The causes of the physiological effects of microplastic pollution, potentially harming reef-building corals, are unclear. Reasons might include increased energy demands for handling particles and ...immune reactions. This study is among the first assessing the effects of long-term microplastic exposure on coral physiology at realistic concentrations (200 polyethylene particles L−1). The coral species Acropora muricata, Pocillopora verrucosa, Porites lutea, and Heliopora coerulea were exposed to microplastics for 11 months, and energy reserves, metabolites, growth, and photosymbiont state were analyzed. Results showed an overall low impact on coral physiology, yet species-specific effects occurred. Specifically, H. coerulea exhibited reduced growth, P. lutea and A. muricata showed changes in photosynthetic efficiency, and A. muricata variations in taurine levels. These findings suggest that corals may possess compensatory mechanisms mitigating the effects of microplastics. However, realistic microplastic concentrations only occasionally affected corals. Yet, corals exposed to increasing pollution scenarios will likely experience more negative impacts.
•Coral physiology remained largely unaffected by long-term microplastic exposure.•Microplastics occasionally had subtle, species-specific effects on coral physiology.•Increased taurine levels may initiate the translocation of carbon fixation products.•Reduced growth may be a trade-off mitigating the increased energy needs.•Altered photosynthetic efficiency may provide additional energy for compensation.
•A frequency support methodology has been proposed, incorporating dynamic-droop control from WTGs, to utilize their kinetic energy to provide enhanced system frequency control.•A consecutive power ...dispatch scheme was proposed to effectively coordinate the responses from different WTGs, with the primary aim of mitigating secondary frequency dips.•To evaluate the efficiency of the proposed method, three simulation scenarios are applied and performed in test power system using DIgSILENT PowerFactory software. Results confirm the effectiveness of the proposed scheme.
With the rapid increase of wind energy integrated into power systems, wind turbine generators (WTGs) are required to provide frequency support to maintain the system frequency stability. However, the frequency regulation is achieved by employing temporary energy reserves from WTGs at the initial stage of a disturbance. Therefore, a second frequency dip (SFD) may occur, if no other energy reserve is available to compensate the power deficiency as WTGs have to recover their operating points and rotor speeds back to the initial operating points. To deal with this problem, this paper proposes a consecutive power dispatch scheme to reduce the SFD and prevent WTGs from over-deceleration. All WTGs are divided into two groups with in a wind farm: Group 1 (G1) WTGs operating at maximum power point tracking (MPPT), Group 2 (G2) WTGs operating at deloading power. If a frequency contingency occurs, the proposed scheme aims to release an amount of kinetic energy (KE) stored in the rotating masses of G1 WTGs to improve the frequency nadir (FN). Following this, energy reserves are released from G2 WTGs to compensate the power shortage during the period when G1 WTGs rotor speeds have to be recovered. The simulation results show that the scheme causes a small SFD while improving the first FN and preventing the rotor from over-decelerations in various wind conditions, contingency sizes, and wind penetration levels.
•Classification of frequency response techniques rigorously discussed.•Advantages and disadvantages of frequency support approaches presented.•Effects of secondary frequency dips on the system ...response addressed.•Frequency control in integrated energy systems elaborated.•New research and applications related directions are addressed.
