Investigación y desarrollo de la optimización de la tecnología agrovoltaica en la zona de Almería.

El presente proyecto ofrece una descripción del estado actual del arte y las oportunidades potenciales para la aplicación de sistemas agrovoltaicos. Además, se discute las posibles alteraciones microclimáticas e impactos resultantes de combinar este tipo de tecnología con la producción de cultivos. Para ello, se ha diseñado una instalación solar fotovoltaica sobre las cubiertas de un invernadero de la región de Almería, cuyo uso está dedicado al cultivo del pimiento, actualmente la hortaliza con mayor producción de la zona. Para comprobar si dicha instalación es viable tanto técnica como económicamente, se realiza un estudio de viabilidad, en el cual se calculan los principales parámetros de rentabilidad (VAN, TIR y Pay-Back) y se discuten los resultados obtenidos. Previamente a este estudio, se realiza una simulación con la herramienta PVSyst para obtener la producción estimada de la instalación solar y de esta manera calcular el ahorro económico que se consigue. Por último, se realiza un breve análisis del impacto social que pueden conllevar los proyectos agrovoltaicos en la zona donde se instalen, y se discuten las conclusiones obtenidas tras el desarrollo de la memoria del trabajo.<br /

On the oxy-combustion of lignite and corn stover in a lab-scale fluidized bed reactor

This paper addresses an experimental investigation concerning oxy-combustion of coal and biomass in a lab-scale fluidized bed reactor. While co-firing has been widely studied under conventional air conditions, few experiences are available to date for O2/CO2 atmospheres. The research is focused on SO2 and NOx emissions, along with the deposition rates and ashes mineralogy. The influences of the atmosphere (air vs. 30/70% O2/CO2), the coal-to-biomass energy input ratio (80/20%, 90/10%), the chlorine mass fraction in the biomass (0.35%, 1%, 2%) and the Ca:S mole ratio (2.5, 4) are reported and discussed in the paper, for two specific fuels: high sulfur lignite and high chlorine corn stover. Concerning SO2 emissions a correlation among the sulfur and the chlorine contents is clearly detected, being affected by the direct desulfurization mechanism occurring under oxy-firing conditions. The single effect of the chlorine content is found to be almost 1.5% of the desulfurization efficiency. NOx emissions are otherwise more dependent on oxygen excess and CO concentration in the reactor, rather than the fuel share or the chlorine supplied. Thick deposition is only detected when chlorine content in the corn is 2%. Potassium aluminosilication is found to be enhanced in comparison to potassium sulfation under oxy-firing, especially for the highest Ca:S mole ratio: observed aluminosilication is five times higher when Ca:S ratio is increased from 2.5 to 4. A significant enrichment in iron is also detected for the fly ash composition, with an increase of 30–50% in comparison to air combustion

Optimization of boiler cold-end and integration with the steam cycle in supercritical units

In order to gain an extra increment of efficiency to compensate for capital costs, one of the main issues in the design of advanced supercritical power plants is the reduction of boiler exit gas temperature below typical values of conventional, subcritical units. Currently, the use of heat exchange surfaces made of plastic has become feasible, thereby avoiding corrosion and fouling problems derived from cold-end acid condensate. In this manner, flue gas temperature can be reduced down to typically 90 °C, which obviously leads to an increase of boiler efficiency. Besides, there is an additional energy available for heating the main condensate flow of the power cycle. If modification of air-gas rotary heaters is also considered, a manifold of possibilities opens up for plant optimization and integration of components. The objective of this paper is to analyze this class of schemes for increasing power output and net efficiency of a reference supercritical plant. A complete simulation of the steam cycle is assembled using Aspen Plus and different plant configurations are examined under reduced exit gas temperatures. Several uses of flue gas energy are considered, taking into account limits of temperature and realistic efficiencies of heat exchangers. Mass flow rates, point of extraction of condensate, pressures and temperatures are selected heuristically to optimize performance. Finally, required exchange areas are estimated, and a cost analysis is carried out in order to economically assess the new configurations and estimate the additional profit for the plant.Supercritical steam cycle Integration Flue gas heat recovery Efficiency

