Greenhouse impact assessment of peat-based Fischer–Tropsch diesel life-cycle

New raw materials for transportation fuels need to be introduced, in order to fight against climate change and also to cope with increasing risks of availability and price of oil. Peat has been recognised suitable raw material option for diesel produced by gasification and Fischer–Tropsch (FT) synthesis. The energy content of Finnish peat reserves is remarkable. In this study, the greenhouse impact of peat-based FT diesel production and utilisation in Finland was assessed from the life-cycle point of view. In 100 year's time horizon the greenhouse impact of peat-based FT diesel is likely larger than the impact of fossil diesel. The impact can somewhat be lowered by producing peat from the agricultural peatland (strong greenhouse gas emissions from the decaying peatlayer are avoided) with new peat production technique, and utilising the produced biomass from the after-treatment area for diesel also. If diesel production is integrated with pulp and paper mill to achieve energy efficiency benefits and if the electricity demand can be covered by zero emission electricity, the greenhouse impact of peat-based FT diesel reduces to the level of fossil diesel when agricultural peatland is used, and is somewhat higher when forestry-drained peatland is used as raw material source.     

Conversion of fossil and biomass fuels to electric power and transportation fuels by high efficiency integrated plasma fuel cell (IPFC) energy cycle

The IPFC is a high efficiency energy cycle, which converts fossil and biomass fuel to electricity and co-product hydrogen and liquid transportation fuels (gasoline and diesel). The cycle consists of two basic units, a hydrogen plasma black reactor (HPBR) which converts the carbonaceous fuel feedstock to elemental carbon and hydrogen and CO gas. The carbon is used as fuel in a direct carbon fuel cell (DCFC), which generates electricity, a small part of which is used to power the plasma reactor. The gases are cleaned and water gas shifted for either hydrogen or syngas formation. The hydrogen is separated for production or the syngas is catalytically converted in a Fischer–Tropsch (F–T) reactor to gasoline and/or diesel fuel. Based on the demonstrated efficiencies of each of the component reactors, the overall IPFC thermal efficiency for electricity and hydrogen or transportation fuel is estimated to vary from 70 to 90% depending on the feedstock and the co-product gas or liquid fuel produced. The CO₂ emissions are proportionately reduced and are in concentrated streams directly ready for sequestration. Preliminary cost estimates indicate that IPFC is highly competitive with respect to conventional integrated combined cycle plants (NGCC and IGCC) for production of electricity and hydrogen and transportation fuels.     

Sustainable rural bioenergy production for developing countries

Bioenergy is a renewable energy source made from biomass, which are organic materials such as plants and animals. Until enough biomass resources to ensure energy demand in the world is available, the bioenergy obtained from biomass, there may be used for heat, electrical and transport. Main biomass thermo-chemical conversion technologies are pyrolysis, gasification, and liquefaction. Biomass can be burned to produce heat and electricity, changed to gas-like fuels such as methane, hydrogen, and carbon monoxide, or changed to a liquid fuel. Modern biomass can be used for the generation of electricity and heat using modern conversion technologies. Technological advances have made modern biomass cogeneration plants cleaner, more efficient, and, under certain conditions, cost-effective as compared to public utility grids and fossil-fuel boilers or generators. Biomass can be converted to liquid biofuels: bioethanol and biodiesel. Two biofuels are becoming more and more attractive and competitive as complementary to or substitutions for petroleum basic products, due to their economic and environmental benefits.     

Biorefineries: Current activities and future developments

This paper reviews the current refuel valorization facilities as well as the future importance of biorefineries. A biorefinery is a facility that integrates biomass conversion processes and equipment to produce fuels, power, and chemicals from biomass. Biorefineries combine the necessary technologies of the biorenewable raw materials with those of chemical intermediates and final products. Char production by pyrolysis, bio-oil production by pyrolysis, gaseous fuels from biomass, Fischer–Tropsch liquids from biomass, hydrothermal liquefaction of biomass, supercritical liquefaction, and biochemical processes of biomass are studied and concluded in this review. Upgraded bio-oil from biomass pyrolysis can be used in vehicle engines as fuel.     