Integrated energy systems are considered as an indispensable part of the pathway towards a low-carbon sustainable future, as well as secure and reliable systems, characterised with a high level of flexibility and resilience. Increased penetration of renewable energy sources into energy systems is contributing to the reduction of carbon emission, thereby reducing the level or air pollution, climate changes and supporting the quality of life on the Earth. In this context, energy conversion systems realized by wind turbine generators have been and are still in the focus of extensive research on different system aspects, from planning, exploitation, monitoring, control, or protection perspective. To maximize the utilisation of available wind energy, modern wind turbine generators are connected to the main grid over power electronics (e.g. Type-3, or Type-4 wind generators). Consequently, they are electromagnetically disconnected from the rest of the power system and they provide little or no inertia, contrary to conventional synchronous generators, synchronously connected to the grid and synchronously operated to each other. This synchronism is necessary to ensure a stable system operation. The reduction of the system inertia imposes serious technical challenges on preserving system frequency stability. As it is known, inertia is one of key factors determining the robustness of power systems against sudden active power imbalances caused by different types of frequency events (generator disconnection, or load connection). The reduction of synchronous power reserves further intensifies this problem by reducing the system ability to maintain frequency within a permissible range following frequency events. Consequently, grid operators demand renewable energy sources, which are also referred to as nonsynchronous generators, to emulate the behaviour of synchronous generators to some extent and to participate in (fast) frequency control upon need. In general, countermeasures applied to these sources to contribute to frequency support are classified into two main categories: a) temporary and b) persistent energy reserve-based approaches. This paper presents a review on latest research findings and developed mechanisms for frequency control using wind energy conversion systems as the most frequently deployed renewable energy sources in modern power systems. Relying on lessons learned from the past two decades, in this paper current and future challenges, feasible solutions and subsequent research prospects are detailed. Some key principles that should underlie future changes of wind integrated energy systems are suggested and further research directions are addressed.
•PVs can meet 100% of extant global primary energy demand more than 12x over, wind 2x over even after reasonable constraints posed by land use and conversion efficiency.•Under a fully electrified ...future scenario, solar power could meet global energy demand 27x over, and wind 5x over.
Energy on our planet is central to the functioning of our ecosystem and modern human society. This work attempts to put the various renewable and non-renewable energy sources at our disposition into context with extant and future human energy consumption. The 79,000 TWyr of solar energy hitting the earth's surface annually constitutes the largest readily accessible energetic resource available on earth and the source from which most other (notably fossil) available energy sources are derived. Using the lens of reasonably assured recoverable reserves, we compare the percentage of this solar energy that can be converted to useable energy (electricity) to the potential of other renewable (wind, hydroelectric, geothermal, ocean thermal, waves, tides, biomass) and conventional reserves (coal, oil, gas, nuclear) and primary demand. We find that solar photovoltaics are capable of meeting 100% of extant global primary energy demand more than 12x over, wind 2x over even after reasonable constraints posed by land use and conversion efficiency. Under a fully electrified future scenario, solar power could meet global energy demand 27x over, and wind 5x over.
Parental investment is any expenditure of time or energy by parents that increases their offspring survival at the cost of future reproduction. The costs associated with parental investment can be ...reflected in a deterioration of their physiological condition. In insects, juvenile hormone has been identified as having a role in the control of parental care. However, its effects on parental investment remain unclear for many taxa, especially in species with exclusive paternal care. We evaluated whether juvenile hormone influences postzygotic parental investment in Abedus ovatus, a waterbug with exclusive paternal care. Males provide parental care by carrying eggs on their backs and ventilating them by generating water currents through push‐ups called brood pumping. In an experiment, we applied methoprene (an analog of juvenile hormone) to males at early and late parental care stages and quantified the frequency of brood pumping and the contents of energy reserves (lipids, carbohydrates, and glycogen) at the end of parental care as a measure of physiological condition. We found that methoprene increases the frequency of brood pumping only when the water temperature increases. However, there was no correlation between the parent's energy reserves and methoprene treatments. We found that males who cared for large egg pads had lower amounts of lipids and carbohydrates at the end of parental care, and both effects are greater as the water temperature increases. These results suggest that energy expenditure during parental care is high due to intense muscular activity during brood pumping, which depletes male energy reserves and could affect future reproduction.
We evaluated the effect of methoprene (juvenile hormone analog) on paternal care behaviors and physiological costs in the waterbug Abedus ovatus. We found that methoprene increases the frequency of parental care behaviors (brood pumping) only when water temperature increases. This effect is greater during prolonged parental care when the eggs are close to hatching. Furthermore, males who care for larger egg pads in warmer waters have low concentrations of lipids and carbohydrates at the end of parental care.
