Potential and Challenges of Low Carbon Fuels for Sustainable Transport

Low carbon fuels seem to be a preferable class of fuels for Internal Combustion Engines (ICEs). It is the simple understanding that if input fuel has low carbon content in its constituents, tailpipe emissions will have lower carbonaceous emissions. Also, low carbon fuels can be produced using renewable resources, and they are economical than conventional fuels. The low carbon fuel family has members like biodiesel, Di-methyl ether, Di-ethyl ether, renewable compressed natural gas, Ethanol, Butanol etc. Automotive industries and policymakers clearly understand that the problem is not the engines but the fuels used to power the engines. Therefore, researchers are working on the adaptation of low carbon fuels. This book covers all possibilities of using low carbon fuels. Also, it covers the effect of low carbon fuels on tailpipe emissions. This book aims to strengthen the knowledge base dealing with low carbon fuels as a sustainable transport fuel.

Alternative biofuels for the internal combustion engines is one of the important options to decrease exhaust emissions, improving engine performance and combustion characteristics. The purpose of this book chapter is to review alternative biofuels such as alcohols and biodiesel. In this regard, the advantages and disadvantages of alcohols (e.g. methanol, ethanol, butanol) have been assessed. Furthermore, the properties of biodiesel, its production potential in Turkey and the World, biodiesel production process and production methods such as dilution method, pyrolysis method, microemulsion method, supercritical method, transesterification method, and their standards were evaluated. This book chapter gives information about alternative biofuels for internal combustion engines that substantially affect the engine performance, combustion process, and exhaust emission characteristics.

The ever increasing energy demands have necessitated the development of alternative energy sources. Unbridled utilization of fossil fuels, coupled with public awareness has directed research focus towards the production of non-polluting and sustainable fuel sources. Algae have garnered tremendous research interest in the present time to meet the challenges faced by existing fuel sources. Ethanol has been widely used since the 1800s as a fuel of choice for internal combustion engines (ICE). Compared to conventional feedstock (corn/sugar beet), microalgae has a better potential in terms of ethanol yield: 40–140 ML ha⁻¹ versus 3–6 ML ha⁻¹ and can be a promising alternative for the future. Although various approaches have been presented to convert algal biomass to fuels, feed and chemicals; none of them are feasible from the economic point of view. Therefore, it is prudent to develop a biorefinery concept where multiple numbers of products can be recovered from the same algal biomass with a limited expense on unit operation. In order to address the present bio-economy challenges, it is pertinent to focus on the development of multiple products from the same biomass. In the present chapter the recent developments on algal refinery concept have been studied focussing on integrated bioethanol production under a biorefinery paradigm. The review also covers the technical challenge which inhibits the realization of algal biorefinery, along with providing insight on how to overcome the technical hurdles.

Application of low carbon alternative fuels for engines has been well-known as an attractive approach to reduce greenhouse gas emissions. In recent years, additional efforts have been made on the research and development of alternative fuel engines that run on natural gas, methanol, hydrogen and ammonia, because they provide more potential to achieve strict emission targets. However, a technical challenge for these alternative fuel engines is whether a qualified fuel delivery system is available. Blending is perhaps the most convenient method to burn alternative fuel. A popular blending fuel is the mixture of gasoline and 10% ethanol (E10) for use in passenger vehicles. In this case, no change is needed for the fuel delivery system. In other cases including using methanol as an alternative, the components of fuel delivery system require materials modification to prevent corrosion. High-pressure direct injection of methanol is preferred for heavy-duty engines because compression ignition exhibits high thermal efficiency. In this case, the conventional fuel delivery system needs more modifications. For example, a higher flow capacity is needed for increased flow rate due to the lower energy density. Additional cooling elements are needed to prevent vaporization. A special coating should also be applied to the surface of the pump plunger and control valve to improve the lubricity because those components are made of the anticorrosive material. For natural gas, an effective combustion mode is so called dual—fuel mode. There, natural gas introduced from the intake port and mixed with air homogenously is ignited by injecting a small amount of diesel fuel when the piston approaches the end of compression stroke. More recently, a more advanced fuel delivery system has been developed, which uses one injector for diesel fuel and another for natural gas (or alternatively a co-axial injector with inner nozzle hole for diesel fuel and outer nozzle holes for natural gas). It has been reported that diesel fuel injected for ignition can be reduced to 5% of total fuel with using this new system. This dual-fuel mode has been used for methanol and ammonia fuel, and could be the next main-stream for alternative fuel engines.

