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1.
Ethanol is one of the most important renewable biofuels contributing to the reduction of negative environmental impacts generated by the worldwide utilization of fossil fuels, and the presence of metal ions in fuel ethanol has significant effect on the performance and the quality of fuel. In the present work, silica gel functionalized by poly(triethylenetetraminomethylenephosphonic acid) SG-Cl-T-P was successfully developed by heterogenous synthesis method, and the adsorption capacity of Hg(II) from fuel ethanol via SG-Cl-T-P was examined. The adsorption isotherms were fitted by the Langmuir model, the Freundlich model and the Dubinin–Radushkevich (D–R) model. Furthermore, the adsorption study was analyzed kinetically. The thermodynamic parameters, including the Gibbs free energy change (ΔG), enthalpy change (ΔH) and entropy change (ΔS) were calculated, they were −3.24 kJ mol−1 (35 °C) , 29.25 kJ mol−1, and 106.20 J K−1 mol−1, respectively. 相似文献
2.
《Biomass & bioenergy》2005,28(5):475-489
Nonrenewable energy consumption and greenhouse gas (GHG) emissions associated with ethanol (a liquid fuel) derived from corn grain produced in selected counties in Illinois, Indiana, Iowa, Michigan, Minnesota, Ohio, and Wisconsin are presented. Corn is cultivated under no-tillage practice (without plowing). The system boundaries include corn production, ethanol production, and the end use of ethanol as a fuel in a midsize passenger car. The environmental burdens in multi-output biorefinery processes (e.g., corn dry milling and wet milling) are allocated to the ethanol product and its various coproducts by the system expansion allocation approach.The nonrenewable energy requirement for producing 1 kg of ethanol is approximately 13.4–21.5 MJ (based on lower heating value), depending on corn milling technologies employed. Thus, the net energy value of ethanol is positive; the energy consumed in ethanol production is less than the energy content of the ethanol (26.8 MJ kg−1).In the GHG emissions analysis, nitrous oxide (N2O) emissions from soil and soil organic carbon levels under corn cultivation in each county are estimated by the DAYCENT model. Carbon sequestration rates range from 377 to 681 kg C ha−1 year−1 and N2O emissions from soil are 0.5–2.8 kg N ha−1 year−1 under no-till conditions. The GHG emissions assigned to 1 kg of ethanol are 260–922 g CO2 eq. under no-tillage. Using ethanol (E85) fuel in a midsize passenger vehicle can reduce GHG emissions by 41–61% km−1 driven, compared to gasoline-fueled vehicles. Using ethanol as a vehicle fuel, therefore, has the potential to reduce nonrenewable energy consumption and GHG emissions. 相似文献
3.
《Journal of power sources》2006,162(2):1073-1076
A 28-W direct borohydride–hydrogen peroxide fuel-cell stack operating at 25 °C is reported for contemporary portable applications. The fuel cell operates with the peak power-density of ca. 50 mW cm−2 at 1 V. This performance is superior to the anticipated power-density of 9 mW cm−2 for a methanol–hydrogen peroxide fuel cell. Taking the fuel efficiency of the sodium borohydride–hydrogen peroxide fuel cell as 24.5%, its specific energy is ca. 2 kWh kg−1. High power-densities can be achieved in the sodium borohydride system because of its ability to provide a high concentration of reactants to the fuel cell. 相似文献
4.
A new design concept using solar utility to supply steam and electricity for biodiesel production was proposed. A new indicator, called the renewability index, was then defined and quantified by exergy to evaluate the benefits of substituting fossil fuel utility facilities with solar utility facilities. To reduce the unfavorable environmental impacts of the biodiesel production process, a novel process on an 8000 t a?1 scale with solar utility facilities was designed and simulated using Aspen Plus. The results show that the amount of fossil fuel consumption saved per year amounts to 1275 t of standard coal and 4676 t of CO2 release is also eliminated every year. The renewability index of the biodiesel production process with solar utility facilities is 99.9%, 10.5% higher than that with fossil fuel utility facilities. The results reported in this paper indicate that the unfavorable environmental impacts of the biodiesel production process also deserve attention and the impacts can be eliminated by using solar utility facilities. 相似文献
5.
