Green Energy Resources Research Articles

Mechanical experiments and constitutive model of natural gas hydrate reservoirs

Natural gas hydrate is a new type of green energy resources and has great development prospects, and it has attracted worldwide attentions. The exploitation of natural gas hydrate may result in a series of geological disasters. Therefore, the constitutive model of natural gas hydrate bearing sediments needs to be established to reveal deformation laws of the reservoir sediments and accurately evaluate mechanical properties of hydrate reservoirs. This is the basic guarantees for the effective exploitation of natural gas hydrate resources. The triaxial compressive tests were conducted on samples of natural gas hydrate sediment. Furthermore, the Duncan-Chang hyperbolic model was modified by considering the influences of hydrate saturation based on the test results to obtain the constitutive model according with the deformation characteristics of natural gas hydrate reservoirs. The results show that the stress-strain curves of natural gas hydrate reservoirs show unobvious compaction stage and peak strength, short elastic stage, long yield stage, and significant strain hardening characteristics. After applying loads on natural gas hydrate bearing sediments, the internal solid particles were dislocated and slid. When the loads were small, the sediments demonstrated elastic deformation. With the increase of loads, plastic flows appeared in the interior, and the hydrate crystals were re-orientated, thus the sediments showing plastic deformation. Initial tangent elastic modulus increased with the effective confining pressures, which had little correlations with hydrate saturation. Furthermore, the damage ratio increases with the increase of effective confining pressures, while slightly decreases with the increase of natural gas hydrate saturation. The predicted results of stress-strain curves of sediments with different hydrate saturations well coincide with the results of triaxial compressive tests, indicting the feasibility and rationality of this model.

Methanolysis of Crude Jatropha Oil using Heterogeneous Catalyst from the Seashells and Eggshells as Green Biodiesel

In this work, heterogeneous calcium oxide catalysts gleaned from Polymedosa expansa and eggshell were investigated for the transesterification of crude jatropha oil with methanol, to access their prospective performance in biodiesel production as an alternative green energy resource. The best yield of biodiesel achieved was 96% in 1 h for Step 1 using 0.01:1 ratio of acid catalyst to oil and 0.6:1 ratio of alcohol to oil ratio, together with 2 h of Step 2 using 0.02:1 ratio with base catalyst CaO, derived from P. expansa, to oil ratio and 5:1 ratio of alcohol to oil. The properties of jatropha biodiesel were analyzed and found to have calorific value of 35.43 MJ/kg, density value of 895 kg/m3 and flash point of 167. The biodiesel was blended with mineral diesel from B0 to B50 for a diesel engine performance test. B20 indicated comparable characteristics with pure mineral diesel, like lowest fuel consumption rate, specific fuel consumption rate, highest brake horsepower and mechanical efficiency.

International Conference on Green and Renewable Energy Resources (ICGRER 2016)

PrefaceThe International Conference on Green and Renewable Energy (ICGRER 2016) was held November 14-15th, 2016 at Solo Paragon Hotel, Surakarta, Central Java, Indonesia. This conference is organized by Faculty of Mathematics & Natural Science, Sebelas Maret University.The scope of parallel classes are solar energy/solar cells, biomass and bio energy, and miscellaneous product. There are 60 presenters were presented and discussed in plenary and parallel session, therefore, a total 28 manuscripts have been peer reviewed with good quality.We are pleased to have Prof. Dr. Sri Adiningsih, M.Sc., Ph.D (Chairman of the Presidential Advisory Council) as our outstanding keynote speaker. We also glad ti have our invited speakers Prof. Renate Egan (University of New South Wales Australian PV Institute, Solinno Pty, Ltd), Dr. Adhi Wibowo (Direktur PPTEK R&D EBTKE Kementerian ESDM), Ir. Hj. Sripeni Inten Chayani, M (President Director PT. Indonesia Power), Prof. Dr. Ir. Kamaruddin Abdullah (Universitas Darma Persada), and William Papet (Business Development at MPS Consortium).We express our gratitude to participants from all researchers and students for join this conference. We also appreciate for sponsors, reviewers, and all member of the organizing committee which prepare this conference. Our gratitude also goes to the IOP Publisher for cooperation in prepare this proceeding. We do realize that the success of the conference depends on both participants and who have worked with us.Prof. Ari Handono RamelanChairman of ICGRER 2016Dean of Faculty Mathematics & Natural Sciences