我国生物质能源现代化应用前景展望(二)——生物质制备液体燃料的转化途径

利用可再生生物质资源转化制备液体燃料已成为全球关注的热点。常见的生物质能源原料主要有草本植物、木本植物、微藻和脂肪类生物质资源,丰富的生物质资源为生物质液体燃料的生产提供了广泛的原料来源,也为生物质能源的多样性发展提供了坚实的物质基础。不同的生物质原料种类和转化方式可生产出性能各异的多种液体燃料,主要包括醇类燃料(乙醇、丁醇等)、烃类燃料和生物柴油等,由此构建出生物质转化制备液体燃料的转化途径网络。醇类燃料的生物质转化途径主要包括生物质直接发酵、生物质合成气发酵、生物质合成气化学合成等;烃类燃料的生物质转化途径主要有生物质液化加氢、微藻热化学途径、生物质合成气费托合成、生物质发酵脂肪酸加氢及油脂类加氢途径等;生物柴油的转化途径主要有油脂酯交换和微藻萃取酯交换。在这些液体燃料的转化途径中,只有生物质发酵制乙醇途径和油脂酯交换途径基本实现了商业化应用,其他大部分转化途径仍处于开发阶段。     

Assessing wood-based synthetic natural gas technologies using the SWISS-MARKAL model

In future, new biomass technologies can gain significant importance in the Swiss energy sector. Therefore, this paper assesses the economic conditions under which new biomass technologies become competitive. The focus of this assessment is on the production of synthetic natural gas (bio-SNG) from wood in a methanation plant. The assessment is conducted with the cost-optimization model SWISS-MARKAL (MARKet ALlocation). SWISS-MARKAL projects future technology investments and provides an integrated analysis of primary, secondary, final and end-use energy in Switzerland. In addition to a reference scenario, the effects of increasing oil and gas prices, the effects of allocating subsidies to the methanation plant and the effects of competition between the methanation plant and a biomass-based Fischer–Tropsch (FT) synthesis are evaluated. Moreover, a sensitivity analysis is performed by varying investment costs of the methanation plant. The results are in favour of bio-SNG in the transportation sector where the synergetic use of bio-SNG and natural gas reduces the dependence on oil imports and the level of CO₂ emissions.     

GC-MS determination of low hydrocarbon species (C1–C6) from a diesel partial oxidation reformer

The partial oxidation (POx) reforming of Ultra Low Sulphur-Diesel (ULSD), rapeseed methyl ester (RME) - biodiesel and Fischer–Tropsch synthetic diesel fuels (SD) were studied by using a fixed-bed reactor. The ease of reforming the three fuels was first examined at different O/C feed ratios at constant gas hourly space velocity (GHSV) of 35 k h⁻¹ over a prototype monolith catalyst (1%Rh/CeO₂–ZrO₂). The hydrocarbon species (C₁–C₆) produced in the reformer were analyzed using direct gas injection gas chromatography mass spectrometry (GC-MS). Under the same O/C ratios for 35 k h⁻¹ the fuels conversion and process efficiency was dependent on the fuel type, and followed the general trend: SD > biodiesel > ULSD. The GC-MS analysis shows that both, biodiesel and ULSD diesel produced significantly higher amounts of alkenes compared to SD fuel. Fuel with relatively high aromatics content such diesel can be efficiently reformed to syngas over the catalyst used in this study but the reformer operating range (e.g. O/C ratio and space velocity) is limited compared to paraffinic fuels such as FT-SD. At increased GHSV of 45 k h⁻¹ and O/C = 1.75, the diesel fuel conversion efficiency to syngas (H₂ and CO) was improved significantly and the formation of intermediate species such as methane, ethylene, and propylene was reduced considerably as a result of the increased peak reaction temperatures. The reduced HC species and increased H₂ concentration in the reactor product gas from the reforming of FT-SD fuel can provide significant advantages to the IC engine applications.     

Comparison of renewable fuels based on their land use using energy densities

In this article energy densities of selected renewable fuels are determined. Energy density is defined here as the annual energy production per hectare, taking energy inputs into account. Using 5 scenarios, consisting of 1 set focusing on technical differences and 1 set focusing on geographical variations, the range of energy densities currently obtained in Europe was determined for the following fuels: biodiesel from rapeseed; bioethanol from sugar beet; electricity from wood, wind and solar PV.The energy densities of the fuels produced from biomass were calculated by determining the energy contained in the energy carrier produced from the crop annually produced on 1 ha, from which the energy inputs for crop cultivation and conversion were subtracted. For wind and solar electricity, the energy density calculation was based on the energy production per turbine or cell and the number of turbines or cells per hectare after which the manufacturing energy was subtracted.Comparing the results shows that, for the average energy density scenarios, the ratio between the energy densities for wind, solar, and biomass is approximately 100:42:1, with wind electricity also having the highest energy output/input ratio.A case study was done in which the energy density was used to calculate the distance a vehicle can cover using the energy carrier annually produced per hectare. This was done for 3 regions, in Mid-Sweden, North-Netherlands, and South-East Spain. The results of the case show that wind electricity results in the largest distance covered, except in Spain, where solar electricity is the most favourable option.     

