Open Access
Life cycle assessment of natural gas fuelled power plants based on chemical looping combustion technology
(Elsevier, 2019-07-30) Navajas León, Alberto; Mendiara, Teresa; Goñi, Víctor; Jiménez, Adrián; Gandía Pascual, Luis; Abad, Alberto; García Labiano, Francisco; Diego, Luis F. de; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Among the different Carbon Capture and Storage (CCS) technologies being developed in the last decades, Chemical Looping Combustion (CLC) stands out since it allows inherent CO2 capture. In the CLC process, there is a solid oxygen carrier circulating between two reactors in a cycle that allows providing the oxygen needed for combustion. In one of the reactors, named as fuel reactor, the fuel is introduced and combusted while the oxygen carrier reduction takes place. In the second reactor, named air reactor, the oxygen carrier is reoxidized in air. Different materials based on copper, nickel and iron oxides have been proposed as oxygen carriers for the CLC process. This work presents an environmental evaluation of the CLC process for natural gas based on Life Cycle Assessment (LCA). Five different oxygen carrier materials already tested in pilot plants were considered and the results compared to the conventional natural gas combustion in a gas turbine in a combined cycle without and with CO2 capture using postcombustion capture with amines. In view of the results, lower impact of the CLC process compared to the base case is expected without and with CO2 capture. The influence of several variables on the results was considered, such as temperature in the air reactor, lifetime of the oxygen carrier and possibility of recuperation of the depleted oxygen carrier. The nickel-based oxygen carriers were identified as the most adequate to be used in natural gas combustion. However, due to their toxicity, several analyses were also performed in order to identify improvements in the known oxygen carriers that can qualify them to replace nickel-based materials.
Open Access
Conversion of a commercial gasoline vehicle to run bi-fuel (hydrogen-gasoline)
(Elsevier, 2012) Sáinz Casas, David; Diéguez Elizondo, Pedro; Sopena Serna, Carlos; Urroz Unzueta, José Carlos; Gandía Pascual, Luis; Ingeniería; Ingeniaritza
Bi-fuel internal combustion engine vehicles allowing the operation with gasoline or diesel and hydrogen have great potential for speeding up the introduction of hydrogen in the transport sector. This would also contribute to alleviate the problem of urban air pollution. In this work, the modifications carried out to convert a Volkswagen Polo 1.4 into a bi-fuel (hydrogen-gasoline) car are described. Changes included the incorporation of a storage system based on compressed hydrogen, a machined intake manifold with a low-pressure accumulator where the hydrogen injectors were assembled, a new electronic control unit managing operation on hydrogen and an electrical junction box to control the change from a fuel to another. Change of fuel is very simple and does not require stopping the car. Road tests with hydrogen fuel gave a maximum speed of 125 km/h and an estimated consumption of 1 kg of hydrogen per 100 km at an average speed of 90 km/h. Vehicle conversion to bi-fuel operation is technically feasible and cheap.
Open Access
Production of aromatic compounds by catalytic depolymerization of technical and downstream biorefinery lignins
(MDPI, 2020) Cornejo Ibergallartu, Alfonso; Bimbela Serrano, Fernando; Moreira, Rui; Hablich Alvarracin, Karina Lissett; García Yoldi, Íñigo; Maisterra Udi, Maitane; Portugal, Antonio; Gandía Pascual, Luis; Martínez Merino, Víctor; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua, PC036-037 Biovalorización; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Lignocellulosic materials are promising alternatives to non-renewable fossil sources when producing aromatic compounds. Lignins from Populus salicaceae., Pinus radiata and Pinus pinaster from industrial wastes and biorefinery effluents were isolated and characterized. Lignin was depolymerized using homogenous (NaOH) and heterogeneous (Ni-, Cu-or Ni-Cu-hydrotalcites) base catalysis and catalytic hydrogenolysis using Ru/C. When homogeneous base catalyzed depolymerization (BCD) and Ru/C hydrogenolysis were combined on poplar lignin, the aromatics amount was ca. 11 wt.%. Monomer distributions changed depending on the feedstock and the reaction conditions. Aqueous NaOH produced cleavage of the alkyl side chain that was preserved when using modified hydrotalcite catalysts or Ru/C-catalyzed hydrogenolysis in ethanol. Depolymerization using hydrotalcite catalysts in ethanol produced monomers bearing carbonyl groups on the alkyl side chain. The analysis of the reaction mixtures was done by size exclusion chromatography (SEC) and diffusion ordered nuclear magnetic resonance spectroscopy (DOSY NMR).31P NMR and heteronuclear single quantum coherence spectroscopy (HSQC) were also used in this study. The content in poly-(hydroxy)-aromatic ethers in the reaction mixtures decreased upon thermal treatments in ethanol. It was concluded that thermo-solvolysis is key in lignin depolymerization, and that the synergistic effect of Ni and Cu provided monomers with oxidized alkyl side chains.
