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the CSP plant with different auxiliary fuels was evaluated, including: NG; biogas from an adjacent plant; and BM withdrawn from the gas network.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

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

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

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

Life Cycle Assessment of bamboo (guadua angustifolia stems) as building material for structural applications

Bamboo products have been proven to be a good altemative to hardwoods in the production of building materials, thus reducing the risk of deforestation primarily in tropical areas. Furthermore, bamboo also benefits from a very fast growing capacity when cultivated under adequate conditions, the ability to grow in non-productive land (e.g. eroded slopes) and the capacity to resprout from its stump due to its resilient root structure. Furthennore, its extensive root network promotes carbon sequestration, facilitates protection against soil erosion and reduces water depletion. Besides, from a social and economic point of view, cultivation and comercial utilization of bamboo materials support local economies in rural areas of developing countries. Bamboo stems have excellent mechanical properties that allow its use as supporting structures replacing conventional construction materials such as hardwood, steel or precast concrete. The environmental benefits of usi ng this material need to be quantified. This paper investigates greenhouse gas (GHG) emissions and energy performance of bamboo stems (guadua angustifolia) produced in Colombia under semi industrial conditions and utilized in Spain. These sustainability indicators are obtained using Life Cycle Assessment (LCA) methodology considering the following stages: stem harvesting in sustainably managed plantations, transport to processing plant, preservation/drying, transport to harbor, transport from harbor to harbor (from Colombia to Spain), transport to warehouse and storage. The functional unit considered in this assessment is a 6 meter-long stem, and the scenarios anal yzed include steam diameters 6, lO and 12 cm (weighing 1O, 14 and 17 kg respectively, dry matter basis). The calculations have been performed using Simapro 8 software and applying LCI databases from Ecoinvent v3 and ELCD v3. The environmental impacts associated with the consumption of electricity throughout the production, harvesting, processing and transportation of the bamboo materials have been adapted to the electricity mix in Colombia

Análisis de sostenibilidad del ciclo de vida de una configuración innovadora de tecnología termosolar