Modern bioenergy from agricultural and forestry residues in Cameroon: Potential,challenges and the way forward

Environmentally benign modern bioenergy is widely acknowledged as a potential substitute for fossil fuels to offset the human dependence on fossil fuels for energy. We have profiled Cameroon, a country where modern bioenergy remains largely untapped due to a lack of availability of biomass data and gaps in existing policies. This study assessed the biomass resource potential in Cameroon from sustainably extracted agricultural and forest residues. We estimated that environmentally benign residues amount to 1.11 million bone dry tons per year. This has the potential to yield 0.12–0.32 billion liters of ethanol annually to displace 18–48% of the national consumption of gasoline. Alternatively, the residues could provide 0.08–0.22 billion liters of biomass to Fischer Tropsch diesel annually to offset 17–45% of diesel fuel use. For the generation of bioelectricity, the residues could supply 0.76–2.02 TW h, which is the equivalent of 15–38% of Cameroon's current electricity consumption. This could help spread electricity throughout the country, especially in farming communities where the residues are plentiful. The residues could, however, offset only 3% of the national consumption of traditional biomass (woodfuel and charcoal). Policy recommendations that promote the wider uptake of modern bioenergy applications from residues are provided.     

Review of NOx reduction technologies in CI engines fuelled with oxygenated biomass fuels

Oxygenated fuels like biodiesel and alcohols have the potential to provide a reliable and a cost effective alternative to India's increasing future energy demands. They have a prospective future since they are renewable and can be produced easily in India's rural areas. Due to rapid industrialization and the increased number of vehicles on the road, the energy needs of the country are increasing rapidly. Oxygenated fuels can substantially replace the large demand for diesel to generate power for the industries and to fuel diesel engines of the vehicles. In spite of the many advantages of using them, most of the researchers have reported higher NO_x emissions, which is a deterrent to the market expansion of these fuels. The present program aims to review the NO_x emissions from the CI engines fuelled with oxygenated fuels. To meet the stringent emission norms, the various NO_x reduction technologies like use of additives, retarded fuel injection timing, biodiesel emulsion with water, and exhaust gas recirculation are reviewed. The results of the most effective and low cost technique of EGR in DI diesel engine fuelled with biodiesel–diesel blends and tri-compound oxygenated diesel fuel blends (ethanol–biodiesel–diesel fuel blends and methanol–biodiesel–diesel fuel blends) are presented.     

Biomass energy perspective in Pakistan based on chemical looping gasification for hydrogen production and power generation

Biomass has appeared as one of the most encouraging renewable energy sources for the replacement of fossil fuels. An extensive study about the prospective of biomass to produce renewable energy in Pakistan has been exhibited in this article, which takes into account Pakistan's current energy and future potential. A new generation of transformative energy conversion technologies has been developed, including chemical looping. This technique has the potential to control air pollution and clean fuel production, all of which have been major global challenges of this century. Through recent research, the study aims to aid in understanding of biomass-based chemical looping gasification and its development. CHP and CCHP systems are developed processes that produce power, heat, and cooling. Systems using fuel cells have greater efficiency, between 60 and 70%. Additionally, the SOFC-based power generating techniques are associated with the best electrical efficiency (67%).     

