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Energies, Volume 4, Issue 2 (February 2011), Pages 215-367

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Research

Jump to: Review

Open AccessArticle Comparison of Ferry Boat and Highway Bridge Energy Use
Energies 2011, 4(2), 239-253; doi:10.3390/en4020239
Received: 18 November 2010 / Revised: 15 January 2011 / Accepted: 20 January 2011 / Published: 27 January 2011
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Abstract
Passenger ferries serve a variety of transport needs in the U.S., such as providing vital links across bodies of water, and supplementing highway bridges. In some cases in which there is a ferry connection but no bridge, a bridge would be impractical; [...] Read more.
Passenger ferries serve a variety of transport needs in the U.S., such as providing vital links across bodies of water, and supplementing highway bridges. In some cases in which there is a ferry connection but no bridge, a bridge would be impractical; in other cases, a bridge might be feasible. The paper compares the energy consumption of ferries and motor vehicles on bridges, to determine which link is more fuel efficient. One finding is that limited data are available on ferry boat fuel consumption: despite there being 208 ferry boat operators in the U.S. as of 2008, only eight were providing energy use data to the National Transit Database. Examinations of three of the systems found that the passenger-MPG of the ferries ranged from 2.61 to 14.00 (1.11 to 5.95 km/L), while that of the motor vehicles on adjacent highway bridge connections ranged from 25.34 to 32.45 (10.77 to 13.79 km/L). Data from the eight systems are used to develop a ferry MPG model. The model is used to show that the Ryer Island and Charles Hall Ferries are less fuel efficient than hypothetical bridges in those locations. The fuel efficiencies and consumptions of the ferries would equal those of motor vehicles on the bridges, however, if smaller vessels were used, and if the frequency of service was reduced. Full article
(This article belongs to the Special Issue Energy-Friendly Transportation)
Open AccessArticle Experiment and Simulation of Medium-Duty Tactical Truck for Fuel Economy Improvement
Energies 2011, 4(2), 276-293; doi:10.3390/en4020276
Received: 26 November 2010 / Revised: 5 January 2011 / Accepted: 26 January 2011 / Published: 4 February 2011
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Abstract
Fuel economy improvement on medium-duty tactical truck has and continues to be a significant initiative for the U.S. Army. The focus of this study is the investigation of Automated Manual Transmissions (AMT) and mild hybridization powertrain that have potential to improve the [...] Read more.
Fuel economy improvement on medium-duty tactical truck has and continues to be a significant initiative for the U.S. Army. The focus of this study is the investigation of Automated Manual Transmissions (AMT) and mild hybridization powertrain that have potential to improve the fuel economy of the 2.5-ton cargo trucks. The current platform uses a seven-speed automatic transmission. This study utilized a combination of on-road experimental vehicle data and analytical vehicle modeling and simulation. This paper presents the results of (1) establishment of a validated, high fidelity baseline analytical vehicle model, (2) modeling and simulation of two AMTs and their control strategy, (3) optimization of transmissions shift schedules, and (4) modeling and simulation of engine idle stop/start and Belt-Integrated-Starter-Generator (B-ISG) systems to improve the fuel economy. The fuel economy discrepancy between experimental average and the baseline simulation result was 2.87%. The simulation results indicated a 14.5% and 12.2% fuel economy improvement for the 10-speed and 12-speed AMT respectively. A stop/start system followed by a B-ISG mild hybrid system incorporating regenerative braking was estimated to improve fuel economy 3.39% and 10.2% respectively. Full article
(This article belongs to the Special Issue Hybrid Vehicles)
Open AccessArticle Numerical Analysis on Gas Production Efficiency from Hydrate Deposits by Thermal Stimulation: Application to the Shenhu Area, South China Sea
Energies 2011, 4(2), 294-313; doi:10.3390/en4020294
Received: 14 December 2010 / Revised: 10 January 2011 / Accepted: 26 January 2011 / Published: 14 February 2011
Cited by 9 | PDF Full-text (839 KB) | HTML Full-text | XML Full-text
Abstract
Gas hydrates have been attracted a great deal of attention because of their potential as an energy substitute and the climate implications. Drilling and sampling research on the hydrate deposit in the Shenhu Area on the northern continental slope of the Southern [...] Read more.
Gas hydrates have been attracted a great deal of attention because of their potential as an energy substitute and the climate implications. Drilling and sampling research on the hydrate deposit in the Shenhu Area on the northern continental slope of the Southern China Sea was a big breakthrough for hydrate investigation in China, but as a new potential energy source, how the gas can be effectively produced from hydrate deposits has become a hot research topic. Besides depressurization heat stimulation is regarded as another important means for producing hydrate-derived gas, however, the production efficiency and economic feasibility of producing gas by heat stimulation have not been clearly understood. In this paper, a simplified model for predicting gas production from hydrate deposits by heat stimulation is developed. The model ideally neglects the effects of heat convection and pressure regime in the sediments for simplicity. We compute the heat consumption efficiency and gas energy efficiency of gas production from hydrate deposits by heat stimulation, only considering effect of hydrate dissociation due to heat input. This model is for predicting the maximum production efficiency. By studying the hydrate reservoirs and significant parameters collected from drilling and sampling researches, we calculate the production potential of the Shenhu hydrate deposits and investigate the production efficiency and feasibility. Our research shows that the maximum amount of cumulative gas production at Shenhu is ~509 m3 per meter in three years. The production potential is much lower than the industrial criterion for marine production. In our discussion the numerical simulations show that a practical potential of the gas production is merely 25 m3/m in 3 years and contribution of thermal stimulation is very small in joint-production schemes. We conclude that production cost is quite high and the economic value of producing gas from the hydrate through a vertical well is not attractive, even though the production by heat stimulation theoretically has a very high heat consumption rate and energy efficiency. Full article
(This article belongs to the Special Issue Natural Gas Hydrate)
