Green ammonia is a promising hydrogen derivative which enables intercontinental transport of dispatchable renewable energy. This research describes the development of a model which optimizes a global ...green ammonia network, considering the costs of production, storage, and transport. In generating the model, we show economies of scale for green ammonia production are small beyond 1 million tonnes per annum (MMTPA), although benefits accrue up to a production rate of 10 MMTPA if a production facility is serviced by a new port or requires a long pipeline. The model demonstrates that optimal sites for ammonia production require not only an excellent renewable resource but also ample land from which energy can be harvested. Land limitations constrain project size in otherwise optimal locations and force production to more expensive sites. Comparison of current crude oil markets to future ammonia markets reveals a trend away from global supply hubs and toward demand centers serviced by regional production.
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•An optimization model to represent a future green ammonia (NH3) market is developed•Each supply chain element is described, including the relationship of cost to scale•NH3 markets will tend toward a many-to-few trading pattern, unlike crude oil today•Limitations on available land may constrain production in optimal sites
Energy resources; Energy policy; Energy engineering; Energy sustainability; Energy Systems
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This paper presents GeoH2, a geospatial model that optimizes the cost of green hydrogen production, storage, transport, and conversion. This model calculates the cost of producing ...green hydrogen in a specified location to meet demand in another location by:
•Optimizing hydrogen conversion and transport from production site to demand site•Optimizing green hydrogen production and storage based on spatially-specific wind and solar generation temporal availability
This method allows users to map production costs throughout a region to identify the lowest-cost location of green hydrogen production to meet demand using a specified end-state for transportation and storage (i.e., pressurized hydrogen, ammonia, or liquefied hydrogen). These modeled costs can be compared to current or projected prices for energy and chemical feedstock in the region to assess the cost-competitiveness of green hydrogen. The model is designed to run at a country or regional scale. A case study application is provided for the context of Namibia.
Abstract
Green ammonia has been proposed as a technologically viable solution to decarbonise global shipping, yet there are conflicting ambitions for where global production, transport and fuelling ...infrastructure will be located. Here, we develop a spatial modelling framework to quantify the cost-optimal fuel supply to decarbonise shipping in 2050 using green ammonia. We find that the demand for green ammonia by 2050 could be three to four times the current (grey) ammonia production, requiring major new investments in infrastructure. Our model predicts a regionalisation of supply, entailing a few large supply clusters that will serve regional demand centres, with limited long-distance shipping of green ammonia fuel. In this cost-efficient model, practically all green ammonia production is predicted to lie within 40° latitudes North/South. To facilitate this transformation, investments worth USD 2 trillion would be needed, half of which will be required in low- and middle-income countries.
In the ovarian follicle, anti-Müllerian hormone (
Amh) mRNA is expressed in granulosa cells from primary to preovulatory stages but becomes restricted to cumulus cells following antrum formation. ...Anti-Müllerian hormone regulates follicle development by attenuating the effects of follicle stimulating hormone on follicle growth and inhibiting primordial follicle recruitment. To examine the role of the oocyte in regulating granulosa cell
Amh expression in the mouse, isolated oocytes and granulosa cells were co-cultured and
Amh mRNA levels were analysed by real-time RT-PCR. Expression in freshly isolated granulosa cells increased with preantral follicle development but was low in the cumulus and virtually absent in the mural granulosa cells of preovulatory follicles. When preantral granulosa cells were co-cultured with oocytes from early preantral, late preantral or preovulatory follicles, and when oocytes from preovulatory follicles were co-cultured with cumulus granulosa cells,
Amh expression was increased at least 2-fold compared with granulosa cells cultured alone. With oocytes from preantral but not preovulatory follicles, this was a short-range effect only observed with granulosa cells in close apposition to oocytes. We conclude that stage-specific oocyte regulation of
Amh expression may play a role in intra- and inter-follicular coordination of follicle development.
Decarbonisation will see mass installation of wind turbines and solar panels to replace conventional energy systems. However, these renewables face two challenges: renewable energy production is ...intermittent, and land requirements are considerable. We propose a solution to both problems: production of green ammonia, a carbon-free fuel, in the ocean. Green ammonia can be produced from intermittent renewables, and can be dispatched as a hydrogen carrier, energy vector, shipping fuel, or decarbonised fertiliser. It is well suited to marine production — it benefits from the ocean’s reliable wind resource, is easily transportable, can be stored cheaply under mild conditions, and only requires water, power and air for production. This article presents the first global heat map for ammonia production which considers ocean production, land availability restrictions, and transport to major demand centres. We show that, even considering the high costs of floating wind turbines, it is likely that cost savings will be realised by producing some of the global ammonia demand in the ocean (the precise fraction depends on the distribution of demand), predominantly because competition for land will limit onshore capacity in the best locations.
•Offshore green ammonia production has no land constraints.•Offshore green ammonia production has reliable wind resources.•We present a global offshore LCOA heat map considering land availability.•Offshore production may be financially competitive in the future.
This contribution offers an overview of recent fieldwork and museum-based projects focused on the Rhodian countryside and Dodecanese islands. The excavations conducted by the Ephorate of Antiquities ...of the Dodecanese over the past two decades, paired with the study of Rhodian collections in the Louvre and British Museum, among other museums, have developed and promoted the archaeological record of the region. The Kymissala Archaeological Research Project led by the University of the Aegean and a collaborative doctoral project investigating the British Museum’s collections from Kamiros each demonstrate the potential of revisiting historic excavations through topographical surveys and archival documentation.
Outer dense fiber 2 (Odf2) is highly expressed in the testis where it encodes a major component of the outer dense fibers of the sperm flagellum. Furthermore, ODF2 protein has recently been ...identified as a widespread centrosomal protein. While the expression of Odf2 highlighted a potential role for this gene in male germ cell development and centrosome function, the in vivo function of Odf2 was not known. We have generated Odf2 knockout mice using an Odf2 gene trapped embryonic stem cell (ESC) line. Insertion of a gene trap vector into exon 9 resulted in a gene that encodes a severely truncated protein lacking a large portion of its predicted coil forming domains as well as both leucine zipper motifs that are required for protein–protein interactions with ODF1, another major component of the outer dense fibers. Although wild‐type and heterozygous mice were recovered, no mice homozygous for the Odf2 gene trap insertion were recovered in an extended breeding program. Furthermore, no homozygous embryos were found at the blastocyst stage of embryonic development, implying a critical pre‐implantation role for Odf2. We show that Odf2 is expressed widely in adults and is also expressed in the blastocyst stage of preimplantation development. These findings are in contrast with early studies reporting Odf2 expression as testis specific and suggest that embryonic Odf2 expression plays a critical role during preimplantation development in mice. genesis 44:515–522, 2006. Published 2006 Wiley‐Liss, Inc.
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