Sourcing Green Power in Bhutan: A Review

Abstract Bhutan is a small Himalayan kingdom with nearly 0.8 million population. Being one of the poorest nations in the world, Bhutan has achieved a significant economic progress in recent years. Export of hydropower contributes most of its foreign exchange (over 85%). It has one of the largest hydropower potentials in the world. Only 5% of the total hydropower potential is currently being utilized. The government of Bhutan has developed a master plan to tap this green energy resource to generate power not only for domestic use but also for export to surrounding countries. One of the primary aims of this paper is to study Bhutan's current and future hydropower projects and examine the potential of a collaboration framework for energy trading. The impact of such a regional energy trading on Bhutanese economy will also be analyzed.

Optimal Power Allocation for Hybrid Energy Harvesting and Power Grid Coexisting System With Power Upper Bounded Constraints

As one of the green energy resources, the technique of energy harvesting harnesses energy from its surrounding environment. In this setting, a power grid is also utilized to serve as a supplementary source to regulate the not-so-stable harvested energy supply of the system. The power allocated to the user(s) from the sum of the harvested energy and the power grid is subject to peak power constraints. The background of these constraints comes from field requirements, such as avoiding the saturation of power allocated to the user(s), avoiding system level out-of-band power leakage, and reducing interference with other transmitter(s) due to the nonlinearity generated via the transmitting mechanisms to the user(s). The proposed problem considers simultaneously 1) the hybrid paradigm of both energy harvesting and grid power supplies, and 2) the peak power constraints in such systems. For our proposed problem, the most efficient known-to-date and popular convex optimization method of primal-dual interior method (PD-IPM) only computes an $\epsilon$ solution, not an optimal solution, even with more computations. The novelty of the proposed algorithms is that they compute the exact solutions with the low degree polynomial computational complexity. To the best of the authors’ knowledge, under the same assumptions, no prior publication, including PD-IPM, can arrive at such results. Numerical examples also illustrate efficiency of the proposed algorithms.

Managing a transition to green energy sources: The perspectives of energy practitioners in the Southern African Development Community region.

The Southern African Development Community (SADC) region has low energy security, exacerbated by electricity power cuts and load-shedding in almost all its member states. Green energy has the potential to contribute to the shortfall in the supply of energy required on the grid network during daily (morning and evening) and seasonal (winter) peak periods. The Statistica 12 program was used to analyse and compare responses between identified groups in the SADC region’s Energy sector. Multivariate analysis of variance and analysis of variance were used to examine associations between variables within the identified categories of respondents, and conclusions were made about six hypotheses. The categories of respondents sampled included: people associated with fossil fuel and renewable energy; people with experience of 1-6 years and more than 6 years; researchers and industry practitioners; practitioners based in South Africa and in other SADC countries; and a category based on practitioners’ positions (junior managers, middle managers, and senior managers) in their respective organisations. The study found that energy practitioners generally support a transition to green energy sources and there is consensus that the uptake of green energy will be slow initially, driven by low costs of fossil-based sources, but the uptake will eventually grow exponentially to a point of driving industries in future. The study recommends that SADC countries prioritise mapping of green energy resources to facilitate the selection of suitable green energy options in order to meet local energy needs and environmental protection. Research and development of suitable green energy storage technologies to overcome intermittency of some green energy sources must be expedited in the region.

Multi-objective Optimization of Integrated Renewable Energy System Considering Economics and CO2 Emissions

Abstract The replacement of environmentally unfriendly fossil fuels with green energy resources plays a fundamental role in resolving environmental pollution and global warming problems. In this paper, a multi-objective optimization method is promoted for the design of an energy system integrating biomass CHP, PV and heat storage. The results give a trade-off between economic and environmental performances while providing feasible generation settlements that take into account the installation of CHP, PV, together with utility grid.

