Life cycle GHG emissions from Malaysian oil palm bioenergy development: The impact on transportation sector's energy security

Malaysia's transportation sector accounts for 41% of the country's total energy use. The country is expected to become a net oil importer by the year 2011. To encourage renewable energy development and relieve the country's emerging oil dependence, in 2006 the government mandated blending 5% palm-oil biodiesel in petroleum diesel. Malaysia produced 16 million tonnes of palm oil in 2007, mainly for food use. This paper addresses maximizing bioenergy use from oil-palm to support Malaysia's energy initiative while minimizing greenhouse-gas emissions from land-use change. When converting primary and secondary forests to oil-palm plantations between 270–530 and 120–190 g CO₂-equivalent per MJ of biodiesel produced, respectively, is released. However, converting degraded lands results in the capture of between 23 and 85 g CO₂-equivalent per MJ of biodiesel produced. Using various combinations of land types, Malaysia could meet the 5% biodiesel target with a net GHG savings of about 1.03 million tonnes (4.9% of the transportation sector's diesel emissions) when accounting for the emissions savings from the diesel fuel displaced. These findings are used to recommend policies for mitigating GHG emissions impacts from the growth of palm oil use in the transportation sector.     

Comparative assessment of a biogas run dual fuel diesel engine with rice bran oil methyl ester,pongamia oil methyl ester and palm oil methyl ester as pilot fuels

The present study tries to explore the potential of three different types of biodiesel viz. Rice bran oil methyl ester (RBME), Pongamia oil methyl ester (PME) and Palm oil methyl ester (POME) as pilot fuels for a biogas run dual fuel diesel engine designed for power generation. The results indicated that under dual fuel mode, RBME-biogas produced a maximum brake thermal efficiency of 19.97% in comparison to 18.4% and 17.4% respectively for PME-biogas and POME-biogas at 100% load. The emission study divulged that under dual fuel mode, on an average, there was an increase of CO emission by 25.74% and 32.58% for PME-biogas and POME-biogas, respectively in comparison to RBME-biogas. Furthermore, on an average, the HC emissions for PME-biogas and POME-biogas increased by 11.73% and 16.27%, respectively in comparison to RBME-biogas. On the other hand, on an average, there was a decrease in NO_X emission by 5.8% and 14%, respectively for PME-biogas and POME-biogas respectively in comparison to RBME-biogas.     

Imported palm oil for biofuels in the EU: Profitability,greenhouse gas emissions and social welfare effects

We examine the social desirability of renewable diesel production from imported palm oil in the EU when greenhouse gas emissions are taken into account. Using a partial market equilibrium model, we also study the sectoral social welfare effects of a biofuel policy consisting of a blend mandate in a small EU country (Finland), when palm oil based diesel is used to meet the mandated quota for biofuels. We develop a market equilibrium model for three cases: i) no biofuel policy, ii) biofuel policy consisting of socially optimal emission-based biofuel tax credit and iii) actual EU biofuel policy. Our results for the EU biofuel market, Southeast Asia and Finland show very little evidence that a large scale use of imported palm oil in diesel production in the EU can be justified by lower greenhouse gas emission costs. Cuts in emission costs may justify extensive production only if low or negative land-use change emissions result from oil palm cultivation and if the estimated per unit social costs of emissions are high. In contrast, the actual biofuel policies in the EU encourage the production of palm oil based diesel. Our results indicate that the sectoral social welfare effects of the actual biofuel policy in Finland may be negative and that if emissions decrease under actual biofuel policy, the emission abatement costs can be high regardless of the land use change emissions.     

Comparative life cycle assessment of hydrogen and other selected fuels

A streamlined life cycle assessment (LCA) is reported of a nuclear-based copper–chlorine (Cu–Cl) hydrogen production cycle, including estimates of fossil fuel energy use and greenhouse gas (GHG) emissions. Calculations revealed that the process requires 474 kJ of fossil fuel energy per MJ of hydrogen, which is less than for other hydrogen production processes. Moreover, GHG emissions are estimated to be 27 gCO₂e per MJ of hydrogen, which is only slightly higher than the corresponding value for wind-based hydrogen production. A sensitivity analysis demonstrated that the performance of the system could be further improved at higher yields of hydrogen. Although the system significantly outperformed fossil-based gasoline and hydrogen production pathways, the integrated nuclear and thermochemical cycle still requires significant research and development before commercialization is possible.     