《Biomass & bioenergy》2006,30(10):826-837
In this paper, bioenergy technologies (BETs) are presented as potential carbon abatement opportunities substituting fossil fuel or traditional (less efficient) biomass energy systems. Cost of energy (produced or saved) of BETs is compared with fossil fuel and traditional biomass energy systems to estimate the incremental cost (IC). The IC of carbon abatement for each of the selected BETs (in $ kWh−1 or $ GJ−1) is estimated using the carbon emission (tC kWh−1 or tC GJ−1) reduction obtained by substituting fossil fuel and traditional biomass alternatives. The abatement costs are estimated and compared for ten combinations of BETs (with seven technology alternatives) substituting conventional technologies. The analysis indicates that out of the ten project cases six have negative ICs in the range of −37 to −688 $ tC−1 and four have positive ICs in the range of 52–162 $ tC−1 mitigation. The negative ICs indicate that the suggested alternatives are cheaper than the original technologies. Thus, results indicate that the chosen BETs are cost-effective mitigation opportunities and are currently aggressive candidates under Clean Development Mechanism. 相似文献
6.
J.C. Meerman A. Ramírez W.C. Turkenburg A.P.C. Faaij 《Renewable & Sustainable Energy Reviews》2012,16(8):6083-6102
This paper investigates the economics of integrated gasification polygeneration (IG-PG) facilities and assesses under which market conditions flexible facilities outperform static facilities. In this study, the facilities use Eucalyptus wood pellets (EP), torrefied wood pellets (TOPS) and Illinois #6 coal as feedstock to produce electricity, FT-liquids, methanol and urea. All facilities incorporate CCS. The findings show production costs from static IG-PG facilities ranging between 12 and 21 €/GJ using coal, 19–33 €/GJ using TOPS and 22–38 €/GJ using EP, which is above the average market prices. IG-PG facilities can become competitive if capital costs drop by 10%–27% for coal based facilities. Biomass based facilities will need lower biomass pellet prices or higher CO2 credit prices. Biomass becomes competitive with coal at a CO2 credit price of 50–55 €/t CO2. Variations in feedstock, CO2 credit and electricity prices can be offset by operating a feedstock flexible IG-PG facility, which can switch between coal and TOPS, thereby altering its electricity production. The additional investment is around 0.5% of the capital costs of a dedicated coal based IG-PG facility. At 30 €/t CO2, TOPS will be the preferred feedstock for 95% of the time at a feedstock price of 5.7 €/GJ. At these conditions, FT-liquids (gasoline/diesel) can be produced for 15.8 €/GJ (116 $/bbl). Historic records show price variations between 5.7 and 7.3 €/GJ for biomass pellet, 1.0–5.6 €/GJ for coal and 0–32 €/t CO2. Within these price ranges, coal is generally the preferred feedstock, but occasionally biomass is preferred. Lower biomass prices will increase the frequency of switching feedstock preference from coal to biomass, raising the desire for flexibility. Of the three investigated chemicals, an IG-PG facility producing FT-liquids benefits the most from flexibility. Our study suggests that if the uncertainty in commodity prices is high, a small additional investment can make flexible IG-PG facilities attractive. 相似文献
7.
《Biomass & bioenergy》2007,31(8):543-555
The energetic and environmental performance of production and distribution of the Brassica carinata biomass crop in Soria (Spain) is analysed using life cycle assessment (LCA) methodology in order to demonstrate the major potential that the crop has in southern Europe as a lignocellulosic fuel for use as a renewable energy source.The Life Cycle Impact Assessment (LCIA) including midpoint impact analysis that was performed shows that the use of fertilizers is the action with the highest impact in six of the 10 environmental categories considered, representing between 51% and 68% of the impact in these categories.The second most important impact is produced when the diesel is used in tractors and transport vehicles which represents between 48% and 77%. The contribution of the B. carinata cropping system to the global warming category is 12.7 g CO2 eq. MJ−1 biomass produced. Assuming a preliminary estimation of the B. carinata capacity of translocated CO2 (631 kg CO2 ha−1) from below-ground biomass into the soil, the emissions are reduced by up to 5.2 g CO2 eq. MJ−1.The production and transport are as far as a thermoelectric plant of the B. carinata biomass used as a solid fuel consumes 0.12 MJ of primary energy per 1 MJ of biomass energy stored. In comparison with other fossil fuels such as natural gas, it reduces primary energy consumption by 33.2% and greenhouse gas emission from 33.1% to 71.2% depending on whether the capacity of translocated CO2 is considered or not.The results of the analysis support the assertion that B. carinata crops are viable from an energy balance and environmental perspective for producing lignocellulosic solid fuel destined for the production of energy in southern Europe. Furthermore, the performance of the crop could be improved, thus increasing the energy and environmental benefits. 相似文献
8.
