Andalusian Association for Research and Industrial Cooperation AICIA

San Sebastián de los Reyes, Spain

Andalusian Association for Research and Industrial Cooperation AICIA

San Sebastián de los Reyes, Spain
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Larraneta M.,Andalusian Association for Research and Industrial Cooperation AICIA | Moreno-Tejera S.,University of Seville | Lillo-Bravo I.,University of Seville | Silva-Perez M.A.,University of Seville
Theoretical and Applied Climatology | Year: 2017

Many of the available solar radiation databases only provide global horizontal irradiance (GHI) while there is a growing need of extensive databases of direct normal radiation (DNI) mainly for the development of concentrated solar power and concentrated photovoltaic technologies. In the present work, we propose a methodology for the generation of synthetic DNI hourly data from the hourly average GHI values by dividing the irradiance into a deterministic and stochastic component intending to emulate the dynamics of the solar radiation. The deterministic component is modeled through a simple classical model. The stochastic component is fitted to measured data in order to maintain the consistency of the synthetic data with the state of the sky, generating statistically significant DNI data with a cumulative frequency distribution very similar to the measured data. The adaptation and application of the model to the location of Seville shows significant improvements in terms of frequency distribution over the classical models. The proposed methodology applied to other locations with different climatological characteristics better results than the classical models in terms of frequency distribution reaching a reduction of the 50% in the Finkelstein-Schafer (FS) and Kolmogorov-Smirnov test integral (KSI) statistics. © 2017 Springer-Verlag Wien


Larraneta M.,Andalusian Association for Research and Industrial Cooperation AICIA | Reno M.J.,Sandia National Laboratories | Lillo-Bravo I.,University of Seville | Silva-Perez M.A.,University of Seville
Renewable Energy | Year: 2017

When modeling the effect of the cloud transients in the Direct Normal Insolation (DNI), it is particularly relevant to identify those moments in which there are no clouds between the observer and the sun. In this paper, we present a simple algorithm for offline detection of situations where the sun path to the observer is not obstructed by any cloud. The algorithm is based on the characterization of the relations between the measured and the clear sky curves. The clear sky identification module consists of three evaluation and detection metrics: hourly mean, slope, and line length criterion. All of them rely on the assessment of the measured data against the clear sky generated data. The conjunction of the fulfillment of the three criteria leads to the clear sky hour identification. We validate our algorithm by comparing our results with those obtained from a recently published clear sky detection algorithm that uses high temporal resolution Global Horizontal Irradiation (GHI) as the input. We obtain a 98% agreement when having more than 50 min identified as clear. © 2017 Elsevier Ltd


Larraneta M.,Andalusian Association for Research and Industrial Cooperation AICIA | Moreno-Tejera S.,Andalusian Association for Research and Industrial Cooperation AICIA | Lillo-Bravo I.,Andalusian Association for Research and Industrial Cooperation AICIA | Silva-Perez M.A.,University of Seville
AIP Conference Proceedings | Year: 2017

In this paper we evaluate the cloud transients by analyzing the dynamics of the direct fraction index kb for one year of solar radiation data in different time steps. We use instant 5-sec data integrated data and compare the number and percentage of occurrences of the different defined sky conditions. We find that the most common situation is a progressive transient and that the average transient lasts between one and 5 minutes. We also perform a cloud transient duration analysis observing that the denser clouds have greater persistence. © 2017 Author(s).


Haro P.,Andalusian Association for Research and Industrial Cooperation AICIA | Haro P.,University of Seville | Johnsson F.,Chalmers University of Technology | Thunman H.,Chalmers University of Technology
Energy | Year: 2016

This study analyzes the modification of an existing process configuration train for Bio-SNG production using an indirectly-heated circulating fluidized bed gasifier. Taking the process design of the Gothenburg Biomass Gasification (GoBiGas) project, we investigate four modifications to the process design in order to analyze what the potential effect from implementation of the results from state-of-the-art research activities on bio-syngas conversion is. Firstly, aromatic compounds are converted into Bio-SNG. Secondly, olefin hydration and hydrodesulfurization units are combined in a high-temperature hydrodesulfurization unit. Thirdly, the methanation section is modified and the pre-reformer unit in the syngas conditioning section is eliminated. Finally, H2S and CO2 removal are combined in the same unit. In order to provide a comprehensive comparison of current GoBiGas process and the configuration investigated in this work, process flowcharts and energy and material balances are provided. The study reveals that the investigated configuration has the potential to reduce capital investment and operating costs. Considering Phase II of GoBiGas project, a potential reduction of 29% of the capital investment and 7 €/MWh of produced Bio-SNG could be achieved comparing planned and investigated configurations. The results prove that investigated modifications can have a large impact in the future commercialization of Bio-SNG. © 2016 Elsevier Ltd. All rights reserved.


