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Study on Fuels
Updated: Jan 28, 2022
The most used fuels in the Automobile sector are Petrol and Diesel. Here we shall discuss about the advantages and disadvantages of using Petrol and Diesel respectively. Since both are fossil fuels, so we should think about some cleaner alternatives. Some of them are Hydrogen Fuel Cell and Lithium ion batteries which can be used for Electric Vehicles. Other Green Energy sources are also available. We will discuss about them later.
Advantages of petrol over other energy sources:
Petroleum is extremely easy to extract and provides the cheapest means for advancement of technology. It is a high-density fuel and generates a power ratio of 1:10000. So, it gives high density energy rating.
Petroleum can be transported over long distances. The liquid form is easier to transport between places because of its viscosity. It can be transported via pipelines, railways, trucking, etc. It provides a fuel that works with our present infrastructure. From the late 17th century, all the infrastructures are widely based on petroleum.
It can be used in a wide variety of ways. There are huge number of by-products of this industry. And possibilities of new product outcome are high in this industry. Truly we can barely manage a day without using products from this industry. Petroleum provides a stable energy resource.
On one hand, we know petroleum is limited but on the other hand it gives us access to new renewable energy sources. For example, over 100 liters of petroleum are necessary to create a single Photovoltaic Panel that collects Sunlight for Energy. This Solar Energy is a green energy.
Disadvantages of petrol over other energy sources:
Combustion contributes dangerous gases to the environment.
Petroleum is a finite resource.
The refinement process of petroleum can be toxic.
Petroleum can be a trigger for acid rain. Hydrocarbon can change the composition of sea water as well.
Petroleum transportation isn’t 100% safe.
It is a commodity that is exploited for political advantages.
The infrastructure of the petroleum industry requires continuous maintenance.
Oil spills during extraction of crude oil or transport have catastrophic effects on the affected areas.
The drawback that we have with hydrocarbons and petroleum in general is that we are almost solely dependent on the products and fuels that it makes. Even renewables indirectly require this fossil fuel to create usable energy. Here we have talked about the advantages and disadvantages of petroleum. Now we discuss the advantages and disadvantages of two main petroleum products, i.e., petrol and diesel, as our main focus is automobile fuel.
Advantages of petrol over diesel:
Petrol cars tend to be cheaper than their diesel counterparts. Though there is a rapid rise in cost of petrol, still it is cheaper than any other fuel. It is relatively safe to store carry and dispense. Petrol can withstand high heat without breakdown.
Petrol engines can be slightly quieter. Repair costs are typically lower.
Disadvantages of petrol over diesel:
Petrol engines are less efficient so use more fuel.
Higher CO2 emissions by 20% so you have to pay more in car tax in the first year, but then the standard £140 a year will apply. They tend to depreciate faster.
Petrol version does not command a good resale value in used car market. Petrol versions haven’t been much of a success with bigger vehicle.
Advantages of diesel over petrol:
Diesel engines are more efficient. They can use up to 30% less fuel. So, diesel cars offer better mileage.
They have lower CO2 emissions by 20%. so are often in a lower tax band. This means that you’ll pay less in car tax in the first year, but then the standard £140 a year will apply.
They're more powerful when towing a caravan or trailer.
Diesel vehicles don’t need ignition tune-up.
Diesel engines are designed to withstand the challenge of higher compression. Torque is very important in getting the vehicle going, particularly when towing or carrying heavy loads. Diesel has an exceptional torque delivery even at low RPM, so they ca easily get moving from standing start.
Diesel engines usually have a longer life span.
Diesel cars depreciate at a slower rate.
Diesel car command a better price in the resale market.
Diesel engine is used as emergency power source in malls, hospitals.
Disadvantages of diesel over petrol:
Diesel cars tend to be more expensive to buy than similar petrol models.
Diesel fuel usually costs more. It costs as much as gasoline.
Diesel doesn’t offer high speed performance.
Servicing can be more expensive, although you don’t need to do it as often.
Insurance can be 10-15% higher.
Diesel cars produce a lot more NO2.
Tiny particles in diesel can cause asthma flareups.
Diesel engines can be slightly noisier.
If you don’t drive on motorways regularly your diesel particulate filter (DPF) could get clogged up and this can be expensive to put right.
Additives used in fuel:
Gasoline additives increase gasoline’s octane rating or act as corrosion inhibitors or lubricants, thus allowing the use of higher compression ratios for greater efficiency and power. Types of additives include metal deactivators, corrosion inhibitors, oxygenates and antioxidants.