Biomass: A modern and environmentally acceptable fuel

The energy of the sun and carbon dioxide from the atmosphere are captured by plants during photosynthesis. Plant biomass can be used to absorb carbon dioxide emissions from fossil fuels, or it can be converted into modern energy carriers such as electricity, and liquid and gaseous fuels. Biomass supplies 13% of the world's energy consumption (55 EJ, 1990), and in some developing countries it accounts for over 90% of energy use. There is considerable potential for the modernisation of biomass fuels through improved utilisation of existing resources, higher plant productivities and efficient conversion processes using advanced technologies. The interest in bioenergy is increasing rapidly, and it is widely considered as one of the main renewable energy resources of the future due to its large potential, economic viability, and various social and environmental benefits. In particular, biomass energy is among the most favourable options for reducing carbon dioxide emissions. Most of the perceived problems such as land availability, environmental impact, economic viability, and efficiency can be overcome with good management. The constraints to achieving environmentally-acceptable biomass production are not insurmountable, but should rather be seen as scientific and entrepreneurial opportunities which will yield numerous advantages at local, national and international levels in the long term.     

A new future for carbohydrate fuel cells

The development of renewable energy sources to reduce our dependence on limiting fossil fuel reserves continues to be a critical research initiative. Utilizing the abundant high energy content of carbohydrates contained in biomass (cellulose and hemicellulose) must be considered to be an important contribution to our overall energy budget. Carbohydrate-derived furan-based liquid fuels and especially ethanol are becoming important added components forming gasoline blends to lower overall fossil fuel use. Alternate renewable energy processes that more efficiently use the carbohydrate energy content are desirable and would lower the overall carbohydrate input requirement for energy production. Recently, new catalysts have shown the feasibility of efficiently transporting the 24 electrons in glucose to fuel cell electrodes making possible the direct conversion of the stored energy in carbohydrates into electricity with the benign formation of carbonate and water as products. The conversion of glycerol, a byproduct of biodiesel production, into three-carbon carbohydrates provides another opportunity to produce electricity from an abundant carbohydrate source. New developments in catalyst systems promise to make carbohydrate fuel cells an important part of future energy strategies.     

Negative carbon intensity of renewable energy technologies involving biomass or carbon dioxide as inputs

Conventional fossil fuel-based energy technologies can achieve efficiency in energy conversion but they are usually completely inefficient in carbon conversion because they generate significant CO₂ emissions to the atmosphere per unit energy converted. In contrast, some renewable energy technologies characterized by negative carbon intensity can simultaneously achieve efficiency in the conversion of energy and in the conversion of carbon. These carbon negative renewable energy technologies can generate useful energy and remove CO₂ from the atmosphere, either by direct capture and recycling of atmospheric CO₂ or indirectly, by involving biofuels. Interestingly, the deployment of carbon negative renewable energy technologies can offset carbon emissions from conventional fossil fuel-based energy technologies and thus reduce the overall carbon intensity of energy systems.The current review analyzes two groups of renewable energy technologies involving biomass or CO₂ as inputs. The discussions focus on useful techniques which enable to achieve negative carbon intensity of energy while being technologically promising in near-term as well as cost-effective. These analyzes include advanced carbon sequestration concepts such as soil carbon sequestration and CO₂ recycling to useful C-rich products such as fuels and fertilizers. The 'drop-in' of renewable energy is achieved by allowing bioenergy and renewable energies in the form of renewable electricity, renewable thermal energy, solar energy, renewable hydrogen, etc. The carbon negative renewable energy technologies are analyzed and perspectives and constraints of each technology are expounded.     

Modelling the promotion of biomass use: A case study of Thailand

This study develops a computable general equilibrium model of the Thailand economy which features several energy-specific enhancements. The model is used to simulate a number of potential policies to achieve the Thai government’s biomass-generated electricity targets contained in its 15-year renewable energy development plan. Examples of simulations conducted with the model include increasing biomass-based electricity purchased from small and very small power producers and increasing other agricultural residue use in electricity generation. The results indicate that implementation of all of the biomass-based electricity promotion policies is likely to achieve the short-run target and reduce somewhat the importation of fuels. However, the policy causes a huge increase in prices of biomass. The sugarcane-based sectors are big winners, while the cassava-based sectors are big losers. The losses can, however, be partly mitigated by promoting other agricultural residue use in electricity generation.     

Pathways to a more sustainable production of energy: sustainable hydrogen—a research objective for Shell

Towards a sustainable energy supply is a clear direction for exploratory research in Shell. Examples of energy carriers, which should be delivered to the envisaged sustainable energy markets, are bio-fuels, produced from biomass residues, and hydrogen (or electricity), produced from renewable sources. In contrast to the readily available ancient sunlight stored in fossil fuels, the harvesting of incident sunlight will be intermittent, efficient electricity and hydrogen storage technologies need to be developed. Research to develop those energy chains is going on, but the actual transformation from current fossil fuel based to sustainable energy markets will take a considerable time. In the meantime the fossil fuel based energy markets have to be transformed to mitigate the impact of the use of fossil fuels. Some elements in this transformation are fuels for ultra-clean combustion (hydrocarbons and oxygenates), hydrogen from fossil fuels, fuels for processors for fuel cells, carbon sequestration.     

