Muthu P.,Green Energy Group |
Sinnaeruvadi K.,Green Energy Group
Transactions of the Indian Institute of Metals | Year: 2017
In this work, synthesis of Ni doped Mg–Ti nanostructured alloys were made using mechanical alloying method. The structural and optical properties of Mg–Ti alloys were studied by X-Ray diffraction (XRD), UV–Vis spectroscopy and Density Functional theoritical (DFT) studies. The electrochemical performance of Mg–Ti alloys was studied by cyclic voltammetry and impedance studies. The XRD pattern of 20 h milled powders revealed the formation of Mg(Ti) solid solution, Mg2Ni and TiNi compounds. DFT studies confirmed the strong modification of the valence band structure of the Ni doped Mg–Ti alloys which could significantly hasten the hydrogenation and dehydrogenation properties. UV–Vis spectrum revealed increase in band gap energy due to blue shift and hyperchromic shift in both absorption and transmission peaks. Obviously, electrochemical studies revealed high exchange current density and Warburg impedance, as well as decrease in diffusion coefficient and charge transfer resistance. Ultimately, it showed the result of high catalytic activity and faster kinetic reaction rates for the good reversibility of hydrogen ions. © 2017 The Indian Institute of Metals - IIM
News Article | November 2, 2016
At the threshold of the Sahara Desert near Ouarzazate, Morocco, some 500,000 parabolic mirrors run in neat rows across a valley, moving slowly in unison as the Sun sweeps overhead. This US$660-million solar-energy facility opened in February and will soon have company. Morocco has committed to generating 42% of its electricity from renewable sources by 2020. Across Africa, several nations are moving aggressively to develop their solar and wind capacity. The momentum has some experts wondering whether large parts of the continent can vault into a clean future, bypassing some of the environmentally destructive practices that have plagued the United States, Europe and China, among other places. “African nations do not have to lock into developing high-carbon old technologies,” wrote Kofi Annan, former secretary-general of the United Nations, in a report last year1. “We can expand our power generation and achieve universal access to energy by leapfrogging into new technologies that are transforming energy systems across the world.” That's an intoxicating message, not just for Africans but for the entire world, because electricity demand on the continent is exploding. Africa's population is booming faster than anywhere in the world: it is expected to almost quadruple by 2100. More than half of the 1.2 billion people living there today lack electricity, but may get it soon. If much of that power were to come from coal, oil and natural gas, it could kill international efforts to slow the pace of global warming. But a greener path is possible because many African nations are just starting to build up much of their energy infrastructure and have not yet committed to dirtier technology. Several factors are fuelling the push for renewables in Africa. More than one-third of the continent's nations get the bulk of their power from hydroelectric plants, and droughts in the past few years have made that supply unreliable. Countries that rely primarily on fossil fuels have been troubled by price volatility and increasing regulations. At the same time, the cost of renewable technology has been dropping dramatically. And researchers are finding that there is more potential solar and wind power on the continent than previously thought — as much as 3,700 times the current total consumption of electricity. This has all led to a surging interest in green power. Researchers are mapping the best places for renewable-energy projects. Forward-looking companies are investing in solar and wind farms. And governments are teaming up with international-development agencies to make the arena more attractive to private firms. Yet this may not be enough to propel Africa to a clean, electrified future. Planners need more data to find the best sites for renewable-energy projects. Developers are wary about pouring money into many countries, especially those with a history of corruption and governmental problems. And nations will need tens of billions of dollars to strengthen the energy infrastructure. Still, green ambitions in Africa are higher now than ever before. Eddie O'Connor, chief executive of developer Mainstream Renewable Power in Dublin, sees great potential for renewable energy in Africa. His company is building solar- and wind-energy facilities there and he calls it “an unparalleled business opportunity for entrepreneurs”. Power outages are a common problem in many African nations, but Zambia has suffered more than most in the past year. It endured a string of frequent and long-lasting blackouts that crippled the economy. Pumps could not supply clean water to the capital, Lusaka, and industries had to slash production, leading to massive job lay-offs. The source of Zambia's energy woes is the worst drought in southern Africa in 35 years. The nation gets nearly 100% of its electricity from hydropower, mostly from three large dams, where water levels have plummeted. Nearby Zimbabwe, South Africa and Botswana have also had to curtail electricity production. And water shortages might get worse. Projections suggest that the warming climate could reduce rainfall in southern Africa even further in the second half of the twenty-first century. Renewable energy could help to fill the gap, because wind