OXYGENATES:
1. Alcohols:
Methanol
Ethanol
Isopropanol
n- butanone
Gasoline grade t-butanol
2. Ethers:
Methyl tert-butyl ether
Tert-amyl methyl ether
Tertiary hexyl methyl ether (THEME)
Ethyl tertiary butyl ether (ETBE)
Tertiary amyl ethyl ether (TAEE)
Diisopropyl ether (DIPE)
3. Antioxidants, stabilizers:
Butylated hydroxytoluene (BHT)
2,4-Dimethyl-6-tert-butylphenol
2,6-Di-tert-butylphenol (2,6-DTBP)
p-Phenylenediamine
Ethylenediamine
4. Antiknock agents:
Tetraethyllead (TEL), now banned almost everywhere for causing brain damage.
Methylcyclopentadienyl manganese tricarbonyl (MMT) is an extremely poisonous neurotoxic substance and is fatal if swallowed/inhaled and will cause a disease similar to Parkinson's called Manganism.
Ferrocene highly toxic
Dimethyl methyl phosphonate
Toluene
Isooctane
Triptane
5. Lead scavengers (for leaded gasoline):
Tricresol phosphate (TCP) (also an AW additive and EP additive)
1,2-Dibromoethane
1,2-Dichloroethane
6. Fuel dyes, most common:
Solvent Red 24
Solvent Red 26
Solvent Yellow 124
Solvent Blue 35
7. Fuel additives in general:
Ether and other flammable hydrocarbons have been used extensively as starting fluid for many difficult-to-start engines, especially diesel engines
Nitromethane, or "nitro", is a high-performance racing fuel
Acetone is a vaporization additive, mainly used with methanol racing fuel to improve vaporization at start up
Butyl rubber (as polyisobutylene succinimide, detergent to prevent fouling of diesel fuel injectors)
Ferrous picrate
Dual-fuel engines:
Bi-fuel Vehicles are vehicles with multifuel engines capable of running on two types of fuels. On internal combustion engines one fuel is gasoline or diesel, and the other is an alternate fuel such as natural gas (CNG), LPG or hydrogen. The two fuels are stored in separate tanks and the engine runs on one fuel at a time in some cases, in others both fuels are used in unison. Bi-fuel vehicles have the capability to switch back and forth from gasoline or diesel to the other fuel, manually or automatically.
Winter diesel:
Indian Oil Corporation Limited has developed winter-grade diesel for Ladakh to address the problem of loss of fluidity in fuel during extreme winter. This product has been developed by IOCL’s Panipat Refinery.
Why we need Winter Diesel:
Recently, Indian Oil Corporation Limited (IOCL) has sought approval from the Directorate General of Quality Assurance (DGQA) for the use of winter diesel by armed forces for operations in high altitude areas such as Ladakh. The winter diesel was introduced as a technological solution by IOCL in 2019 in high-altitude sectors like Ladakh, Kargil, Kaza and Keylong, which face the problem of loss of fluidity or freezing of diesel in their vehicles in extreme weather conditions.
It also meets the Bureau of Indian Standards (BIS) specification of BS-VI grade.
Characteristics:
Low Viscosity: It contains additives to maintain lower viscosity by enabling the fuel to remain fluid in such conditions.
Regular diesel fuel contains paraffin wax which is added for improving viscosity and lubrication. At low temperatures, the paraffin wax thickens or “gels” and hinders the flow of the fuel in the car engine.
The viscosity of a fluid is a measure of its resistance (due to internal friction) to deformation thereby maintaining the state of being thick and semi-fluid in consistency.
Paraffin wax is a soft colorless solid derived from petroleum, coal or shale oil that consists of a mixture of hydrocarbon molecules.
Low Pour Point: It has a low pour point (as low as minus 30-degree Celsius). It is the temperature below which the liquid loses its flow characteristics.
The flow characteristics of regular diesel change at low temperatures and using it may be detrimental to vehicles.
Earlier, the IOCL provided the Diesel High sulphur Pour Point (DHPP -W) to armed forces, which also has a pour point of -30°C.
Higher Cetane Rating: It has a higher cetane rating—which is an indicator of the combustion speed of diesel and compression needed for ignition.
Lower Sulphur Content: It would lead to lower chemical deposits in engines and better performance.
Significance:
Border Tensions with China in Ladakh: It is expected that demand for the winter fuel may rise due to the border tensions in the Galwan Valley in Ladakh for the patrolling purposes.
Boost to Local Economy: Supply of the special fuel to Ladakh would reduce the hardships faced by the local people for transportation and mobility during winter months, therefore facilitate the local economy and tourism.
Curb in Air Pollution: Before the launch of winter diesel, consumers in such areas were using kerosene to dilute diesel to make it usable, which leads to more air pollution.
Now use of winter diesel would replace use of Kerosene therefore helping in the reduction of air pollution.