Owing to the increasing global demand for energy, the consumption of fossil fuels has increased; however, the utilization of such fuels negatively affects the environment. This has also led to major issues, including global warming, climate change, rising sea levels, and the depletion of carbon-based fuels. Petroleum-based energy supplements are mainly responsible for these problems. More specifically, environmental concerns have peaked after the critical CO₂ level was exceeded. Thus, now more than ever, it is imperative to increase the percentage of clean and renewable energy sources used to address energy demands. In this regard, this study intends to reveal the performance, combustion, and emission characteristics of various means of transportation using alcohols, such as methanol, ethanol, propanol, and butanol, as alternative fuels. The primary means of transportation include passenger cars, commercial vehicles, ships, locomotives, non-road vehicles, and alternative powering systems employing fuel cells supplied with alcohols. The effects of using alcohols as alternative fuels and carbon neutral characteristics, combustion characteristics, and emissions such as NO_x, CO, HC, particulate matter, and CO₂ were also investigated.

Commercialization of biofuels as alternative fuels to conventional diesel fuel for application as transport-fuels for diesel engines is fast becoming attainable owing to the merits offered by the inclusion of significant quantities of an alcohol (ethanol) and a member of the “ether” group (dimethyl ether) as additives or property-improvers for biofuels obtained from biomass. These additives are fuels in kind, but have lower viscosities, flash points, flammability etc., hence they infuse some measures of atomization and moderation in the densities and viscosities of biofuels towards ensuring their suitability for use in Internal Combustion Engines (ICEs). Biofuels need be improved in terms of fuel quality such as performance, emission and combustion characteristics to meet market specification. This then informs the need for suitable fuel-modifiers which must be tested for their compatibilities with different biofuel-sources before they are used as fuels in ICEs. The mixing ratio of the added components with the biofuels is also to be given utmost attention as an alcohol such as ethanol and an ether (dimethyl ether), are known for their high volatilities which in turn regulate the BTEs and combustion potentials of the fuels, all aimed at improving the cetane numbers or indices of the blended fuels. Owing to the relative abundance of bioresources as precursors for biofuels relative to other sources of ethers and alcohols, literature has it that some prospective alcohols and ethers have been admixed with biofuels as means of upgrading their properties towards ensuring their high suitability for diesel engines with little or no modifications; this then implies that there might be need to begin to look into reconfiguring some diesel engines in order to abate engine wear, fuel degradation as well as catalyst-poisoning towards ensuring/maintaining high engine-compatibilities with these fuels. Therefore, this chapter is proposed for inclusion in Book 1 “Engine and fuels for future transport”, and its focus will be on the effects of using lone ethanol, dimethyl ether or biofuels as well as their blends for use as future transport fuels.

Effort for reduction of global emission level is currently one of the prime areas of concern for the research community across the globe. Particularly due to more stringent standards of emission control, the prevailing diesel engines are on the verge of losing their permission to operate. Engine fuel modification technologies are reported to improve engine combustion and reduce engine emission levels. The enhancement in liquid fuel using oxygenated additives can be a sustainable and cost effective solution to address the issues of the existing diesel engine emission. Among the existing vehicular fuel improvements technologies, the use of biodiesel, alcohols viz. methanol, ethanol, propanol, butanol, and ethers improves performance as well as emission characteristics of engine significantly. As found in open source, the application of biodiesel-alcohol blended fuels can reduce carbon emission by 50–60% and hence considered as a possible conventional fuel substitution for engine applications. These fuels can be applied either completely or as blends with diesel in diesel engines. Moreover, water emulsification with different blends of biofuels can further restrict the engine emission levels particularly the NOx and smoke emission levels up to 25%. Therefore, the current chapter delivers a critical analysis of the use of oxygenated additives for running diesel engines. The improvements in the physiochemical properties of biodiesel/diesel-alcohol blended fuels and their influence on the engine emission characteristics are discussed in the chapter.

