Improved oxidative stability of biodiesel via alternative processing methods using cottonseed oil

Biodiesel from waste cooking oil (WCO) requires antioxidants to meet oxidation stability specifications set forth in ASTM D6751 or EN 14214. In contrast, unrefined cottonseed oil (CSO), containing tocopherols and gossypol, produces biodiesel of higher oxidation stability. However, only a portion of these CSO endogenous antioxidants are suspected to be retained in biodiesel. Because the economics of biodiesel manufacturing rely upon inexpensive sources of triglycerides, emphasis was placed on developing improved alternative processing methods where WCO was the main source of methyl esters (WCOME) and CSO was used as a supplemental source of triglycerides and antioxidants in a 4:1 ratio. This study compared four processing methods for their ability to produce biodiesel of increased oxidative stability prepared from a 4:1 ratio of WCO:CSO. Two novel processing methods developed for this study utilise solvent properties of fatty acid methyl esters and glycerol to avoid additional chemical inventory for biodiesel processors. This study concludes that the two new processing methods resulted in biodiesel that had statistically significant improved oxidation stability when compared to two common industrial processing methods. Another significant finding is that high-shear homogenisation during transesterification reduced reaction time from the published one hour to 16 minutes.     

Synthesis of biodiesel from chicken’s skin waste by homogeneous transesterification

ABSTRACT

Poultry skin waste is considered to be a promising source of biodiesel. However, this source presents an environmental threat as it is being discharged into landfills without any treatment. We studied the feasibility of biodiesel production from poultry skin waste. Two-step extraction of lipids from chicken’s skin was developed and gave 97.5% yield using the optimum time and temperature. Esterification was then optimised to remove free fatty acids (FFA) where the ideal parameters were 65 °C during 30min with a molar ratio of methanol to oil of (1:3) and 1% of H₂SO₄. The third step was the transesterification which was performed using 60 °C and 300–600 rpm agitation for 1 h, with 1% basic catalyst and 1:3 (molar ratio) of methanol to oil. The biodiesel (FAME), was characterised using gas chromatography coupled with mass spectrometry (GC-MS) followed by chemical and physical analyses such as iodine number, acid number, flash point and cetane number. The total conversion was obtained using above conditions and most of the studied proprieties of produced biodiesel meet the EN14214 standard. This is an extremely encouraging result, offering a good source of biodiesel by valuing poultry skin waste.     

Recalculating GHG emissions saving of palm oil biodiesel

In 2010, the Renewable Energy Directive (RED) came into force in the EU and establishes a framework for achieving legally binding greenhouse gas (GHG) emission reductions. Only sustainable biofuels can be counted towards Member State targets. The aim of this paper is to calculate realistic and transparent scenario-based CO₂-emission values for the GHG emissions savings of palm oil fuel compared with fossil fuel. Using the calculation scheme proposed by the RED, we derive a more realistic overall GHG emissions saving value for palm oil diesel by using current input and output data of biofuel production (e.g. in South-East Asia). We calculate different scenarios in which reliable data on the production conditions (and the regarding emission values during the production chain) of palm oil diesel are used. Our results indicate values for the GHG emissions savings potential of palm oil biodiesel not only above the 19 % default and 36 % typical value published in RED but also above the 35 % sustainable threshold. Our findings conclude the more accurate GHG emissions saving value for palm oil feedstock for electricity generation to be 52 %, and for transportation biodiesel between 38.5 and 41 %, depending on the fossil fuel comparator. Our results confirm the findings by other studies and challenge the official typical and default values published in RED. As a result, the reliability of the Directive to support the EU’s low-carbon ambitions is being undermined, exposing the EU and commission to charges of trade discrimination and limiting the ability of Member States to achieve their legally binding GHG emission reductions.     

Combustion and emission characteristics of a direct injection CI engine when operated on Marotti oil methyl ester and blends of Marotti oil methyl ester and diesel