Open Access
Conversion of a gasoline engine-generator set to a bi-fuel (hydrogen/gasoline) electronic fuel-injected power unit
(Elsevier, 2011) Sáinz Casas, David; Diéguez Elizondo, Pedro; Urroz Unzueta, José Carlos; Sopena Serna, Carlos; Guelbenzu, E.; Pérez Ezcurdia, Amaya; Benito Amurrio, Marta; Marcelino Sádaba, Sara; Arzamendi Manterola, Gurutze; Gandía Pascual, Luis; Ingeniería; Ingeniaritza
The modifications performed to convert a gasoline carbureted engine-generator set to a bi-fuel (hydrogen/gasoline) electronic fuel-injected power unit are described. Main changes affected the gasoline and gas injectors, the injector seats on the existing inlet manifold, camshaft and crankshaft wheels with their corresponding Hall sensors, throttle position and oil temperature sensors as well as the electronic management unit. When working on gasoline, the engine-generator set was able to provide up to 8 kW of continuous electric power (10 kW peak power), whereas working on hydrogen it provided up to 5 kW of electric power at an engine speed of 3000 rpm. The air-to-fuel equivalence ratio (λ) was adjusted to stoichiometric (λ = 1) for gasoline. In contrast, when using hydrogen the engine worked ultra-lean (λ = 3) in the absence of connected electric load and richer as the load increased. Comparisons of the fuel consumptions and pollutant emissions running on gasoline and hydrogen were performed at the same engine speed and electric loads between 1 and 5 kW. The specific fuel consumption was much lower with the engine running on hydrogen than on gasoline. At 5 kW of load up to 26% of thermal efficiency was reached with hydrogen whereas only 20% was achieved with the engine running on gasoline. Regarding the NOx emissions, they were low, of the order of 30 ppm for loads below 4 kW for the engine-generator set working on hydrogen. The bi-fuel engine is very reliable and the required modifications can be performed without excessive difficulties thus allowing taking advantage of the well-established existing fabrication processes of internal combustion engines looking to speed up the implementation of the energetic uses of hydrogen.