《Journal of power sources》2006,156(2):472-479
Current high temperature fuel cell (HTFC) systems used for stationary power applications (in the 200–300 kW size range) have very limited dynamic load following capability or are simply base load devices. Considering the economics of existing electric utility rate structures, there is little incentive to increase HTFC ramping capability beyond 1 kWs−1 (0.4% s−1). However, in order to ease concerns about grid instabilities from utility companies and increase market adoption, HTFC systems will have to increase their ramping abilities, and will likely have to incorporate electrical energy storage (EES). Because batteries have low power densities and limited lifetimes in highly cyclic applications, ultra capacitors may be the EES medium of choice. The current analyses show that, because ultra capacitors have a very low energy storage density, their integration with HTFC systems may not be feasible unless the fuel cell has a ramp rate approaching 10 kWs−1 (4% s−1) when using a worst-case design analysis. This requirement for fast dynamic load response characteristics can be reduced to 1 kWs−1 by utilizing high resolution demand data to properly size ultra capacitor systems and through demand management techniques that reduce load volatility. 相似文献
9.
《Biomass & bioenergy》2006,30(1):28-37
A partial equilibrium model with a break-even price approach was used to create supply curves for the energy crop reed canary grass (Phalaris arundinacea L.) (RCG) in Västerbotten County in northern Sweden. The impact of the European Union's (EU) Common Agricultural Policy (CAP) on the supply curves was studied by comparison of three different scenarios. Supply curves were created including agricultural subsidies under the current subsidy scheme, the Commission's proposal for a new subsidy scheme for implementation in 2004, and without subsidies. The geographical distribution of the potential supply was determined by the use of GIS tools. Under the current subsidy scheme, the lowest RCG farmgate fuel price would be 56 SEK MWh−1. A RCG production equalling 360 GWh could be available at that fuel price level. Under the proposed subsidy scheme of 2004, a farmgate fuel price of 99 SEK MWh−1 is required for RCG production amounting to 910 GWh. In the scenario where no subsidies are disbursed, the lowest break-even price would be 115 SEK MWh−1. In all scenarios, a biofuel feedstock production from RCG equivalent to 1.3 TWh could be available at a farmgate fuel price of 116 SEK MWh−1. The RCG supply would be concentrated in the coastal area of the county, which has the most developed infrastructure and the highest population density, thus providing a nearby market for the fuel. 相似文献
10.
The impact of anaerobic digestion (AD) technology on mitigating greenhouse gas (GHG) emissions from manure management on typical dairy, sow and pig farms in Finland was compared. Firstly, the total annual GHG emissions from the farms were calculated using IPCC guidelines for a similar slurry type manure management system. Secondly, laboratory-scale experiments were conducted to estimate methane (CH4) potentials and process parameters for semi-continuous digestion of manures. Finally, the obtained experimental data were used to evaluate the potential renewable energy production and subsequently, the possible GHG emissions that could be avoided through adoption of AD technology on the studied farms. Results showed that enteric fermentation (CH4) and manure management (CH4 and N2O) accounted for 231.3, 32.3 and 18.3 Mg of CO2 eq. yr?1 on dairy, sow and pig farms, respectively. With the existing farm data and experimental methane yields, an estimated renewable energy of 115.2, 36.3 and 79.5 MWh of heat yr?1 and 62.8, 21.8 and 47.7 MWh of electricity yr?1 could be generated in a CHP plant on these farms respectively. The total GHG emissions that could be offset on the studied dairy cow, sow and pig farms were 177, 87.7 and 125.6 Mg of CO2 eq. yr?1, respectively. The impact of AD technology on mitigating GHG emissions was mainly through replaced fossil fuel consumption followed by reduced emissions due to reduced fertilizer use and production, and from manure management. 相似文献
11.
《Journal of power sources》2006,155(2):286-290
The interfacial structure between an electrolyte membrane and an electrode catalyst layer plays an important role in determining performance of proton exchange membrane fuel cell (PEMFC) since the electrochemical reactions produce electricity occur on the interfaces that are in contact with hydrogen or oxygen gas, so-called three phase boundaries. To improve performance of the PEMFC by enlarging effective area of the interfaces, surface of Nafion® 115 membrane was roughened by Ar+ ion beam bombardment before being coated with a catalyst ink to form the electrode layer. With increasing ion dose density from 0 to 1 × 1017 ions cm−2, roughness and hydrophobicity of the membrane surface increased, which could be favored for a high-performance PEMFC. In fuel cell tests, the single cell using Nafion® membrane bombarded at an ion dose density of 1016 ions cm−2 exhibited maximum power density of 0.62 W cm−2, which was two times higher than that of the single cell employing untreated Nafion® 115 membrane, i.e. 0.30 W cm−2. 相似文献
12.