and solar projects can be built much more quickly than hydropower, nuclear or fossil-fuel plants. And green-power installations can be expanded piecemeal as demand increases. Egypt, Ethiopia, Kenya, Morocco and South Africa are leading the charge to build up renewable power, but one of the biggest barriers is insufficient data. Most existing maps of wind and solar resources in Africa do not contain enough detailed information to allow companies to select sites for projects, says Grace Wu, an energy researcher at the University of California, Berkeley. She co-authored a report2 on planning renewable-energy zones in 21 African countries, a joint project by the Lawrence Berkeley National Laboratory (LBNL) in California and the International Renewable Energy Agency (IRENA) in Abu Dhabi. The study is the most comprehensive mapping effort so far for most of those countries, says Wu. It weighs the amount of solar and wind energy in the nations, along with factors such as whether power projects would be close to transmission infrastructure and customers, and whether they would cause social or environmental harm. “The IRENA–LBNL study is the only one that has applied a consistent methodology across a large region of Africa,” says Wu. High-resolution measurements of wind and solar resources have typically been done by government researchers or companies, which kept tight control of their data. The Berkeley team used a combination of satellite and ground measurements purchased from Vaisala, an environmental monitoring company based in Finland that has since made those data publicly available through IRENA's Global Atlas for Renewable Energy. The team also incorporated geospatial data — the locations of roads, towns, existing power lines and other factors — that could influence decisions about where to put energy projects. “If there's a forest, you don't want to cut it down and put a solar plant there,” says co-author Ranjit Deshmukh, also an energy researcher at Berkeley. The amount of green energy that could be harvested in Africa is absolutely massive, according to another IRENA report3, which synthesized 6 regional studies and found potential for 300 million megawatts of solar photovoltaic power and more than 250 million megawatts of wind (see 'Power aplenty'). By contrast, the total installed generating capacity — the amount of electricity the entire continent could produce if all power plants were running at full tilt — was just 150,000 megawatts at the end of 2015. Solar and wind power accounted for only 3.6% of that. The estimate of wind resources came as a surprise, says Oliver Knight, a senior energy specialist for the World Bank's Energy Sector Management Assistance Program in Washington DC. Although people have long been aware of Africa's solar potential, he says, as of about a decade ago, few local decision-makers recognized the strength of the wind. “People would have told you there isn't any wind in regions such as East Africa.” The World Bank is doing its own studies, which will assess wind speeds and solar radiation at least every 10 minutes at selected sites across target countries. It will ask governments to add their own geospatial data, and will combine all the information into a user-friendly format that is freely available and doesn't require advanced technical knowledge, says Knight.“It should be possible for a mid-level civil servant in a developing country to get online and actually start playing with this.” In the semi-arid Karoo region of South Africa, a constellation of bright white wind turbines rises 150 metres above the rolling grassland. Mainstream Renewable Power brought this project online in July, 17 months after starting construction. The 35 turbines add 80 megawatts to South Africa's supply, enough to power about 70,000 homes there. The Noupoort Wind Farm is just one of about 100 wind and solar projects that South Africa has developed in the past 4 years, as prices fell below that of coal and construction lagged on two new massive coal plants. South Africa is primed to move quickly to expand renewable energy, in part thanks to its investment in data. Environmental scientist Lydia Cape works for the Council for Scientific and Industrial Research, a national lab in Stellenbosch. She and her team have created planning maps for large-scale wind and solar development and grid expansion. Starting with data on the energy resources, they assessed possible development sites for many types of socio-economic and environmental impact, including proximity to electricity demand, economic benefits and effects on biodiversity. The South African government accepted the team's recommendations and designated eight Renewable Energy Development Zones that are close to consumers and to transmission infrastructure — and where power projects will cause the least harm to people and ecosystems. They total “about 80,000 square kilometres, the size of Ireland or Scotland, roughly”, says Cape. The areas have been given streamlined environmental authorization for renewable projects and transmission corridors, she says. But for African nations to go green in a big way, they will need a huge influx of cash. Meeting sub-Saharan Africa's power needs will cost US$40.8 billion a year, equivalent to 6.35% of Africa's gross domestic product, according to the World Bank. Existing public funding falls far short, so attracting private investors is crucial. Yet many investors perceive African countries as risky, in part because agreements there require long and complex negotiations and