Life cycle assessment of earth-abundant photocatalysts for enhanced photocatalytic hydrogen production

Hydrogen (H₂) can play a critical role in global greenhouse gas (GHG) mitigation. Photocatalytic water splitting using solar radiation is a promising H₂ technology. Titanium dioxide (TiO₂) and carbon nitride (g–C₃N₄)–based photocatalysts are the most widely used photocatalytic materials because of their activity and abundance. Several attempts have been made to improve the photocatalytic performance of these materials in terms of their activity level, life span, response to visible radiation, and stability. However, the environmental impacts of these modifications are often not included in existing studies. This research, therefore, develops a cradle-to-grave life cycle assessment (LCA) framework to evaluate and compare the GHG footprints of four alternative pathways: TiO₂ nanorods and fluorine-doped carbon nitride quantum dots embedded with TiO₂ (CNF: TNR/TiO₂), g-C₃N₄, and g-C₃N₄/BiOI composite. Unlike most studies that focus only on certain stages such as laboratory-scale photocatalytic fabrication, this study includes utility-scale cell production, assembly, operation, and end of life to give a more accurate and precise environmental performance estimation. The results show that g-C₃N₄/BiOI has the lowest GHG footprint (0.38 kg CO₂ eq per kg of H₂) and CNF: TNR/TiO₂ has the lowest energy payback time (0.4 years). In every pathway, energy use in material extraction processes makes up the largest GHG contribution, between 83% and 89%. Sensitivity and uncertainty analyses were conducted under the impact of various input parameters on the life cycle GHG emissions of hydrogen production. Photocatalytic water splitting is highly feasible for adaptation as a mainstream hydrogen production pathway in the future.     

A well to pump life cycle environmental impact assessment of some hydrogen production routes

In the present study, a comparative well to pump life cycle assessment is conducted on the hydrogen production routes of water electrolysis, biomass gasification, coal gasification, steam methane reforming, hydrogen production from ethanol and methanol. The CML 2001 impact assessment methodology is employed for assessment and comparison. Comparatively higher life cycle Carbon dioxide and Sulphur oxide emissions of 27.3 kg/kg H₂ and 50.0 g/kg H₂ respectively are determined for the water electrolysis hydrogen production route via U.S. electricity mix. In addition, the life cycle global warming potential of this route (28.6 kg CO_2eq/kg H₂) is found to be comparatively higher than other routes followed by coal gasification (23.7 kg CO_2eq/kg H₂)_. However, the ethanol based hydrogen production route is estimated to have comparatively higher life cycle emissions of nitrogen dioxide (19.6 g/kg H₂) and volatile organic compounds (10.3 g/kg H₂). Moreover, this route is determined to have a comparatively higher photochemical ozone creation potential of 0.0045 kg-ethene_eq/kg H₂ as well as eutrophication potential of 0.0043 kg PO_4eq/kg H_2. The results of this study are comparatively discussed to signify the importance of life cycle assessment in comparing the environmental sustainability of hydrogen production routes.     

Greenhouse gas emissions reduction by use of wind and solar energies for hydrogen and electricity production: Economic factors

