Sustainable waste derived biodiesel can substitute significant amount of fossil-based fuels currently used for marine propulsion, agricultural processes, small scale power generation, and in heavy ...goods vehicles. However, biodiesel fuel quality varies depending on the feedstock type, production method and storage conditions. Meeting biodiesel standards and reduction of NOx emissions are two main challenges when biodiesels are being used in the internal combustion engines. This study aims to address these two challenges by using biodiesel-biodiesel blending and various NOx reduction techniques. Biodiesels produced from waste resources and inedible plant seed oils are investigated. Fuel properties, biodiesels standards, and engine test results are reviewed. It was found that blends of animal fat biodiesels and vegetable oil biodiesels are likely to improve fuel properties and combustion characteristics. The biodiesel-biodiesel blends also help to reduce exhaust pollutants. The saturation level of the biodiesel fuel is increased through this technique. Animal fat biodiesels are composed of saturated fatty acid methyl esters, and vegetable oil biodiesels are composed of unsaturated fatty acids. The NOx gas emission reduction techniques are investigated and categorised under three sub-groups, fuel treatment, engine adjustment and exhaust after-treatment. Based on the state of art review, scopes for future R&D topics are presented for researchers and relevant industries.
•Blends of animal fat and WCO biodiesels can improve the fuel properties.•Biodiesel emulsification by 30% water can reduce the NOx emission by up to 60%.•Antioxidant additives can reduce biodiesels NOx emission by up to 9%.•Water injection through inlet manifold can reduce biodiesels NOx emission by 50%.•SCR is the leading NOx mitigation technique with efficiency of up to 85%.
Hydrogen delivered at hydrogen refuelling station must be compliant with requirements stated in different standards which require specialized sampling device and personnel to operate it. Currently, ...different strategies are implemented in different parts of the world and these strategies have already been used to perform 100s of hydrogen fuel sampling in USA, EU and Japan. However, these strategies have never been compared on a large systematic study. The purpose of this paper is to describe and compare the different strategies for sampling hydrogen at the nozzle and summarize the key aspects of all the existing hydrogen fuel sampling including discussion on material compatibility with the impurities that must be assessed. This review highlights the fact it is currently difficult to evaluate the impact or the difference these strategies would have on the hydrogen fuel quality assessment. Therefore, comparative sampling studies are required to evaluate the equivalence between the different sampling strategies. This is the first step to support the standardization of hydrogen fuel sampling and to identify future research and development area for hydrogen fuel sampling.
•Detailed description of different strategies for sampling hydrogen at the nozzle.•Discussion on the representativeness of the sample collected.•Results from different stability studies for gaseous species in different cylinders.•Highlight the need of comparative studies to assess equivalence between strategies.
•The biochars were produced from woody and non-woody biomass by pyrolysis.•Woody biomass showed higher biochar and energy yields than non-woody biomass.•Woody biomass showed lower decomposition rate ...than non-woody biomass.•The biochars exhibited significantly improved combustion behaviors.•Slagging and fouling issues were similar for raw biomass and biochars combustion.
Low temperature pyrolysis was employed to produce solid fuel biochars from woody (pine wood) and non-woody biomass (coconut fiber) in the present study. Chemical evolution of biomass under pyrolysis conditions was determined and fuel qualities of the biochars were evaluated including energy densities, ash-related problems and combustion behaviors. The results showed that dehydration reaction of the biomass had same preference with decarboxylation reaction under pyrolysis conditions. The hemicellulose and cellulose in non-woody biomass showed faster decomposition than those in woody biomass. The biochars derived from coconut fiber showed lower energy densities and energy yields than those from pine wood under identical conditions. All major ash forming metals originally contained in raw biomass were accumulated in the resultant biochars and more serious slagging and fouling problems were present during combustion of pyrolytic biochars compared to raw biomass. The reactivity of biomass decreased and the main mass loss shifted to elevated temperature zone with the increasing pyrolysis temperature, indicating increased thermal efficiency and environmental benefits were achievable during biochar combustion compared to raw biomass combustion. Taking into account combustion characteristics and energy yield, optimal pyrolysis temperatures for solid fuel production were around 300°C for coconut fiber and 330°C for pine wood.
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•Wet flue gas torrefaction could improve fuel quality of rice husk more effectively.•O2, CO2 and H2O synergistically accelerated the removal of cellulose and hemicellulose.•Adding H2O ...was beneficial to enlarge specific surface area of torrefied rice husk.•Wet flue gas torrefaction was more likely to promote enrichment of edge nitrogen.•Rice husk upgraded in wet flue gas at 543 K showed a better combustion behaviour.
