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More than 60 oil and gas companies committed on 23 November to a new framework to report methane emissions as the United Nations reported that atmospheric levels of the greenhouse gas reached a record high. As a part of the voluntary framework, companies will share their own methane reduction targets with OGMP, an initiative managed by the UN Environment Programme. The plan revamps an existing OGMP framework and calls on companies to outline how they will realize their objectives to cut methane emissions. The 62 companies that have joined OGMP represent an estimated 30% of global oil and gas production, according to the partnership. The group said it seeks to deliver a 45% reduction in the oil and gas industry’s methane emissions by 2025.
In this 27 November 2007 file photo, a rough-legged hawk feeds on a rodent in a field near Great Falls, Montana. Down to its final weeks, the Trump administration is working to push through dozens of environmental rollbacks that could weaken century-old protections for migratory birds, expand Arctic drilling, and hamstring future regulation of public health threats. Down to its final weeks, the Trump administration is working to push through dozens of environmental rollbacks that could weaken century-old protections for migratory birds, expand Arctic drilling, and hamstring future regulation of public health threats. The pending changes, which benefit oil and gas and other industries, deepen the challenges for President-elect Joe Biden, who made restoring and advancing protections for the environment, climate, and public health a core piece of his campaign. The proposed changes cap 4 years of unprecedented environmental deregulation by President Donald Trump, whose administration has worked to fundamentally change how federal agencies apply and enforce the Clean Water Act, Clean Air Act, and other protections.
For any offshore development, especially an ORE project, a specific site investigation is required to qualify environmental, geophysical, metocean-related, and geopolitical issues. Most ORE developments will cover a significant area of ocean or seabed and will require investigation to ensure that marine life, antiquities, unexploded ordinance, and other ocean users will not be put at risk when installation and operation activities are performed. Obtaining the required permits and approvals from all those potentially affected by an ORE development is a complex and time-consuming operation. All stakeholders connected with a development must be considered because the installation could be in position for 30 or more years. A summary of the types of wind and MHK devices is presented in Table 1 of the complete paper.
Offshore wind is a rapidly maturing sector, increasingly seen as a major contributor to electricity supply in states with coastal demand centers and good wind resources. While an almost 3-decade history exists in European experience, the US only recently is beginning to move forward with grid-scale projects on national and state levels. As floating wind is scaled up, to minimize technical risks experienced in the past, formal processes will help to identify the novel features, novel applications, and highest-risk components. Large offshore wind farms have been built by all countries with coastlines on the southern North Sea, the area with the most favorable conditions: strong, consistent winds; water depths of less than 40 m; sand or clay deeper than 70 m; and close proximity to onshore electrical distribution networks and centers of high demand. Rapid reductions have been realized in the cost of electricity, calculated over the full project lifetime, from well over 200 Euros/MWhr for the first large-scale wind farms to 50/MWhr.
Natural gas flaring from a Williams Energy facility can be seen from Garfield County Road 215 in Colorado on 14 August 2020. Flaring, the practice of burning off gas from oil and gas wells, will be limited to a handful of state-approved circumstances under the most comprehensive rules in the nation, adopted by Colorado regulators. When oil comes out of a well, it is mixed with natural gas, mainly methane. Operators who do not have a way to separate and use or ship the gas through pipelines burn, or flare, it off. Alaska is the only other state with a flaring rule limiting the practice to emergencies on producing wells and requiring that the gas be either used or reinjected into the wells.
Canada’s methane emissions from the oil and gas sector in Alberta and Saskatchewan are almost twice as high as had been previously reported, according to a new study by federal government scientists. The study, published online in the journal Environmental Science and Technology, says the scientists measured methane in the atmosphere at four spots in the western provinces from 2010 to 2017. That’s almost double the sector’s annual average of 1.6 megatonnes as reported by the government’s yearly tally of national greenhouse gas emissions, the study says. Because methane is a powerful greenhouse gas, this difference equates to an extra 35 megatonnes of carbon dioxide pollution each year, the study says, using the same conversion ratio as the government. The study was done by scientists in the same department that releases this annual emissions “inventory.”
