Hybridizing concentrated solar power (CSP) with biogas and biomethane as an alternative to natural gas: Analysis of environmental performance using LCA

Concentrating Solar Power (CSP) plants typically incorporate one or various auxiliary boilers operating in parallel to the solar field to facilitate start up operations, provide system stability, avoid freezing of heat transfer fluid (HTF) and increase generation capacity. The environmental performance of these plants is highly influenced by the energy input and the type of auxiliary fuel, which in most cases is natural gas (NG). Replacing the NG with biogas or biomethane (BM) in commercial CSP installations is being considered as a means to produce electricity that is fully renewable and free from fossil inputs. Despite their renewable nature, the use of these biofuels also generates environmental impacts that need to be adequately identified and quantified. This paper investigates the environmental performance of a commercial wet-cooled parabolic trough 50 MWe CSP plant in Spain operating according to two strategies: solar-only, with minimum technically viable energy non-solar contribution; and hybrid operation, where 12 % of the electricity derives from auxiliary fuels (as permitted by Spanish legislation). The analysis was based on standard Life Cycle Assessment (LCA) methodology (ISO 14040-14040). The technical viability and the environmental profile of operating the CSP plant with different auxiliary fuels was evaluated, including: NG; biogas from an adjacent plant; and BM withdrawn from the gas network. The effect of using different substrates (biowaste, sewage sludge, grass and a mix of biowaste with animal manure) for the production of the biofuels was also investigated. The results showed that NG is responsible for most of the environmental damage associated with the operation of the plant in hybrid mode. Replacing NG with biogas resulted in a significant improvement of the environmental performance of the installation, primarily due to reduced impact in the following categories: natural land transformation, depletion of fossil resources, and climate change. However, despite the renewable nature of the biofuels, other environmental categories like human toxicity, eutrophication, acidification and marine ecotoxicity scored higher when using biogas and BM

Life cycle assessment of concentrated solar power (CSP) and the influence of hybridising with natural gas

Purpose Concentrating Solar Power (CSP) plants based on parabolic troughs utilize auxiliary fuels (usually natural gas) to facilitate start-up operations, avoid freezing of HTF and increase power output. This practice has a significant effect on the environmental performance of the technology. The aim of this paper is to quantify the sustainability of CSP and to analyse how this is affected by hybridisation with different natural gas (NG) inputs. Methods A complete Life Cycle (LC) inventory was gathered for a commercial wet-cooled 50 MWe CSP plant based on parabolic troughs. A sensitivity analysis was conducted to evaluate the environmental performance of the plant operating with different NG inputs (between 0 and 35% of gross electricity generation). ReCiPe Europe (H) was used as LCA methodology. CML 2 baseline 2000 World and ReCiPe Europe E were used for comparative purposes. Cumulative Energy Demands (CED) and Energy Payback Times (EPT) were also determined for each scenario. Results and discussion Operation of CSP using solar energy only produced the following environmental profile: climate change 26.6 kg CO2 eq/KWh, human toxicity 13.1 kg 1,4-DB eq/KWh, marine ecotoxicity 276 g 1,4-DB eq/KWh, natural land transformation 0.005 m2/KWh, eutrophication 10.1 g P eq/KWh, acidification 166 g SO2 eq/KWh. Most of these impacts are associated with extraction of raw materials and manufacturing of plant components. The utilization NG transformed the environmental profile of the technology, placing increasing weight on impacts related to its operation and maintenance. Significantly higher impacts were observed on categories like climate change (311 kg CO2 eq/MWh when using 35 % NG), natural land transformation, terrestrial acidification and fossil depletion. Despite its fossil nature, the use of NG had a beneficial effect on other impact categories (human and marine toxicity, freshwater eutrophication and natural land transformation) due to the higher electricity output achieved. The overall environmental performance of CSP significantly deteriorated with the use of NG (single score 3.52 pt in solar only operation compared to 36.1 pt when using 35 % NG). Other sustainability parameters like EPT and CED also increased substantially as a result of higher NG inputs. Quasilinear second-degree polynomial relationships were calculated between various environmental performance parameters and NG contributions. Conclusions Energy input from auxiliary NG determines the environmental profile of the CSP plant. Aggregated analysis shows a deleterious effect on the overall environmental performance of the technology as a result of NG utilization. This is due primarily to higher impacts on environmental categories like climate change, natural land transformation, fossil fuel depletion and terrestrial acidification. NG may be used in a more sustainable and cost-effective manner in combined cycle power plants, which achieve higher energy conversion efficiencies

Prototipo metodológico para la mejora del espacio público en proyectos de regeneración urbana, programa del IMU (Instituto Municipal Urbano). Casos de estudio: el Besòs i el Maresme y Trinitat Vella.