This paper presents a feasibility study of Marotti oil biodiesel as an alternative to diesel fuel for a compression ignition engine. Marotti oil is inedible and available mainly in the state of Kerala. The oil is extracted from Marotti seeds. However, the high viscosity, poor volatility and cold flow characteristics of many vegetable oils in general, and Marotti oil in particular, can cause problems such as injector coking, severe engine deposits, filter gumming, piston ring sticking and thickening of lubrication from long-term use in diesel engines. These problems can be eliminated or minimised by transesterification of the vegetable oils to form monoesters. Although transesterification improves the fuel properties of vegetable oil, the viscosity and volatility of biodiesel are still worse than for petroleum diesel fuel. Subsequently, Marotti oil was converted into its methyl ester by the process of transesterification. The methyl ester was blended with diesel in various proportions to obtain different blends of Marotti oil with diesel. The performance, emission and combustion characteristics of Marotti methyl ester and its blends with diesel were studied and the results were compared with the base line data generated for diesel operation. Experiments were conducted using an injection timing of 23° before top dead centre (BTDC) and an injection pressure of 205 bar at various power outputs and at a constant rated speed of 1500 rpm. The engine manufacturer specifies an injection timing of 23° BTDC and injection pressure of 205 bar for the standard diesel fuel operation. The heat release rates, maximum rate of pressure rise, ignition delay and combustion duration for these fuel combinations were obtained.

From the results obtained, it was observed that the biodiesel produced from Marotti oil and its blends with diesel have slightly reduced brake thermal efficiency and increased smoke, hydrocarbon, carbon monoxide and reduced NO _x emissions compared with diesel-only operation. The investigation showed that the B20 biodiesel blend of Marotti oil with diesel produced better performance in terms of higher brake thermal efficiency, lower specific fuel consumption and comparatively lower emissions compared to the other blend ratios considered.     

Life cycle inventory of the commercial production of compost from oil palm biomass: a case study

This paper compared the life cycle inventory (LCI) obtained from three commercial oil palm biomass composting projects in Malaysia which use the open windrow composting system. The LCI was obtained and calculated based on the functional unit of 1 t of compost produced. The input of the inventory are the feed materials such as empty fruit bunches (EFB) and palm oil mill effluent (POME); and utilities which include electricity generated at palm oil mill and diesel used. Composting 2.0–2.5 t of EFB and 5.0–7.5 t of POME required diesel from 218.7 to 270.2 MJ and electricity from 0 to 6.8 MJ. It is estimated that the composting emitted from 0.01 to 0.02 t CO_2eq/t_compost mainly from diesel used to operate machineries. Composting saved 65 % of time required for a complete degradation of POME when compared to ponding system, and 89 % of time required for a complete degradation of EFB compared to mulching. In terms of land required, it required 36 % less land as compared to ponding for POME and 99 % less land as compared to mulching for EFB. Based on the case study, diesel was found to be the main contributor to the environmental impact. There is a potential of upgrading the process to be more economical and environmental friendly. Using electricity as the source of energy has a lower footprint for the composting process. Instead of using raw POME, studies had reported that using treated POME either from anaerobic ponding or digested tank can accelerate the composting process.     

The methylic versus the ethylic route: considerations about the sustainability of Brazilian biodiesel production

Brazil is considered one of the world’s leading producers of biofuels given the predominance of ethanol fuel in its energy matrix. However, despite the prominence of Brazil in ethanol production, the vast majority of biodiesel production plants in Brazil use methanol instead of ethanol as the alcohol for transesterification reaction, as is generally the case in the rest of the world. The aim of this paper is therefore to examine the transesterification process in the Brazilian biodiesel production in terms of sustainability. In this regard, it was necessary to evaluate the way in which the industrial process is currently carried out, the role of government incentives or subsidies for the use of ethanol to produce biodiesel, and the investments of companies in technology development for the same purpose. This study presents indications that the development of the biodiesel market in Brazil is still oriented toward a production model which is inconsistent with the environmental and social aspects of sustainability.     

OPTIONS FOR ENVIRONMENTAL SUSTAINABILITY OF THE CRUDE PALM OIL INDUSTRY IN THAILAND THROUGH ENHANCEMENT OF INDUSTRIAL ECOSYSTEMS

The crude palm oil industry plays an important role in the economic development of Thailand and in enhancing the economic welfare of the population. Despite obvious benefits of this industrial development, it also significantly contributes to environmental degradation, both at the input and the output sides of its activities. On the input side, crude palm oil mills use large quantities of water and energy in the production process. On the output side, manufacturing processes generate large quantities of wastewater, solid waste/by-products and air pollution. Current industrial wastes and recoverable materials are empty fruit bunches, fibers, shells and ash. It is estimated that in 2003, a total of 2.1 million ton of solid wastes/by-products and 2.5 million m³ of wastewater were generated. The concept of the industrial ecosystem points at the potential of industrial waste recycling resembling food chains, food webs and nutrient cycles of nature. Following the notion of industrial ecology crude palm oil mills can develop a number of waste recycling and reuse systems. This paper analyzes the nature of these industrial ecosystems, divided in in-plant ecosystems (clean technology options) and external waste exchange between crude palm oil industries and other economic activities in Thailand.     

