Carbon Engineering (Canada)

The accelerating global demand for clean energy has placed hydrogen as a pivotal vector for achieving carbon neutrality. However, over 95% of current hydrogen is still derived from fossil-based routes such as steam methane reforming (SMR), which remains energy-intensive and carbon-emitting. Chemical looping technology (CLT) has emerged as an innovative low-carbon pathway capable of inherently separating CO2 during hydrogen generation. This review systematically examines recent advances in methane-based CLT, emphasizing oxygen carrier (OC) design, process efficiency, and environmental implications. Across different CLT configurations, the technology shows excellent performance, with CH4 conversion above 95% and H2 purity reaching 99.9%. It also achieves 10–15% higher thermal efficiency than conventional SMR with carbon capture. Among key variants, CLPO produces syngas with a H2/CO ratio of ∼2, CLSR yields 90–95 vol % pure H2, and CLCHP achieves >97% CO2 capture with >90% OC regeneration sustained over 100 cycles. Meanwhile, CLMC enables theoretical 100% CH4 conversion at 1000 °C without CO2 emissions and produces valuable solid carbon. Environmentally, Fe2O3-based OCs outperform Ni- or Co-based counterparts due to low toxicity, thermal stability (750–950 °C), and a reduction in lifecycle emissions to 3009 g CO2-eq/kg H2. The review identifies research priorities for scalable deployment, including the development of durable OCs, system integration with waste heat or biomass, and reactor optimization capable of reducing capital costs by up to 37%.

ABSTRACT The southeastern Amazon region represents one of the critical hotspots of land‐use change (LUC) in Brazil. Conversion of natural ecosystems to agricultural fields triggers mineralization of soil organic matter and decomposition of residual forest biomass, releasing large amounts of nitrogen (N) that, together with subsequent high N‐fertiliser applications, disrupt N biogeochemical cycles. Therefore, we hypothesize that deforestation disrupts surface soil N‐pools, causing their gradual percolation into deeper layers of these highly weathered tropical soils. To test this, we measured total‐N and key fractions—particulate organic matter N (POM‐N), mineral‐associated organic matter N (MAOM‐N), water‐extractable N (WEN), ammonium (NH 4 + ‐N) and nitrate (NO 3 − ‐N)—to 800 cm depth in forest, recently deforested, single‐crop soybean and double‐crop soybean–corn systems in Mato Grosso, Brazil. Compared to the forest, the deforested site showed a 40% reduction in soil total‐N stocks at 10 cm; however, it was 62% higher at depths of 100–300 cm. In the croplands, the soil total‐N stocks remained similar to those in the forest. The POM‐N was nearly absent in the deforested site, whereas the MAOM‐N was consistently lower in both croplands and deforested soils than in the forest. The deforested site had the highest WEN and inorganic‐N (NH 4 + ‐N and NO 3 − ‐N) stocks to 800 cm, with most concentrated in the top 0–200 cm. Croplands had the greatest NO 3 − ‐N stocks at 300–600 cm. Principal component analysis (PCA) showed that WEN and inorganic‐N in the top 100 cm clustered with the deforested site, whereas POM‐N, MAOM‐N and total‐N at the surface clustered with the forest. Below 100 cm, the soil total‐N stock was clustered with the deforested site. These results provide critical insight into the initial mechanism of deep nitrate formation: the breakdown of the N biogeochemical cycle after deforestation, fueled by decomposition and N mineralization from soil organic matter and remaining forest biomass following slash‐and‐burn events on the Amazon–Cerrado agricultural frontier. However, further studies are needed to confirm the spatial and temporal persistence of these patterns across the region.

Abstract Disruptive menstrual symptoms are often normalized, contributing to delayed care and reliance on self-management. Menstrual tracking apps (MTAs) are widely used to monitor cycle-related experiences, yet little is known about their role in menstrual health management or healthcare engagement. We conducted a global cross-sectional survey of Clue MTA users (n = 11 910) assessing menstrual health experiences, healthcare interactions, and app use. Two-thirds reported being worried about their cycles or symptoms. Among those, 47% experienced severe symptoms. Just over half (53%) had spoken to a healthcare provider, but only 9% felt they were managing well with current treatments. Most (59%) were attempting to manage on their own. Users reported tracking improved feelings of period preparedness (96%), cycle awareness (90%), control over health (72%), and confidence speaking to healthcare providers (60%). MTAs may offer meaningful support for menstrual management, reflecting both their value to users and ongoing gaps in care and cultural support.

