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Abstract Many countries are implementing energy policies that focus on the transformation of national power generation mixes into highly efficient and sustainable systems. In the case of the Spanish electricity sector, regulations applicable to existing coal thermal plants and the proximity to the end of the lifetime of nuclear power plants arise as critical concerns to be addressed. In this respect, a sensible energy strategy is required in order to fill the future gap of coal and nuclear power plants. Within this context, this work applies a novel methodological framework for the prioritisation of 15 energy scenarios formulated for power generation in Spain. In addition to a business-as-usual scenario, alternative ones are built based on potential restrictions on fossil-based technologies and lifetime extensions of coal and nuclear power plants. The novel multi-criteria decision analysis approach for enhanced, sustainability-oriented energy planning is based on the combined use of energy systems modelling, life cycle assessment, and data envelopment analysis. Besides conventional techno-economic results, the evolution of life-cycle indicators endogenously integrated into the energy system model of Spain is provided. The subsequent use of a dynamic data envelopment analysis model leads to identify and rank the most suitable energy scenarios according to sustainability criteria. Graphical abstract Image 1 Highlights • Joint Life Cycle Assessment, Energy Systems Modelling and Data Envelopment Analysis. • 15 scenarios on coal and nuclear extension and penetration of CO 2 capture systems. • Thorough prioritisation of 15 prospective scenarios for power generation in Spain. • Modification of the original ranking according to short/long-term prioritisation. • Proven feasibility of the methodological framework for enhanced energy planning. [ABSTRACT FROM AUTHOR]

This paper describes the construction and analysis of a disaggregated input-output model and its extension to a social accounting matrix (SAM) for the Spanish economy in 2013. Our focus is the specific disaggregation of the electricity industry into the generating, transmission, distribution and marketing businesses, which were decoupled in 1997 under legislation prohibiting any single company from conducting more than one of them. The multi-sectoral framework also allows disaggregation of electricity generating by production technologies (wind, nuclear, conventional thermal, hydropower, solar and other technologies). To the best of our knowledge, this is the first paper in which this information is presented in a multi-sectoral framework for the Spanish economy, which is enormously dependent on the electricity industry. The structural analysis reveals the industry's role in Spain and the importance of its activities. None of the electricity generating businesses is a Rasmussen key sector, and generating and distribution are both capital-intensive activities. Meanwhile, conventional thermal and hydropower generating together make up more than 50% of total output in value terms, while nuclear power accounts for only around 7%. Finally, imports and exports of electricity are small, and almost all demand is covered by domestic production. [ABSTRACT FROM AUTHOR]

Proper planning for the dimensions of an electricity production and transmission system requires the availability of medium- and long-term electricity demand projections that are sufficiently reliable. Generally, these projections are directly linked to the estimated growth for the whole real GDP (gross domestic product), although an in-depth historical evolution of this demand, as that given in this article, advises the explicit consideration of several determinants. The aim of this paper is to present an alternative analysis of the demand for electricity based on a simple growth rate decomposition scheme that allows the key factors behind this evolution to be identified. It is possible, taking this scheme as a starting point, to develop a long-term forecasting model to obtain projections of electricity demand given the expected evolution of the key factors. The proposed methodology is illustrated using Spain as a case study to obtain demand projections till 2030. [ABSTRACT FROM AUTHOR]

Abstract: Renewable energy sources are believed to reduce drastically greenhouse gas emissions that would otherwise be generated from fossil fuels used to generate electricity. This implies that a unit of renewable energy will replace a unit of fossil-fuel, with its CO2 emissions, on an equivalent basis – with no other effects on the grid. But, the fuel economy and emissions in the existing power systems are not proportional with the electricity production of intermittent sources due to cycling of the fossil-fuel plants that make up the balance of the grid (i.e. changing the power output makes thermal units to operate less efficiently). This study focuses in the interactions between wind generation and thermal plants cycling, by establishing the levels of extra fuel use caused by decreased efficiencies of fossil back-up for wind electricity in Spain. We analyze the production of all thermal plants in 2011, studying scenarios where wind penetration causes major deviations in programming and we define a procedure for quantifying CO2 reductions using emission factors and efficiency curves from existing installations; the objective is to discuss the real contribution of renewable energy to the environmental targets: the results show that CO2 reductions are still relevant at high wind penetration, whilst we also suggest alternatives to improve reliability of the power system. [Copyright &y& Elsevier]

Abstract: The Iberian power systems went through important changes at the legal, regulatory and organizational levels in the last 20 years. One of the most relevant ones was the increasing penetration of distributed generation, namely wind parks, together with the development of the common market involving Portugal and Spain. In Portugal, distributed generation is paid using feed in tariffs while in Spain it can choose between receiving a regulated feed in tariff or the market price plus a participation prize. The feed in scheme is now under discussion since it is argued that it represents an excessive cost that is internalized in the end user tariffs. However, this discussion is frequently conducted without complete knowledge of the real impact of wind power on the electricity market price, since it contributes to reduce the demand on the market thus inducing a price reduction. To clarify these issues we used a long term System Dynamics based model already reported in a previous publication to estimate the long term evolution of the market price. This model was applied to the Iberian generation system using different shares of wind power capacity to quantify the impact of wind power on the day-ahead electricity market price. [Copyright &y& Elsevier]