This study addresses economic aspects of introducing renewable technologies in place of fossil fuel ones to mitigate greenhouse gas emissions. Unlike for traditional fossil fuel technologies, greenhouse gas emissions from renewable technologies are associated mainly with plant construction and the magnitudes are significantly lower. The prospects are shown to be good for producing the environmentally clean fuel hydrogen via water electrolysis driven by renewable energy sources. Nonetheless, the cost of wind- and solar-based electricity is still higher than that of electricity generated in a natural gas power plant. With present costs of wind and solar electricity, it is shown that, when electricity from renewable sources replaces electricity from natural gas, the cost of greenhouse gas emissions abatement is about four times less than if hydrogen from renewable sources replaces hydrogen produced from natural gas. When renewable-based hydrogen is used in a fuel cell vehicle instead of gasoline in a IC engine vehicle, the cost of greenhouse gas emissions reduction approaches the same value as for renewable-based electricity only if the fuel cell vehicle efficiency exceeds significantly (i.e., by about two times) that of an internal combustion vehicle. It is also shown that when 6000 wind turbines (Kenetech KVS-33) with a capacity of 350 kW and a capacity factor of 24% replace a 500-MW gas-fired power plant with an efficiency of 40%, annual greenhouse gas emissions are reduced by 2.3 megatons. The incremental additional annual cost is about $280 million (US). The results provide a useful approach to an optimal strategy for greenhouse gas emissions mitigation.     

Blending blue hydrogen with natural gas for direct consumption: Examining the effect of hydrogen concentration on transportation and well-to-combustion greenhouse gas emissions

Jurisdictions are looking into mixing hydrogen into the natural gas (NG) system to reduce greenhouse gas (GHG) emissions. Earlier studies have focused on well-to-wheel analysis of H₂ fuel cell vehicles, using high-level estimates for transportation-based emissions. There is limited research on transportation emissions of hythane, a blend of H₂ and NG used for combustion. An in-depth analysis of the pipeline transportation system was performed for hythane and includes sensitivity and uncertainty analyses. When hythane with 15% H₂ is used, transportation GHG emissions (gCO2eq/GJ) increase by 8%, combustion GHG emissions (gCO2eq/GJ) decrease by 5%, and pipeline energy capacity (GJ/hr) decreases by 11% for 50–100 million m³/d pipelines. Well-to-combustion (WTC) emissions increase by 2.0% without CCS, stay the same with a 41% CCS rate, decrease by 2.8% for the 100% CCS scenario, and decrease by 3.6% in the optimal CO₂-free scenario. While hythane contains 15% H₂ by volume only 5% of the gas’ energy comes from H₂, limiting its GHG benefit.     

Life cycle assessment of hydrogen and diesel dual-fuel class 8 heavy duty trucks

Heavy-duty trucks, in particular class 8 tractor-trailer combinations for freight, are a major contributor to the total greenhouse gas (GHG) emissions in transportation systems worldwide. Diesel fuel vastly dominates this market due to its relatively low operating cost. However, both GHG and air pollutant emissions from diesel combustion are significant, which raises doubts about the long-term sustainability of this mode of transportation. A possible short-term opportunity to address this problem is to blend diesel with hydrogen by retrofitting existing fuel injection systems and fuel storage onboard the trucks. Thus, a life cycle assessment is conducted to evaluate the overall environmental and economic impacts of implementing hydrogen and diesel dual-fuel solutions in heavy-duty trucks. The results show a significant reduction in emissions, proportionally to the diesel displacement ratio. Importantly, the use of hydrogen fuel is also shown to provide potential cost savings in this highly cost-sensitive application for hydrogen pricing below C$4/kg. Hence, waste hydrogen available at low cost can facilitate immediate emission reduction and operational cost savings for existing truck fleets, and act as an economical bridge solution for sustainable heavy-duty freight.     

Environmental and economic assessment of hydrogen compression with the metal hydride technology

A critical step in the hydrogen supply chains is the compression phase, which is often associated with high energy consumption and environmental impacts. An environmental and cost analysis of a metal hydride (MH) compressor and competing technologies (an air booster and a commercial hydrogen compressor), is performed for an application to fuel cell driven forklifts. The MH compressor shows limited environmental impacts only when a source of waste heat is available for hydrogen desorption. In these case, impacts would be similar to a generic compressor, but larger than those generated by an air booster. The equivalent economic cost is 6 € per kg of compressed hydrogen for the MH compressor, which is much higher than for the air booster, but lower than for a generic hydrogen compressor. Technical aspects to be improved for large-scale applications of MH compressors are identified.     