La complejidad de una ciudad, implica diversos retos y problemáticas a solventar. El Instituto Municipal de Urbanismo de Barcelona pretende resolver la gestión urbanística desde la rehabilitación, regeneración y remodelación urbana, combinando factores sociales, económicos y ambientales para su correcto desarrollo e implementación de las políticas de mejora urbana en curso. Este Instituto, a través del Programa de Regeneración Urbana de Barcelona, estudia desde hace dos años los polígonos residenciales más vulnerables de Barcelona. Es por ello que el presente trabajo final de máster, recopila, analiza y propone una nueva metodología de seguimiento enfocada en el estudio del espacio público y cohesión social específicamente en el caso de dos barrios: El Besòs i el Maresme y Trinitat Vella. La base fundamental de la metodología empleada es la contribución de una forma de análisis y propuestas que abarcan lo cualitativo y lo cuantitativo. Para la elaboración de esta metodología se han elaborado esquemas de colaboración y aporte de ideas entre expertos (arquitectos, urbanistas o sociólogos), entrevistas, encuestas y visitas de campo que han servido para plantear una valoración y evaluación general que deriva en un conjunto de criterios y lineamientos para el desarrollo de una propuesta de regeneración urbana integral para etapas futuras. Los análisis y resultados obtenidos dan cuenta del reto que representa el manejo de este tipo de proyectos, pero también complementa las metodologías existentes de trabajo abordando temas sensibles que inciden en la percepción e implicación del ciudadano, el reconocimiento de las características físicas, sociales y urbanas de su barrio y a su vez, su posible y más viable participación dentro de los proyectos de regeneración que se llevan a cabo

Environmental Assessment of a HYSOL CSP Plant Compared to a Conventional Tower CSP Plant

The aim of this paper is to evaluate the environmental performance of a Concentrating Solar Power (CSP) plant based on HYSOL technology. The plant under investigation is a solar tower system with 14 hours thermal energy storage using biomethane as auxiliary fuel and using a 100 MWe steam turbine and a 80 MWe gas turbine in the combined cycle (Brayton and Rankine) characteristic of the HYSOL technology. The results evidence that HYSOL technology performs significantly better in environmental terms than conventional CSP. This evidence is particularly relevant in the climate change category where HYSOL plants presents 43.0 kg CO2 eq /MWh. In contrast, the hybrid CSP plant operating with natural gas emits 370 kg CO2 eq /MWh. This difference is attributable primarily to the nature of the auxiliary fuel (biomethane in HYSOL and natural gas in conventional CSP), but also to the higher thermal efficiencies achieved in the HYSOL configuration, which prevents the emission of 106 kg CO2 eq /MWh. The environmental significance of the additional components and infrastructure associated with the Brayton cycle in the HYSOL technology (gas turbine, Heat Recovery System and Low Temperature Energy Storage) are negligible

Socio-economic effects of a HYSOL CSP plant located in different countries: An input output analysis

The aim of this paper is to estimate the socioeconomic effects associated with the production of electricity by a CSP plant with HYSOL configuration, using Input Output Analysis. These effects have been estimated in terms of production of Goods and Services (G&S), multiplier effect, value added, contribution to GDP, employment creation and labor intensity. The analysis has been performed considering that the plant was established in four countries contemplated as suitable for HYSOL technology: Spain, Mexico, Chile and Kingdom of Saudi Arabia. The results indicate that producing electricity in a HYSOL CSP plant generates positive impacts on the economy and the employment in every country, producing the following ranges of socio-economic effects: a 0.05%-0.38% increment of the national GDP, creation of 11662-21053 jobs-year and production of 1412-2565 M$ of domestic G&S. The economic results are particularly favorable for Spain and Chile, which has been associated with higher multiplier effects (2.05 and 2.01 respectively) and higher demand of G&S in the Operation and Maintenance phase. In the case of Chile, favorable results are also due to the national production of nitrate salts employed in the thermal energy storage system. Employment results are more favorable in Mexico and Chile, which has been associated with the higher labor intensity of its national economies

Social Life Cycle Assessment of a Concentrated Solar Power Plant in Spain: A Methodological Proposal