《Journal of power sources》2006,161(2):1187-1191
We recently reported on a high-power nanoporous proton-conducting membrane (NP-PCM)-based direct methanol fuel cell (DMFC) operated with triflic acid. However, accompanying the advantages of methanol as a fuel, such as low cost and ease of handling and storage, are several pronounced disadvantages: toxicity, high flammability, low boiling point (65 °C) and the strong tendency to pass through the polymer-exchange membrane (high crossover). The focus of this work is the development of a high-power direct ethylene glycol fuel cell (DEGFC) based on the NP-PCM. Ethylene glycol (EG) has a theoretical capacity 17% higher than that of methanol in terms of Ah ml−1 (4.8 and 4, respectively); this is especially important for portable electronic devices. It is also a safer (bp 198 °C) fuel for direct-oxidation fuel cell (DOFC) applications. Maximum power densities of 320 mW cm−2 (at 0.32 V) at 130 °C have been achieved in the DEGFC fed with 0.72 M ethylene glycol in 1.7 M triflic acid at 3 atm at the anode and with dry air at 3.7 atm at the cathode. The cell platinum loading was 4 mg Pt cm−2 on each electrode. The overpotentials at the cathodes and at the anodes of the DEGFC and DMFC were measured, compared and discussed. 相似文献
13.
In this paper an attempt has been made to develop a simple methodology to calculate embodied energy of the adobe house at Solar Energy Park, Indian Institute of Technology Delhi, New Delhi (28°35′N, 77°12′E) and its effect on the environment. The special feature of the adobe house is that, the whole house is constructed by using low energy intensive materials like soil, sand cow dung, etc. The embodied energy involved in construction of main structure, foundation, flooring, finishes, furniture, maintenance and electric work are 102 GJ, 214 GJ, 55 GJ, 5 GJ, 18 GJ, 59 GJ and 4 GJ, respectively. It is seen that the embodied energy involved in the maintenance of the adobe house (12% of total embodied energy) is significant. It has been found that approximately 370 GJ energy can be saved per year. The energy pay back time (EPBT) for the adobe house is 1.54 years. By using low energy intensive materials the mitigation of CO2 in the environment is reduced by an amount 101 tonnes/year. The adobe house is more environmentally friendly house in comparison to conventional buildings. 相似文献
14.
《Journal of power sources》2006,156(2):224-231
One way to alleviate the emission of air pollutants and CO2 due to burning fossil fuels is the use of fuel cells. Sputter deposition techniques are good candidates for the fabrication of electrodes used for proton exchange membrane fuel cells (PEMFCs). Input power and sputtering-gas pressure are two important parameters in a sputtering process. However, little is known about the effects of these sputtering parameters on the performance of PEMFC electrodes. Therefore, this study applied a radio frequency (RF) magnetron sputter deposition process to prepare PEMFC electrodes and investigated the effects of RF power and sputtering-gas pressure in electrode fabrication on electrode/cell performance. At a Pt loading of 0.1 mg cm−2, the electrode fabricated at 100 W, 10−3 Torr was found to exhibit the best performance mainly due to its lowest kinetic (activation) resistance (dominating the cell performance) in comparison to those fabricated by 50 and 150 W at 10−3 Torr, as well as by 10−4 and 10−2 Torr at 100 W. In the tested ranges, the control of sputtering-gas pressure seems to be more critical than that of RF power for the activation loss. In addition to electrochemically active surface area, electrode microstructure should also be responsible for electrode/cell polarization, particularly the activation polarization. 相似文献
15.
《Biomass & bioenergy》2008,32(10):978-980
Eucalypts are widely grown throughout the world for timber, essential oil, fuel, biomass and cut foliage. In experiments in University College Dublin (UCD), Eucalyptus gunnii yielded an average dry weight of 4.74 kg per plant per annum, equivalent to 12.59 t dm ha−1. The average calorific values of 17.60 MJ kg−1 (leafy material) and 17.09 MJ kg−1 (woody material) are less than the values reported for other species of Eucalyptus. 相似文献
16.