A Novel Design of Energy-saving Wireless Intelligent Agricultural Detecting System

In order to meet the needs of modern intelligent agricultural detection, this paper designs and develops a novel energy-saving intelligent wireless agricultural detecting system combined with technologies green power supply, wireless transmission and digital control. This system can be powered by green energy resources such as solar energy or wind power and combined with digital control and wireless communication technologies it can achieve collection of a large amount of parameters in terms of modern agricultural cultivation, which will meet the needs of different application scenarios. Results of repeated experiments have shown that it has such advantages as being green and environment-friendly, flexible and reliable.

Global electricity demand, generation, grid system, and renewable energy polices: a review

The rising concerns on the impacts of greenhouse gas (GHG) emissions and global warming have forced the world to search for alternative clean and green energy resources. Renewable energy is one of the most sustainable forms of energy, and is an increasingly popular replacement to fossil fuels. In line with this, the world has witnessed tremendous growth in renewable energy technologies as well as unprecedented adoption of renewable‐based electricity generation in the past few decades. This review paper focuses on the global energy demand, power generation, electricity production, electrical grid system as well as current global polices to move forward for renewable energy‐based power generation. This work compiles the latest literature (i.e., journal articles, conference proceedings, reports, etc.) on global energy demand, power generation, electrical grid system as well as current global polices related to renewable energy. From the review, it is found that renewable energy is one of the potential resources to fulfill the future energy demand with mitigating GHG emissions and global warming. It is also found that many polices has been implementing globally to promote renewable energy‐based power generation. WIREs Energy Environ 2017, 6:e222. doi: 10.1002/wene.222This article is categorized under: Energy Infrastructure > Climate and Environment Energy and Climate > Climate and Environment Energy Policy and Planning > Economics and Policy

Synthesis and Electrochemical Properties of K-Rich Prussian Blue for Non-Aqueous Potassium Batteries