Logistical case study for the AragÓn region using the locagistics tool

LocaGIStics is a support tool for the design of regional biomass delivery chains. It enables to further design and evaluate regional biomass delivery chains that are e.g. the result of initial planning by an energy company or a biobased producer. These general plans are translated in several biomass delivery designs using the variation in logistical concepts covering transport, pre-treatment and conversion options. The performance of every chain design can then be analyzed by comparing the different biomass delivery chains on the following environmental and economic indicators. A regional case study was performed in Aragón (Spain) using the LocaGIStics tool. In this case study maps were used where the biomass availability is specified for 2.5 x 2.5 grid cells. Data about the logistical components were supplied partly by the energy supplying company that was involved. This paper shows the main outcomes of this case study

Effect of co-firing on emissions and deposition during fluidized bed oxy-combustion

The relevance of coal oxy-firing in fluidized bed reactors has increased during the last years as an alternative for the development of CO2 capture technologies. The addition of biomass in the fuel blend is well-known in conventional combustion, but few experiences are found under oxy-combustion conditions. This paper discusses the results obtained when oxy-firing anthracite and corn stover in a lab-scale fluidized bed, paying attention to pollutant emissions, deposition rates and composition of the ashes. While SO2 emissions are affected by the chlorine content supplied with the biomass, NOx are much more dependent on operating conditions in a similar way to conventional combustion. As concerns the ash composition, chlorine is detected in fly ashes while the bed solids are mostly composed by aluminosilicates. Oxy-firing increases the chlorine detected in fly ashes in comparison to the air-fired tests. Deposition rates are barely modified by the O2/CO2 atmosphere; severe deposition is only detected for the blend with the highest chlorine content. Mixed Ca-K sulfates are found in deposits, minimizing the risk of chlorine-induced corrosion.The work described in this paper is being partially funded by the R+D Spanish National Program from the Spanish Ministry of Economy and Competitiveness, under the Project ENE2012- 39114. The project is also co-funded by the European Commission (European Regional Development Funds).Peer reviewe

Future applications of hydrogen production and CO 2 utilization for energy storage: Hybrid Power to Gas-Oxycombustion power plants

International audiencePower to Gas (PtG) has appeared in the last years as a potential long-term energy storage solution, which converts hydrogen produced by renewable electricity surplus into synthetic methane. However, significant economic barriers slow down its massive deployment (e.g. operating hours, expensive investments). Within this framework, the PtG-Oxycombustion hybridization can palliate these issues by improving the use of resources and increasing the overall efficiency. In this study we assess the requirements for electrolysis, depending on the size of the oxycombustion plant, the fuel physical and chemical properties and the final application of the hybrid system. Most suitable heat demanding options to implement this PtG-Oxycombustion hybridization are district heating, industrial processes and small combined cycled power plants. The latter case is modelled and simulated in detail and thermally integrated. The global efficiency of this hybrid system increases from 56% to 68%, thanks to avoiding the requirement of an air separation unit and integrating up to 88% of the available heat from methanation in a LP steam cycle

On the oxy-combustion of lignite and corn stover in a lab-scale fluidized bed reactor

This paper addresses an experimental investigation concerning oxy-combustion of coal and biomass in a lab-scale fluidized bed reactor. While co-firing has been widely studied under conventional air conditions, few experiences are available to date for O2/CO2 atmospheres. The research is focused on SO2 and NOx emissions, along with the deposition rates and ashes mineralogy. The influences of the atmosphere (air vs. 30/70% O2/CO2), the coal-to-biomass energy input ratio (80/20%, 90/10%), the chlorine mass fraction in the biomass (0.35%, 1%, 2%) and the Ca:S mole ratio (2.5, 4) are reported and discussed in the paper, for two specific fuels: high sulfur lignite and high chlorine corn stover. Concerning SO2 emissions a correlation among the sulfur and the chlorine contents is clearly detected, being affected by the direct desulfurization mechanism occurring under oxy-firing conditions. The single effect of the chlorine content is found to be almost 1.5% of the desulfurization efficiency. NOx emissions are otherwise more dependent on oxygen excess and CO concentration in the reactor, rather than the fuel share or the chlorine supplied. Thick deposition is only detected when chlorine content in the corn is 2%. Potassium aluminosilication is found to be enhanced in comparison to potassium sulfation under oxy-firing, especially for the highest Ca:S mole ratio: observed aluminosilication is five times higher when Ca:S ratio is increased from 2.5 to 4. A significant enrichment in iron is also detected for the fly ash composition, with an increase of 30e50% in comparison to air combustion.The work described in this paper was partially co-funded by the RþD Spanish National Program (Spanish Ministry of Economy and Competitiveness) and the European Regional Development Funds (European Commission), under the Project ENE2012-39114.Peer reviewe