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Open AccessArticle Investigation on the Factors Affecting the Temperature in Urban Distribution Substations and an Energy-Saving Cooling Strategy
Energies 2011, 4(2), 314-323; doi:10.3390/en4020314
Received: 8 December 2010 / Revised: 16 January 2011 / Accepted: 14 February 2011 / Published: 16 February 2011
Cited by 2 | PDF Full-text (295 KB) | HTML Full-text | XML Full-text
Abstract
The different locations of the equipment in urban distribution substations (DSSs) and the location of inlet holes and outlet holes usually result in different ventilation effect, which means the power consumed by any ventilating devices present is different. In this paper the [...] Read more.
The different locations of the equipment in urban distribution substations (DSSs) and the location of inlet holes and outlet holes usually result in different ventilation effect, which means the power consumed by any ventilating devices present is different. In this paper the temperature field distribution in an urban distribution substation with different locations of the equipment in the substation was calculated first, then factors influencing the temperature field distribution were investigated, and the influence of the different factors was analyzed. When the distance between the apparatus and walls exceeds 3 m, the change of the temperature in the DSS is very small. Therefore considering the floor area of the DSS, 3 m is the best value of the distance between the apparatus. With the change of the environment temperature or the velocity of the ventilation fans, the maximum temperature in the DSS or apparatus will change. Hence an energy saving ventilation strategy is proposed in the paper, and an intelligent cooling control system is developed, which can modify the velocity of the ventilation fans according to the environment temperature, and thus realize energy savings. Full article
Open AccessArticle Energy Chain Analysis of Passenger Car Transport
Energies 2011, 4(2), 324-351; doi:10.3390/en4020324
Received: 19 December 2010 / Revised: 10 January 2011 / Accepted: 14 February 2011 / Published: 17 February 2011
Cited by 3 | PDF Full-text (202 KB) | HTML Full-text | XML Full-text
Abstract
Transport makes up 20 percent of the World’s energy use; in OECD countries this has exceeded 30 percent. The International Energy Agency (IEA) estimates that the global energy consumption will increase by 2.1 percent annually, a growth rate that is higher than [...] Read more.
Transport makes up 20 percent of the World’s energy use; in OECD countries this has exceeded 30 percent. The International Energy Agency (IEA) estimates that the global energy consumption will increase by 2.1 percent annually, a growth rate that is higher than for any other sector. The high energy consumption means that transportation accounts for nearly 30 percent of CO2 emission in OECD countries and is also one of the main sources of regional and local air pollution. In this article, we analyze energy consumption and greenhouse gas emissions from passenger car transport using an energy chain analysis. The energy chain analysis consists of three parts: the net direct energy use, the energy required for vehicle propulsion; the gross direct chain, which includes the net direct energy consumption plus the energy required to produce it; and, finally, the indirect energy chain, which includes the energy consumption for production, maintenance and operation of infrastructure plus manufacturing of the vehicle itself. In addition to energy consumption, we also analyze emissions of greenhouse gases measured by CO2-equivalents. We look at the trade-offs between energy use and greenhouse gas emissions to see whether some drivetrains and fuels perform favourable on both indicators. Except for the case of electric cars, where hydropower is the only energy source in the Norwegian context, no single car scores favourably on both energy consumption and greenhouse gas emissions. Full article
(This article belongs to the Special Issue Energy-Friendly Transportation)
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Open AccessArticle The Health Impacts of Ethanol Blend Petrol
Energies 2011, 4(2), 352-367; doi:10.3390/en4020352
Received: 9 December 2010 / Revised: 19 December 2010 / Accepted: 16 February 2011 / Published: 21 February 2011
Cited by 4 | PDF Full-text (370 KB) | HTML Full-text | XML Full-text
Abstract
A measurement program designed to evaluate health impacts or benefits of using ethanol blend petrol examined exhaust and evaporative emissions from 21 vehicles representative of the current Australian light duty petrol (gasoline) vehicle fleet using a composite urban emissions drive cycle. The [...] Read more.
A measurement program designed to evaluate health impacts or benefits of using ethanol blend petrol examined exhaust and evaporative emissions from 21 vehicles representative of the current Australian light duty petrol (gasoline) vehicle fleet using a composite urban emissions drive cycle. The fuels used were unleaded petrol (ULP), ULP blended with either 5% ethanol (E5) or 10% ethanol (E10). The resulting data were combined with inventory data for Sydney to determine the expected fleet emissions for different uptakes of ethanol blended fuel. Fleet ethanol compatibility was estimated to be 60% for 2006, and for the air quality modelling it was assumed that in 2011 over 95% of the fleet would be ethanol compatible. Secondary organic aerosol (SOA) formation from ULP, E5 and E10 emissions was studied under controlled conditions by the use of a smog chamber. This was combined with meteorological data from Sydney for February 2004 and the emission data (both measured and inventory data) to model pollutant concentrations in Sydney’s airshed for 2006 and 2011. These concentrations were combined with the population distribution to evaluate population exposure to the pollutant. There is a health benefit to the Sydney population arising from a move from ULP to ethanol blends in spark-ignition vehicles. Potential health cost savings for Urban Australia (Sydney, Melbourne, Brisbane and Perth) are estimated to be A$39 million (in 2007 dollars) for a 50% uptake (by ethanol compatible vehicles) of E10 in 2006 and $42 million per annum for a 100% take up of E10 in 2011. Over 97% of the estimated health savings are due to reduced emissions of PM2.5 and consequent reduced impacts on mortality and morbidity (e.g., asthma, cardiovascular disease). Despite more petrol-driven vehicles predicted for 2011, the quantified health impact differential between ULP and ethanol fuelled vehicles drops from 2006 to 2011. This is because modern petrol vehicles, with lower emissions than their older counterparts, will make up a higher proportion of the fleet in the future. Hence the beneficial effects of reductions in particulate matter become less significant as the fleet as a whole produces lower emissions. Full article
(This article belongs to the Special Issue Energy-Friendly Transportation)
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Review