Haro P.,Andalusian Association for Research and Industrial Cooperation AICIA | Haro P.,University of Seville | Aracil C.,Andalusian Association for Research and Industrial Cooperation AICIA | Aracil C.,University of Seville | And 2 more authors.
Applied Energy | Year: 2015

The incorporation of Bio-CCS, which involves an increase in investment and operating costs, would not be of interest in thermochemical biorefineries unless some economic benefit were provided. The rewarding of extra-avoided emissions encourages larger savings of GHG emissions in thermochemical biorefineries incorporating Bio-CCS. Therefore, there is a need for policies which reward of Bio-CCS incorporation, and in a broader sense, all extra-avoided emissions. In this study, we analyze how the geological storage of already captured CO2 (i.e. the incorporation of Bio-CCS) could be rewarded, taking different policy scenarios in the EU into consideration. Since thermochemical biorefineries achieve a GHG saving above the minimum target in the EU, the sale of all extra-avoided GHG emissions (not only from the geological storage of captured CO2) from energy carriers and chemicals is analyzed. Two different configurations of thermochemical biorefineries are analyzed: a biorefinery producing an energy carrier and a biorefinery co-producing an energy carrier and chemicals. Considering the sale of CO2 allowances in the European Emissions Trading Scheme (EU-ETS), current prices (5-15€/t) would not make Bio-CCS incorporation profitable. However, it would be profitable compare with current sequestration costs for conventional power plants (50-100€/t). If the sale of extra-avoided emissions from the production of energy carriers were included in the EU-ETS, the CO2 sequestration cost would be reduced, although not enough to enhance the process economy. If chemicals were included, the sequestration cost would decrease significantly. © 2015 Elsevier Ltd.


Haro P.,Andalusian Association for Research and Industrial Cooperation AICIA | Aracil C.,Andalusian Association for Research and Industrial Cooperation AICIA | Aracil C.,University of Seville | Vidal-Barrero F.,University of Seville | Ollero P.,University of Seville
Applied Energy | Year: 2015

In this study, a simplified methodology for the calculation of the balance of greenhouse gas (GHG) emissions and corresponding saving compared with the fossil reference is presented. The proposed methodology allows the estimation of the anthropogenic GHG emissions of thermochemical biorefineries (net emitted to the atmosphere). In the calculation of the GHG balance, all relevant factors have been identified and analyzed including multiproduction, emissions from biogenic carbon capture and storage (Bio-CCS), co-feeding of fossil fuels (secondary feedstock) and possible carbon storage in biomass-derived products (chemicals). Therefore, it is possible to calculate the balance of GHG emissions of a hypothetical thermochemical biorefinery considering different alternatives of land-use, biomass feedstock, co-feeding of fossil fuels, Bio-CCS incorporation and final use of the products. The comparison of the estimated GHG balance with the corresponding fossil reference for each product is of special relevance in the methodology since it is the parameter used in European regulation for the fulfillment of sustainability criteria in biomass-derived fuels and liquids. The proposed methodology is tested using a previously assessed set of different process concepts of thermochemical biorefineries (techno-economic analysis). The resulting GHG balance and saving are analyzed to identify uncertainties and provide recommendations for future regulation. In all process concepts, the GHG savings are above the minimum requirement of GHG emissions for 2018. In the case of incorporating Bio-CCS, cradle-to-grave negative GHG emissions are obtained. However, in order to assess the role of chemical co-production from biomass, they need to be included in future regulation. © 2015 Elsevier Ltd.


Larraneta M.,Andalusian Association for Research and Industrial Cooperation AICIA | Moreno-Tejera S.,University of Seville | Silva-Perez M.A.,University of Seville | Lillo-Bravo I.,University of Seville
Solar Energy | Year: 2015

Several studies have confirmed the relevant impact of the resolution and frequency distribution of solar radiation data on the results of detailed production models. Many of the available direct normal irradiance (DNI) databases generated from the satellite images have an hourly resolution. In the present work, we have proposed improvements to an existing model for the generation of 10-min synthetic DNI data from the hourly average DNI values. In the original model, the irradiance is divided into a deterministic and a stochastic component, i.e., the contribution from the hourly mean and stochastic fluctuation obtained from the mean depending on the sky condition, respectively. We have implemented several improvements, and the most relevant is the consistency of the synthetic data with the state of the sky. The adaptation and application of the model to the location of Seville show significant improvements over its predecessor as it achieved 7% rRMSD in hourly values and 1% rRMSD in daily values and presented a realistic frequency distribution in the 10-min resolution. In comparison with the original model, the application of the improved model showed significant performance improvements without any further adaptations to other locations with different climatological characteristics than Seville. © 2015 Elsevier Ltd.

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