capital costs are high. “It's a real challenge,” says Daniel Kammen, a special envoy for energy for the US Department of State and an energy researcher at the University of California, Berkeley. “Many of these countries have not had the best credit ratings.” Elham Ibrahim, the African Union's commissioner for infrastructure and energy, advises countries to take steps to reassure private investors. Clear legislation supporting renewable energy is key, she says, along with a track record of enforcing commercial laws. South Africa is setting a good example. In 2011, it established a transparent process for project bidding called the Renewable Energy Independent Power Producer Procurement Programme (REIPPPP). The programme has generated private investments of more than $14 billion to develop 6,327 megawatts of wind and solar. Mainstream Renewable Power has won contracts for six wind farms and two solar photovoltaic plants through REIPPPP. “This programme is purer than the driven snow,” says O'Connor. “They publish their results. They give state guarantees. They don't delay you too much.” Although the country's main electricity supplier has wavered in its support for renewables, the central government remains committed to the programme, he says. “I would describe the risks in South Africa as far less than the risks in England in investing in renewables.” For countries less immediately attractive to investors, the World Bank Group launched the Scaling Solar project in January 2015. This reduces risk to investors with a suite of guarantees, says Yasser Charafi, principal investment officer for African infrastructure with the International Finance Corporation (IFC) in Dakar, which is part of the World Bank Group. Through the Scaling Solar programme, the IFC offers low-priced loans; the World Bank guarantees that governments will buy the power generated by the projects; and the group's Multilateral Investment Guarantee Agency offers political insurance in case of a war or civil unrest. Zambia, the first country to have access to Scaling Solar, has won two solar projects that will together provide 73 megawatts. Senegal and Madagascar were next, with agreements to produce 200 and 40 megawatts, respectively. Ethiopia has just joined, and the IFC will give two further countries access to the programme soon; its target is to develop 1,000 megawatts in the first 5 years. That power won't be useful if it can't get to users. One of the big barriers to a clean-energy future in Africa is that the continent lacks robust electricity grids and transmission lines to move large amounts of power within countries and across regions. But that gap also provides some opportunities. Without a lot of existing infrastructure and entrenched interests, countries there might be able to scale up renewable projects and manage electricity more nimbly than developed nations. That's what happened with the telephone industry: in the absence of much existing land-line infrastructure, African nations rapidly embraced mobile phones. The future could look very different from today's electricity industry. Experts say that Africa is likely to have a blend of power-delivery options. Some consumers will get electricity from a grid, whereas people in rural areas and urban slums — where it is too remote or too expensive to connect to the grid — might end up with small-scale solar and wind installations and minigrids. Still, grid-connected power is crucial for many city dwellers and for industrial development, says Ibrahim. And for renewables to become an important component of the energy landscape, the grid will need to be upgraded to handle fluctuations in solar and wind production. African nations can look to countries such as Germany and Denmark, which have pioneered ways to deal with the intermittent nature of renewable energy. One option is generating power with existing dams when solar and wind lag, and cutting hydropower when they are plentiful. Another technique shuttles electricity around the grid: for example, if solar drops off in one place, power generated by wind elsewhere can pick up the slack. A third strategy, called demand response, reduces electricity delivery to multiple customers by imperceptible amounts when demand is peaking. These cutting-edge approaches require a smart grid and infrastructure that connects smaller grids in different regions so that they can share electricity. Africa has some of these 'regional interconnections', but they are incomplete. Four planned major transmission corridors will need at least 16,500 kilometres of new transmission lines, costing more than $18 billion, says Ibrahim. Likewise, many countries' internal power grids are struggling to keep up. That's part of what makes working in energy in Africa challenging. Prosper Amuquandoh is an inspector for the Ghana Energy Commission and the chief executive of Smart and Green Energy Group, an energy-management firm in Accra. In Ghana, he says, “there's a lot of generation coming online”. The country plans to trade electricity with its neighbours in a West African Power Pool, Amuquandoh says, but the current grid cannot handle large amounts of intermittent power. Despite the challenges, he brims with enthusiasm when he talks about the future: “The prospects are huge.” With prices of renewables falling, that kind of optimism is spreading across Africa. Electrifying the continent is a moral imperative for everyone, says Charafi. “We cannot just accept in the twenty-first century that hundreds of millions of people are left out.”
