https://hdl.handle.net/10481/14750 2026-04-21T12:32:51Z 2026-04-21T12:32:51Z Valencia-Isaza, Anderson Romero Gámez, Mercedes Serrano Bernardo, Francisco Antonio Fernández Arteaga, Alejandro https://hdl.handle.net/10481/112917 2026-04-20T12:44:23Z

Valorization of spent coffee grounds: techno-economic and environmental assessment of a multi-product biorefinery Valencia-Isaza, Anderson; Romero Gámez, Mercedes; Serrano Bernardo, Francisco Antonio; Fernández Arteaga, Alejandro Spent coffee grounds are an abundant agro-industrial residue with significant potential for valorization within circular bioeconomy frameworks. This study proposes an integrated hydrothermal carbonization-based biorefinery for the simultaneous recovery of products targeting renewable energy, nutraceutical and agricultural applications. HTC is used as a platform process enabling the generation of a liquid and a solid carbon-rich fraction, which are subsequently upgraded into value-added products. Four process configurations were systematically evaluated, including a baseline scenario integrating oil recovery, prebiotics, iron-functionalized melanoidins and iron-functionalized hydrochar, and three alternative scenarios derived by progressive removal of selected unit operations to assess the impact of process simplification on economic and environmental performance. The baseline configuration proved economically viable at a processing capacity of 10t/batch (1.4 kt/year), achieving an NPV of 108.2 M$, an IRR of 18.53% and a payback period of 3.98 years under average market prices, while Scenario 2 exhibited the highest techno-economic performance, increasing the NPV by 463%. From an environmental perspective, simplified configurations that excluded solvent-intensive stages showed the lowest impacts across all categories, with the production of Prebiotics and iron-functionalized hydrochar in scenario 3 and iron-functionalized melanoidins in scenario 1 being the most environmentally favorable. Overall, the results underline the potential of SCG biorefineries to achieve economic viability and resource circularity through integrated multiproduct strategies, while indicating that further reductions in energy (steam comsuption) and water consumption are essential to fully validate their industrial scalability and environmental sustainability.

Ramos Escudero, Adela Toledo, Carlos Gómez-Gómez, Juan-de-Dios Bloemendal, Martin Collados Lara, Antonio J. Pulido Velázquez, David https://hdl.handle.net/10481/112087 2026-03-12T13:04:38Z

Spatial assessment of groundwater variability and drought impacts on ATES system suitability in Spain Ramos Escudero, Adela; Toledo, Carlos; Gómez-Gómez, Juan-de-Dios; Bloemendal, Martin; Collados Lara, Antonio J.; Pulido Velázquez, David Study region This study is conducted across groundwater bodies within mainland Spain, as defined under the European Water Framework Directive. Study focus We conduct a preliminary, national-scale assessment of groundwater-body suitability for Aquifer Thermal Energy Storage (ATES) in Spain from a water-energy nexus perspective. The methodology is based on two complementary indicators derived from long-term piezometric records: (i) a Drought Stress Response Index (DSRI), reflecting aquifer reliability, resilience, and vulnerability over decadal time scales, and (ii) groundwater-level variability and long-term trends as proxies for hydraulic stability. Together, these indicators support a first-order screening of groundwater bodies from less suitable to more suitable conditions for ATES operation. New hydrological insight of the region The analysis of drought-response indicators reveals clear spatial patterns in aquifer vulnerability, resilience, and reliability across Spain, with only weak correlations with mean groundwater levels. Groundwater-level amplitude and trend analyses indicate that unstable conditions are concentrated in southern and eastern Spain, whereas northern regions generally exhibit more stable regimes. Building on these indicators, the results reveal pronounced spatial contrasts in ATES suitability, with generally more favorable conditions in northern regions and lower suitability in large parts of southeastern Spain, while extensive areas with intermediate suitability are also identified. Based on this national-scale screening, the study provides a preliminary assessment of ATES suitability for the main Spanish urban areas, offering an initial indication of where groundwater conditions are more or less favorable for ATES deployment.