This study initially investigated the coral status during the unexpected bleaching event in three coastal areas in Northwest Hainan coastal areas and analyzed changes in coral holobionts of the ...healthy and bleached Galaxea fascicularis. Coral coverage had declined severely, and the bleaching rate was extremely high during heat stress. The bleached corals had lower maximum photosynthetic yield, actual photosynthetic yield, zooxanthellae density, and chlorophyll a content than the healthy G. fascicularis, but there was no significant difference in protein, carbohydrate and lipid in eutrophic waters. The diversity and community composition of Symbiodiniaceae and symbiotic bacteria between healthy and bleached G. fascicularis showed no difference. Function prediction of the symbiotic bacteria revealed that the metabolism process was the main pathway of annotation. Present findings suggested that energy reserve functioning and high stability of the holobiont structure and might provide opportunities to G. fascicularis to adapt to eutrophication and heat stress.
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•Changes in coral community and holobionts under eutrophication and bleaching events were studied.•Bleached corals maintained some photosynthetic capacity in moderate nutrient concentrations and heat stress.•Energy storage of bleaching Galaxea fascicularis in eutrophic waters was not reduced due to strong heterotrophy ability.•Stable community structure of Symbiodiniaceae and microbiota potentially favoring the survival of G. fascicularis.
•A real geothermal energy application with mine water in the U.S. is introduced.•The proposed energy application is the most efficient and second economical option.•Traditionally neglected thermal ...energy recharge to mine water is very significant.•Annual extractable energy from a typical mine is comparable to annual energy produced by a power station.
Geothermal energy recovery from abandoned flooded mines provides a viable high-tech solution to reuse the abandoned mines for meeting humanity’s energy needs worldwide in an environmental, economic, and reliable way. This unique energy application with mine water in the U.S., however, has not been reported. This study reports on a real geothermal energy application in the U.S. for the use of water in flooded mines for house heating. First, the site exploration of a typical flooded copper mine in the Upper Peninsula of Michigan is presented to discuss three essential components of the proposed large-scale energy application, i.e., bedrock geology, mining background, and energy reserve analyses. Then, the key technical details and data monitoring of a demonstration project for the use of mine water for heating a 15,000 ft2 (1394 m2) building are introduced. For the energy reserve, energy reserve analyses were conducted considering the renewability of the thermal energy in the natural system, which was usually neglected in the literature. The analyses revealed that the annual extractable energy from the explored flooded mine with the energy replenishment is comparable to the annual energy generated by a small-scale power station, which can support over 82,000 households. The results from the demonstration project indicated that house heating with geothermal energy via the mine water is the most efficient and the second most economical heating option in very unfavorable conditions with a high electricity price and a low annual average air temperature. The intention of this study is to share the background and practical knowledge that has been learned from this ongoing project to guide future real installations in other mining areas with deep flooded mines in the U.S. and around the world.
Summary
Reactive oxygen species (ROS) play a key role in the acclimation process of plants to abiotic stress. They primarily function as signal transduction molecules that regulate different pathways ...during plant acclimation to stress, but are also toxic byproducts of stress metabolism. Because each subcellular compartment in plants contains its own set of ROS‐producing and ROS‐scavenging pathways, the steady‐state level of ROS, as well as the redox state of each compartment, is different at any given time giving rise to a distinct signature of ROS levels at the different compartments of the cell. Here we review recent studies on the role of ROS in abiotic stress in plants, and propose that different abiotic stresses, such as drought, heat, salinity and high light, result in different ROS signatures that determine the specificity of the acclimation response and help tailor it to the exact stress the plant encounters. We further address the role of ROS in the acclimation of plants to stress combination as well as the role of ROS in mediating rapid systemic signaling during abiotic stress. We conclude that as long as cells maintain high enough energy reserves to detoxify ROS, ROS is beneficial to plants during abiotic stress enabling them to adjust their metabolism and mount a proper acclimation response.
Significance Statement
Reactive oxygen species (ROS) primarily function as signal transduction molecules that regulate different pathways during acclimation to stress, but are also toxic byproducts of stress metabolism. Different subcellular compartments contain different sets of ROS‐producing and ROS‐scavenging pathways, and thus ROS levels can have different signatures in different cellular compartments. Here we review recent work on ROS and abiotic stress, and propose that different stresses, such as drought, heat, salinity and high light, result in different ROS signatures that determine the specificity of the acclimation response to a particular stress.
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