Effects of torrefaction condition on fuel qualities and combustion characteristics of rice husk were studied. The distribution of typical elements and components exhibited that rising torrefaction severity initially decreased and subsequently increased the values of H/C and O/C. The effects of torrefaction condition on lignin content and heating value for torrefied samples expressed identical law. Increasing torrefaction severity decreased the solid yield monotonically, while the corresponding energy yield expressed first upward and then downward trend. The participation of H2O in the torrefaction process was beneficial to the generation of edge nitrogen and the enrichment of reactive functionalities at the expense of hydrophilic groups. The addition of multiple oxidants was conducive to enlarging specific surface area and optimizing fuel combustion behavior at mild temperatures. According to the results obtained from this research, the upgraded sample derived from torrefaction occurred in wet flue gas at 543 K expressed the best fuel quality.
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•Filter samples from unexplainable non-mibrobial filterblocking events were collected.•Applying extraction methods and various analyticals did not explain the root cause.•Mass ...spectrometry was successfully used to distinguish reference and blocked filters.•All blocked filters showed distinct amounts of saturated monoglycerides.•Findings lead to improved guidelines for fuel quality control and fuelling techniques.
Non-microbial filter blocking can be observed in filters of fuel dispensers that dispense biodiesel B7 (diesel with 7 % bio content). Initially, to identify the cause(s), an extensive matrix of affected sample filters (blocked) and reference filters in used and unused conditions were screened over 1.5 years. Information about possible influencing factors such as changes in temperature, weather, duration of use and location was gathered wherever possible. Furthermore, a gentle extraction method was set up to remove large amounts of fuel from selected filters and retrieve those blocking substances. For essential characterisation, the filter surfaces were assessed by light microscopy and gravimetry, and the deposits were analysed by ATR-FTIR and ICP-OES. However, a differentiation between blocked and reference filters was not possible. A qualitative assessment of fuel samples and filter deposits was carried out by direct infusion electrospray ionisation high-resolution mass spectrometry (ESI-HR-MS), which showed an apparent accumulation of saturated monoglycerides (SMGs) within the range of C16:0 to C22:0 in blocked filters. However, only unsaturated monoglycerides (from C16 to C18) were predominantly found in reference filters. Furthermore, a gas chromatography (GC)-flame ionisation detection (FID)-MS method was applied to evaluate the difference in SMG content in good and blocked filter samples.
The levels of BTEX (benzene, toluene, ethylbenzene and xylenes) in a congested urban area of Hanoi were characterized in a winter and a transitional period in 2015. Monitoring was conducted at two ...roads simultaneously with traffic flows and one ambient site together with meteorology. Hourly and bi-hourly BTEX samples collected using charcoal tubes were analyzed by GC-FID. BTEX levels in winter, 131 ± 71 μg/m3 in heavy traffic Truong Chinh (TC) road, 101 ± 29 μg/m3 in small residential Nguyen Ngoc Nai (NN) road, and 30 ± 15 μg/m3 in the ambient air site (AA, about 150 m from each road) were 1.3–2.1 times higher than the respective levels in the transitional period. Hourly benzene levels exceeded the Vietnam national standard more frequently at TC (45%) than at NN (32%) and least at AA (5%) out of 120–180 measurements, respectively. Roadside hourly levels well reflected the diurnal traffic flow pattern and higher BTEX levels were measured at TC than NN. The ambient site exhibited lower BTEX levels and different diurnal patterns, with more pronounced evening peaks than morning rush hour peaks. BTEX pollution rose showed a strong influence of wind to levels measured at AA. Species ratios (T/B and X/E) showed typical ranges for traffic emissions at roadsides. Ratios for AA and NN after midnight with no vehicles operating showed the aging effects with typical low X/E ratios. Multivariate analysis results suggested association of gasoline vehicles with BTEX at roadsides. Backward trajectory analysis indicated potential regional transport of long-lived benzene associated with continental airmass categories. BTEX at TC our study were 2–3 times lower for every species compared to those previously reported, showing results of fuel quality and vehicle technologies improvement. Health risks of people working at the roadside also reduced by about 3 times during the 10 years.