《Journal of power sources》2004,133(2):329-336
The behavior of two types of mesoporous carbons with different pore structures (i.e. unimodal and bimodal) as electrode material in an electrochemical double-layer capacitor has been analyzed. The carbon samples were prepared using mesostructured silica materials (MSM) as templating agents. The unimodal mesoporous carbon has a BET surface area of 1550 m2 g−1, and a pore volume of 1.03 cm3 g−1; the porosity is mainly made up of structural mesopores of ca. 3 nm that exhibit a narrow pore size distribution (PSD). The bimodal carbon shows larger surface area (1730 m2 g−1) and larger pore volume (1.50 cm3 g−1); the porosity is composed of two types of mesopores: structural (size around 3 nm) and complementary (size around 16 nm) mesopores. Both carbons show a disordered 3-D pore structure. Heat treatments at high temperatures (1000 °C) for long times (11 h) do not significantly change the pore structure with respect to the two synthesised carbons (800 °C). From the synthesized and heat-treated carbons, electrodes were processed as composites in which the carbons, polivinilidene fluoride (PVDF) and carbon black (CB) were the components. The effect of the heat treatment and relative CB content on specific capacitance, energy density and power density were studied. We found a specific capacitance of 200 F g−1 for low current density (1 mA cm−2) and 110 F g−1 for high current density (150 mA cm−2). Moreover, the curve of the specific capacitance versus current density shows three regimes, which are related to the three types of pore: micropores, structural mesopores and complementary mesopores. An energy density of 3 Wh kg−1 at a power density of 300 W kg−1 was obtained in some particular cases. 相似文献
17.
《Biomass & bioenergy》2005,28(1):7-14
This paper reviews the e economics of short rotation coppice willow as an energy crop in Northern Ireland. Gross margins are presented for willow production and compared with, in the particular circumstances of Northern Ireland, equivalent outputs from grain production, lowland sheep and suckler cow production. The model used indicated a gross margin of £45 ha−1 yr−1 for a 12 tDM ha−1 annual coppice crop without subsidies where the crop value was placed at £40 t−1. This was equivalent to a 7 t winter wheat crop at £70 t−1 and compared favourably with both lowland sheep and suckler cows.Currently the industry in Northern Ireland is at a very early stage of development and this imposes cost penalties on the pioneer growers. This situation is compared with the situation in Sweden where there is an established industry of 15,000 ha, where costs are significantly lower. Gross margin for the pioneer grower in Northern Ireland is about £100 ha−1 yr−1 less than for Swedish willow growers. 相似文献
18.
《Journal of power sources》2006,158(2):1313-1316
Solid oxide fuel cells (SOFCs) were characterized with methane as the fuel, both with and without an inert porous layer placed between the anode and the fuel stream. For a given set of operating conditions, SOFCs were stable without coking above a critical current density. The barrier layer decreased the critical current density, e.g. from 1.8 to <0.6 A cm−2 at 800 °C. This much-increased stable operating range is discussed in terms of mass transport through the barrier layer. 相似文献
19.
《Journal of power sources》2006,159(1):12-20
Among the possible systems investigated for energy production with low environmental impact, polymeric electrolyte membrane fuel cells (PEMFCs) are very promising as electrochemical power sources for application in portable technology and electric vehicles. For practical applications, operating FCs at temperatures above 100 °C is desired, both for hydrogen and methanol fuelled cells. When hydrogen is used as fuel, an increase of the cell temperature produces enhanced CO tolerance, faster reaction kinetics, easier water management and reduced heat exchanger requirement. The use of methanol instead of hydrogen as a fuel for vehicles has several practical benefits such as easy transport and storage, but the slow oxidation kinetics of methanol needs operating direct methanol fuel cells (DMFCs) at intermediate temperatures. For this reason, new membranes are required. Our strategy to achieve the goal of operating at temperatures above 120 °C is to develop organic/inorganic hybrid membranes. The first approach was the use of nanocomposite class I hybrids where nanocrystalline ceramic oxides were added to Nafion. Nanocomposite membranes showed enhanced characteristics, hence allowing their operation up to 130 °C when the cell was fuelled with hydrogen and up to 145 °C in DMFCs, reaching power densities of 350 mW cm−2. The second approach was to prepare Class II hybrids via the formation of covalent bonds between totally aromatic polymers and inorganic clusters. The properties of such covalent hybrids can be modulated by modifying the ratio between organic and inorganic groups and the nature of the chemical components allowing to reach high and stable conductivity values up to 6.4 × 10−2 S cm−1 at 120 °C. 相似文献
20.
《Journal of power sources》2006,160(1):353-358
The performances of the proton exchange membrane fuel cell (PEMFC), direct formic acid fuel cell (DFAFC) and direct methanol fuel cell (DMFC) with sulfonated poly(ether sulfone) membrane are reported. Pt/C was coated on the membrane directly to fabricate a MEA for PEMFC operation. A single cell test was carried out using H2/air as the fuel and oxidant. A current density of 730 mA cm−2 at 0.60 V was obtained at 70 °C. Pt–Ru (anode) and Pt (cathode) were coated on the membrane for DMFC operations. It produced 83 mW cm−2 maximum power density. The sulfonated poly(ether sulfone) membrane was also used for DFAFC operation under several different conditions. It showed good cell performances for several different kinds of polymer electrolyte fuel cell applications. 相似文献