Renewable Energy Storage Systems Based on Chemical Compounds: Sustainability Evaluation and Integration with Other Systems

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Publications

Life cycle assessment of a renewable energy generation system with a vanadium redox flow battery in a NZEB household

Publication . Gouveia, J.R.; Silva, E.; Mata, T.M.; Mendes, A.; Caetano, Nídia; Martins, A.A.

Buildings are responsible for a significant part of the global energy consumption. Besides the need to improve their energy efficiency, new buildings also need to generate their own energy, preferably from renewable sources, to become more sustainable. As renewable energy generation is strongly dependent on the climatic conditions, energy storage must be considered when designing such a system. In this study, a cradle-to-grave life cycle assessment (LCA) study of a renewable energy generation system with a prototype Vanadium flow battery integrated in a Near Zero Energy Building (NZEB) is performed. A combined grid-connected PV and a solar thermal system generates the energy, and it was dimensioned to supply the annual energy needs of a household in Porto, Portugal considering the local climatic conditions. As an end of life scenario, it is assumed that the battery is dismantled and most of the materials are recycled. A functional unit of 1 kWh of supplied energy to the system was considered, and study results show that environmental impacts are reduced when the energy is produced onsite and the battery components are recycled or reused. A sensitivity analysis was conducted changing the household’s geographic location.

2019Conference object

Open access

Flocculation of Arthrospira maxima for improved harvesting

Publication . Caetano, Nídia; Martins, A.A.; Gorgich, M.; Gutiérrez, D.M.; Ribeiro, T.J.; Mata, T.M.

The environmental impacts associated with the burning of fossil fuels coupled with growing concerns about security of energy supply, motivated the search for more sustainable forms of energy production, among which came microalgae for biofuels production. However, the commercial production of microalgae biofuels is still not competitive compared to fossil fuels, as it is necessary to solve some process bottlenecks, among which biomass harvesting, that is the focus of this work. Hence, this work intends to study the harvesting of microalga Arthrospira maxima through flocculation by pH variation and/or addition of CaCl2 as flocculant. Thus, it is described the effect of pH variation (in the range 6 to 12), followed by the addition of flocculant, on the harvesting efficiency. Results show that by pH increase over 10 using NaOH, or by flocculation using CaCl2 at a concentration of 0.2-2.0 g/L and at a 1:30 ratio (v/v) of CaCl2/microalgae culture, it is possible to effectively harvest this microalga.

2019Conference object

Open access

Sustainability evaluation of a Portuguese “terroir” wine

Publication . Martins, A.A.; Costa, M.C.; Araújo, A.R.; Morgado, A.; Pereira, J.M.; Fontes, N.; Graça, A.; Caetano, Nídia; Mata, T.M.

The challenges of sustainability are transversal to all human activities, and the wine sector has its own role to play in the march for a more sustainable development. The proper definition of the most adequate measures and/or policies must be based on an objective and quantitative evaluation of the sustainability of a product or process. In this work the sustainability of a “terroir” wine is assessed taking into account its life cycle and using the following indicators: carbon and water footprint, material intensity, solid waste generated, worker turnover rate, investment in H&S training and EBITDA. All indicators are expressed per functional unit of 0.75 L of wine. The evaluation used data from the company complemented with data/information from the literature or life cycle inventory databases. To account for climatic variability, data from three consecutive years was used. Average values of 3.51 kgCO2eq and 481.4 L per functional unit were obtained for the carbon and water footprint respectively, both values within the range of values reported in the literature.

2019Conference object

Open access

Syngas production by bi-reforming of methane on a bimetallic Ni-ZnO doped zeolite 13X

Publication . Cunha, Adelino F.; Morales-Torres, Sergio; Pastrana-Martínez, Luisa M.; Maldonado-Hódar, Francisco J.; Caetano, Nídia S.

Ennoblement of carbon dioxide, particularly the one produced by anaerobic digestion or by biomass combustion, is a motivation to develop novel or improving already existing processes. In this context, an interesting idea is to use carbon dioxide combined together with methane and water. Therefore, bi-reforming of methane (BRM) for syngas production appears to be a good choice. In this work, BRM was studied over a Ni-catalyst supported on a ZnO-doped zeolite 13X in the temperature range 300 to 900 ◦C. This material was deeply characterized by different techniques. The pure zeolite 13X shows relative good sorption capacity for CO2 at low temperatures (<100 ◦C). The ZnO phase introduced on zeolite 13X did not show a significant improvement for BRM, while 13X zeolite material impregnated with Ni and ZnO showed promising activities, achieving CO2 conversions in the range of 50–60% at a maximum operating temperature of 800 ◦C and atmospheric pressure. The results obtained suggest that ZnO acts as an oxygen supplier when methane is activated by surface nickel, thus destabilizing the feed in the following order: methane, water and carbon dioxide. The influence of the operating conditions in the reactants conversion and products distribution was also analyzed, and it can be concluded that the molar ratios of hydrogen-to-carbon monoxide are close to two at high temperatures.

2022Journal article

Restricted access

Potential of Phaeodactylum tricornutum for Biodiesel Production under Natural Conditions in Chile

Publication . Branco-Vieira, Monique; San Martin, Sergio; Agurto, Cristian; Santos, Marco; Freitas, Marcos; Mata, Teresa; Martins, António; Caetano, Nídia

Diatoms are very diverse and highly productive organisms, found in a wide variety ofenvironments. This study aims to analyze the growth and lipid composition ofPhaeodactylum tricornutum,cultured in an outdoor pilot-scale bubble column photobioreactor under natural conditions in Chile forbiodiesel production.Results showed thatP. tricornutumcultures reached their highest biomassconcentration (0.96±0.04 kg m−3) after 14 days of culturing, at the stationary phase, with avolumetric productivity of 0.13 kg m−3d−1. Biomass samples showed a total lipid content of9.08±0.38 wt %. The fatty acid methyl ester analysis revealed a composition of 24.39% C16-C18 fattyacids, 42.34% saturated fatty acids, 21.91% monounsaturated fatty acids and 31.41% polyunsaturatedfatty acids. These findings suggest thatP. tricornutumoil can be used as an alternative raw materialfor the production of biodiesel capable of meeting international quality standards.

2017-12-28Journal article

Open access