Measuring the sustainability of goods and services in a systematic and objective manner has become an issue of paramount importance. Life cycle sustainability assessment (LCSA) is a holistic methodology whose aim is to integrate into a compatible format the analysis of the three pillars of sustainability, namely, economy, environment, and society. Social life cycle assessment (S-LCA) is a novel methodology still under development, used to cover the social aspects of sustainability within LCSA. The aim of this article is to provide additional discussion on the practical application of S-LCA by suggesting a new classification and characterization model that builds upon previous methodological developments. The structure of the social analysis has been adapted to maintain coherence with that of standard LCA. The application of this methodology is demonstrated using a case study—the analysis of power generation in a concentrated solar power plant in Spain. The inventory phase was completed by using the indicators proposed by the United Nations Environment Program/Society for Environmental Toxicology and Chemistry (UNEP/SETAC) Guidelines on S-LCA. The impact assessment phase was approached by developing a social performance indicator that builds on performance reference points, an activity variable, and a numeric scale with positive and negative values. The social performance indicator obtained (+0.42 over a range of –2 to +2) shows that the deployment of the solar power plant increases the social welfare of Spain, especially in the impact categories of socioeconomic sustainability and fairness of relationships, whose results were 1.38 and 0.29, respectively

Environmental analysis of a Concentrated Solar Power (CSP) plant hybridised with different fossil and renewable fuels

The environmental performance of a 50 MW parabolic trough Concentrated Solar Power (CSP) plant hybridised with different fuels was determined using a Life Cycle Assessment methodology. Six different scenarios were investigated, half of which involved hybridisation with fossil fuels (natural gas, coal and fuel oil), and the other three involved hybridisation with renewable fuels (wheat straw, wood pellets and biogas). Each scenario was compared to a solar-only operation. Nine different environmental categories as well as the Cumulative Energy Demand and the Energy Payback Time (EPT) were evaluated using Simapro software for 1 MWh of electricity produced. The results indicate a worse environmental performance for a CSP plant producing 12% of the electricity from fuel than in a solar-only operation for every indicator, except for the eutrophication and toxicity categories, whose results for the natural gas scenario are slightly better. In the climate change category, the results ranged between 26.9 and 187 kg CO2 eq/MWh, where a solar-only operation had the best results and coal hybridisation had the worst. Considering a weighted single score indicator, the environmental impact of the renewable fuels scenarios is approximately half of those considered in fossil fuels, with the straw scenario showing the best results, and the coal scenario the worstones. EPT for solar-only mode is 1.44 years, while hybridisation scenarios EPT vary in a range of 1.72 -1.83 years for straw and pellets respectively. The fuels with more embodied energy are biomethane and wood pellets

Rebound effects of circular business models on the consumer level: a review

This paper addresses consumer behaviour in circular economy (CE), specifically by examining consumer-level rebound effects in response to circular business models (CBMs). Despite the centrality of consumer behaviour in CE, there is a limited understanding of how consumers engage with CBMs and to what extent the environmental benefits of circular strategies may be offset by their behaviour. To this end, we conducted a systematic literature review to assess the evidence from real-life case studies of CBMs. We identified consumer behaviours leading both to rebound effects, and to reduction of environmental costs of consumption. We also showed that consumer behaviour was influenced by contextual factors and by the characteristics of the CBMs. This suggests that CBMs may only enable sustainable consumption in specific contexts

Importancia de desarrollar competencias profesionales en ingeniería.

Los mapas curriculares de los Planes de Estudio de las carreras de ingeniería, de forma tradicional han incluido competencias específicas en las asignaturas que los conforman. Sin embargo, los cambios debidos al proceso de globalización en los mercados laborales, obliga a que se incluyan las competencias genéricas tanto en su perfil de egreso como en  sus mapas curriculares. Esto ha dado lugar a las competencias profesionales las cuales conjuntan a las competencias antes mencionadas. En este documento se presenta un análisis de ambos tipos de competencias, así como sugerencias para trabajarlas con los estudiantes en el aula

Metodología para definir las competencias genéricas docentes con base al mapa curricular y referentes institucionales.

En educación es necesario considerar a los tres principales actores: alumnos, proceso enseñanza - aprendizaje y profesores. Por tanto, no basta con definir las competencias genéricas y específicas del alumno, establecer las estrategias de enseñanza - aprendizaje que lo harán adquirir los conocimientos y habilidades que requerirá para adquirir el perfil definido para la carrera que estudia; si no que es necesario definir las competencias genéricas y específicas del docente que empaten con las del alumno, a manera de alinear a los tres actores. Este artículo muestra una propuesta de metodología que permite definir las competencias genéricas del docente con base en el mapa curricular, perfil de la carrera, modelo educativo y modelo académico para el caso particular de la carrera de Ingeniería en Sistemas Automotrices (ISISA) del Instituto Politécnico Nacional (IPN). Se definen cuatro competencias genéricas, las cuales son comparadas con las establecidas por el Sistema Nacional de Bachillerato (SNB) con el propósito de validar congruencia entre ambos niveles educativos, y por que los autores hasta el momento no han encontrado documentos oficiales en México que definan las competencias del docente de nivel superior