Electric double layers (EDLs) at a liquid|liquid interface between a fluorous solvent (F) and water (W) were examined using molecular dynamics (MD) simulation, where methyl nonafluorobutyl ether (HFE-7100), a hydrofluloroether, used as an F contained a hydrophobic ionic liquid (IL, trioctylmethylammonium bis(nonafluorobutanesulfonyl)amide) as a supporting electrolyte to polarize the F|W interface electrochemically. The F molecules were found to be accumulated on the noncharged F|W interface; however, on the charged interface, they were replaced with IL ions that formed a monolayer-like structure, nevertheless maintaining the F accumulation below the ionic monolayer. The MD simulation using a different hydrofluoroether (HFE-7300) revealed that the distributions of IL ions and F molecules in the EDL varied with their structures. Since the F–W two-phase system in our simulation box was sandwiched between the two graphene (G) electrodes to polarize the F|W interface, we were able to investigate the EDL at the electrode interface of F. Ionic multilayers were formed at the F|G interface, expelling the F molecules from the interface even though F was a dilute solution of IL. These accumulation and depletion behaviors at the water and electrode interfaces of F, combined with recent neutron reflectometry results, demonstrate that the EDL structures in F are strongly affected not only by the phase-boundary potential difference but also by the relative polarity of F molecules and IL ions. These findings can help design and control the EDL structures in F, contributing to the electrochemical application of F molecules at liquid/liquid and solid/liquid interfaces.

Abstract Hylurgus ligniperda (F.) is a highly successful invader among bark beetles (Scolytinae) and forest insects in general. Native to the western Palearctic region, it has become established in every continent where its host plants ( Pinus spp.) occur. Especially in southern hemisphere regions with large pine plantations, it is often highly abundant. As a repeat invader with a wealth of information on various aspects relevant for biological invasions, it is highly suitable as a model organism for studying the role of international trade, the planting of non-native trees, and the potential occurrence of bridgehead invasions (where abundant non-native populations precipitate further invasions). In the present study, our specific objectives were to reconstruct the worldwide invasions of H. ligniperda and the pathways involved by using a multi-pronged approach including population genetics, analysis of historic interception data generated from inspections of imports, and records of establishments in the literature. Our review of the native and non-native ranges of H. ligniperda and the chronology of establishments revealed at least 13 separate invasions of non-native regions, beginning with Madeira (Portugal) before 1850, and, most recently, eastern China in 2019. We compared the population genetics of 464 specimens from eight countries in the native range and eight countries in the non-native range. Sequencing of the mitochondrial COI gene revealed the presence of 29 haplotypes in six well-supported clades, based on a Bayesian analysis. Non-native populations had significantly lower haplotype diversity (mean h = 0.219) than populations in the native range (mean h = 0.691). Countries in the non-native range had an average of about two haplotypes compared with about four haplotypes in native countries. In the non-native range, only one or two haplotypes were dominant, and these differed among invaded regions except for haplotype HL-H3 which occurred in Australia, New Zealand and China as well as in four countries in southern Europe, and HL-H4 which was dominant in New Zealand, California, New York State, and eastern China as well as two countries in southern Europe. Analyses of interceptions of H. ligniperda with imports arriving in five countries revealed that between 74% and 99% of interceptions originated from other non-native regions while in the USA, most interceptions were linked to imports from the native range beginning in the 1970s. Based on the combined evidence of the chronology of invasions, interception data, and analysis of haplotype distribution, we conclude that the early invasions (before 1950) probably all originated from the native range, while several of the more recent invasions probably originated from parts of the non-native range (suggestive of a bridgehead effect). However, it cannot be determined with certainty what the original sources of each of the invading populations were.

