Uncertainty Analysis of the Life-Cycle Greenhouse Gas Emissions and Energy Renewability of Biofuels

Biofuels can contribute substantially to energy security and socio-economic development. However, significant disagreement and controversies exist regarding the actual energy and greenhouse gas (GHG) savings of biofuels displacing fossil fuels. A large number of publications that analyze the life-cycle of biofuel systems present varying and sometimes contradictory conclusions, even for the same biofuel type (Farrell et al., 2006; Malca and Freire, 2004, 2006, 2011; Gnansounou et al., 2009; van der Voet et al., 2010; Borjesson and Tufvesson, 2011). Several aspects have been found to affect the calculation of energy and GHG savings, namely land use change issues and modeling assumptions (Gnansounou et al., 2009; Malca and Freire, 2011). Growing concerns in recent years that the production of biofuels might not respect minimum sustainability requirements led to the publication of Directive 2009/28/EC in the European Union (EPC 2009) and the National Renewable Fuel Standard Program in the USA (EPA 2010), imposing for example the attainment of minimum GHG savings compared to fossil fuels displaced. The calculation of life cycle GHG emission savings is subject to significant uncertainty, but current biofuel life-cycle studies do not usually consider uncertainty. Most often, life-cycle assessment (LCA) practitioners build deterministic models to approximate real systems and thus fail to capture the uncertainty inherent in LCA (Lloyd and Ries, 2007). This type of approach results in outcomes that may be erroneously interpreted, or worse, may promote decisions in the wrong direction (Lloyd and Ries, 2007; Plevin, 2010). It is, therefore, important for sound decision support that uncertainty is taken into account in the life-cycle modeling of biofuels. Under this context, this chapter has two main goals: i) to present a robust framework to incorporate uncertainty in the life-cycle modeling of biofuel systems; and ii) to describe the application of this framework to vegetable oil fuel in Europe. In addition, results are compared with conventional (fossil) fuels to evaluate potential savings achieved through displacement. Following this approach, both the overall uncertainty and the relative importance of the different types of uncertainty can be assessed. Moreover, the relevance of addressing uncertainty issues in biofuels life-cycle studies instead of using average deterministic approaches can be evaluated, namely through identification of important aspects that deserve further study to reduce the overall uncertainty of the system

Life-cycle assessment of microalgae biodiesel: a review

Microalgae are an attractive way to produce biofuels due to the ability to accumulate lipids and very high photosynthetic yields. This article presents a review of life-cycle assessment studies of microalgae biodiesel production, including an analysis of modeling choices and assumptions. A high variation in GHG emissions (between -0.75 and 2.9 kg CO2eq MJ-1) was found and the main causes were investigated, namely modeling choices (e.g. the approach used to deal with multifunctionality), and a high parameter uncertainty in microalgae cultivation, harvesting and oil extraction processes

Physical rehabilitation programs for bedridden patients with prolonged immobility: a scoping review

Bedridden patients usually stay in bed for long periods, presenting several problems caused by immobility, leading to a long recovery process. Thus, identifying physical rehabilitation programs for bedridden patients with prolonged immobility requires urgent research. Therefore, this scoping review aimed to map existing physical rehabilitation programs for bedridden patients with prolonged immobility, the rehabilitation domains, the devices used, the parameters accessed, and the context in which these programs were performed. This scoping review, guided by the Joanna Briggs Institute’s (JBI) methodology and conducted in different databases (including grey literature), identified 475 articles, of which 27 were included in this review. The observed contexts included research institutes, hospitals, rehabilitation units, nursing homes, long-term units, and palliative care units. Most of the programs were directed to the musculoskeletal domain, predominantly toward the lower limbs. The devices used included lower limb mobilization, electrical stimulation, inclined planes, and cycle ergometers. Most of the evaluated parameters were musculoskeletal, cardiorespiratory, or vital signs. The variability of the programs, domains, devices and parameters found in this scoping review revealed no uniformity, a consequence of the personalization and individualization of care, which makes the development of a standard intervention program challenging.This research was co-financed by the European Regional Development Fund (ERDF) through the partnership agreement Portugal 2020—Operational Programme for Competitiveness and Internationalization (COMPETE2020) under the project POCI-01-0247-FEDER-047087 ABLEFIT: Desenvolvimento de um Sistema avançado para Reabilitação

Renewability and life-cycle energy efficiency of bioethanol and bio-ethyl tertiary butyl ether (bioETBE): Assessing the implications of allocation

Biofuels are expected to play an increasingly important role in the transportation market, as we search for ways to reduce fossil fuels depletion and emissions. However, the extent to which biofuel can displace petroleum-based fuels depends on the efficiency with which it can be produced. To demonstrate that biofuel has a positive energy balance--i.e. more energy is contained in the fuel than is used in the production--a life-cycle approach must be employed. This paper presents a Life-Cycle Energy Analysis of bioethanol (from sugar beet or wheat) and bioETBE systems in France. Physical and economic data was collected. A systemic description was implemented and the energy used throughout was calculated. A novel indicator aiming at characterizing the renewability of (bio)energy sources is proposed--the energy renewability efficiency (ERenEf). ERenEf measures the fraction of final fuel energy obtained from renewable sources. Inventory results--calculated using four different allocation approaches and ignoring co-product credits--are analyzed in order to understand the effect of allocation in the energy efficiency and renewability results. Sensitivity analysis shows that allocation has a major influence in the results. This research concludes that bioethanol produced in France is clearly favorable in terms of primary energy. A maximum ERenEf value of 48% was obtained for wheat-based ethanol (mass allocation), meaning that 48% of the biofuel energy content is indeed renewable energy. Fossil energy savings when gasoline is displaced by bioethanol, bioETBE or E5 are calculated. In particular, pure bioethanol may save up to 0.70 MJ, depending on whether wheat or sugar beet is used and on the allocation procedure adopted.http://www.sciencedirect.com/science/article/B6V2S-4JXPS3B-2/1/84b597975c3dd0fd0d673cfc637e5f6

