A methodology such as near-infrared (NIR) spectroscopy, which enables in situ and in real-time analysis, is crucial to perform quality control of biodiesel, since it is blended into diesel fuel and the presence of contaminants can hinder its performance. This work aimed to compare the performance of a benchtop Fourier Transform (FT) NIR spectrometer with a prototype of a portable, miniaturized near-infrared spectrometer (miniNIR) to detect and quantify contaminants in biodiesel and biodiesel in diesel. In general, good models based on principal component analysis-linear discriminant analysis (PCA-LDA) of FT-NIR spectra were obtained, predicting with high accuracies biodiesel contaminants and biodiesel in diesel (between 75% to 95%), as well as good partial least square (PLS) regression models to predict contaminants concentration in biodiesel and biodiesel concentration in diesel/biodiesel blends, with high coefficients of determination (between 0.83 and 0.99) and low prediction errors. The miniNIR prototype’s PCA-LDA models enabled the prediction of target contaminants with good accuracies (between 66% and 86%), and a PLS model enabled the prediction of biodiesel concentration in diesel with a reasonable coefficient of determination (0.68), pointing to the device’s potential for preliminary analysis of biodiesel which, associated with its potential low cost and portability, could increase biodiesel quality control.

The increased demand for alternative sustainable energy sources has boosted research in the field of fuel cells (FC). Among these, microbial fuel cells (MFC), based on microbial anodes and different types of cathodes, have been the subject of renewed interest due to their ability to simultaneously perform wastewater treatment and bioelectricity generation. Several different MFCs have been proposed in this work using different conditions and configurations, namely cathode materials, membranes, external resistances, and microbial composition, among other factors. This work reports the design and optimization of MFC performance and evaluates a hydrogel (Ion Jelly^®) modified air-breathing cathode, with and without an immobilized laccase enzyme. This MFC configuration was also compared with other MFC configuration performances, namely abiotic and biocathodes, concerning wastewater treatment and electricity generation. Similar efficiencies in COD reduction, voltage (375 mV), PD (48 mW/m²), CD (130 mA/m²), and OCP (534 mV) were obtained. The results point out the important role of Ion Jelly^® in improving the MFC air-breathing cathode performance as it has the advantage that its electroconductivity properties can be designed before modifying the cathode electrodes. The biofilm on MFC anodic electrodes presented a lower microbial diversity than the wastewater treatment effluent used as inocula, and inclusively Geobacteracea was also identified due to the high microbial selective niches constituted by MFC systems.

In the eventuality of a major volcanic eruption or nuclear war, particles would accumulate in the stratosphere and reduce sunlight, potentially altering climate conditions severely and decreasing crop yields. Mass starvation could be prevented with the help of resilient foods, such as transforming natural gas into protein, wood into sugar, and relocating crops. One intervention not yet analysed is expanding cropland area by converting other types of land, such as pasture and second-growth forests into land that could be cultivated. We find approximately 515 million hectares would be fit for cropland expansion during a catastrophe. Three land-clearing scenarios were explored: the global-equipment-sharing scenario, in which the area fit for expansion is cleared in 12 months, feeding 39% of the global population by the end of the first year after the catastrophe; the no-equipment-trade scenario, in which 442 million hectares of land are cleared in 7 years, feeding 20% of people by the end of the first year, and the export-pool-equipment-trade scenario, where the supply of extra machinery to a few countries allows for the clearing of 511 million hectares in 7 years, feeding 27% of people by the end of the first year. This project shows the potential to mitigate starvation during catastrophes. By sparing old-growth forests, the impact on biodiversity would be limited and could mitigate desperate humans from hunting species to extinction.

An abrupt-sunlight-reduction scenario combined with a catastrophic collapse of electricity/industry has the potential to disrupt food production and distribution worldwide, creating widespread food insecurity. This paper explores the potential of animal draught power to cultivate current cropland and expand cropland area in each country with winter wheat during an abrupt-sunlight-reduction scenario with global collapse of industry. For a 150 tera-gram soot injection with no fertiliser application, the country-level allocation of draught animals allows for the global cultivation of over 700 million hectares (Mha) of current cropland, and expansion of global cropland area by 120 Mha, mostly focused in tropical regions of the globe. Over the course of seven years, over 8.3 billion tons of wheat are produced globally, 25% of which is fed to working animals, while the remaining surplus is used to meet human calorie demand. Although enough wheat is eventually produced to meet 80% of the human global calorie demand, animal demand and trade collapse only makes it possible to meet 30% of the global calorie demand. This presents outdoor agriculture and cropland expansion as viable and sustainable methods to mitigate starvation and prevent animal extinction in a catastrophe in some select countries.

A nuclear war has the potential to cause an abrupt-sunlight-reduction scenario and the collapse of electricity/industry, disrupting food production and distribution worldwide and creating widespread food insecurity. In this work, we explore the potential of using animal draught as a power source to cultivate current cropland and expand cropland area during a nuclear winter with loss of industry. For a 150 tera-grams soot injection with no fertiliser application, the current animal count would be able to cultivate over 700 million hectares (Mha) of current cropland, and expand cropland area by 100 Mha. The grain produced from these areas would be used partly to feed the working animals, and the remaining wheat would be enough to feed more than half of the global population by the fourth year of the catastrophe, making outdoor agriculture and cropland expansion viable methods to mitigate starvation in such a scenario.