Wang B.,City University of Hong Kong |
Wang B.,Green Energy Group |
Lu X.-Y.,The Hong Kong Institute of Education |
Yu L.K.,Green Energy Group |
And 4 more authors.
CrystEngComm | Year: 2014
In this study, facile synthesis of hollow TiO2 spheres composed of a high percentage of reactive facets (~85%) is successfully prepared with TiOSO4 and HBF4 by the hydrothermal method. Results reveal that hollow TiO2 spheres of 605 nm to 1.21 μm in size are in the anatase phase with sulfur doping. The variation in shell morphologies (e.g. polyhedron and nanosheet) can be realized by adjusting the reactant concentrations, while the molar ratio of TiOSO4 to HBF4 is maintained at 5:3. Based on the time-dependent morphology evolution study, the growth mechanism of hollow structure formation via self-templating and dissolution-recrystallization processes is discussed. The effects of reactant concentrations on TiO2 morphology are investigated to understand the dual roles of HBF4. Results also indicate that hollow TiO2 spheres with nanosheet morphology having 85% (001) facets exhibit 1.4-5 times higher performance than their counterparts in photocatalytic hydrogen production. The enhanced photocatalytic activity is ascribed to the combined effects of their unique hollow structure, high BET specific surface area (139.1 m2 g-1) and high percentage of exposed reactive facets (85%). This study demonstrates a promising strategy for large-scale production of hollow TiO2 spheres using a template- and surfactant-free process for photocatalysis applications. © the Partner Organisations 2014.
Wang L.,Xi'an Jiaotong University |
Chen Z.,Xi'an Jiaotong University |
Yang B.,Xi'an Jiaotong University |
Zeng K.,Xi'an Jiaotong University |
And 2 more authors.
SAE Technical Papers | Year: 2016
An applicable and comprehensive control strategy of a natural gas/diesel dual fuel engine is presented in this paper. The dual fuel engine is converted from a conventional mechanical pump, turbo charged, heavy duty diesel engine. In the dual fuel mode, the pedal position is explained as demanded total fuel quantity, the quantity of pilot diesel and natural gas are calculated in order to provide the equal energy with the original diesel engine at the same operation condition, the proportion of the natural gas is primarily determined by the load rate and the speed of the engine. When the engine is working under light or moderate load, the intake air is throttled in order to improve the brake mean effective pressure and reduce the hydrocarbon emissions of the dual fuel engine, according to target excess air ratio and the quantities of the two fuels, the desired air mass per cycle can be obtained. After that a mean value model based feedforward control is adopted to calculate the electronic throttle position, with a universal exhaust gas oxygen sensor, a proportional-integral controller is designed, therefore feedback control is introduced to the air/fuel ratio control system to enhance its accuracy and robustness. Verification test results show that: the engine which employs the control strategy in this paper can work stably and reliably with less calibration data; the air/fuel ratio is regulated accurately and quickly; dual fuel engine has better fuel economy even though its brake thermal efficiency is lower due to the comparatively low price of natural gas; intake throttling has significant effect on improving the economy and hydrocarbon emission of the dual fuel engine under light and moderate load. © Copyright 2016 SAE International.
Bokhove J.,TU Eindhoven |
Kerkhof P.J.A.M.,TU Eindhoven |
Schuur B.,Green Energy Group |
de Haan A.B.,Technical University of Delft
Chemical Engineering Science | Year: 2015
Solvent impregnated resins are promising for the removal of polar organic compounds from aqueous streams, but have low mass-transfer rates. A thorough understanding of the phenomena occurring inside the pores of the solvent impregnated resin is therefore required. In this study a mathematical model was developed to describe the simultaneous diffusion and reaction. The diffusion was described using the Maxwell-Stefan approach towards multi-component diffusion and included the volume-expansion of the organic phase. The model was validated using experimental data from the literature on the extraction of phenol by Cyanex923 impregnated in macro-porous polypropylene. The model described the experimental data as function of temperature and initial concentration accurately with an R2>0.96 and a regressed reaction rate constant with a confidence interval of ± 6%. Analysis of the model results revealed that multi-component effects as described by the Maxwell-Stefan model were of limited importance whereas the volume expansion was essential to accurately describe the experimental data. © 2015 Elsevier Ltd.