There is currently no consensus in the literature as to whether the mineralogical composition and theoretical weatherability or grain size and surface area of feedstock materials used for carbon capture via enhanced rock weathering are stronger determinants of weathering rates of silicate minerals applied to agricultural soils. Felsic source rocks have typically been discounted for enhanced rock weathering in favor of more easily weatherable mafic and ultramafic rocks. However, previous work has indicated that Greenlandic glacial rock flour, a potential feedstock with an exceedingly fine grain size (d50 = 2.6 µm) but a felsic composition, can weather at sufficiently rapid rates to be effective for carbon capture and improving crop yields through the release of nutrients during weathering. Here we present initial experimental results comparing the use of Greenlandic glacial rock flour and several sources of basaltic material as feedstocks for enhanced rock weathering. Two field trials installed in Ghana and South Carolina demonstrate the varying effects of these materials on maize yield, and two flow-through laboratory experiments, one with plants and one without, assess the differences in alkalinity generation and cation release between these feedstocks over time. Among the tested basalts, chemical composition seems to be a stronger driver of weathering rates than differences in grain size. However, none were as finely ground as the glacial rock flour, which was found to weather at a rate comparable to or, in some cases, higher than the basaltic materials, despite being composed of less chemically reactive minerals. These results suggest that mineral weatherability is an important predictor of weathering rates, but with a large enough difference in grain size the amount of surface area available for reaction can be equally important.  

The Z-scheme water splitting system with a redox couple (oxidant/reductant) that transfers electrons from an oxygen-evolving photocatalyst (OEP) to a hydrogen-evolving photocatalyst (HEP) is promising for achieving high solar-to-hydrogen conversion efficiency by harvesting a wide range of visible light and for enabling separate production of H2 and O2. However, a preference for backward electron transfer often hampers the demonstration of aforementioned advantages of the Z-scheme system. Here, we show that the loading of CrOx/M cocatalysts (CrOx represents Cr2O3·nH2O, M = Pt, Rh, and Ni)─where nanoparticulate M metal core species are coated with a thin CrOx shell─can effectively enhance H2 evolution on HEPs, such as SrTiO3 and Rh-doped SrTiO3 (SrTiO3:Rh), with the redox couple IO3–/I–, by suppressing IO3– rereduction on the M metal surface. Electrochemical measurements using CrOx-coated and uncoated metal wires strongly support the function of CrOx shells, which are permeable to H+ (or water) and H2 molecules, but not IO3–, affording selective H2 evolution on the CrOx/M cocatalysts. The impact of the CrOx shell on suppressing backward electron transfer becomes more prominent for reactions in a two-component cell with a membrane filter, wherein the accumulation of a relatively high concentration of IO3– is indispensable for the transfer of IO3– anions from the H2 cell to the O2 cell containing an OEP. The use of CrOx/Rh/SrTiO3 and CrOx/Pt/SrTiO3:Rh coupled with appropriate OEPs affords almost stoichiometric and separate production of H2 and O2 under UV- or visible-light irradiation, respectively, from an aqueous solution containing I– and IO3–. The effectiveness of the CrOx coating for enhancing H2 evolution on the SrTiO3:Rh HEP was confirmed for various redox species [Fe(CN)6]3–/4–, [Co(bpy)3]3+/2+, and [SiVW11O40]5–/6– that are operating under nearly neutral conditions, whereas CrOx dissolution under acidic conditions with Fe3+/2+ and VO2+/VO2+ redox was detrimental. The use of CrOx-based core–shell cocatalysts was proven to enhance the efficiency of visible-light-driven Z-scheme water splitting not only with IO3–/I– but also with other redox couples such as [SiVW11O40]5–/6–.

Integration with a Cu 3 BiS 3 photocathode enables a BiVO 4 –Cu 3 BiS 3 tandem cell for unbiased, solar-driven, coupled urea oxidation and hydrogen evolution, delivering a photocurrent density of 2.0 mA cm −2 and stable operation exceeding 20 hours.

This study examines hydrogen permeation and trapping in three types of natural gas pipeline steels from different decades in Canada—modern, vintage, and legacy steels. Electrochemical permeation experiments were conducted to measure the diffusion coefficient, subsurface concentration, and trap density of hydrogen. The results were analyzed to evaluate the susceptibility of these steels to hydrogen embrittlement and to understand the effects of hydrogen on their mechanical properties. Vintage steel exhibited 50% higher steady-state permeation current and 97% greater effective diffusivity compared to modern steel, while legacy steel showed intermediate values. Hydrogen diffusion increased with grain size and pearlite content but decreased with dislocation density. Modern steel demonstrated the highest resistance to hydrogen permeation due to its finer grain structure and higher dislocation density. This study provides essential insights into the diffusion behavior and trapping mechanisms of hydrogen in natural gas pipeline steels, enhancing the understanding of material performance under hydrogen exposure.

The concept and first demonstration of an effective direct air capture molten carbonate chemistry is presented.