Hydrogen fuel cell:
Hydrogen fuel is a zero-emission fuel burned with oxygen. A fuel cell combines hydrogen and oxygen to produce electricity, heat, and water. It can be used in fuel cells or internal combustion engines. It has begun to be used in commercial fuel cell vehicles, such as passenger cars, and has been used in fuel cell buses for many years. It is also used as a fuel for spacecraft propulsion.
Working principle:
A fuel cell is composed of an anode, cathode, and an electrolyte membrane. A typical fuel cell works by passing hydrogen through the anode of a fuel cell and oxygen through the cathode. At the anode site, a catalyst splits the hydrogen molecules into electrons and protons. The protons pass through the porous electrolyte membrane, while the electrons are forced through a circuit, generating an electric current and excess heat. At the cathode, the protons, electrons, and oxygen combine to produce water molecules. As there are no moving parts, fuel cells operate silently and with extremely high reliability.
Why should we use?
Hydrogen is the most abundant element on world
Zero-emission fuel, reduced greenhouse gas emissions
Development of renewable energy resources
High efficiency (IC engine efficiency in most of the case is 25%, Fuel cell goes up to 35%)
Quick Charging
High Reliability
No energy loss
Flexibility in installation and operation
Improved environmental quality
Hydrogen production have neutral foot-print
Hydrogen is a by-product of many industry which can be used
Hydrogen is better transportable and storable
Reduced demand for foreign oil
Disadvantages:
Uncontrolled reaction is explosive. So, the hydrogen is stored in liquid form in thick-walled tanks that are particularly safe
Expensive to manufacture due the high cost of catalysts (platinum)
Lack of infrastructure
Rocket Fuel:
Rockets create thrust by expelling mass backward at high velocity. The thrust produced can be calculated by multiplying the mass flow rate of the propellants with their exhaust velocity relative to the rocket (specific impulse). A rocket can be thought of as being accelerated by the pressure of the combusting gases against the combustion chamber and nozzle, not by "pushing" against the air behind or below it. Rocket engines perform best in outer space because of the lack of air pressure on the outside of the engine. In space it is also possible to fit a longer nozzle without suffering from flow separation.
Most chemical propellants release energy through redox chemistry, more specifically combustion. As such, both an oxidizing agent and a reducing agent (fuel) must be present in the mixture. Decomposition, such as that of highly unstable peroxide bonds in monopropellant rockets, can also be the source of energy.
Chemical rockets can be grouped by phase. Solid rockets use propellant in the solid phase, liquid fuel rockets use propellant in the liquid phase, gas fuel rockets use propellant in the gas phase, and hybrid rockets use a combination of solid and liquid or gaseous propellants.
Types of propellant:
Solid Chemical Rocket Propellants
Liquid Chemical Rocket Propellants
Hybrid Propellants
Gaseous Propellants
Inert Propellants
An overview:
Solid Propellants:
In the case of solid rocket motors, the fuel and oxidizer are combined when the motor is cast. Propellant combustion occurs inside the motor casing, which must contain the pressures developed. Solid rockets typically have higher thrust, less specific impulse, shorter burn times, and a higher mass than liquid rockets, and additionally cannot be stopped once lit.
Liquid Propellants:
In the case of bipropellant liquid rockets, a mixture of reducing fuel and oxidizing oxidizer is introduced into a combustion chamber, typically using a turbopump to overcome the pressure. As combustion takes place, the liquid propellant mass is converted into a huge volume of gas at high temperature and pressure. This exhaust stream is ejected from the engine nozzle at high velocity, creating an opposing force that propels the rocket forward in accordance with Newton's laws of motion.
Hybrid Propellants:
A hybrid rocket usually has a solid fuel and a liquid or NEMA oxidizer. The fluid oxidizer can make it possible to throttle and restart the motor just like a liquid-fueled rocket. Hybrid rockets can also be environmentally safer than solid rockets since some high-performance solid-phase oxidizers contain chlorine (specifically composites with ammonium perchlorate), versus the more benign liquid oxygen or nitrous oxide often used in hybrids. This is only true for specific hybrid systems. There have been hybrids which have used chlorine or fluorine compounds as oxidizers and hazardous materials such as beryllium compounds mixed into the solid fuel grain. Because just one constituent is a fluid, hybrids can be simpler than liquid rockets depending motive force used to transport the fluid into the combustion chamber. Fewer fluids typically mean fewer and smaller piping systems, valves and pumps (if utilized).
Gaseous Propellants:
GOX (gaseous oxygen) was used as the oxidizer for the Buran program's orbital maneuvering system.
Inert Propellants:
Some rocket designs impart energy to their propellants with external energy sources.
For example, water rockets use a compressed gas, typically air, to force the water reaction
mass out of the rocket. Such as: Ion thruster, Thermal Rocket, compressed gas.
Fuels used in Aircrafts:
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