Alternate Fuels

Abstract— Alternative fuels are fuels which are not derived from fossil fuels. They are often referred to as renewable or clean fuels because they are typically derived from renewable sources and produce fewer emissions than traditional fossil fuels. Examples of alternative fuels include biodiesel, ethanol, compressed natural gas (CNG), hydrogen, and electricity. Alternative fuels are becoming increasingly popular as a way to reduce emissions and dependence on fossil fuels. At present they are commercially available as many countries and companies invest in research and development of alternative fuel technologies for making it accessible and sustainable.

                                                                                              I.    Introduction

The availability of energy has transformed the course of humanity over the last few centuries. Initially, humans were dependent on the coal and hydropower; however, with advancement in technology, new sources of energy have been unlocked – compressed natural gas (CNG), hydrogen, ethanol, methanol, solar energy, wind energy, etc. The production rate of these energy forms, required for commercial/domestic purposes, are increasing gradually. 

Fig. 1 Global Energy Consumption rate over the years.

1. Coal

Coal one of the most important primary fossil fuels, a solid carbon-rich material that is usually brown or black and

most often occurs in stratified sedimentary deposits. Figure 2 shows the date of coal consumption over the years. As it is seen that, in comparison with other sources of energy coal consumption rate is high.

Fig. 2 Coal consumption rate over the years.

coal deposits

Coal is defined as having more than 50 percent by weight (or 70 percent by volume) carbonaceous matter produced by the compaction and hardening of altered plant remains—namely, peat deposits. Different varieties of coal arise because of differences in the kinds of plant material (coal type), degree of coalification (coal rank), and range of impurities (coal grade). Although most coals occur in stratified sedimentary deposits, the deposits may later be subjected to elevated temperatures and pressures caused by igneous intrusions or deformation during orogenesis (i.e., processes of mountain building), resulting in the development of anthracite and even graphite. Although the concentration of carbon in Earth’s crust does not exceed 0.1 percent by weight, it is indispensable to life and constitutes humankind’s main source of energy.

2. Natural Gas

Natural gas is an alternative fuel that burns clean and is widely available to people in many countries such as Russia, Uzbekistan, Iran to name a few. Use of natural gas for domestic and commercial purposes have pros and cons as follows. Pros: Cars and trucks with specially designed engines produce fewer harmful emissions than gasoline or diesel. cons: Natural gas creates methane, a greenhouse gas which produces global warming 21 times more than the CO2.

 

3. Ethanol

An alcohol-based alternative fuel made by fermenting and distilling crops such as corn, barley or wheat. It can be blended with gasoline to increase octane levels and reduces harmful emissions significantly. Pros: Materials are renewable. cons: Ethanol subsidies have a negative impact on food prices and availability.

 

4. Electricity

Electricity can be used as an alternative fuel for battery-powered electric and fuel-cell vehicles. Battery powered electric vehicles store power in batteries that are recharged by plugging the vehicle into a standard electrical source. Fuel-cell vehicles run on electricity that is produced through an electrochemical reaction that occurs when hydrogen and oxygen are combined. Pros: Electricity for transportation is highly efficient, and we already have an extensive electricity network. In the case of fuel cells, they produce electricity without combustion or pollution. cons: Much electricity is generated today from coal or natural gas, leaving a bad carbon footprint. (Nonetheless, electric vehicles are still the greenest option around when it comes to cars.)

 

 

5. Propane

Propane—also called liquefied petroleum gas or LPG—is a by-product of natural gas processing and crude oil refining. Already widely used as a fuel for cooking and heating, propane is also a popular alternative fuel for vehicles.  Pros: Propane produces fewer emissions than gasoline, and there is also a highly developed infrastructure for propane transport, storage and distribution. cons: Natural gas production creates methane, a greenhouse gas that is 21 times worse for global warming than CO2

 

6. Biodiesel

Biodiesel is an alternative fuel based on vegetable oils or animal fats. To burn the biodiesel in its purest form, vehicle engine needs modifications. However, when blended with petrol/diesel, no significant engine modification is required. Pros: Biodiesel is safe, biodegradable, reduces air pollutants associated with vehicle emissions, such as particulate matter, carbon monoxide and hydrocarbons. cons: Limited production and distribution infrastructure.

Fig. 3 Biodiesel

7. Methanol

Methanol, also known as wood alcohol, can be used as an alternative fuel in flexible fuel vehicles that are designed to run on M85, a blend of 85 percent methanol and 15 percent gasoline, but automakers are no longer manufacturing methanol-powered vehicles. Pros: Methanol could become an important alternative fuel in the future as a source of the hydrogen needed to power fuel-cell vehicles. cons: Automakers are no longer manufacturing methanol-powered vehicles.

 

8. Hydrogen

Hydrogen can be mixed with natural gas to create an alternative fuel for vehicles that use certain types of internal combustion engines. Hydrogen is also used in fuel-cell vehicles that run on electricity produced by the petrochemical reaction that occurs when hydrogen and oxygen are combined in the fuel “stack.” Pros: No bad emissions. cons: Cost. And also, the lack of fuelling infrastructure and difficulty of putting it in place.