Abstract: The knowledge of the potentially achievable reduction of greenhouse gas (GHG) emissions by biomass co-firing is a powerful tool in supporting decision makers when it comes to undertaking energy planning. The main goal of this work was to develop a methodology by which significant biomass co-firing potentials and subsequent reduced GHG emissions, could be obtained at large territories. This methodology has been applied to Spain. It has been found that agricultural and forestry residual biomass feedstocks, available within 100 km of coal-fired power plants (CPP), currently total up to 75.8 PJth/yr. If energy crop feedstocks are included, this quantity increases up to 91.1 PJth/yr. However, the utilisation of biomass in CPPs is constrained by technical limitations. Taking into account these restrictions, biomass could be co-fired to generate up to 7.7% of electricity produced in CPPs (42.1 PJth/yr of biomass). A life cycle assessment has been performed to all the processes involved. The results indicate that up to 87 tCO2eq can be reduced by utilising 1 TJth of biomass replacing coal. The combination of these figures points out that biomass co-firing could contribute to mitigating 3.4 MtCO2eq in Spain annually. This value equates to almost 1% of its total GHG emissions. [Copyright &y& Elsevier]

Abstract: This work develops a design and operation support tool for an Integrated Gasification Combined Cycle (IGCC) power plant, which allows the efficiency and environmental issues of alternative process designs and feedstock to be assessed. The study is based on a conceptual model of an IGCC plant, validated with data from the ELCOGAS power plant in Spain. The layout of the model includes an Air Separation Unit (ASU), a Pressurized Entrained Flow (PRENFLO) gasifier, a series of purification gas units (venturi scrubber, sour water steam stripper, COS hydrolysis reactor, MDEA absorber columns and a sulphur recovery Claus plant), a Heat Recovery Steam Generator (HRSG) and a Combined Cycle (CC) system. It comprises steady state models. One of the purposes of this work is to analyze the feasibility of coal co-gasification using waste materials; specifically petcoke and olive pomace (orujillo) are considered here. The model has been developed in Aspen Hysys. It uses electrolyte models that have been implemented in Aspen Plus which are connected to Aspen Hysys by means of Artificial Neural Networks (ANNs) models. Results of the model''s, gas composition and generated power, are in agreement with the industrial data. [Copyright &y& Elsevier]

Abstract: In this paper, different electricity demand scenarios for Spain are presented. Population, income per capita, energy intensity and the contribution of electricity to the total energy demand have been taken into account in the calculations. Technological role of different generation technologies, i.e. coal, nuclear, renewable, combined cycle (CC), combined heat and power (CHP) and carbon capture and storage (CCS), are examined in the form of scenarios up to 2050. Nine future scenarios corresponding to three electrical demands and three options for new capacity: minimum cost of electricity, minimum CO2 emissions and a criterion with a compromise between CO2 and cost (CO2-cost criterion) have been proposed. Calculations show reduction in CO2 emissions from 2020 to 2030, reaching a maximum CO2 emission reduction of 90% in 2050 in an efficiency scenario with CCS and renewables. The contribution of CCS from 2030 is important with percentage values of electricity production around 22–28% in 2050. The cost of electricity (COE) increases up to 25% in 2030, and then this value remains approximately constant or decreases slightly. [Copyright &y& Elsevier]

The European energy transition implies a relevant increase of renewable energies in the electric power generation mix. Integrating additional renewables is becoming more challenging due to their variability. Spain's peninsular situation aggravates this problem because it is an electric island. Within this framework, Liquid Air Energy Storage (LAES) is a promising technology for balancing the power grid. This work proposes a transient thermodynamic modelling of a 100 MW LAES plant. The cycle incorporates a packed-bed cold-storage system to enhance the charge/discharge efficiency. The appearance of a thermocline in the cold-storage unit is relevant regarding the round-trip efficiency. An economic study based on the simulation results is performed considering different scenarios of renewables grid penetration (photovoltaic and wind power). Depending on the installed LAES capacity, the levelized cost of delivered energy is evaluated. The results suggest that it is more interesting to store photovoltaic energy in the daytime peak hours and release energy during the night-time valleys to maximize the use of storage plants. This allows the levelized cost of energy and storage to be reduced to values as low as 150 and 50 €/MWh respectively. These prices are competitive with compressed air energy storage and even with pumped-hydro storage. Image 10252 • Transient LAES simulation including packed-bed cold storage unit. • Techno-economical study of LAES integration into the Spanish electric power grid. • LCOE ∼ 250 €/MWh in valley charge/peak discharge configuration. • LCOE ∼ 150€/MWh with the opposite concept considering important PV power increase. • Competitive with pumped-hydro storage or Compressed Aire Energy Storage (CAES). [ABSTRACT FROM AUTHOR]