1. Introduction Nowadays, rechargeable lithium batteries are the most mature energy storage systems. But high cost hinders its further application as large-scale energy storage device which is essential for the utilization of green and sustainable energy resources. Hence, various low cost battery systems have been proposed. Among them, rechargeable sodium batteries is a kind of promising candidate because sodium resources are unlimited, the second-lightest and smallest alkali metal next to lithium [1]. The working voltage of sodium batteries, however, is lower than it of lithium batteries because standard electrode potential of Na (-2.71 V vs. SHE) is about 0.33 V higher than Li (-3.04 V vs. SHE). Whereas, as another earth abundant alkali element, potassium (-2.93 V vs. SHE) has lower standard electrode potential than sodium. Consequently, research of rechargeable potassium batteries would be helpful for developing low cost large-scale energy storage system with high working voltage. It cannot be denied that the radius of potassium is larger than sodium and lithium. Therefore, electrode material for potassium batteries should provide large migration tunnel for potassium ion. As a kind of good host for alkali ions, Prussian blue analogues provide open framework with large interstitial sites. Potassium insertion properties of Prussian blue thin film (40-300 nm) had been researched in aqueous solution by Murray and Neff for the first time [2,3]. Then, Eftekhari researched electrochemical performance of Prussian blue thin film (1 μm) positive electrode in non-aqueous Potassium secondary cell [4]. This thin film electrode exhibited about 80 mAh g-1 reversible capacity and excellent cycle performance within 500 cycles. However, thin film electrode is far away from practical application. In this study, we synthesized K-rich Prussian blue powder with convenient precipitation method. Electrochemical properties of the product in non-aqueous potassium batteries will be shown in this presentation. For the practical application, potassium full cell with graphite negative electrode, which had been reported by us, will be also shown [5]. 2. Experimental 2 mmol K4Fe(CN)6 and 4 mmol FeCl2 were dissolved in to 40 and 80 ml of saturated KCl solutions. These two solutions were slowly dropped together with magnetic stirring under N2 atmosphere at 60 oC. Then, the precipitate was centrifuged and washed thoroughly with 500 ml deionized water. The final product was obtained after drying in 80 oC oven for 12 h. Electrochemical measurements were carried out using 2032 coin cell with KFSI in EC:DEC (1:1) solution as electrolyte and potassium metal as negative electrode. Prussian blue electrode contains 70 % active material, 20 % Ketjen black carbon and 10 % PVdF binder. 3. Results and Discussion Figure 1 shows the XRD pattern of K-rich Prussian blue. The sample is single phase product which belongs to monoclinic structure and space group of P21/n [6]. The lattice parameters are calculated as a=10.1303(1) Å, b=7.2574(7) Å, c=7.0208(1) Å and β=89.54(9)⁰. Figure 2 is the charge-discharge curves of sample in K half-cell with current density of 60 mA g-1 in voltage range of 2.0-4.0 V. K-rich Prussian blue delivers 98 and 83 mAh g-1 initial charge and discharge capacity, respectively. Meanwhile, the charge-discharge plateaus are located around 3.35~3.48 V, which relates with the redox reaction of Fe in nitrogen coordinate. After 100 cycles, the reversible capacity remains 75 mAh g-1. Capacity retention is about 90 %. The as-prepared K-rich Prussian blue exhibits promising electrochemical performance in non-aqueous potassium battery. More details such like morphology, element composition and electrochemical mechanism of the sample will be given in the presentation. References 1) K. Kubota and S. Komaba, Journal of The Electrochemical Society, 2015, 162, A2538-A2550 2) C. A. Lundgren and R. W. Murray, Inorg. Chem., 1998, 27, 933-939 3) V. Krishnan, A. L. Xidis and V. D. Neff, Analytica Chimica Acta, 1990, 239, 7-12 4) A. Eftekhari, Journal of Power Sources, 2004, 126, 221-228 5) S. Komaba and K. Kubota, Electrochemistry Communications, 2015, 60, 172-175 6) J. Song and J. B. Goodenough, Journal of the American Chemical Society, 2015, 137, 2658-2664 Figure 1

Wind turbine condition monitoring and fault diagnosis in China

With the advent of a more severe energy crisis and environment contamination, wind energy, as one of the green and renewable energy resources, has attracted more and more attention worldwide [1], [2]. According to statistics issued by the Global Wind Energy Council (GWEC), by the end of 2014, the global installed capacity had reached 360,000 MW, while the installed capacity in China accounted for 114,763 MW, nearly one third of the total, as illustrated in Fig. 1. Meanwhile, it is envisioned in 2050 Blueprint of Wind Power Development in China that by the years 2030 and 2050, the scale of installed capacity will exceed 4 × 105 MW and 106 MW, respectively, so as to meet 8.4% and 17% of the demand for electricity nationwide, enabling wind energy to be one of five main energy resources.

Designing sustainable energy regions using genetic algorithms and location-allocation approach

Geographical areas have diverse green energy resources and different levels of energy consumptions. An important challenge to satisfy the energy demand using green energy resources is to balance energy supply and demand. Territory design deals with the problem of grouping geographic areas into larger geographic clusters called territories in such a way that the grouping is acceptable according to a planning criterion. The aim of this study is to group geographic areas so that energy requirement in a geographic cluster matches the available green energy potential in the same cluster. In this way, investments may be supported through region specific policies. The problem is formulated as a mixed-integer linear programming model. A location-allocation approach is employed to solve the model. The location and allocation problems are solved iteratively. In order to solve the initial location problem, a Genetic Algorithm is developed to find the results of the p-median problem. Then, the allocation problem is solved optimally using the ILOG Cplex solver. The territory design problem is solved for Turkey and the results of various numbers of territories are compared. Among those trials, 10 territories result in the best balance of demand and supply.

