scholarly journals A Numerical Assessment of Artificial Reef Pass Wave-Induced Currents as a Renewable Energy Source

2019 ◽  
Vol 7 (9) ◽  
pp. 284 ◽  
Author(s):  
Damien Sous
Keyword(s):  
Renewable Energy ◽  
Artificial Reef ◽  
Positive Energy ◽  
Reef Lagoon ◽  
Numerical Assessment ◽  
Flow Through ◽  
Induced Currents ◽  
Wave Induced ◽  
Averaged Model ◽  
Lagoon Systems

The present study aims to estimate the potential of artificial reef pass as a renewable source of energy. The overall idea is to mimic the functioning of natural reef–lagoon systems in which the cross-reef pressure gradient induced by wave breaking is able to drive an outward flow through the pass. The objective is to estimate the feasibility of a positive energy breakwater, combining the usual wave-sheltering function of immersed breakwater together with the production of renewable energy by turbines. A series of numerical simulations is performed using a depth-averaged model to understand the effects of each geometrical reef parameter on the reef–lagoon hydrodynamics. A synthetic wave and tide climate is then imposed to estimate the potential power production. An annual production between 50 and 70 MWh is estimated.

scholarly journals PHYSICAL PROCESSES AND SEDIMENT FLUX THROUGH REEF-LAGOON SYSTEMS

1980 ◽  
Vol 1 (17) ◽  
pp. 58 ◽  
Author(s):  
Harry H. Roberts
Keyword(s):  
Energy Loss ◽  
Wave Breaking ◽  
Sediment Flux ◽  
Reef Crest ◽  
Trade Wind ◽  
Breaking Wave ◽  
Physical Processes ◽  
Reef Lagoon ◽  
Wave Induced ◽  
Lagoon Systems

Studies of physical processes in reef-lagoon systems continue to emphasize the importance of waves and wave-induced currents at the reef crest as agents of sediment transport to backreef environments. These across-the-reef currents are also largely responsible for driving backreef lagoon circulation. Rapid energy transformations associated with the process of wave breaking at the reef crest are responsible for strong reef-normal surge currents. Estimates of energy loss, as determined by wave height changes caused by wave breaking, can be as high as 70-80%' for discontinuous reefs and >90% for continuous examples. The amount of energy loss is related to depth of water over the reef crest, a function of reef topography and tidal regime. Low-tide conditions promote the greatest incident wave modification and attenuation as a result of increased breaking-wave intensity. Under trade-wind conditions found in the Caribbean, surge currents of 50-80 cm/sec for durations of 2-6 sec are common in a low to moderate wave-energy setting (4-6 sec input waves, 40- 50 cm average heights). Sediments through the sand sizes up to pebbles are easily transported lagoonward by these periodic bursts of energy. Flow in shallow backreef lagoons (generally

scholarly journals Assessment of Indonesia’s Future Renewable energy Plan: A Meta-Analysis of Biofuel Energy Return on Investment (EROI)

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2803
Author(s):  
Wiraditma Prananta ◽  
Ida Kubiszewski
Keyword(s):  
Renewable Energy ◽  
Palm Oil ◽  
Return On Investment ◽  
Meta Analysis ◽  
Renewable Energy Sources ◽  
Energy Sources ◽  
Positive Energy ◽  
Land Restoration ◽  
Energy Return On Investment ◽  
Land Preparation

In early 2020, Indonesia implemented the biodiesel 30 (B30) program as an initiative to reduce Indonesia’s dependency on fossil fuels and to protect Indonesia’s palm oil market. However, palm oil has received international criticism due to its association with harmful environmental externalities. This paper analysed whether an investment in palm oil-based biofuel (POBB) provides Indonesia with the ability to achieve its environmental and financial goals. In this research, we performed a meta-analysis on biofuel energy return on investment (EROI) by examining 44 biofuel projects using ten types of biofuel feedstocks from 13 countries between 1995 and 2016. Results showed an average EROI of 3.92 and 3.22 for POBB and other biomass-based biofuels (OBBB), respectively. This shows that if only energy inputs and outputs are considered, biofuels provide a positive energy return. However, biofuels, including those from palm oil, produce externalities especially during land preparation and land restoration. We also compared these EROI biofuel results with other renewable energy sources and further analysed the implications for renewable energies to meet society’s energy demands in the future. Results showed that biofuel gives the lowest EROI compared to other renewable energy sources. Its EROI of 3.92, while positive, has been categorised as “not feasible for development”. If Indonesia plans to continue with its biofuel program, some major improvements will be necessary.