 

                                                                     I.    The hydrogen colour spectrum

From green to pink hydrogen, we reveal the rainbow of hydrogen colours and the different types of technology used to produce each which is shown in below Figure 4 The hydrogen colour spectrum.

Fig. 4 The hydrogen colour spectrum

 

Why is a colorless gas given so many colourful terms?

Green hydrogen, blue hydrogen, brown hydrogen and even yellow hydrogen, turquoise hydrogen and pink hydrogen. They’re essentially colour codes, or nicknames, used within the energy industry to differentiate between the types of hydrogen.

Depending on the type of production used, different colours are assigned to the hydrogen. But there is no universal naming convention and these colour definitions may change over time, and even between countries.

    I.    We’re currently used to a blue flame from gas, so what colour will a hydrogen flame be?

The industry has not yet reached a consensus on this, but it will be the most obvious difference for people who’ve been used to seeing a blue gas flame inside their boilers or when igniting their hobs. The flame colour for hydrogen would be specifically added. Are you ready for a green flame?

1)   Blue hydrogen

Blue hydrogen is produced mainly from natural gas, using a process called steam reforming, which brings together natural gas and heated water in the form of steam. The output is hydrogen – but also carbon dioxide as a by-product. That means carbon capture and storage (CCS) is essential to trap and store this carbon. Blue hydrogen is sometimes described as ‘low-carbon hydrogen’ as the steam reforming process doesn’t actually avoid the creation of greenhouse gases.

2)   Grey hydrogen

Currently, this is the most common form of hydrogen production. Grey hydrogen is created from natural gas, or methane, using steam methane reformation but without capturing the greenhouse gases made in the process.

3)   Black and brown hydrogen

Using black coal or lignite (brown coal) in the hydrogen-making process, these black and brown hydrogen are the absolute opposite of green hydrogen in the hydrogen spectrum and the most environmentally damaging. Just to confuse things, any hydrogen made from fossil fuels through the process of ‘gasification’ is sometimes called black or brown hydrogen interchangeably. Japan and Australia announced a new brown coal-to-hydrogen project recently. This project will use brown coal in Australia to produce liquefied hydrogen, which will then be shipped to Japan for low-emission use.

4)   Pink hydrogen

Pink hydrogen is generated through electrolysis powered by nuclear energy. Nuclear-produced hydrogen can also be referred to as purple hydrogen or red hydrogen. In addition, the very high temperatures from nuclear reactors could be used in other hydrogen productions by producing steam for more efficient electrolysis or fossil gas-based steam methane reforming.

5)   Turquoise hydrogen

This is a new entry in the hydrogen colour charts and production has yet to be proven at scale. Turquoise hydrogen is made using a process called methane pyrolysis to produce hydrogen and solid carbon. In the future, turquoise hydrogen may be valued as a low-emission hydrogen, dependent on the thermal process being powered with renewable energy and the carbon being permanently stored or used.

6)   Yellow hydrogen

Yellow hydrogen is a relatively new phrase for hydrogen made through electrolysis using solar power.

7)   White hydrogen

White hydrogen is a naturally-occurring geological hydrogen found in underground deposits and created through fracking. There are no strategies to exploit this hydrogen at present.

                                                                                        II.    Green hydrogen

 

In the kaleidoscope of hydrogen colours, green hydrogen is the one produced with no harmful greenhouse gas emissions. Green hydrogen is made by using clean electricity from surplus renewable energy sources, such as solar or wind power, to electrolyse water. Electrolysers use an electrochemical reaction to split water into its components of hydrogen and oxygen, emitting zero-carbon dioxide in the process.

Green hydrogen currently makes up a small percentage of the overall hydrogen, because production is expensive. Just as energy from wind power has reduced in price, green hydrogen will come down in price as it becomes more common.

Fig. 5   Electrolysis method

[1]     Development of Data Acquisition System and Hardware Simulator for Turbojet Engine Test Bench Using Alternative Fuels

INSPEC Accession Number: 19078532 DOI: 10.1109/MILTECHS.2019.8870037.

[2]     Amarnath HK and Prabhakaran P. A Study on the Thermal Performance and Emissions of a Variable Compression Ratio Diesel Engine Fuelled with Karanja Biodiesel and the Optimization of Parameters Based on Experimental Data. International Journal of Green Energy, 2012; 9: 841–863.

[3]     R. Jeeragal, S. Biradar and U. A. Inamdar, "Performance and Emission Charecteristics of Ethanol Fueled Transportation Engine," 2020 IEEE Bangalore Humanitarian Technology Conference (B-HTC), pp. 1-4, 2020.

[4]     Jaichandar S, Annamalai K. Combined impact of injection pressure and combustion chamber geometry on the performance of a biodiesel fuelled diesel engine. Energy, 2013; 55: 330–339.

 

[5]     Demirbas A. Biofuel resources, biofuel policy, biofuel economy and global biofuel projection. Energy conservation and Management, 2008; 49: 2106-2116.