Cong, Peiwen (State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology) | Teng, Bin (State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology) | Bai, Wei (Manchester Metropolitan University) | Ning, Dezhi (State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology)
A combined concept consisting of a torus-type oscillating water column (OWC) device and an offshore wind turbine is proposed in this study for the multi-purpose utilization of offshore renewable energy resources. The wind turbine is supported by a monopile foundation, and the OWC is coaxial with the foundation. The OWC is of torus shape, and partly submerged with its bottom open to the sea. An air duct, which houses an air turbine, is installed on the roof of the chamber. The exterior shell of the OWC is connected rigidly to the monopile by four thin rigid stiffening plates. Correspondingly, the whole chamber of the OWC is divided into four fan-shaped sub-chambers by the plates. A numerical model is then developed to simulate the wave interactions with the system as well as the air-fluid interactions within the chamber by establishing an extended boundary integral equation and using a higher order boundary element method. In addition, the optimal pneumatic damping coefficient, which is expressed in terms of radiation susceptance and radiation conductance, is determined by solving a pressure-dependent wave radiation problem. Based on the developed model, a detailed numerical analysis is conducted, and the hydrodynamic characteristics related to the combined concept are explored.
The ocean is vast and powerful, enabling marine renewable energy potentially be a significant energy supply. Due to the high-power density and longtime availability, considerable efforts and advances have been made in exploiting the marine renewable energy. A variety of wave energy converters has been invented to harvest the wave energy. In the meantime, many offshore wind energy converters have been used to harvest the available enormous wind energy resources.
Among different classes of designs, the oscillating water column (OWC) device has been widely regarded as one of the most promising options (Falcão, 2010). A typical OWC device mainly consists of two key components: a collector chamber with an underwater bottom open to the sea and a power take-off (PTO) system, mostly an air turbine, on the roof of the chamber (Heath, 2012). The incident waves excite the water column inside the chamber to oscillate, and transfer energy to the air above the water column. The pneumatic power can then be converted into electricity when the air flows through the air turbine coupled with an electric generator. Due to the nature of simplicity, the OWC device can be flexibly adapted to the shoreline, nearshore and offshore through different forms.
Peng, Wei (Key Laboratory of Ministry of Education for Coastal Disaster and Protection, Hohai University / School of Mechanical Engineering, Shandong University) | Zhang, Yingnan (Key Laboratory of Ministry of Education for Coastal Disaster and Protection, Hohai University) | Liu, Chang (Key Laboratory of Ministry of Education for Coastal Disaster and Protection, Hohai University) | Chen, Renwen (State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics) | Liu, Yanjun (School of Mechanical Engineering, Shandong University)
This study investigates on the hydrodynamic efficiency of a wave energy converting device using multiple floats. The floats have the same size and mass, arranged along the wave propagation direction and close to each other. A scale model was built in the laboratory at Hohai University and then employed to study the device's performance in wave controlling and wave energy conversion. During the physical tests, the water surface fluctuation around the structures, the motion of floats, and the voltage output of the dynamos are simultaneously measured. Results show that the incoming wave energy is effectively dissipated by the interactions between waves and structures for the waves with an intermediate wave period. The energy conversion is also helpful for the wave controlling as electricity generation modules absorb part of incident wave energy. Meanwhile, the advantage of the present device in extracting wave energy efficiently at a wide range of wave frequency is confirmed. When the wave period is 1.2~1.6 s, the device's performance is optimal, and the energy conversion efficiency is about 15%.
