which takes into consideration multiple impacts such as: • Energy impacts; • Water resources impacts; • Social-economics development impacts; • Agricultural sector impacts; • Environmental impacts. In order to establish a ranking of the 14 new medium and large (power above 10 MW) hydropower plants identified in the Centre Region of Portugal, a multi-disciplinary team of Coimbra University carried out a study about the impacts associated to each of the hydropower plants. The analysis considered the different aspects associated to the multi-functional character of the hydropower plants. The overall ranking of the hydropower plants was achieved using a methodology that integrates the different aspects using a weighing function [2] .