A rapid ultrasound-assisted production of biodiesel from a mixture of Karanj and soybean oil

Karanj oil having high free fatty acid was neutralized with a dilute alkali solution and then mixed with soybean oil in different ratios in order to reduce the free fatty acid content significantly. The mixture of the oils was then transesterified with methanol to produce fatty acid methyl ester. The transesterification was carried out using ultrasonication energy of 20 kHz in pulse mode. It was found that up to 60% Karanj oil in the blended mixture could produce good quality biodiesel that met the ASTM standards. However, the lesser content of Karanj oil in the mixture, the lesser the reaction parameters viz. alcohol to oil molar ratio, catalyst concentration, and reaction time. About 99% yield of methyl esters was obtained when the Karanj oil content in the mixture was 20% with a reaction time of 30 min, catalyst concentration 1 wt%, and a temperature of 55°C.     

Environmental life cycle feasibility assessment of hydrogen as an automotive fuel in Western Australia

A life cycle assessment has been undertaken in order to determine the environmental feasibility of hydrogen as an automotive fuel in Western Australia. The criterion for environmental feasibility has been defined as having life cycle impacts equal to or lower than those of petrol. Two hydrogen production methods have been analysed. The first is steam methane reforming (SMR), which uses natural gas (methane) as a feedstock. The second method analysed is alkaline electrolysis (AE), a mature technology that uses water as a feedstock. The life cycle emissions and impacts were assessed per kilometre of vehicle travel.     

Environmental and energy efficiency assessments of offshore hydrogen supply chains utilizing compressed gaseous hydrogen,liquefied hydrogen,liquid organic hydrogen carriers and ammonia

Hydrogen has emerged as an eco-friendly energy to replace fossil fuels. But, it is difficult to store large capacity and to transport long distance due to a low volumetric energy density. In order to overcome the disadvantages of hydrogen, hydrogen supply chains are being widely studied and reported to compare which chains are better to be deployed. However, few studies have reported in terms of an environmental impact assessment. Therefore, in this study, an environmental impact is analyzed using a life cycle assessment (LCA) for offshore hydrogen supply chains linked to offshore wind farms, as well as an energy efficiency. The hydrogen supply chains include all stages of converting hydrogen produced on an offshore platform into compressed gaseous hydrogen (CGH₂), liquefied hydrogen (LH₂), liquid organic hydrogen carriers (LOHC), or ammonia (NH₃), transporting them to an onshore plant and storing as CGH₂. In particular, in order to calculate the amount of fuel consumed in ship transportation, the weight of cargo is estimated accordingly. The results vary depending on the electrical energy sources used and the transport distance. In almost all stages except for transport, electrical energy sources have a significant impact on the environmental load. The global warming potential (GWP), which is an alternate value of greenhouse gas emissions, is in the range of 1.15–10.11 kg CO₂ eq when the national electricity grid and the offshore wind power (W + G) are used together. On the other hand, it shows a much lower value as 1.15–2.05 kg CO₂ eq when using only offshore wind power (W). As the transport distance increased, it is significantly affected in some impact categories, i.e. GWP, acidification potential (AP), and eutrophication potential (EP). The contribution of transport gradually increased, and at 10,000 km, the value was 25.32–35.42 kg CO₂ eq for W + G and 24.88–27.49 kg CO₂ eq for W. Comparing the efficiency, CGH₂ is the highest at all transport distances, followed by NH₃, LOHC, and LH₂. Considering that CGH₂ is typically unfeasible for ship transport, hydrogen transport using NH₃ can be the most attractive option. Finally, it is found that the longer the transport distance, the greater the effect on chain efficiency. Accordingly, the efficiency of the chains sharply decreases as the transport distance increases.     