Performance studies of a low heat rejection engine operated on non-volatile vegetable oils with exhaust gas recirculation

During recent decades, considerable effort has been expended world-wide to reduce dependency on petroleum fuels for power generation and transportation through the search for suitable alternative fuels that are environmentally friendly. In this respect, vegetable oils are a promising alternative to diesel fuel. However, the high viscosity, poor volatility and cold flow characteristics of vegetable oils can cause some problems such as injector coking, severe engine deposits, filter gumming and piston ring sticking and thickening of lubrication from long-term use in diesel engines. These problems can be eliminated or minimised by transesterification of the vegetable oils to form monoesters. Although transesterification improves the fuel properties of vegetable oil, the viscosity and volatility of biodiesel are still worse than those of petroleum diesel fuel. The performance of a diesel engine with such biodiesel operation can be improved further with the concept of the low heat rejection (LHR) engine. In the LHR engine, combustion surfaces on the pistons, cylinder walls and valves can be coated with ceramic materials. The objective of this study was to apply the LHR engine concept for improving engine performance when either honge biodiesel, known as honge oil methyl ester (HOME), or neem biodiesel, known as neem oil methyl ester (NOME) oils was used as an alternative fuel. For this purpose, experiments were conducted on a single cylinder, four-stroke, direct injection, water-cooled compression ignition engine using diesel, HOME and NOME oils at different injection timings of 19, 23 and 27° before top dead centre (BTDC) with and without the induction of exhaust gas recirculation (EGR). The percentage of EGR was varied from 5 to 20% in steps of 5%. The results showed that specific fuel consumption and brake thermal efficiency were improved for both of the biodiesel fuels in the LHR engine. An EGR of 10% resulted in better performance with trade-off between oxides of nitrogen and hydrocarbons/carbon monoxide emissions and hence 10% EGR is taken as the best of the range from 5 to 20%. However, readings with other EGR ratios are not reported.     

Feasibility of PV–biodiesel hybrid energy system for a cement technology institute in India

This paper compares an existing unreliable grid supply with a proposed PV–biodiesel hybrid energy system in order to find the feasibility of the latter for improvement in reliability of power supply, lower pollutant emissions and saving of coal reserves. In the present study, the electrical load of a cement technology institute located in Bhilai, India, has been selected for the purpose of analysis. The results show that hybrid PV–biodiesel system comprising 25 kW PV array, 8 kW biodiesel generator-1, 20 kW biodiesel generator-2, 10 kW inverter and 10 kW rectifier will supply power to the institute avoiding addition of 27.744 tons of CO₂ in atmosphere and save 55,080 kg of coal per year with improvement in reliability from 93.15 to 100%.     

The effect of the initial concentration of glycerol on the hydrogen produced by strains of the genus Clostridium spp.

Hydrogen produced by microorganisms is a topic of growing interest because of its potential for derivation from several agro-industrial by-products. In this study, we evaluated the hydrogen production of strains of genus Clostridium (Clostridium acetobutylicum and Clostridium butyricum) using glycerol as a carbon source. Fermentation studies were conducted using three initial concentrations of glycerol: 10, 30 and 50 g/L. The micro-organism growth kinetics and the amounts of solvents and gases were recorded over 48 h. The strain C. acetobutylicum exhibited the best results in terms of hydrogen production, the highest production yield (Y _p/s) of 0.37 mol H₂/mol glycerol and the highest level of productivity (0.75 mg H₂/(L·h)). Based on these results, it is reasonable to conclude that glycerol could be effectively exploited as a carbon source for hydrogen production, which adds value to this primary by-product of standard biodiesel processes.     