Modelação numérica de fenómenos de transferência num meio poroso húmido submetido a uma solicitação térmica externa

Dissertação de mestrado em Engenharia Mecânica apresentada à Fac. Ciências e Tecnologia da Univ. Coimbr

Numerical and experimental assessment of the hygrothermal conditions in Azorean residential buildings

Dissertação de Mestrado em Reabilitação de Edifícios apresentada à Faculdade de Ciências e TecnologiaA presente dissertação pretendeu contribuir, através de avaliação experimental e de simulação numérica, para a caracterização das condições higrotérmicas de edifícios residenciais no arquipélago dos Açores e para a definição de estratégias que contribuam para a melhoria do ambiente interior nas habitações. Estes objetivos passaram, numa primeira fase, pela monitorização in-situ das condições higrotérmicas de edifícios de habitação nas ilhas Terceira e de São Miguel, por recurso a sensores de temperatura e humidade e pela realização de ensaios complementares de determinação da condutibilidade térmica de paredes exteriores e da taxa de renovação de ar. Observou-se que, independentemente do local monitorizado, a percentagem de tempo em que vigoram condições de conforto térmico para os ocupantes é bastante reduzida, variando de 5% a 32%. A causa principal de desconforto está relacionada com o nível de humidade presente no ambiente interior.Paralelamente à componente experimental, desenvolveu-se um modelo de simulação higrotérmica em DesignBuilder e EnergyPlus, tendo por base as soluções construtivas e materiais típicos do arquipélago, os dados climáticos disponíveis para a região e os perfis de utilização do edifício. Assumiu especial relevância a modelação dos fenómenos de geração e transporte de vapor de água, pela importância de que se reveste a humidade no contexto açoriano. O modelo numérico desenvolvido permitiu avaliar, ainda que de forma condicionada pelo insuficiente processo de validação com dados experimentais rigorosos, diferentes estratégias de intervenção no edifício em análise.Compararam-se os resultados numéricos com registos recolhidos nos compartimentos monitorizados do edifício, sendo possível perceber a concordância existente entre os valores medidos experimentalmente in-situ e os resultados obtidos por via numérica. Para quantificar o potencial de redução da humidade absoluta das habitações por via da renovação do ar, estabeleceram-se cenários para simular diferentes estratégias de ventilação. Os resultados obtidos evidenciam a sensibilidade do problema em análise, mostrando que a simples ação de ventilar pode não ser, por si só, benéfica para o conforto dos utilizadores dos edifícios. Importa, sobretudo, que os regimes de ventilação sejam estabelecidos tendo em conta outros critérios que não apenas a taxa de renovação de ar, nomeadamente os períodos do dia e do ano em que essa ventilação é feita e a duração desses períodos.This dissertation contributes to the numerical and experimental assessment of the hygrothermal conditions of residential buildings in the Azores archipelago and to define strategies that may contribute to the improvement of indoor air quality in those buildings. These objectives were fulfilled by in-situ monitoring of the hygrothermal conditions of selected residential buildings in the Terceira and São Miguel islands with temperature and humidity sensors and by performing complementary tests to determine the thermal conductivity of exterior walls and actual ventilation rates. Regardless of the site being monitored, the percentage of time in which thermal comfort conditions are achieved is very low, varying from 5% to 32%, being the main cause for discomfort the humidity level in the indoor environment.A hygrothermal simulation model was also developed in DesignBuilder and EnergyPlus, based on the typical construction methods and materials of the archipelago, reference weather data sets available for the region and building usage profiles. Modeling the phenomena of generation and transport of moisture was of particular relevance because of the importance of humidity in the Azorean context. The numerical model developed allowed the assessment of different ventilation strategies in the building under analysis.A good agreement between numerical results and values measured experimentally in-situ was achieved. To quantify the potential for reducing the absolute humidity of buildings through air renewal, scenarios were established to simulate different ventilation strategies. Results point out to the sensitivity of the problem under analysis, showing that ventilation may not by itself be beneficial to thermal comfort inside buildings. In particular, ventilation systems should be established taking into account criteria other than the air renewal rate, namely the periods of the day and year in which ventilation should be performed, as well as the length of those periods

Incorporating uncertainty in the life-cycle modeling of biofuels : energy renewability and GHG intensity of biodiesel and bioethanol in Europe

Tese de doutoramento em Engenharia Mecânica, apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbr

Integrating life-cycle assessment and multi-criteria decision analysis to compare alternative biodiesel chains

This is the author version of an article copyrighted by Springer. The journal version, after typesetting and proof revisions is available at: http://link.springer.com/article/10.1007/s10479-016-2329-