Matching of Energy Provisions in Multihop Wireless Infra-Structures

Recently there have been large advances in energy technologies for battery-operated systems, including green energy resources and high capacity batteries. The effective use of battery energy resources in wireless infrastructure networks to improve the versatility and reliability of wireless communications is an important issue. Emerging applications of smart cities, Internet of Things (IoT), and emergency responses highly rely on the basic communication network infrastructures that enable ubiquitous network connections. However, energy consumption by nodes in a wireless infrastructure network depends on the transmissions of other nodes in the network. Considering this inter-dependence is necessary to achieve efficient provision of energy in wireless networks. This paper studies the issue of energy provision for wireless relay nodes in Wireless Multihop Infrastructures (WMI) assuming constraints on the total energy provision. We introduce a scheme of Energy Provision Matching (Matching-EP) for WMI which optimizes energy provision based on matching of energy provision with estimates of differentiated position-dependent energy consumption by wireless nodes distributed in the network. The evaluation results show that Matching-EP with 4%–34% improvement in energy matching degree enables 10%–40% improvement of the network lifetime, and 5%–40% improvement of packet delivery compared with conventional WMI networks.

A Dual Operation of PV-Statcom as Reactive Power Compensator and Active Power Injector in Grid Tie System: Power Quality

The Green Energy Resources like Solar and Wind energy sources are playing a vital role to reach the capital power demand. The distribution system consist almost all reactive and sensitive loads, which may cause the power quality concerns like reactive power demand, low power factor, harmonic currents and etc. in power system. Reactive power is a determinant factor for efficient and effective operation of electric power system, so that the power engineers are concentrating to manage the reactive power at desired level. This article describes the dual operation of PV Solar plant as PV-Statcom for active power (P) and reactive power (Q) injection and absorption for power quality improvement in grid integrated proposed system. The PV-Statcom control pattern for enlarging quality of power is simulated in MATLAB/Simulink.

Feasibility of Small Autonomous Solar Powered Water Desalination Units for Arid Regions

The main objective of this work is to conduct a feasibility study of utilizing small autonomous water desalination units powered by photovoltaic modules as a green renewable energy resource to be employed in different isolated zones as a source of drinking water for some scattered societies where the installation of huge desalination stations are discarded owing to the unavailability of electric grid in remote areas. Yanbu City is chosen as a case study where the Renewable Energy Center exists and equipped with all sensors to assess the availability of solar energy all over the year. The study included two types of available water: the first type is brackish well water and the second type is seawater of coastal regions. In the case of well water, two versions of desalination units are involved in the study: the first version is based on day operation only. While the second version takes into consideration the night operation, which requires energy storage system as batteries to provide the necessary electric power at night. According to the feasibility study results, it is found that utilization of small autonomous desalinations unit is applicable and economically accepted in the case of brackish well water. However, in the case of seawater the capital costs are extremely high and the cost of desalinated water will not be economically feasible unless governmental subsidies are provided.In addition, the study indicated that, for the same water production, the utilization of energy storage version (day-night) adds additional capital cost for batteries, and extra running cost for their replacement, which makes the unit price not only incompetent with day-only unit but also with conventional units powered by diesel generator (fossil fuel) owing to the low prices of fuel in the kingdom. However, the cost analysis shows that the price of the produced water per cubic meter of day-night unit is similar to that produced from the day-only unit provided that the day-night unit operates theoretically for a longer period of 50 %.

Exogenous Gene Integration for Microalgal Cell Transformation Using a Nanowire-Incorporated Microdevice.