Using biomass residues from oil palm industry as a raw material for pulp and paper industry: potential benefits and threat to the environment

Oil palm industries produce an enormous quantity of lignocellulosic biomass; in the form of large leaves of palm tree, pruned fronds (OPF) and oil palm trunks (OPT) at the plantations site. Besides this, the processing of fresh fruit bunches in the oil mills generates empty fruit bunches (EFB), shells, kernel cake and mesocarp fibers. The proper management of this burgeoning waste and its disposal is an ardent task and creates environmental hazards. In order to deal with the biomass residues, the urgent need is that it should be transformed into resources with industrial utility. As the economic development has resulted in the significant increased demand for paper, the industry is looking for eccentric sources to fulfill the requirement. The pulp and paper industry preferred use of coniferous and deciduous trees for papermaking because their cellulose fibers in the pulp make durable paper. With improvements in pulp processing technology, fibers of almost any non-wood of plants species like bamboo, cereal straw, sugarcane, flax, hemp and jute can be used for paper pulp. Substituting this lignocellulosic material can reduce the burden on forest while supporting the natural biodiversity. The present review deals with the possibilities of using oil palm biomass as a raw material for pulp and papermaking, as this would ameliorate its waste management problem. The potential of oil palm biomass and the challenges regarding its use in papermaking are discussed. The use of oil palm biomass will apparently prove that the oil palm industry is ecofriendly in every aspect of its activities and aid in sustainability of forest ecosystem.     

中国液态生物质燃料的潜力测算

中国液态生物质燃料潜力测算为下一步开发提供依据.该文对我国发展液态生物质燃料原料的分布进行整合,从宜能荒地测算、高浓度酒精降度模拟和餐饮地沟油估算等方面,对生产燃料乙醇和生物柴油的原料潜力进行梳理.利用覆盖甜高粱、木薯、甘薯、食用酒精、麻疯树、黄连木和餐饮地沟油等原料来源的数据,测算了我国液态生物质燃料的潜力产量,发现:到2030年,我国燃料乙醇生产潜力将达到5 500万t左右,生物柴油生产潜力将达到3 200万t左右,将能有效保证我国经济增长对能源的需求和缓解化石能源对外依存度过离的能源安全威胁.同时,应该在生物质燃料产业化的关键技术研究上寻求突破,并配套以政府部门的补贴政策,提升我国生物质燃料产业化初期的综合实力.     

Benefits and costs of oil palm expansion in Central Kalimantan,Indonesia, under different policy scenarios

Deforestation and oil palm expansion in Central Kalimantan province are among the highest in Indonesia. This study examines the physical and monetary impacts of oil palm expansion in Central Kalimantan up to 2025 under three policy scenarios. Our modelling approach combines a spatial logistic regression model with a set of rules governing land use change as a function of the policy scenario. Our physical and monetary analyses include palm oil expansion and five other ecosystem services: timber, rattan, paddy rice, carbon sequestration, and orangutan habitat (the last service is analysed in physical units only). In monetary terms, our analysis comprises the contribution of land and ecosystems to economic production, as measured according to the valuation approach of the System of National Accounts. We focus our analysis on government-owned land which covers around 97 % of the province, where the main policy issues are. We show that, in the business-as-usual scenario, the societal costs of carbon emissions and the loss of other ecosystem services far exceed the benefits from increased oil palm production. This is, in particular, related to the conversion of peatlands. We also show that, for Central Kalimantan, the moratorium scenario, which is modelled based on the moratorium currently in place in Indonesia, generates important economic benefits compared to the business-as-usual scenario. In the moratorium scenario, however, there is still conversion of forest to plantation and associated loss of ecosystem services. We developed an alternative, sustainable production scenario based on an ecosystem services approach and show that this policy scenario leads to higher net social benefits including some more space for oil palm expansion.     

Effect of mixing chamber venturi,injection timing,compression ratio and EGR on the performance of dual-fuel engine operated with HOME and CNG

Stringent environmental policies and the ever increasing demand for energy have triggered interest in novel combustion technologies that use alternative fuels as energy sources. Of these, pilot-ignited compressed natural gas (CNG) engines that employ small biodiesel pilot to ignite a premixed natural gas–air mixture have received considerable attention. This paper discusses the effect of mixing chamber venturi, injection timing, compression ratio and exhaust gas recirculation (EGR) on the performance of dual-fuel engine operated on biodiesel derived from honge oil and is called honge oil methyl ester (HOME) and CNG. The proposed study mainly focuses on the manifold induction of CNG along with HOME injection. However, CNG can also be injected using port or direct gas injector (Lakshmanan and Nagarajan 2010, Energy 35, pp. 3172–3178). The future study will involve these methods of CNG injection. From this study, it is concluded that an advanced injection timing and an increased compression ratio resulted in increased brake thermal efficiency and reduced smoke, hydrocarbons and carbon monoxide emissions. However, nitrogen oxides (NO _x ) emission increased significantly. The increased NO _x emission was effectively reduced with EGR method. A mixing chamber venturi of 3 mm size, injection timing of 27° before top dead centre (BTDC), compression ratio of 17.5 and 10% EGR were found to be optimum for the modified compression ignition engine that was operated on CNG–HOME dual-fuel mode.     