Jump to: Research

Open AccessReview Towards Commercial Gas Production from Hydrate Deposits
Energies 2011, 4(2), 215-238; doi:10.3390/en4020215
Received: 13 November 2010 / Revised: 24 December 2010 / Accepted: 20 January 2011 / Published: 25 January 2011
Cited by 5 | PDF Full-text (1020 KB) | HTML Full-text | XML Full-text
Abstract
Over the last decade global natural gas consumption has steadily increased since many industrialized countries are substituting natural gas for coal to generate electricity. There is also significant industrialization and economic growth of the heavily populated Asian countries of India and China. [...] Read more.
Over the last decade global natural gas consumption has steadily increased since many industrialized countries are substituting natural gas for coal to generate electricity. There is also significant industrialization and economic growth of the heavily populated Asian countries of India and China. The general consensus is that there are vast quantities of natural gas trapped in hydrate deposits in geological systems, and this has resulted in the emerging importance of hydrates as a potential energy resource and an accompanying proliferation of recent studies on the technical and economic feasibility of gas production from hydrates. There are then the associated environmental concerns. This study reviews the state of knowledge with respect to natural gas hydrates and outlines remaining challenges and knowledge gaps. Full article
(This article belongs to the Special Issue Natural Gas Hydrate)
Open AccessReview Renewable Hydrogen Carrier — Carbohydrate: Constructing the Carbon-Neutral Carbohydrate Economy
Energies 2011, 4(2), 254-275; doi:10.3390/en4020254
Received: 15 December 2010 / Revised: 8 January 2011 / Accepted: 28 January 2011 / Published: 31 January 2011
Cited by 14 | PDF Full-text (2931 KB) | HTML Full-text | XML Full-text
Abstract
The hydrogen economy presents an appealing energy future but its implementation must solve numerous problems ranging from low-cost sustainable production, high-density storage, costly infrastructure, to eliminating safety concern. The use of renewable carbohydrate as a high-density hydrogen carrier and energy source for [...] Read more.
The hydrogen economy presents an appealing energy future but its implementation must solve numerous problems ranging from low-cost sustainable production, high-density storage, costly infrastructure, to eliminating safety concern. The use of renewable carbohydrate as a high-density hydrogen carrier and energy source for hydrogen production is possible due to emerging cell-free synthetic biology technology—cell-free synthetic pathway biotransformation (SyPaB). Assembly of numerous enzymes and co-enzymes in vitro can create complicated set of biological reactions or pathways that microorganisms or catalysts cannot complete, for example, C6H10O5 (aq) + 7 H2O (l) à 12 H2 (g) + 6 CO2 (g) (PLoS One 2007, 2:e456). Thanks to 100% selectivity of enzymes, modest reaction conditions, and high-purity of generated hydrogen, carbohydrate is a promising hydrogen carrier for end users. Gravimetric density of carbohydrate is 14.8 H2 mass% if water can be recycled from proton exchange membrane fuel cells or 8.33% H2 mass% without water recycling. Renewable carbohydrate can be isolated from plant biomass or would be produced from a combination of solar electricity/hydrogen and carbon dioxide fixation mediated by high-efficiency artificial photosynthesis mediated by SyPaB. The construction of this carbon-neutral carbohydrate economy would address numerous sustainability challenges, such as electricity and hydrogen storage, CO2 fixation and long-term storage, water conservation, transportation fuel production, plus feed and food production. Full article
(This article belongs to the Special Issue Hydrogen Storage)
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