Contar con herramientas para cuantificar la sostenibilidad de productos y servicios es fundamental para que la actividad humana se desarrolle de forma beneficiosa para la sociedad y el medioambiente. Por ello, el Análisis de Sostenibilidad del Ciclo de Vida (ASCV) está actualmente desarrollándose como una herramienta holística que permite evaluar de forma conjunta los impactos ambientales, económicos y sociales de un producto o servicio a lo largo de su ciclo de vida completo. La producción de electricidad es una de las actividades humanas con mayor repercusión en el desarrollo sostenible, y su consumo resulta vital para satisfacer gran parte de nuestras necesidades humanas. La inestabilidad actual en el suministro de combustibles fósiles, junto con la demanda creciente de electricidad y el avance del cambio climático antropogénico, refuerzan la necesidad y preocupación humana por abastecerse urgentemente de fuentes de energía limpias y asequibles. En este contexto nace HYSOL (Innovative Configuration of a Fully Renewable Hybrid CSP Plant, nº 308912), un proyecto europeo del séptimo programa marco encaminado a desarrollar una tecnología híbrida de producción de electricidad mediante energía solar térmica y combustibles gaseosos biomásicos. Esta tesis doctoral se realiza en el marco del proyecto HYSOL, cuantificando su impacto ambiental mediante la metodología de Análisis de Ciclo de Vida, y expandiendo esta cuantificación a las áreas de economía y sociedad con el objetivo de obtener un análisis de sostenibilidad completo. Para la consecución del ASCV llevado a cabo en esta tesis se han realizado las siguientes actividades: • Se ha estudiado el estado del arte actual de la metodología de ASCV para recopilar las recomendaciones y lecciones aprendidas hasta la fecha por la comunidad científica. Dichas lecciones se han integrado en el marco metodológico propuesto en esta tesis para la evaluación de la sostenibilidad de la tecnología HYSOL. • En la evaluación del área ambiental, se ha realizado un Análisis de Ciclo de Vida para determinar y comparar el impacto ambiental potencial de la tecnología HYSOL en sus dos escenarios principales (HYSOL BIO para la operación con biometano y HYSOL GN para la operación con gas natural). Los resultados también se han comparado con el impacto ambiental de la tecnología termosolar convencional en España. Además se ha aplicado el enfoque consecuencial para determinar las consecuencias ambientales de introducir electricidad de la planta HYSOL en el mercado eléctrico español. • Para evaluar el área económica se ha realizado un análisis de Costes de Ciclo de Vida considerando costes internos y externos de los escenarios HYSOL BIO y HYSOL GN así como de la termosolar convencional. Además, se ha realizado un análisis Input Output Multi-regional para estimar los efectos socio-económicos de los escenarios HYSOL BIO, HYSOL GN, y termosolar convencional. También se ha profundizado en el desarrollo del análisis Input Output para estimar el efecto neto de incluir la tecnología HYSOL en el mercado eléctrico español. • Para evaluar el área social, se ha avanzado en el desarrollo de la metodología de Análisis de Ciclo de Vida Social proponiendo un nuevo método de caracterización para evaluar el comportamiento social del ciclo de vida de la tecnología HYSOL en España. También se ha llevado a cabo un análisis de riesgos sociales del ciclo de vida de la tecnología HYSOL y termosolar convencional utilizando la Social Hotspots Database. • Por último, se han integrado los resultados obtenidos mediante el análisis de las tres áreas de la sostenibilidad (medioambiente, economía y sociedad) en un sistema de preguntas y respuestas que representan la sostenibilidad del sistema analizado. Además, se han confeccionado unos diagramas visuales que facilitan la interpretación de los resultados y la toma de decisiones. Los resultados han revelado que la aplicación del ASCV a una tecnología innovadora como HYSOL puede proporcionar una base cuantitativa, científica, apta y eficaz para la toma de decisiones sostenible respecto al desarrollo de la tecnología y del sector de la electricidad. El análisis indica que la tecnología HYSOL presenta diferencias significativas de sostenibilidad cuando se utiliza biometano o gas natural como combustible de hibridación. La operación con biometano presenta mejor sostenibilidad ambiental y social que el gas natural, aunque la sostenibilidad económica del escenario con biometano es inferior que la del gas natural a nivel empresa y superior a nivel nacional. La mejor eficiencia de conversión de energía térmica que presenta la tecnología HYSOL respecto a la tecnología cilindro-parabólica o torre convencionales producen una mejora ambiental, económica y social. Este resultado indica que la innovación tecnológica conseguida mediante el proyecto HYSOL está bien encaminada a mejorar la sostenibilidad de la tecnología termosolar y del sector eléctrico español. ABSTRACT The use of specific tools to quantify the sustainability of products and services is essential in order to develop human activities in a profitable way for the society and the environment. To this purpose, Life Cycle Sustainability Assessment (LCSA) is being developed as a holistic tool to evaluate environmental, economic and social impacts of one product or service throughout their full life cycle. Electricity generation is one of the human activities with highest repercussion on sustainable development, while electricity consumption is vital to meet most of our necessities. The current instability of fossil fuels’ supply, the increasing electricity demand and the advance of anthropogenic climate change, reinforce the human necessity for clean and affordable energy sources. In this context emerge HYSOL (Innovative Configuration of a Fully Renewable Hybrid CSP Plant, nº 308912), an European project within the seventh framework program aiming at developing a hybrid electricity generation technology using solar thermal energy and biomass gaseous fuels. This doctoral thesis is carried out in the framework of the HYSOL project, quantifying its environmental impact using Life Cycle Assessment (LCA) and expanding this quantification to the economic and social areas in order to obtain a full sustainability assessment. The following activities have been carried out for the consecution of the HYSOL LCSA: • The LCSA state of art was explored in order to compile the recommendations and lessons learned by the scientific community up to date. Such lessons were integrated into the methodological framework proposed in this thesis. • In the environmental area, a LCA was performed in order to determine and compare the potential environmental impact of the HYSOL technology in two main scenarios (HYSOL BIO for the power plant operation with biomethane, and HYSOL GN for the operation with natural gas). The results were also compared with the environmental impact of the conventional solar thermal technology in Spain. The consequential life cycle approach was also applied in order to determine the environmental consequences of introducing HYSOL electricity into the Spanish electricity market. • In the economic area, a Life Cycle Cost Analysis was performed in order to estimate the internal and external costs of the HYSOL BIO, HYSOL GN and conventional solar thermal power plants. A Multiregional Input Output Analysis was also performed to estimate the socio-economic effects of HYSOL BIO, HYSOL GN and conventional solar thermal technology. This analysis was extended to also considerate the net effects of introducing HYSOL technology in the Spanish electricity market. • In the social area, a Social Life Cycle Assessment was applied, and a new characterization method was proposed in order to evaluate the social performance of the HYSOL technology life cycle in Spain. A social risk assessment of the HYSOL technology and conventional solar thermal technology was also performed using the Social Hotspots Database. • The obtained results in the three areas (environment, economy and society) were integrated by a “questions and answers” layout, representing the sustainability of the analyzed system. Visual diagrams representing the sustainability of the analyzed scenarios were also provided in order to facilitate the interpretation of results and the decision making process. The results revealed that the application of LCSA to an innovative technology such as HYSOL can provide a quantitative, scientific, suitable and effective base for a sustainable decision making process regarding the technology development and the electricity sector. The analysis indicates that the HYSOL technology presents significant sustainability differences when the power plant uses biomethane or natural gas as hybridization fuel. The operation with biomethane presents better environmental and social sustainability than the operation with natural gas, although the biomethane economic sustainability is lower than the natural gas at a company level and higher at a national level. The better thermal energy conversion efficiency achieved by the HYSOL technology with respect to the conventional solar thermal technology generates an environmental, economic and social improvement. These results indicate that the technologic innovation developed by the HYSOL project is well aimed to improve the sustainability of solar thermal energy and the Spanish electricity sector

