Search

Parameterizing the dissipative effects of small, unresolved coastal features, is fundamental to improve the skills of wave models. The established technique to deal with this problem consists in reducing the amount of energy advected within the propagation scheme, and is currently available only for regular grids. To find a more general approach, Mentaschi et al., 2015b formulated a technique based on source terms, and validated it on synthetic case studies. This technique separates the parameterization of the unresolved features from the energy advection, and can therefore be applied to any numerical scheme and to any type of mesh. Here we developed an open-source library for the estimation of the transparency coefficients needed by this approach, from bathymetric data and for any type of mesh. The spectral wave model WAVEWATCH III was used to show that in a real-world domain, such as the Caribbean Sea, the proposed approach has skills comparable and sometimes better than the established propagation-based technique. [ABSTRACT FROM AUTHOR]

Direct air capture (DAC) is considered one of the mitigation strategies in most of the future scenarios trying to limit global temperature to 1.5 °C. Given the high expectations placed on DAC for future decarbonisation, this study presents an extensive review of DAC technologies, exploring a number of techno-economic aspects, including an updated collection of the current and planned DAC projects around the world. A dedicated analysis focused on the production of synthetic methane, methanol, and diesel from DAC and electrolytic hydrogen in the European Union (EU) is also performed, where the carbon footprint is analysed for different scenarios and energy sources. The results show that the maximum grid carbon intensity to obtain negative emissions with DAC is estimated at 468 gCO2e/kWh, which is compliant with most of the EU countries' current grid mix. Using only photovoltaics (PV) and wind, negative emissions of at least −0.81 tCO2e/tCO2 captured can be achieved. The maximum grid intensities allowing a reduction of the synthetic fuels carbon footprint compared with their fossil-fuels counterparts range between 96 and 151 gCO2e/kWh. However, to comply with the Renewable Energy Directive II (REDII) sustainability criteria to produce renewable fuels of non-biological origin, the maximum stays between 30.2 to 38.8 gCO2e/kWh. Only when using PV and wind is the EU average able to comply with the REDII threshold for all scenarios and fuels, with fuel emissions ranging from 19.3 to 25.8 gCO2e/MJ. These results highlight the importance of using renewable energies for the production of synthetic fuels compliant with the EU regulations that can help reduce emissions from difficult-to-decarbonise sectors. [ABSTRACT FROM AUTHOR]

The European Green Deal was published at the end of 2019 and represents EU's biggest action to reach climate neutrality. The European Recovery Fund was presented in July 2020 as a response to the COVID-19 crisis. This study looks at the role that photovoltaics could play to support the successful implementation of these initiatives, in particular in regard to the increased climate ambition. The European Commission proposal of September 2020 (55% emission reduction in 2030 compared to 1990) and the European Parliament proposal that followed soon after (−60%), have changed the level of greenhouse gas reduction ambitions. Energy system modelling shows that achieving the updated targets will require large quantities of renewables deployed at an unprecedented pace. Over the past 10 years solar PV has achieved the technological and market maturity to spearhead EU efforts to reach the energy and climate targets. The paper looks at future projections of solar PV deployment, also considering ongoing sectorial policies (e.g. the EU hydrogen strategy, the building renovation wave) and overarching aims for system integration and a just transition. • The European Green Deal increased climate ambition and the need for renewables. • Photovoltaics need to be deployed in high rates to reach the updated targets. • Until 2030, 21–22 GW of PV is needed annually in EU to decrease emissions by 55%. • PV deployment rates increase to 26–32 GW annually to reach −60% emissions. • Green Deal's initiatives (H2 strategy, renovation wave) may increase projections. [ABSTRACT FROM AUTHOR]