scholarly journals Numerical simulation of the three-dimensional wave-induced currents on unstructured grid

2017 ◽  
Vol 31 (5) ◽  
pp. 539-548
Author(s):  
Ping Wang ◽  
Ning-chuan Zhang ◽  
Shuai Yuan ◽  
Wei-bin Chen
Keyword(s):  
Numerical Simulation ◽  
Unstructured Grid ◽  
Three Dimensional ◽  
Induced Currents ◽  
Wave Induced ◽  
Dimensional Wave

scholarly journals Predictive model for wave-induced currents and 3D beach evolution based on FAVOR Method

2010 ◽  
Vol 2 (2) ◽  
pp. 68-74
Author(s):  
Masamitsu Kuroiwa ◽  
Mazen Abualtayef ◽  
Tetsushi Takada ◽  
Ahmed Khaled Sief ◽  
Yuehi Matsubara
Keyword(s):  
Predictive Model ◽  
Induced Currents ◽  
Wave Induced

scholarly journals Technology Selection Assistance Tool for Positive Energy Districts

2021 ◽  
Vol 11 (1) ◽  
pp. 18
Author(s):  
Andrea Gabaldón Moreno ◽  
Beril Alpagut ◽  
Cecilia Sanz Montalvillo
Keyword(s):  
Decision Making ◽  
Renewable Energy ◽  
Selection Process ◽  
Holistic Approach ◽  
Technology Selection ◽  
Positive Energy ◽  
Innovative Technologies ◽  
Lack Of Information ◽  
Decision Making Tool ◽  
Assistance Tool

Positive energy districts (PEDs) consist of more than three interconnected buildings that annually produce more renewable energy than what is consumed within the district boundaries. To achieve the annual surplus of energy, implementation of renewable-driven and innovative technologies is needed. However, most cities struggle in deciding what technologies are more suitable for their environment due to the lack of information and experience in a holistic approach. A decision-making tool has been developed within MAKING-CITY, with the collaboration of ATELIER project, to assist in the PED technology selection process, empowering cities with information and recommendations, in line with their district context and city objectives.

Sediment Resuspension and Transport by Internal Solitary Waves

2019 ◽  
Vol 51 (1) ◽  
pp. 129-154 ◽  
Author(s):  
Leon Boegman ◽  
Marek Stastna
Keyword(s):  
Internal Waves ◽  
Laboratory Experiments ◽  
Sediment Resuspension ◽  
Vital Role ◽  
Continental Margins ◽  
Scale Models ◽  
Key Driver ◽  
Induced Currents ◽  
Wave Induced ◽  
Oriented Research

Large-amplitude internal waves induce currents and turbulence in the bottom boundary layer (BBL) and are thus a key driver of sediment movement on the continental margins. Observations of internal wave–induced sediment resuspension and transport cover significant portions of the world's oceans. Research on BBL instabilities, induced by internal waves, has identified several mechanisms by which the BBL is energized and sediment may be resuspended. Due to the complexity of the induced currents, process-oriented research using theory, direct numerical simulations, and laboratory experiments has played a vital role. However, experiments and simulations have inherent limitations as analogs for oceanic conditions due to disparities in Reynolds number and grid resolution, respectively. Parameterizations are needed for modeling resuspension from observed data and in larger-scale models, with the efficacy of parameterizations based on the quadratic stress largely determining the accuracy of present field-scale efforts.

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