Greenhouse gas emissions and energy balances of jatropha biodiesel as an alternative fuel in Tanzania

This paper evaluates GHG emissions and energy balances (i.e. net energy value (NEV), net renewable energy value (NREV) and net energy ratio (NER)) of jatropha biodiesel as an alternative fuel in Tanzania by using life cycle assessment (LCA) approach. The functional unit (FU) was defined as 1 tonne (t) of combusted jatropha biodiesel. The findings of the study prove wrong the notion that biofuels are carbon neutral, thus can mitigate climate change. A net GHG equivalent emission of about 848 kg t⁻¹ was observed. The processes which account significantly to GHG emissions are the end use of biodiesel (about 82%) followed by farming of jatropha for about 13%. Sensitivity analysis indicates that replacing diesel with biodiesel in irrigation of jatropha farms decreases the net GHG emissions by 7.7% while avoiding irrigation may reduce net GHG emissions by 12%. About 22.0 GJ of energy is consumed to produce 1 t of biodiesel. Biodiesel conversion found to be a major energy consuming process (about 64.7%) followed by jatropha farming for about 30.4% of total energy. The NEV is 19.2 GJ t⁻¹, indicating significant energy gain of jatropha biodiesel. The NREV is 23.1 GJ t⁻¹ while NER is 2.3; the two values indicate that large amount of fossil energy is used to produce biodiesel. The results of the study are meant to inform stakeholders and policy makers in the bioenergy sector.     

Analysis of performance and emission patterns of novel biofuel feedstock neat coconut fatty acid distillate (CFAD) fuelled single-cylinder diesel engine

This study examined the potential of using coconut fatty acid distillate (CFAD), a by-product of the processing of edible oils, as a diesel engine fuel. The major novelty of this study is to assess the CFAD as a viable feedstock of biodiesel to address global energy demands. CFAD has not been specifically researched as a feedstock for producing biodiesel or as a fuel for diesel engines, despite the fact that numerous studies on the production and performance of biodiesel have already been conducted. Fourier transform infrared (FTIR) spectroscopy, gas chromatography (GC), and FTIR were used to analyze the fuel. According to the results of the GC test, CFAD oil contains 91.53% saturated fatty acids, compared with only 8.47% unsaturated fatty acids. High saturation values can be seen in myristic acid (16.92%) and lactic acid (45.33%). Longer hydrocarbon chain lengths indicate higher energy density and boiling point, which also indicate lesser volatility. At a frequency of 1708.54 cm⁻¹, C─H stretching vibrations have been identified through FTIR investigation. The vibrations of C─C stretching at 1465.47 cm⁻¹ indicate the presence of alkenes/fingerprint phase. The blends used for this investigation include 90% diesel with 10% CFAD (CFAD10), 80% diesel with 20% CFAD (CFAD20), 70% diesel with 30% CFAD (CFAD30), and 100% CFAD. The CFAD 10%, 20%, and 30% blends as well as the CFAD100 had brake thermal efficiency values of 27.24%, 26.23%, 24.88%, and 21.52%, correspondingly, at full load. The average increment in brake-specific energy consumption for CFAD10, CFAD20, CFAD30, and CFAD100 over diesel fuel was 8.23%, 10.88%, 13.77%, and 25.90%, respectively. The behavior of CFAD exhibits reduced cylinder pressure because of the large content of moderate saturated fatty acids in this substance. The net heat release rate (NHRR) and cylinder pressure have a similar relationship in that the NHRR increases with increasing diesel volume. In comparison to diesel, the CO emissions from the CFAD20, CFAD30, and CFAD100 blends increased by 10.79%, 16.66%, and 35.89% at maximum load, respectively. It has been reported that NO_x is reduced more significantly the more CFAD is present in the mixture. The blend CFAD10 had the least amount of smoke. The high viscosity of the CFAD and its blends influences the fuel droplets range and the development of spray in the cylinder, which results in delayed combustion and higher unburned hydrocarbon emissions.     