Wave energy has the limitless foreground as a kind of newly arisen and renewable energy due to numbers of advantages, such as wide distribution and pollution-free. In previous studies, the global gross wave energy resource is estimated to be about 3.7 TW (Mørk et al. 2010). However, the development of wave energy industry is still limited due to a few factors when compared with fossil energy, including conversion efficiency and economic feasibility. Therefore, it is essential to improve the wave energy conversion efficiency and reduce the construction and maintenance cost of wave energy converters (WECs). In recent years, hundreds of patents have been issued to harness the wave energy or improve WECs' performance (Falcão, 2010; Bahaj, 2011; Vicinanza, 2019; Qiu, 2019). Among them, one category is combining WECs with other coastal structures, to save costs and avoid extra sea area fees.
The objective of this study is to design and optimize the layout of the offshore wind farms to maximize the power at a specific location. The energy production of the downstream wind turbines decreases because of the reduced wind speed and increased level of turbulence caused by the wakes formed by the upstream wind turbines. Therefore, the overall power efficiency is lowered due to the wake interference among wind turbines. This paper focuses on using the application of a Gaussian-based wake model and different optimization algorithms like the differential evolution particle swarm optimization (DPSO). The Gaussian wake model uses an exponential function to evaluate the velocity deficit, in contrast to the Jensen wake model that assumes a uniform velocity profile inside the wake. The layout optimization framework has been created for the energy production in order to provide reference for specific conditions and constraints at the Gulf of Maine and other typical projects in the future.
With the growing requirement of energy and environmental protection, the sustainable energy like wind energy has been significantly concerned in recent years. In this case, the investigations about wind farm optimization have been concerned by lots of researchers. In wind farms, one of the most critical power reduction is caused by the wake and turbulence from the blades of previous turbines. Generally, this phenomenon would drop the power production and mechanical performance of turbines. The layout optimization of wind farms according to the wake has been an essential concern for both onshore and offshore wind energy applications.
Figure 1 indicates the annual average offshore wind speeds (m/s) in the United States. From this diagram, the Gulf of Maine have one of the greatest wind energy potential on the east coast. The Gulf of Maine locates very close to the cities such as Portland and Boston with magnificent electricity requirement. So, it is considerably valuable to investigate how to develop wind power in the Gulf of Maine.
He, Zechen (The State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology ) | Ning, Dezhi (The State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology ) | Gou, Ying (The State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology )
An optimization model of buoy dimension of wave energy converter is established by using differential evolution algorithm. The linear potential flow method is used in hydrodynamic calculation. Taking the vertical oscillating cylindrical buoy as the research object, the radius and draft of the buoy are optimized under each specified volume. Through the comparison of different volume optimization results, it is found that there is an optimal buoy volume for a specific wave condition. With the increase of the volume, the optimal draft tends to a fixed value, and the optimal radius tends to be an asymptote. In addition, the influence of different damping of power take-off systems on the optimization results is also studied.
Wave energy is a kind of renewable and clean energy. The development and utilization of wave energy is attracting the attention of many scholars and research institutions around the world, which may make a significant contribution to the world' power consumption. For the commercial feasibility of wave energy, it is very important to improve the production efficiency of wave energy device and reduce its construction, installation and operation costs. Obviously, the volume of the Wave Energy Converter (WEC) is a key factor affecting both the efficiency and the cost. De Andres et al. (2015) discussed that small equipment is usually more economical due to reduced material costs and deployment. Göteman et al. (2014) and Göteman (2017) showed that the total power production can be improved if the wave energy array consists of devices of different dimensions that are similar to the WECs that have been developed at Uppsala University since 2006 (Leijon et al.,2009). Most previous optimal studies focus on the buoy dimensions instead of the buoy volume. For example, Giassi and Göteman (2017) optimized the parameters of the single wave energy converter by parameter sweep optimization of the variables and genetic algorithm, in which the radius, draft and damping of the Power Take Off (PTO) systems are optimized simultaneously in discrete parameter space. Because there are many combinations of radius and draft under a certain volume even for a truncated cylinder buoy, it' difficult to get the relationship between the volume and the efficiency directly. That means the designer couldn't balance the cost and the efficiency with the optimal dimensions.