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•High roadside BTEX levels with diurnal patterns and species ratios showed predominant influence of traffic.•BTEX levels and species ratios obtained at ambient site indicate interactions of several influencing factors.•Effects of aging, local wind and regional transport on ambient BTEX were pronounced.•Traffic technology improvement during last decade lowered roadside BTEX and health risks.
•The performance of HTC and LTP was compared to produce solid fuel from waste biomass.•Fuel qualities of the biochars produced from HTC and LTP were investigated.•Ash problem related metal contents ...in two biochars were analyzed.•Combustion characteristics of two biochars were determined.•Hydrothermally prepared biochar is suitable for use as a solid fuel.
Hydrothermal carbonization (HTC) and low temperature pyrolysis (LTP) were compared on the basis of fuel qualities of biochars obtained from the upgrading of raw biomass in the present study. The results showed that the hydrothermally prepared biochar had higher energy density while the pyrolytic biochar had higher energy yield due to higher biochar yield. Nearly 100% major ash-forming metals were retained in the pyrolytic biochars while the contents of these metals in hydrothermally prepared biochars were less than 40% relative to those of raw biomass, especially for Na and K (less than 11% retention rate). The reactivities of pyrolytic biochars were higher than their respective raw biomass and the main mass loss occurred at low temperatures. The higher combustion temperature ranges and sharply decreased residue suggested that higher thermal efficiency and lower pollutant emissions could be achieved with the hydrothermally prepared biochars than with pyrolytic biochars. As for the process kinetics, HTC showed lower activation energy in the temperature range of 150–300°C in spite of deeper decomposition and carbonization of biomass as compared to LTP.
There is abundant worldwide research into combustion engine applications for tyre pyrolysis oil (TPO). However, many of these studies demonstrate conflicting or ambiguous results, so although the ...huge number of used tyres promises good availability for TPO, its role as fuel for transport applications is still uncertain. This review´s goal is to clarify the case for TPO as transport fuel by means of a critical, wide-ranging and updated review of TPO's engine applications. The work gathers, collates and analyses the results of over 200 influential original research papers, aiming to answer the governing research questions related to TPO production and quality, post-processing and quality improvement and its final end-use engine validation. The work re-evaluates the environmental aspects of TPO technology, setting it against the latest backdrop of growing climate change concern and the urgency to find alternative fuels. The hard economics of TPO are also addressed, for example, assessing other end-of-life tyre management routes and competing fuel alternatives.
The critical discussion on the key issues, including the most relevant drivers and boundaries, points towards TPO's use as a fuel component in marine, off-road and heavy-duty road applications. The results indicate that state-of-the-art production methods yield fuel that could be used directly in bunkering chains for marine transport as low-sulphur fuel oil. Discussion reveals that automotive applications are limited to blends not exceeding 10% tyre pyrolytic oil: sulphur and polyaromatic hydrocarbons contents and particulate emissions are the main constraints. Pyrolysis process efficiency is high and feedstock for TPO is both available and flexible. Waste tyre-derived pyrolytic oils could function as a supplementary solution to biofuels, blended to take advantage of their complementary properties.
The particular added value of this review is that it bridges the latest knowledge from several domains related to TPO fuel: industrial management, process chemistry, fuel science and combustion/engine research. The resultant analysis is expressed in terms that are accessible to all those domains. It underlines how studies from an individual domain perspective fail to produce the holistic view. The review creates a route towards modern multidisciplinary research supporting TPO´s role in global transition to circular economy.
The fuel quality of hydrogen dispensed from 10 refuelling stations in Europe was assessed. Representative sampling was conducted from the nozzle by use of a sampling adapter allowing to bleed sample ...gas in parallel while refuelling an FCEV. Samples were split off and distributed to four laboratories for analysis in accordance with ISO 14687 and SAE J2719. The results indicated some inconsistencies between the laboratories but were still conclusive. The fuel quality was generally good. Elevated nitrogen concentrations were detected in two samples but not in violation with the new 300 μmol/mol tolerance limit. Four samples showed water concentrations higher than the 5 μmol/mol tolerance limit estimated by at least one laboratory. The results were ambiguous: none of the four samples showed all laboratories in agreement with the violation. One laboratory reported an elevated oxygen concentration that was not corroborated by the other two laboratories and thus considered an outlier.
•10 samples collected from nozzle of public HRS in Europe.•Standardized sampling methodology applied.•All samples analysed by four laboratories = 40 analyses.•Extensive evaluation of interlaboratory results.•Discrepancies in H2 fuel violation depending on laboratory.
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