Superior green algal cells showing high lipid production and rapid growth rate are considered as an alternative for the next generation green energy resources. To achieve the biomass based energy generation, transformed microalgae with superlative properties should be developed through genetic engineering. Contrary to the normal cells, microalgae have rigid cell walls, so that target gene delivery into cells is challengeable. In this study, we report a ZnO nanowire-incorporated microdevice for a high throughput microalgal transformation. The proposed microdevice was equipped with not only a ZnO nanowire in the microchannel for gene delivery into cells but also a pneumatic polydimethylsiloxane (PDMS) microvalve to modulate the cellular attachment and detachment from the nanowire. As a model, hygromycin B resistance gene cassette (Hyg3) was functionalized on the hydrothermally grown ZnO nanowires through a disulfide bond and released into green algal cells, Chlamydomonas reinhardtii, by reductive cleavage. During Hyg3 gene delivery, a monolithic PDMS membrane was bent down, so that algal cells were pushed down toward ZnO nanowires. The supply of vacuum in the pneumatic line made the PDMS membrane bend up, enabling the gene delivered algal cells to be recovered from the outlet of the microchannel. We successfully confirmed Hyg3 gene integrated in microalgae by amplifying the inserted gene through polymerase chain reaction (PCR) and DNA sequencing. The efficiency of the gene delivery to algal cells using the ZnO nanowire-incorporated microdevice was 6.52 × 10(4)- and 9.66 × 10(4)-fold higher than that of a traditional glass bead beating and electroporation.

ChemInform Abstract: Enzymatic Conversion of Carbon Dioxide

AbstractReview: 49 refs.

Orchestrating connectivity services to support elastic operations in datacenter federations

Datacenter federations are able to manage appropriately the green energy resources available in each datacenter (DC) thanks to their geographically distributed infrastructure, thus reducing energy expenditure. Scheduling algorithms can compute virtual machine migration, transferring huge amounts of raw data from one DC to another to minimize operational costs and ensuring a certain Quality of Experience. Because green energy availability greatly depends on weather conditions, in this work we present a statistical model to improve green solar energy availability estimation accuracy and we use it in a mixed integer linear programming formulation to compute optimal virtual machine placement. Optical connections can be used to provide connectivity services of enough capacity to support those migrations. In particular, elastic optical networks can provide connections with multi-granular bitrate, which can be adapted on demand. DC resource managers can request optical connections and control their capacity. However, that scheme involves the resource managers to implement algorithms and interfaces to deal with network specifics and complexity. To solve that issue, in this paper we propose coordinating transfer-based inter-DC connectivity services; inter-DC connectivity is requested in terms of volume of data and completion time. We analyze cost savings when each connectivity model is applied in a DC federation. For the sake of a compelling analysis, exhaustive simulation experiments are carried out considering realistic scenarios. Results show that the notification-based model can save up to 20 % of energy costs and more than 40 % of communication costs in the evaluated scenarios.

Electric utility regulation and investment in green energy resources

Electric utility investment in end-use efficiency and renewable energy resources is examined with current forms of Pigouvian taxes and subsidies that encourage investment in green energy resources. A model of a rate-of-return-regulated firm considers the impacts of policies on social optimality. It shows that cap-and-trade/floor-and-trade forms of Pigouvian taxes and subsidies cause electric utilities to (over) underinvest in conventional generation and (under) overinvest in green resources when the allowed rate of return (is above) equals the cost of capital. Therefore, these forms of taxes and subsidies combined with rate base rate-of-return regulation result in suboptimal investment in one type of asset or another regardless of the level of return exogenously set by regulators. Therefore, public utility investment is always suboptimal, one way or another. The form of regulation is empirically tested from stock price signals and observed by lack of investment in the electric power infrastructure and too much investment in green resources that will not meet renewable portfolio standards and the demand for electric services.

Thickness Simulation and Analysis of CdS/CdTe Solar Cell to Increase the Efficiency and Decrease the Toxicant Material of Cadmium

Population growth as well as the growth in energy demand is one of the most challenging problems in the world. Therefore, there is great need of green energy technologies and one of the green energy resources is solar cell that converts sun rays in a photovoltaic way into electrical energy. Firstly, we have presented a structure and after simulating this structure and reaching to approximately close results we expect any improvement in simulated model can be accessible in manufactured model. In this article, synchronous analysis of layer thickness for reaching to the maximum efficiency has been done. Our analysis performs to maximize the efficiency and minimize the thickness of layers with toxicant and expensive cd material. The results, shows increase of the efficiency and extreme decreasing in Cd layers thickness.