Experimental investigation of diesel engine using EGR and fuelled with Karanja oil methyl ester

Karanja oil methyl ester (KOME), a biodiesel prepared from Karanja oil, a potential source of non-edible oil in India and a prospective alternative to the diesel fuel, shows comparable performance and considerable reduction in emissions except NO_x. Exhaust gas recirculation (EGR) is a popular method of reducing the NO_x emission. The aim of this experimental work was to study the potential of the cooled EGR in a direct injection compression ignition engine operating with the KOME and its blend. The study was conducted with the different EGR rates. Performance and emission parameters were compared by using diesel, KOME and its blend employing EGR and with the same fuels without EGR. The study also differentiates the effect of EGR on KOME and its blend with the neat diesel. The effect of EGR was found to be slightly higher for KOME biodiesel and its blend than for neat diesel. Increased NO_x emission using KOME biodiesel was also found to be reduced by using EGR.     

Comparative study on effect of blending,thermal barrier coating (LHR) and injector nozzle geometry on biodiesel-fuelled engines

Increased petroleum prices, increased threat to the environment from exhaust emissions and global warming have generated intense international interest in developing renewable and alternative non-petroleum fuels for internal combustion engines. Evolving suitable technology for addressing energy crisis creates a continued investigation into the search for sustainable and clean-burning renewable fuels. This work investigates suitability of different non-edible-derived biodiesels such as cotton seed oil methyl ester (COME), Honne oil methyl ester (HnOME) and Rubber seed oil methyl ester (RuOME) to four stroke, single cylinder compression ignition (CI) engine. Engine tests were conducted to study the effect of fuel blending, thermal barrier coating (TBC) or Low Heat Rejection (LHR) and injector nozzle geometry on the performance, combustion and emission characteristics of COME, HnOME and RuOME in the modified CI engine. Blends of biodiesels with diesel were varied from 20 to 80% in steps of 20%. Two thermal barrier coatings of partially stabilized zirconium (PSZ) and aluminium oxide (Al₂O₃) were provided on the engine to make it fully adiabatic. Nozzle injectors of 3, 4 and 5 holes, with size of orifice varied from 0.2 to 0.3 mm size were selected for the study. It was concluded that B20 biodiesel blend, PSZ-coated engine and four hole nozzle injector of 0.2 mm size resulted in overall better engine performance with increased brake thermal efficiency (BTE) and reduced HC, CO, smoke emissions for the fuel combinations tested. Combustion analysis to study the effect of biodiesel blends, LHR coatings, injector nozzle geometry on the performance of the biodiesel-fuelled engine has been presented to give more insight into the behaviour of operation.     

Combustion performance and emission characteristics on HCCI engine of waste plastic pyrolysis oil biodiesel blends with external PFI and vaporiser

ABSTRACT

Analysis of plastic oil obtained from waste plastic through pyrolysis process, as an alternative to biodiesel is presented in this paper. The HCCI engine is considered for experimental validation of combustion performance and emission characteristics. To accumulate pyrolysis oil as fuel, the design modifications were made in external mixture formation on the existing computerised 4-stroke, single cylinder, water cooled, direct injection kirloskar diesel engine connected with eddy current dynamometer to satisfy HCCI conditions. HCCI engine can be worked on wide assortment of fuels beginning from diesel to different blends (WPPO 5%,10%,15% and 20% by volume) of biodiesel .The designed additional device connected to the engine is utilised for fuel vaporisation and mixture arrangement. In the experimental study, the combustion results were initiate to be of 39.69 % higher Rate of Heat Release (RoHR) for biodiesel HCCI as compared with diesel HCCI. Higher brake thermal efficiency (BTE) was found 37 % without exhaust gas recirculation (EGR) at WPPO 20 % biodiesel blend. And also found 50 % and 65 % reduction in NOx emission and 18 % and 28 % reduction in smoke opacity are obtained for biodiesel vapour induction without EGR and biodiesel vapour induction with 15 % EGR as compared with diesel fuel. The CO (0.34 %), and UHC (2.15 %) emissions are increases with 15 % EGR, but the emissions are within the standard limits specified by the emissions standards.     