Oxy-co-firing in fluidized beds: control of sulfur emissions and assessment of corrosion issues

Poster presented at 13th International Conference on Greenhouse Gas Control Technologies (GHGT-13), Lausanne, Switzerland, Nov.14-18, 2016.Oxy-co-combustion of coal and biomass in fluidized bed shows outstanding advantages, like fuel/operation flexibility and good control of SO2 and NOx emissions. But inorganic matter in biomass can be responsible of operational problems such us agglomeration in the bed, and solid deposition and corrosion in heat exchange surfaces, mainly due to KCl content in crops. Goal: To analyze the relationship between Chlorine and Sulfur content in the fuel blend with the deposition tendency for a range of conditions studied.The work described in this paper was partially funded by the R+D Spanish National Program from the Spanish Ministry of Economy and Competitiveness, under the Project ENE2015-67448-C2-2-R. The project is also co-funded by the European Commission (European Regional Development Funds).Peer reviewe

Oxy-co-firing in fluidized beds: control of sulfur emissions and assessment of corrosion issues

13th International Conference on Greenhouse Gas Control Technologies (GHGT-13), Lausanne, Switzerland, Nov.14-18, 2016The main objective of this work is to experimentally analyse the effect of firing blends of coal and biomass in oxy-firing atmospheres on SO2 emissions and deposition/corrosion issues. The research has been conducted in a lab-scale fluidized bed unit, and chemical reactivity of deposited species has been simulated at bench scale. Two very different Spanish coals were selected for the oxy-combustion experiments: anthracite, with a very low volatile matter, and lignite with high sulphur content. As concerns the biomass, a short campaign was conducted with forest residues, but most effort was done firing corn stover (with three different chlorine levels). The experimental matrix was designed to analyse the effects of the following parameters: atmosphere (air vs. O2/CO2), coal-to-biomass ratio in the blend (90/10% vs. 80/20%) and bed temperature (850-900ºC). Control of SO2 emissions was largely dependent on the governing desulfurization mechanism, while chlorine in the biomass plays a role in the condensed alkali sulfates. No significant deposition rates were detected even for the higher biomass shares in the blend (20%). Only when corn stover with the highest chlorine content (2%) was fired, a thick deposition scale was found. For the original corn stover, oxy-firing barely affects the deposition rate and slightly reduces the corrosion risk in comparison to conventional air-firing.The work described in this paper was partially funded by the R+D Spanish National Program from the Spanish Ministry of Economy and Competitiveness, under the Project ENE2012-39114. The project is also co-funded by the European Commission (European Regional Development Funds).Peer reviewe

The role of limestone during fluidized bed oxy-combustion of coal and biomass

© 2016. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/The interest in bio-CCS technologies is growing due to their potential to reduce CO2 emission in power generation. Oxy-co-firing in fluidized-bed units is one of the available techniques to develop bio-CCS, offering wide fuel flexibility and low SO2 and NOx emissions. This paper discusses the results of an experimental campaign carried out in a lab-scale fluidized bed reactor. The work focuses on the influence of limestone when oxy-firing blends of lignite and corn stover. Two different types of limestone with two Ca:S molar ratios were tested, and operational conditions were selected to compare the mechanisms governing desulphurization. Emissions of SO2, NO and HCl, together with deposition rates and ash mineralogy are studied in the paper. SO2 capture increases with the Ca:S ratio and bed temperature, but to a different extent depending on the limestone fragmentation. The amount of NO emitted rises with the Ca:S ratio and the presence of calcined limestone (indirect desulphurization). The HCl concentration in the gas phase is dominated by alkali sulfation. Finally, the conditions for the highest desulphurization efficiency diminished the deposition rates, but increased the risk for chlorine-induced corrosion.The work described in this paper was partially funded by the R+D Spanish National Program from the Spanish Ministry of Economy and Competitiveness, under the Project ENE2012-39114. The project is also co-funded by the European Commission (European Regional Development Funds).Peer reviewe