Heavy duty vehicles fitted with internal combustion engines have been instrumental in helping human for meeting their economic and social goals. In the pursuit we have put enormous burden on our environment. And now we are facing the challenges to limit and reduce the burden on environment over a period of time. Presently, there are plethora of technology concepts which are worldwide discussed and projected as a sustainable solution for future heavy duty transportation. However, there are number of considerations for a nation like India that needs careful analysis before we adopt a particular transport solution. There is no denying the fact that eventually we have to make heavy duty vehicles fossil and emission free for reducing their impact on environment to minimum. But this would happen over a period of time. Now given the large number of heavy duty vehicles on road and new vehicles that are forecasted to be produced, combustion engines will be around for another two decades. Meeting the goal of net zero GHG emission by 2050 requires number of parallel approaches. Hence, we have to work on various fronts, like related to combustion engines we need to put effort on improving newly developed heavy duty engine efficiencies, improving existing fleet emission, introducing low carbon fuels like natural gas and carbon neutral bio fuels and drop-in fuels. Simultaneously we also have to progress on the long term new developments like electrification of urban transport and hydrogen fuel cell truck for long haul operations. In this regard, we will briefly discuss here the several ways to make transportation in India more environment benign, role and potential of several prospective bio-fuels and various base and advanced engine technologies to improve the carbon footprint of existing and new developed fleet of heavy duty vehicles.

Alternative green fuels play a vital role in meeting the energy demand. Biodiesel has been recognized as a sustainable low-carbon alternative fuel for diesel engines. This chapter reviews the potential and various challenges associated with the use of biodiesel as a fuel in a compression ignition engine. The chapter further reviews various thermo-physical–chemical properties of biodiesel and their significant effects on combustion characteristics like cylinder pressure, rate of pressure rise, mean gas temperature, and engine performance parameters including Brake specific fuel consumption (BSFC), Brake Thermal Efficiency (BTE), and Brake power (BP). Moreover, engine emissions and various emission control techniques i.e. blending of fuels, hardware modifications in engines are thoroughly reviewed. The literature reports the use of different refined oils and feedstocks to produce biodiesel utilizing different methods e.g., pyrolysis, wet washing, blending or direct use, transesterification, and microemulsions. But still, considerable efforts are needed for the commercialization of biodiesels due to their properties of higher viscosity, corrosivity, and less stable nature. So, the present work concludes with an optimized approach to consider the potentiate biodiesel as a fuel in CI engines.

Some of the biggest problems facing our world on a global scale are global warming, climate change, and air pollution. The transport and logistics sector causes these problems to become even more intractable with the internal combustion engines used, and the role of maritime transport in this regard is substantial. The International Maritime Organization (IMO), which is the United Nations’ (UN) specialized agency for regulating maritime transportation, began its studies on the topic of greenhouse gas within the scope of the UN’s sustainable goals for the future and announced the initial greenhouse gas (GHG) strategy plan in April 2018. In these ongoing studies, the importance of alternative marine fuels becomes more and more critical day by day. There are many types of alternative marine fuels with different properties, such as liquefied petroleum gas, liquefied natural gas, methanol, ethanol, and biofuels. Each alternative fuel has its own characteristics, which leads to some advantages and disadvantages in terms of use. During the transition to alternative fuels from conventional fuels, drop-in fuels such as biodiesel and renewable diesel can be used to meet the reduction target of the IMO Initial GHG Strategy. The advantage of these biofuels is that it can be used with the existing fuel system and a diesel engine without any retrofit requirement or can be used with minor modifications. The purpose of this study is to state the steps that IMO has taken for decarbonization and then to explain the properties, raw materials, and production methods of biodiesel and renewable diesel, an alternative marine fuel, and to determine its usability and suitability by comparing it with other promising alternative fuels and revealing their pros and cons for decarbonizing the maritime industry.