Xu H.J.,China University of Petroleum - East China |
Luo X.,China University of Petroleum - East China |
Mao Q.J.,Green Energy Group |
Gong L.,China University of Petroleum - East China |
Huang S.B.,China University of Petroleum - East China
Applied Mechanics and Materials | Year: 2014
Considerable cold energy embodied in liquefied natural gas (LNG)can be recycled in LNG regasification, which can not only save energy but also avoid cold pollution within the low-temperature fluid emission. Review on both domestic and overseas is conducted on the recycling of LNG cold energy in different applications. Against the single purpose utilization of LNG cold energy with a large amount of energy loss, the cascade recycling strategy is proposed for highly-efficient utilization of LNG cold energy. Based on the defined cold exergy efficiency, the exergy analysis is performed for some different recycling applications of LNG cold energy. The system exergy rate method is used to compare the superiority of modes in which the LNG is converted into NG under normal temperature. The results show that the exergy efficiency of a LNG cold energy cascade recycling system is higher than that of asingle utilization system. Apart from the improved efficiency, the cascade recycling strategy can expand the applicable temperature range of LNG cold energy compared with the single utilization. Finally, the entropy and entransy for evaluating the LNG cold energy transport process are compared and discussed, from which it is indicated that entransy is more appropriate for the heat transfer process with low-temperature or large temperature difference, as is the case for LNG cold energy recycling. © (2014) Trans Tech Publications, Switzerland.
Hassan M.Z.,Green Energy Group |
Zainal Ariffin H.I.,Green Energy Group
Applied Mechanics and Materials | Year: 2013
Blind spot of a passenger car is an area around the vehicle that cannot be seen while looking either forward or through side or rear view mirror. In this paper, a blind spot system known as ZRT Vehicle Blind Spot System (ZRT-VBSS) has been developed using Arduino and ultrasonic sensors to overcome the problem. The system is capable to detect a moving vehicle in blind spot area under three main condition of which static, dynamic speed operation at 60 and 100 km/h and also overtake position. The results from the experimental investigation show that ZRT-VBSS is capable to perform at various operating condition that make it reliable to provide solution for driver to overcome the blind spot phenomenon. © (2013) Trans Tech Publications, Switzerland.
Kobayashi R.,Green Energy Group |
Hayashi K.,Green Energy Group |
Sugita S.,Green Energy Group
NTT Technical Review | Year: 2013
The long-lasting commercial power outage caused by the catastrophic earthquake in eastern Japan in 2011 demonstrated the importance of the power supply in providing continuous telecommunication services. This article introduces an approach to power supply to ensure that telecommunication services operate normally in all situations and describes the development of high energy density secondary batteries and highly efficient fuel cells to achieve energy storage and generation for that purpose.
Choi M.,Myongji University |
Cierpka C.,University of Federal Defense Munich |
Kim Y.-H.,Green Energy Group
European Journal of Mechanics, B/Fluids | Year: 2014
Two dimensional unsteady numerical simulations were conducted using a commercial code with a userdefined- function to investigate the effect of the distance between two cantilevers vibrating in counterphase or in phase. The performance of the cantilevers with different distances was mainly evaluated by the time-averaged axial velocity and the mass flow rate. It is evident that there is no interaction between the vortices by two cantilevers if they are too far apart. However, if two cantilevers are too close, they hinder each other in vortex generation. In particular, the interaction between two inner vortices generates a reversed flow which has a negative effect on the performance. Unless the distance is too close, the performance of the cantilever pair vibrating in counter-phase is always superior to the cantilever pair vibrating in phase. The optimal distance between two cantilevers in counter-phase is approximately equal to twice the size of a fully-grown vortex generated by the single cantilever, while there is no distinct optimal distance for a cantilever pair vibrating in phase. In case the distance is larger than three times the vortex size, the flow field generated by each cantilever is similar to the flow field of a single cantilever, which implies that two cantilevers work independently of each other. © 2013 Elsevier Masson SAS. All rights reserved.
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