Open Access
Application of eco-design and life cycle assessment standards for environmental impact reduction of an industrial product
(MDPI, 2017) Navajas León, Alberto; Uriarte Elizaga, Leire; Gandía Pascual, Luis; Kimika Aplikatua; Institute for Advanced Materials and Mathematics - INAMAT2; Química Aplicada
Eco-design is included within the framework of the standard for “Environmental management systems—Guidelines for incorporating Eco-design” (ISO 14006:2011). Eco-design process, as defined in standard, has six steps: (i) Specify product functions; (ii) Environmental assessment of products; (iii) Strategies of improvement; (iv) Environmental objectives; (v) Product specification; and (vi) Technical solutions. Step (ii), determination of the stage or process of the product life cycle that has the highest environmental impact; this is perhaps the most controversial step because the standard does not specify which tool should be used. This lack of specification has generated some distrust with regard to eco-design, hindering its development. In order to make a trustworthy eco-design, Life Cycle Assessment (LCA) should be applied as a tool for environmental impact quantification. The main objective of this work is to apply standardised eco-design methodology for the reduction of the environmental impact of an industrial product in Spain using LCA as a tool for the environmental product assessment. LCA standardised process (ISO 14040,14044:2006) is included in the eco-design process. A glass container intended for cough syrup delivery has been selected as an industrial product to be eco-designed. Following the methodology described, the overall normalised impact decreased 35.1% when a PET container substituted a glass container. Environmental impacts have been reduced following standardised eco-design and LCA methodologies, serving as an example to industry and administration regarding how to eco-design with the confidence of obtaining reliable results
Open Access
Acoustic and psychoacoustic levels from an internal combustion engine fueled by hydrogen vs. gasoline
(Elsevier, 2022) Arana Burgui, Miguel; San Martín Murugarren, Ricardo; Urroz Unzueta, José Carlos; Diéguez Elizondo, Pedro; Gandía Pascual, Luis; Zientziak; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Ingeniería; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Whereas noise generated by road traffic is an important factor in urban pollution, little attention has been paid to this issue in the field of hydrogen-fueled vehicles. The objective of this study is to analyze the influence of the type of fuel (gasoline or hydrogen) on the sound levels produced by a vehicle with an internal combustion engine. A Volkswagen Polo 1.4 vehicle adapted for its bi-fuel hydrogen-gasoline operation has been used. Tests were carried out with the vehicle when stationary to eliminate rolling and aerodynamic noise. Acoustics and psychoacoustics levels were measured both inside and outside the vehicle. A slight increase in the noise level has only been found outside when using hydrogen as fuel, compared to gasoline. The increase is statistically significant, can be quantified between 1.1 and 1.7 dBA and is mainly due to an intensification of the 500 Hz band. Loudness is also higher outside the vehicle (between 2 and 4 sones) when the fuel is hydrogen. Differences in sharpness and roughness values are lower than the just-noticeable difference (JND) values of the parameters. Higher noise levels produced by hydrogen can be attributed to its higher reactivity compared to gasoline.
Open Access
Pseudo-homogeneous and heterogeneous kinetic models of the NaOH-catalyzed methanolysis reaction for biodiesel production
(MDPI, 2021) Zabala, Silvia; Reyero Zaragoza, Inés; Campo Aranguren, Idoia; Arzamendi Manterola, Gurutze; Gandía Pascual, Luis; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Methanolysis of vegetable oils in the presence of homogeneous catalysts remains the most important process for producing biodiesel. However, there is still a lack of accurate description of the reaction kinetics. This is in part due to the complexity of the reacting system in which a large number of interconnected reactions take place simultaneously. In this work, attention is focused on the biphasic character of the reaction medium, formed by two immiscible liquid phases. The behavior of the phases is investigated regarding their physicochemical properties, mainly density and mutual solubility of the components, as well as composition. In addition, two kinetic models with different level of complexity regarding the biphasic character of the reaction medium have been developed. It has been found that a heterogeneous model considering the presence of the two phases and the distribution of the several compounds between them is indispensable to get a good description of the process in terms of oil conversion and products yields. The model captures the effects of the main variables of an isothermal batch methanolysis process: methanol/oil molar ratio, reaction time and catalyst concentration. Nevertheless, some adjustment is still required as concerns modelling of the saponification reactions and catalyst deactivation.
Open Access
Environmental impact improvement of chitosan-based mixed-matrix membranes manufacture for CO2 gas separation by life cycle assessment
(Wiley, 2023) Echarri San Martín, Itsaso Andrea; Casado-Coterillo, Clara; Rumayor, Marta; Navajas León, Alberto; Gandía Pascual, Luis; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The environmental impacts of the manufacture of chitosan (CS) and polymeric poly(1-trimethylsilyl-1-propyne) (PTMSP) mixed-matrix membranes (MMMs) for CO2 separation by life cycle assessment (LCA) are compared. An ionic liquid of non-reported toxicity is used in CS membranes to enhance the mechanical strength, and different fillers are used to increase mechanical and functional properties: ETS-10, ZIF-8, HKUST-1, and Zeolite A. Results with the same CO2 permeation flux indicate that ETS-10/IL-CS is the membrane manufacture with highest impacts due to its lower permeability. When comparing impacts with same permeation areas, the polymeric one is the membrane with highest impacts. Biopolymer and polymer manufacture are the components with highest contribution to the total environmental impacts of each membrane. To decrease all their impacts below fossil polymer membrane for the same CO2 permeation flux, CS membranes permeabilities should be improved by a numerical factor of 1000, 100, and 2 for the ETS-10, ZIF-8, and HKUST-1/IL-CS MMMs, respectively.
