• Energy Research
• 2025-2025close
• Closed Access close
• Restricted close
• Open Source close
• GB close
• DK close

ABSTRACTThe concept of “blue carbon” is, in this study, critically evaluated with respect to its definitions, measuring approaches, and time scales. Blue carbon deposited in ocean sediments can only counteract anthropogenic greenhouse gas (GHG) emissions if stored on a long‐term basis. The focus here is on the coastal blue carbon ecosystems (BCEs), mangrove forests, saltmarshes, and seagrass meadows due to their high primary production and large carbon stocks. Blue carbon sequestration in BCEs is typically estimated using either: 1. sediment carbon inventories combined with accretion rates or 2. carbon mass balance between input to and output from the sediment. The inventory approach is compromised by a lack of accurate accretion estimates over extended time periods. Hence, short‐term sedimentation assays cannot be reliably extrapolated to long timescales. The use of long‐term tracers like 210Pb, on the other hand, is invalid in most BCEs due to sediment mobility by bioturbation and other physical disturbances. While the mass balance approach provides reasonable short‐term (months) estimates, it often fails when extrapolated over longer time periods (> 100 years) due to climatic variations. Furthermore, many published budgets based on mass balance do not include all relevant carbon sources and sinks. Simulations of long‐term decomposition of mangrove, saltmarsh (Spartina sp.), and eelgrass (Zostera sp.) litter using a 3‐G exponential model indicate that current estimates of carbon sequestration based on the inventory and mass balance approaches are 3–18 times too high. Most published estimates of carbon sequestration in BCEs must therefore be considered overestimates. The climate mitigation potential of blue carbon in BCEs is also challenged by excess emissions of the GHG methane (CH4) and nitrous oxide (N2O) from biogenic structures in mangrove forests and saltmarsh sediments. Thus, in many cases, carbon sequestration into BCE sediments cannot keep pace with the simultaneous GHG emissions in CO2 equivalents.

The high expansion rate of renewable generation in the last years was mainly driven by the green transition and the net zero emission targets for 2050. Concerns on the volatility of wind and solar energy, can be mitigated by combining these renewable energy sources with energy storage and operating them coordinately, creating hybrid power plants. Price of batteries has also dropped significantly reaching US$139/kWh in 2023 (battery pack price) and it is expected that by the end of this decade the price will fall below US$100/kWh. Thus, more developers and owners of large renewable plants are looking into their hybridization for both off-grid and grid-connected configurations. The advantages for such a hybrid renewable power plant include complementarity of energy production, better utilization of grid connection while reducing the connection costs, firm capacity of energy production, increase of revenue streams by providing ancillary services, etc. However, the control of a wide range of technologies i.e. wind turbines, solar PV and batteries, from different suppliers poses challenges during their integration into a hybrid power plant.This paper aims to provide an overview of the most common configurations of co-located hybrid power plants including their control architectures. The advantages and challenges for each configuration are discussed in detail from the perspective of OEMs and system integrators.The work presented is part of the ongoing activities in the IEA Wind TCP Task 50 on Hybrid Power Plants that aims to provide a systematic framework and guidelines in this area.

Understanding the causes of past atmospheric methane (CH4) variability is important for characterizing the relationship between CH4, global climate and terrestrial biogeochemical cycling. Ice core records of atmospheric CH4 contain rapid variations linked to abrupt climate changes of the last glacial period known as Dansgaard-Oeschger (DO) events and Heinrich events (HE)1,2. The drivers of these CH4 variations remain unknown but can be constrained with ice core measurements of the stable isotopic composition of atmospheric CH4, which is sensitive to the strength of different isotopically distinguishable emission categories (microbial, pyrogenic and geologic)3-5. Here we present multi-decadal-scale measurements of δ13C-CH4 and δD-CH4 from the WAIS Divide and Talos Dome ice cores and identify abrupt 1‰ enrichments in δ13C-CH4 synchronous with HE CH4 pulses and 0.5‰ δ13C-CH4 enrichments synchronous with DO CH4 increases. δD-CH4 varied little across the abrupt CH4 changes. Using box models to interpret these isotopic shifts6 and assuming a constant δ13C-CH4 of microbial emissions, we propose that abrupt shifts in tropical rainfall associated with HEs and DO events enhanced 13C-enriched pyrogenic CH4 emissions, and by extension global wildfire extent, by 90-150%. Carbon cycle box modelling experiments7 suggest that the resulting released terrestrial carbon could have caused from one-third to all of the abrupt CO2 increases associated with HEs. These findings suggest that fire regimes and the terrestrial carbon cycle varied contemporaneously and substantially with past abrupt climate changes of the last glacial period.

PurposeThis study aims to deepen the understanding of what stakeholders talk about when it comes to sustainable fashion on social media and how. Sustainable fashion is a broad umbrella term, which can distract attention from the differences between the individual subtopics and the sentiments ascribed to them. However, little systematic research exists on how the stakeholder activity and dominant sentiments vary across different sustainable fashion topics.Design/methodology/approachThis study is based on a social media analysis of 19,179 tweets authored by 1,819 distinct stakeholders on Twitter (now “X”) from 2007 to 2022. A large language model, a type of artificial intelligence (AI) that focuses on understanding and generating human language, is used to conduct a sentiment analysis of six stakeholder groups and 81 keywords linked to sustainable fashion. Two case examples are used to highlight the differences in stakeholder perceptions of sustainable fashion.FindingsThe social media analysis demonstrates how subcategories of sustainable fashion significantly differ in terms of stakeholder interest, activity and sentiments. For instance, tweets on circular economy and relevant subcategories (closed loop, recycling, upcycling, etc.) are popular, whereas issues linked to environmental, social and governance (ESG) and due diligence receive little attention on social media. While sentiments toward sustainable fashion are in general positive, discussions on topics such as labor rights issues are consistently associated with negative sentiments across most stakeholder groups.Originality/valueThis study contributes to the literature by demonstrating how stakeholders and sentiments vary across different topics linked to sustainable fashion on social media, which has become one of the main channels for communicating sustainability content. The findings thereby shed new light on dominant stakeholder positions regarding a wide variety of sustainable fashion topics.

Over the past billion years, the fungal kingdom has diversified to more than two million species, with over 95% still undescribed. Beyond the well-known macroscopic mushrooms and microscopic yeast, fungi are heterotrophs that feed on almost any organic carbon, recycling nutrients through the decay of dead plants and animals and sequestering carbon into Earth's ecosystems. Human-directed applications of fungi extend from leavened bread, alcoholic beverages and biofuels to pharmaceuticals, including antibiotics and psychoactive compounds. Conversely, fungal infections pose risks to ecosystems ranging from crops to wildlife to humans; these risks are driven, in part, by human and animal movement, and might be accelerating with climate change. Genomic surveys are expanding our knowledge of the true biodiversity of the fungal kingdom, and genome-editing tools make it possible to imagine harnessing these organisms to fuel the bioeconomy. Here, we examine the fungal threats facing civilization and investigate opportunities to use fungi to combat these threats.