The Paris Agreement has underlined the role of cities in combating climate change. The Global Covenant of Mayors for Climate & Energy (GCoM) is the largest international initiative dedicated to promoting climate action at a city level, covering globally over 10 000 cities and almost half the population of the European Union (EU) by end of March 2020. The fifth Intergovernmental Panel on Climate Change (IPCC) report notes that there is a lack of comprehensive, consistent datasets of cities' greenhouse gas (GHG) emission inventories. In order to partly address this gap, we present a harmonised, complete and verified dataset of GHG inventories for 6200 cities in European and Southern Mediterranean countries, signatories of the GCoM initiative. To complement the reported emission data, a set of ancillary data that have a direct or indirect potential impact on cities' climate action plans were collected from other datasets, supporting further research on local climate action and monitoring the EU 27 (the 27 member states of the EU) progress on Sustainable Development Goal (SDG) 13 on climate action. The dataset (Kona et al., 2020) is archived and publicly available with the DOI 10.2905/57A615EB-CFBC-435A-A8C5-553BD40F76C9. [ABSTRACT FROM AUTHOR]

The Paris Agreement has underlined the role of cities in combating climate change. The Global Covenant of Mayors for Climate and Energy (GCoM) is the largest dedicated international initiative to promote climate action at city level, covering globally over 10,000 cities and almost half the population of the European Union (EU) by end of March 2020. The latest Intergovernmental Panel on Climate Change (IPCC) report denotes that there is a lack of comprehensive, consistent datasets of cities' Greenhouse Gas (GHG) emissions inventories. To address part of this gap, we present here a harmonised, complete and verified dataset of GHG inventories for 6,200 cities in European and Southern Mediterranean countries, signatories of the GCoM initiative. To complement the emission data reported, a set of ancillary data that have a direct or indirect potential impact on cities' climate action plans were collected from other databases, supporting further research on local climate action and monitoring the EU's progress on Sustainable Development Goal 13 on Climate Action. The dataset is archived and publicly available with the DOI number https://doi.org/10.2905/57A615EB-CFBC-435A-A8C5- 553BD40F76C9 [ABSTRACT FROM AUTHOR]

The Unresolved Obstacles Source Term (UOST) is a general methodology for parameterizing the dissipative effects of subscale islands, cliffs, and other unresolved features in ocean wave models. Since it separates the dissipation from the energy advection scheme, it can be applied to any numerical scheme or any type of mesh. UOST is now part of the official release of WAVEWATCH III, and the freely available package alphaBetaLab automates the estimation of the parameters needed for the obstructed cells. In this contribution, an assessment of global regular and unstructured (triangular) wave models employing UOST is presented. The results in regular meshes show an improvement in model skill, both in terms of spectrum and of integrated parameters, thanks to the UOST modulation of the dissipation with wave direction, and to considering the cell geometry. The improvement is clear in wide areas characterized by the presence of islands, like the whole central-western Pacific Basin. In unstructured meshes, the use of UOST removes the need of high resolution in proximity of all small features, leading to (a) a simplification in the development process of large scale and global meshes, and (b) a significant decrease of the computational demand of accurate large-scale models. [ABSTRACT FROM AUTHOR]

River plume source-front connectivity, or the relationship between processes at the source, plume body and front, is investigated with numerical simulations of the Merrimack River plume using the Regional Ocean modeling System (ROMS). Source water, i.e. water discharged from the estuary during an ebb pulse, overtakes the front as it propagates offshore, resulting in the strong convergence that exists there. Model results show that much of the water released over an ebb pulse does not interact with the propagating tidal plume front, suggesting that the front decouples from the source and sustains itself as a distinct water mass. When a gate is closed at the estuary mouth during early ebb, the overall plume structure changes; gates closed late in ebb do not significantly effect the along- or cross-shore scale of the plume. The change in plume extent is only evident hours after the early-ebb gate closing, when source water is no longer supplied to the front. These experiments suggest that the growing distance between the highly energetic liftoff region and the radial expansion of the plume front results in a flattening of the surface gradient driving flow in the interior, diminishing source-front connectivity. • Much of the water released over an ebb does not interact with the propagating tidal plume front. • The plume front decouples from the source and sustains itself as a distinct water mass during ebb. • Distance between the mouth and front results in flattening of plume interior sea surface gradient, diminishing source-front connectivity. [ABSTRACT FROM AUTHOR]