Open Access
Exploring a low-cost valorization route for amazonian cocoa pod husks through thermochemical and catalytic upgrading of pyrolysis vapors
(American Chemical Society, 2023) Villasana, Yanet; Armenise, Sabino; Ábrego, Javier; Hablich, Karina; Bimbela Serrano, Fernando; Cornejo Ibergallartu, Alfonso; Gandía Pascual, Luis; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Ecuador as an international leader in the production of cocoa beans produced more than 300 000 tons in 2021; hence, the management and valorization of the 2 MM tons of waste generated annually by this industry have a strategic and socioeconomic value. Consequently, appropriate technologies to avoid environmental problems and promote sustainable development and the bioeconomy, especially considering that this is a megadiverse country, are of the utmost relevance. For this reason, we explored a low-cost pyrolysis route for valorizing cocoa pod husks from Ecuador’s Amazonian region, aiming at producing pyrolysis liquids (bio-oil), biochar, and gas as an alternative chemical source from cocoa residues in the absence of hydrogen. Downstream catalytic processing of hot pyrolysis vapors using Mo- and/or Ni-based catalysts and standalone γ-Al2O3 was applied for obtaining upgraded bio-oils in a laboratory-scale fixed bed reactor, at 500 °C in a N2 atmosphere. As a result, bimetallic catalysts increased the bio-oil aqueous phase yield by 6.6%, at the expense of the organic phase due to cracking reactions according to nuclear magnetic resonance (NMR) and gas chromatography–mass spectrometry (GC–MS) results. Overall product yield remained constant, in comparison to pyrolysis without any downstream catalytic treatment (bio-oil ∼39.0–40.0 wt % and permanent gases 24.6–26.6 wt %). Ex situ reduced and passivated MoNi/γ-Al2O3 led to the lowest organic phase and highest aqueous phase yields. The product distribution between the two liquid phases was also modified by the catalytic upgrading experiments carried out, according to heteronuclear single-quantum correlation (HSQC), total correlation spectroscopy (TOCSY), and NMR analyses. The detailed composition distribution reported here shows the chemical production potential of this residue and serves as a starting point for subsequent valorizing technologies and/or processes in the food and nonfood industry beneficiating society, environment, economy, and research.
Open Access
Life cycle assessment of power-to-methane systems with CO2 supplied by the chemical looping combustion of biomass
(Elsevier, 2022) Navajas León, Alberto; Mendiara, Teresa; Gandía Pascual, Luis; Abad, Alberto; García Labiano, Francisco; Diego, Luis F. de; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Power-to-methane (PtM) systems may allow fluctuations in the renewable energy supply to be smoothed out by storing surplus energy in the form of methane. These systems work by combining the hydrogen produced by electrolysis with carbon dioxide from different sources to produce methane via the Sabatier reaction. The present work studies PtM systems based on the CO2 supplied by the chemical looping combustion (CLC) of biomass (PtM-bioCLC). Life- cycle- assessment (LCA) was performed on PtM-bioCLC systems to evaluate their environmental impact with respect to a specific reference case. The proposed configurations have the potential to reduce the value of the global warming potential (GWP) climate change indicator to the lowest values reported in the literature to date. Moreover, the possibility of effectively removing CO2 from the atmosphere through the concept of CO2 negative emissions was also assessed. In addition to GWP, as many as 16 LCA indicators were also evaluated and their values for the studied PtM-bioCLC systems were found to be similar to those of the reference case considered or even significantly lower in such categories as resource use-depletion, ozone depletion, human health, acidification potential and eutrophication. The results obtained highlight the potential of these newly proposed PtM schemes.