MacIntyre, Sally Crowe, Adam T. Cortés Cortés, Alicia Arneborg, Lars https://hdl.handle.net/10481/111132 2026-02-18T07:47:06Z

Turbulence in a small arctic pond MacIntyre, Sally; Crowe, Adam T.; Cortés Cortés, Alicia; Arneborg, Lars Small ponds, numerous throughout the Arctic, are often supersaturated with climate-forcing trace gases. Improving estimates of emissions requires quantifying (1) their mixing dynamics and (2) near-surface turbulence which would enable emissions. To this end, we instrumented an arctic pond (510 m2, 1 m deep) with a meteorological station, a thermistor array, and a vertically oriented acoustic Doppler velocimeter. We contrasted measured turbulence, as the rate of dissipation of turbulent kinetic energy, ε, with values predicted from Monin–Obukhov similarity theory (MOST) based on wind shear as u*w, the water friction velocity, and buoyancy flux, β, under cooling. Stratification varied over diel cycles; the thermocline upwelled as winds changed allowing ventilation of near-bottom water. Near-surface temperature stratification was up to 7°C per meter. With respect to predictions from MOST: (1) With positive β under heating and strong near-surface stratification, turbulence was suppressed; (2) under heating with moderate stratification and under cooling with light to moderate winds, measured ε was in agreement with MOST; (3) under cooling with no wind and when surface currents had ceased, as occurred 20% of the time, turbulence was measurable and predicted from β. Near-surface turbulence was enhanced under cooling and light winds relative to that under a neutral atmosphere due to higher values of drag coefficients under unstable atmospheres. Small ponds are dynamic systems with wind-induced thermocline tilting enabling vertical exchanges. Near-surface turbulence, similar to that in larger systems, can be computed from surface meteorology enabling accurate estimates of gas transfer coefficients and emissions.

MacIntyre, Sally Cortés Cortés, Alicia Sadro, Steven https://hdl.handle.net/10481/111130 2026-02-18T07:40:43Z

Sediment respiration drives circulation and production of CO2 in ice-covered Alaskan arctic lakes MacIntyre, Sally; Cortés Cortés, Alicia; Sadro, Steven The goals of our study were to (1) quantify production of CO2 during winter ice-cover in arctic lakes, (2) develop methodologies which would enable prediction of CO2 production from readily measured variables, and (3) improve understanding of under-ice circulation as it influences the distribution of dissolved gases under the ice. To that end, we combined in situ measurements with profile data. CO2 production averaged 20 mg C m−2 d−1 in a 3 m deep lake and ∼ 45 mg C m−2 d−1 in four larger lakes, similar to experimental observations at temperatures below 4°C. CO2 production was predicted by the initial rate of loss of oxygen near the sediments at ice-on and by the full water column loss of oxygen throughout the winter. The time series data also showed the lake-size and time dependent contribution of sediment respiration to under-ice circulation and the decreased near-bottom flows enabling anoxia and CH4 accumulation.

Bruce, Louise C. Frassl, Marieke A. Arhonditsis, George B. Gal, Gideon Hamilton, David P. Hanson, Paul C. Hetherington, Amy L. Melack, John M. Read, Jordan S. Cortés Cortés, Alicia Rueda Valdivia, Francisco José Hipsey, Matthew R. https://hdl.handle.net/10481/111129 2026-02-18T07:36:49Z

A multi-lake comparative analysis of the General Lake Model (GLM): Stress-testing across a global observatory network Bruce, Louise C.; Frassl, Marieke A.; Arhonditsis, George B.; Gal, Gideon; Hamilton, David P.; Hanson, Paul C.; Hetherington, Amy L.; Melack, John M.; Read, Jordan S.; Cortés Cortés, Alicia; Rueda Valdivia, Francisco José; Hipsey, Matthew R. The modelling community has identified challenges for the integration and assessment of lake models due to the diversity of modelling approaches and lakes. In this study, we develop and assess a one-dimensional lake model and apply it to 32 lakes from a global observatory network. The data set included lakes over broad ranges in latitude, climatic zones, size, residence time, mixing regime and trophic level. Model performance was evaluated using several error assessment metrics, and a sensitivity analysis was conducted for nine parameters that governed the surface heat exchange and mixing efficiency. There was low correlation between input data uncertainty and model performance and predictions of temperature were less sensitive to model parameters than prediction of thermocline depth and Schmidt stability. The study provides guidance to where the general model approach and associated assumptions work, and cases where adjustments to model parameterisations and/or structure are required. GLM development and funding support for LCB, BDB, CB and MRH was provided by the Australian Research Council (ARC) (grants DP130104078 & LP130100756).