Life Cycle Sustainability Analysis of an innovative configuration of Concentrated Solar Power technology

The use of specific tools to quantify the sustainability of products and services is essential in order to develop human activities that are profitable for both society and the environment. To this purpose, Life Cycle Sustainability Analysis (LCSA) is being developed as a holistic tool to evaluate environmental, economic and social impacts of one product or service throughout their full life cycle. The methodology employed in this work is based on the LCSA Analysis approach and has been applied to evaluate the sustainability of a Concentrated Solar Power (CSP) plant based on HYSOL technology, an innovative configuration that delivers improved efficiency and power dispatchability. This work responds to the need expressed by the scientific community to test LCSA methodology in different products and sectors

Analysing the effect of geographic location on the environmental performance of a high concentration photovoltaic power plant

High Concentration Photovoltaic (HCPV) technology uses multi-junction solar cells made of different layers of semiconducting materials (GaInP2/GaAs/Ge) to produce electricity from solar radiation in a sustainable and efficient manner. The environmental performance of this technology has been investigated using Life Cycle Analysis (LCA) methodology (ISO14040) using a complete inventory of a commercial 1.008 MWp HCPV plant. The analysis has been conducted in six geographic locations with potential for this technology (Morocco, Peru, South Africa, United States, Mexico and Brazil) but showing differences in terms of availability of solar resource, nature of the national electricity mix, technology capacity to produce plant components, location and availability of natural resources for the manufacturing of these components, and average transportation distance of components and resources. The origin of power consumed on-site (either from the grid or self-consumption) has given rise to two analytical scenarios.The ReCiPe Midpoint World (H) method was used for the characterization and normalization of environmental impacts in climate change, human toxicity, freshwater eutrophication, freshwater ecotoxicity, marine ecotoxicity and terrestrial acidification. The Cumulative Energy Demand (CED) and Energy Payback Time (EPBT) were used to evaluate the energy performance of the system. The results showed significant differences depending on the electricity consumption scenario considered for the plant (self or grid). This is due to the fact that electricity from the grid has a much higher impact than that obtained from the HCPV plant. This effect was more marked in countries where their electricity mix is highly depending on fossil fuels (such as South Africa) and less notable in countries with a higher contribution of renewable energies (like Brazil). The HCPV plant located in Peru exhibited the best environmental and energy performance, both in the grid and the self-consumption scenarios. This was followed by South Africa when considering environmental impacts and Brazil when considering the CED indicator. Morocco showed the worst environmental performance, with impacts nearly doubling those calculated in Peru. The results suggest that the most important parameter in the environmental performance of the HCPV plant is the amount of electricity produced (related to solar resource), followed by the share of renewable energies in the national electricity mix. This latter item plays a significant role only when assuming that the grid consumption scenario. The effect of other items, like manufacturing location and transportation of plant components, is not significant