The global energy transition will require both fossil fuels and renewable energy, alongside metals essential for low-carbon technologies. Given the growing role of energy-metal nexus playing in energy system, the availability of these resources is vital to energy security. While fossil fuel and metal supply patterns have been studied seperatedly, few have integrated both into a comprehensive energy security assessment. To address this gap, we examine how fossil and metal supplies affect global energy security using a two-phase assessment framework. Firstly, we analyze the supply concentration of fossil fuels (oil, natural gas, coal) and copper using the Herfindahl Hirschman Index (HHI). Secondly, we assess energy security by weighing the HHI based on the global historic energy mix. Key findings include: (a) Copper production is geographically more concentrated (61 countries) compared to fossil fuels (73–101 countries); (b) Oil and coal supply concentrations have increased, while natural gas and copper concentrations have decreased; (c) Energy security risks have risen, with mineral supply concentration increasing by 48% from 2000 to 2022; (d) Global energy security has experienced decrease from 2000 to 2022, while it is projected to recover by the middle of this century. These highlights the need for further research on the interplay between fossil fuels and metal extraction in the low-carbon transition.

The economic downturn caused by the COVID-19 pandemic increased the existing inequalities. In this study we focus on the depth and severity of housing-costs-induced energy poverty, mostly overlooked in the existing analysis, and examine disparities among the energy poor in eleven Central and Eastern European countries in 2020. We measure housing-costs-induced energy poverty and follow the Foster-Greer-Thorbecke approach to assess energy poverty. The microdata comes from the EU Survey on Income and Living Conditions. We select eight variables describing household, dwelling, and area density and use censored regression to tease out the effect of factors making a household fall deeper into energy poverty. Our results show that in 2020 energy poverty ranged between 16.4% (Czechia) and 29.6% (Bulgaria). The median depth in absolute terms is about 594.8–1951 euros per year depending on the country. We provide evidence that living in multi-family buildings and densely populated areas decreases the energy poverty depth. Generally, renters are more vulnerable than owners; large families need more money to get out of energy poverty. The analysis reveals that increased depth correlates with heightened severity, thereby highlighting the disparities among individuals experiencing energy poverty. We suggest policymakers account for the depth and severity aspects because deep energy poverty requires more effort to eliminate even if the scale of the problem is not large.

Hydrogen plays an increasingly important role in the world’s carbon neutrality, but due to the high cost of storage, underground hydrogen storage (UHS) especially in depleted natural gas fields is considered. An important factor for UHS is the ability to predict gas loss during the cycles of injection and production. The use of reservoir simulation can be computationally exhaustive. Alternatively, we can use semi-analytical data-tuned methods such as the hybrid capacitance resistance model and long short-term memory model. We apply this model for the first time to UHS. The hybrid model closely aligns with actual data, reducing the maximum error rate from 4.32% to 2.37% and increasing computational time from 3.5 s to over 4.5 s. The study also highlights the unique challenges of storing hydrogen, which has a lower density than methane and a smaller molecular size with risks of escaping or leakage. In 2030, hydrogen production is set to rise significantly, with three key areas of strategic development expected to contribute over 70% of the national output in China, emphasizing the role of three key areas in bolstering global energy sustainability. Predictions indicate substantial potential hydrogen loss rates, particularly in these key areas, with projections showing losses exceeding 0.4 million tons/year in one of the key areas alone.

Energy production in Microbial Fuel Cell can be affected by microorganisms developed during organic matter degradation in wastewater from sugar cane, such as tequila and mezcal industry. Efficiencies of energy conversion remain insufficient for large-scale implementation of this technology. Geobacter sulfurreduscens and Shewanella oneidensis have been exhaustively studied; however, there are few reports about the capabilities of mixed consortiums for the degradation of organic matter and bioelectricity production. In this study, the most abundant bacterial genera were Bacteroides, Lactobacillus, Gluconobacter, Pseudomonas, and Rikenellaceae in Dual Chamber-Microbial Fuel Cell, whose consortia generated a maximum voltage of 160 mV from a chemical oxygen demand of 4200 mg/L. Furthermore, we evaluate performance by equivalent circuit modeling; results suggest that internal resistances affect performance, and high-power density is observed when ohmic resistance decreases. In addition, capacitive and ion transport elements and load transfer resistance can be influenced by the consortiums developed, which determines that the bioelectrochemical performance depends to a greater extent on the microbial community. Scanning electronic microscopy analysis showed differences in the apparent density of anodic biofilm. We found that the substrate directly affects the development of electrogenic microbial consortiums, their organic matter degradation, and bioelectricity production capacities.