Life cycle assessment study of solar PV systems: An example of a 2.7 kWp distributed solar PV system in Singapore

In life cycle assessment (LCA) of solar PV systems, energy pay back time (EPBT) is the commonly used indicator to justify its primary energy use. However, EPBT is a function of competing energy sources with which electricity from solar PV is compared, and amount of electricity generated from the solar PV system which varies with local irradiation and ambient conditions. Therefore, it is more appropriate to use site-specific EPBT for major decision-making in power generation planning. LCA and life cycle cost analysis are performed for a distributed 2.7 kW_p grid-connected mono-crystalline solar PV system operating in Singapore. This paper presents various EPBT analyses of the solar PV system with reference to a fuel oil-fired steam turbine and their greenhouse gas (GHG) emissions and costs are also compared. The study reveals that GHG emission from electricity generation from the solar PV system is less than one-fourth that from an oil-fired steam turbine plant and one-half that from a gas-fired combined cycle plant. However, the cost of electricity is about five to seven times higher than that from the oil or gas fired power plant. The environmental uncertainties of the solar PV system are also critically reviewed and presented.     

氨基磺酸非均相催化菜籽油及废油脂制备生物柴油

采用正交试验和单因素试验的方法研究了氨基磺酸催化菜籽油及废油脂与甲醇的酯交换过程,考察了醇油物质的量比、催化剂用量、反应温度和反应时间对反应收率的影响。结果表明:菜籽油酯交换的最佳反应条件为醇油物质的量比6∶1,氨基磺酸用量为原料油质量的1.0%,反应温度60℃,反应时间20 min,此工艺条件下,脂肪酸甲酯的收率达到95.6%;废油脂酯交换的最佳反应条件为醇油物质的量比8∶1,氨基磺酸用量为原料油质量的1.0%、反应温度65℃,反应时间30 min,此工艺条件下,脂肪酸甲酯的收率达到87.5%。利用红外光谱表征了菜籽油和生物柴油的结构,气相色谱分析了生物柴油的组成。     

Life cycle assessment of hydrogen production from biomass gasification. Evaluation of different Spanish feedstocks

Gasification of biomass can be used for obtaining hydrogen reducing the total greenhouse gases emissions due the fixation of CO₂ during photosynthetic processes. The kind of raw materials is an important variable since has a great influence on the energy balance and environmental impacts. Wastes from forestry are considered as the most appropriate raw materials since they do not compete for land. The aim of this work is to determine the environmental feasibility of four Spanish lignocellulosic wastes (vine and almond pruning and forest waste coming from pine and eucalyptus plantation) for the production of hydrogen through gasification. LCA methodology was applied using global warming potential, acidification, eutrophication and the gross energy necessary for the production of 1 Nm³ of hydrogen as impact categories. As expected, the use of biomass instead of natural gas leads to the reduction of CO₂ emissions. Regarding to the different feedstocks, biomass coming from forestry is more environmental-friendly since does not need cropping procedures. Finally, the distribution of environmental charges between pruning wastes and fruits (grape and almond) and the use of obtained by-products have a great influence, reducing the environmental impacts.     

Biodiesel production from two stage esterification of simarouba glauca seed oil and its characterization

In this work, biodiesel was produced from simarouba glauca seed oil through a two-stage acid-alkali esterification process. Concentrated sulphuric acid and sodium hydroxide were used as catalysts for acid and alkaline catalyzed esterification process, respectively. The free fatty acid content of the oil was reduced from 3.5 to 0.2%. The major properties of oil and its biodiesel were studied. Upon two-stage esterification, kinematic viscosity was reduced from 45.75 to 3.1 cSt and the acid value was reduced from 6.9348 to 0.4 mg KOH/g. The measured physio-chemical properties are within the limits set by ASTM biodiesel standards.     

Production of biodiesel from Citrus limetta seed oil

The production of biodiesel from edible oils may cause negative impact to any country through food crisis which may lead to economic imbalance. Hence, this study focuses on viability of extracting the oil from the Citrus limetta seeds for biodiesel production for the first time. Composition of C. limetta oil was determined by gas chromatography. C. limetta biodiesel was produced by simple transesterification process, and further physiochemical properties were analyzed as per the standards. This study also describes the suitable characterization and optimization parameters used for conversion of C. limetta seed oil into biodiesel.