Effects of injection timing,injector opening pressure and nozzle geometry on the performance of cottonseed oil methyl ester-fuelled diesel engine

Increasing petroleum prices, increasing threat to the environment from exhaust emissions and global warming have generated intense international interest in developing renewable and alternative non-petroleum fuels for engines. Evolving technology and a recurring energy crisis necessitates a continuous investigation into the search for sustainable and clean-burning renewable fuels. In this paper, cottonseed oil methyl ester (COME) was used in a four-stroke, single-cylinder variable compression ratio diesel engine. Tests were carried out to study the effects of fuel injection timing, fuel injector opening pressure (IOP) and injector nozzle geometry on the performance and combustion of COME biodiesel fuel used in a compression ignition engine with a single fuel mode. Fuel injection timing varied from 19° to 27° before top dead centre (bTDC) in incremental steps of 4° bTDC; fuel IOP varied from 210 to 240 bar in incremental steps of 10 bar. Fuel nozzle injectors with three, four and five holes, each of 0.3 mm size, were selected for the study. The results suggested that with retarded injection timing of 19° bTDC, increased IOP of 230 bar and a four-hole nozzle injector of 0.3 mm size resulted in overall better engine performance with an increased brake thermal efficiency and reduced HC, CO and smoke emission levels.     

Changing the planting date as a climate change adaptation strategy for rice production in Kurunegala district, Sri Lanka

The effect of changing the planting date on the dry season rice yield was simulated by using the software Decision Support System for Agrotechnology Transfer (DSSAT 4.5) for four rice varieties grown in Kurunegala district, Sri Lanka under expected climate change. Daily weather data up to the year 2090 were downscaled to the district from Global Climate Model outputs under the emission scenarios A2 and B2 published by the Intergovernmental Panel on Climate Change using the Statistical Downscaling Model (SDSM 4.2). The DSSAT model was applied to simulate future rice yields from four rice varieties grown in the district under three different planting dates: (1) planting in May—the base condition; (2) advancing the planting date by 1 month, i.e., to June; and (3) planting 1 month earlier, i.e., in April. Results show that the seasonally averaged dry season rice yield would increase compared to the base condition when the planting date is advanced by 1 month and, on the other hand, the seasonally averaged rice yield would decrease compared to the base condition when the planting date is delayed by 1 month for all four varieties under both A2 and B2 scenarios. Advancing the rice planting date by 1 month for all four rice varieties can be identified as a non-cost climate change adaptation strategy for rice production in Kurunegala district.     

Fuel efficiency enhancement of modified diesel engine operated in dual fuel mode using renewable and sustainable fuels

ABSTRACT

Renewable and sustainable fuels for diesel engine applications provide energy protection, overseas exchange saving and address atmospheric and socio-economic concerns. This study presents the investigational work carried out on a single cylinder, four-stroke, direct injection diesel engine operated in dual fuel (DF) mode using renewable and sustainable fuels. In the first phase, a Y-shaped mixing chamber or venture was developed with varied angle facility for gas entry at 30°, 45° and 60°, respectively, to enable homogeneous air and gas mixing. Further effect of different gas and air mixture entry on the DF engine performance was studied. In the next phase of the work, hydrogen flow rate influence on the combustion and emission characteristics of a compression ignition (CI) engine operated in DF mode using diesel, neem oil methyl ester (NeOME) and producer gas has been investigated. During experimentation, hydrogen was mixed in different proportions varied from 3 to 12 l/min (lpm) in step of 3 lpm along with air-producer gas and the mixtures were directly inducted into engine cylinder during suction stroke. Experimental investigation showed that 45° Y-shaped mixing chamber resulted in improved performance with acceptable emission levels. Further, it is observed that investigation showed that at maximum operating conditions and hydrogen flow rate of 9 lpm, Diesel–producer gas and NeOME–producer gas combination showed increased thermal efficiency by 13.2% and 3.8%, respectively, compared to the DF operation without hydrogen addition. Further, it is noticed that hydrogen-enriched producer gas lowers the power derating by 5–10% and increases nitric oxide (NO_x) emissions. However, increased hydrogen addition beyond the 12 lpm leads to sever knocking.

Abbreviations: NeOME: Neem oil methyl ester; BTE: brake thermal efficiency; CI: compression ignition; ITE: indicated thermal efficiency; PG: producer gas; CA: crank angle; K: Kelvin; BP: brake power; IP: indicated power; H₂: hydrogen; HC: unburnt hydrocarbon; CO: carbon dioxide; CO₂: carbon dioxide; NO_x: nitric oxide; HRR: heat release rate; %: percentage; PPM: parts per million; CMFIS: conventional mechanical fuel injection system.