The development of bioenergy technology in China

Among renewable energy resources, bioenergy is one of the fastest growth energy alternatives with tremendous potential in China. The thermal, physical, and biological processes of conversion of biomass yield a number of products and can be obtained as gases, liquids, solid fuels, and electricity as well as a variety of chemicals. Various bioenergy technologies that have been developed are at the fundamental research, demonstration, and commercialization stages. This review concentrates on the processes that are attracting the most attention in China.     

Comprehensive chemical kinetic modeling of the oxidation of 2-methylalkanes from C7 to C20

Conventional petroleum jet and diesel fuels, as well as alternative Fischer–Tropsch (FT) fuels and hydrotreated renewable jet (HRJ) fuels, contain high molecular weight lightly branched alkanes (i.e., methylalkanes) and straight chain alkanes (n-alkanes). Improving the combustion of these fuels in practical applications requires a fundamental understanding of large hydrocarbon combustion chemistry. This research project presents a detailed and reduced chemical kinetic mechanism for singly methylated iso-alkanes (i.e., 2-methylalkanes) ranging from C₇ to C₂₀. The mechanism also includes an updated version of our previously published C₈–C₁₆n-alkanes model. The complete detailed mechanism contains approximately 7200 species 31400 reactions. The proposed model is validated against new experimental data from a variety of fundamental combustion devices including premixed and non-premixed flames, perfectly stirred reactors and shock tubes. This new model is used to show how the presence of a methyl branch affects important combustion properties such as laminar flame propagation, ignition, and species formation.     

Hydroprocessed vegetable oil as a fuel for transportation sector: A review

Renewable fuels produced from vegetable oils are an attractive alternative to fossil-based fuel. Different type of fuels can be derived from these triglycerides. One of them is biodiesel which is a mono alkyl ester of the vegetable oil. The biodiesel is produced by transesterification of the oil with an alcohol in the presence of a catalyst. Another kind of fuel (which is similar to petroleum-derived diesel) can be produced from the vegetable oil using hydroprocessing technique. This method uses elevated temperature and pressure along with a catalyst to produce a fuel termed as ‘renewable diesel’. The fuel produced has properties that are beneficial for the engine as well as the environment. It has high cetane number, low density, excellent cold flow properties and same materials can be used as are used for engine running on petrodiesel. It can effectively reduce NOx, PM, HC, CO emissions and unregulated emissions as well as greenhouse gases as compared to diesel. The fuel is also beneficial for the after-treatment systems. Trials in the field have shown that the volumetric fuel consumption of renewable diesel is higher than petrodiesel and nearly proportional to the volumetric heating value. The present review focuses on the hydroprocessing technique used for the renewable diesel production and the effect of different parameters such as catalyst, reaction temperature, hydrogen pressure, liquid hourly space velocity (LHSV) and H₂/oil ratio on oil conversion, diesel selectivity, and isomerization. The review also summarizes the effect; renewable diesel has on combustion, performance, and emission characteristics of a compression ignition engine.     

Combined production of second-generation biofuels and electricity from sugarcane residues

This paper describes a preliminary analysis of two technological routes (based on hydrolysis and on gasification + Fischer–Tropsch conversion process) of biofuels production from cellulosic materials. In this paper it was considered the integration of the two alternative routes to a conventional distillery of ethanol production based on fermentation of sugarcane juice. Sugarcane bagasse is the biomass considered as input in both second-generation routes. Results show that the integration of gasification + FT process to a conventional distillery is slightly more efficient (from an energetic point of view) and also offers the advantage of products diversification (ethanol from the conventional plant, plus diesel, gasoline and more surplus electricity regarding the hydrolysis route). Considering typical Brazilian conditions, at this stage it is not possible to foresee any significant advantage of any of the alternatives, but potentially the gasification route would have an advantage regarding avoided GHG emissions depending on the emission factor of the electric sector in which cogeneration units will be installed.