Is Methanol the Fuel of the Future?

Methanol as the fuel of the future- Yes or No?

Abstract

Methanol or methyl alcohol received a great amount of attention in the early 1990s as an alternative fuel to gasoline in the United States. It can be easily produced from several resources found abundant in nature like coal and natural gas. Though toxic in nature, it has certain properties making it a worthy substitute as the alternative green fuel of the future. China is a leading user of methanol as fuel in their public transports and the private sector as well and many countries are starting to follow this example. Researches are starting afresh to put methanol back in the trend of being used as an automotive fuel.

Table of Contents

• Introduction
• Production/Manufacture
• Advantages and Disadvantages
• Technical/Legislative challenges
• Critical Analysis
• Conclusion
• Reference and Bibliography

Introduction

Methanol or methyl alcohol is a liquid organic chemical. Its chemical formula is CH3OH. Methanol is created from the destructive distillation of wood, this being the primary reason it is also called wood alcohol. Some of its distinctive properties include it being volatile, flammable, colourless and highly poisonous.

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History shows ethanol being used by ancient Egyptians sing it as an embalming liquid. In modern times, methanol was isolated as a chemical by the pyrolysis or destructive distillation of boxwood by Irish chemist Robert Boyle in 1661. But it was in 1834 when French chemists Eugene Peligot and jean-Baptiste Dumas introduced its properties in organic chemistry and also coined the term Methylene meaning ‘methy=wine’ and ‘hyle=wood’.

Production/ Manufacture:

Pyrolysis or destructive distillation of wood has always been the primary method of producing methyl alcohol. Methanol is also produced naturally, by the anaerobic metabolism of organic matter by a variety of bacteria. Huge reserves of methane gas are found in sea beds due to decay of sea life.

In 1923, German chemist duo Alwin Mittasch and Mathias Pier produced methanol by converting synthesis gas i.e. a mixture of carbon mono oxide, carbon dioxide and hydrogen gases. This was a catalytic process and manganese and chromium oxides were the chief catalysts used in this process. But the process required very high temperature ranging from 50-20 atmospheres and 450⸰C.

In late 1960s, low pressure methanol (LPM) started getting produced using copper as the chief catalyst which required much lower temperature and pressure.[1][2]

Synthesis gas is derived from feedstock which is primarily coal, natural gas or oil. However, this is not the ‘green’ method of producing methanol. Green methods include producing methanol from industrial, agricultural or city wastes. This process is near similar to the process of manufacturing methanol from coal.

A modern plant, located in the Netherlands, uses liquid propane, 1,2,3-triol (glycerol) derived as by-products from production of bio-diesel from animal fats and vegetable oils to produce synthesis gas. Another method is to use waste carbon dioxide.[5]

The reaction equation for production of methanol from synthesis gas is as follows:

$\mathit{CO}+2H_{2}O\rightleftarrows C{H}_3\mathit{OH}$

$\mathrm{\Delta }H= –91\mathit{ KJ}{\mathit{mol}}^{–1}$

This shows that low temperature and high pressure favour the formation of methanol. This is achieved industrially at 457-575 K and around 100 atmospheres with the aid of copper catalysts. [1]

Several new methods of production of methanol on large scale are still an area of active research.

Annual production of methanol

1. M Alvarado, Methanol, 2016, IHS
   2.  Expected to be approaching 80 million tonnes in 2016 and 100 million tonnes in 2020
   3.  Methanol Market Services Asia, 2016.  Data estimated for 2015
   4.  2015 Guide to the Business of Chemistry, American Chemistry Council, 2016

Advantages and Disadvantages

Methanol is a volatile and flammable liquid. But it burns cooler and faster than gasoline. Methanol has a Research Octane Number of 108.7 and Measured Octane Number of 88.6. This is higher than regular gasoline with a Research Octane Number of 87. This makes the flame front in spark plug engines spread faster and help to create a complete combustion of fuels in the combustion chamber. Methanol is also not as explosive as gasoline, this being the primary reason race car drivers prefer it over gasoline since in case of a crash. Methanol is also sulphur free hence there is no need of worrying about sulphur oxides as an emission. It is also free from BTEX pollutants found in gasoline i.e. benzene, toluene, ethyl-benzene and xylene. BTEX pollutants are highly carcinogenic in nature. [2][3]

Another large advantage of methanol is that it can be produced from multiple resources abundant in nature. Although methane is a green house gas and participates in global warming, trying to harness it as an energy source can help us solve a large part of the energy crisis problem. Methanol emissions contain much less CO2 and NOx percentages than gasoline. It is also less reactive than gasoline in atmosphere. The half-life of methanol in ground and water is just 1-7 days while that of gasoline is 10-370 days. Thus, methanol is much more bio-degradable and safer than gasoline. This also reduces green house gases releasing into the atmosphere.

However, there are also a lot of drawbacks when using methanol as a fuel. Its volatility is comparably low to that of gasoline, so engines using it as a fuel has problems in cold starting. This alone leads to a tremendous amount of pollution when cold starting.

Calorific value of methanol is 23 MJ/kg while that of petrol is 45.8 MJ/kg. So technically, to produce the same amount of power produced by a certain amount of petrol, twice the amount of methanol needs to be burned. This requires for large on-board storage tanks on the vehicle which is inconvenient and dangerous. Moreover, it is miscible in water and leakages can cause it to release in the atmosphere increasing greenhouse gas effect. The major emission from methanol burning is formaldehyde (500% by volume) which when ingested can cause hypoxia and metabolic acidosis. Methanol, itself is very poisonous and toxic. Ingestion or long periods of contact can cause permanent blindness and also lead to degradation of liver and optic nerve.

Also, methanol reacts with certain type of metal constituents, especially aluminium for oil and seal rings inside the combustion chamber leading to corrosion of the engine.

Production and manufacture of methanol is still not properly planned and developed in accordance with current needs and pollution norms. Hence, cost of production is higher than that of gasoline.

Applications

Methanol has wide range of applications. These include small scale to large scale applications.

It is a polar liquid at room temperature and is used as an anti-freezing agent. It is also a very popular industrial solvent for paints and aerosol sprays. It is also widely used as an extractant for animal fats and vegetable oils (transesterification). It is also used as a denaturant for ethanol, giving it the name ‘methylated spirit’.

Methanol, by far is largely used for manufacturing other chemicals. Forty percent of the produced methanol is used to convert it into formaldehyde which is used to produce a wide variety of polymers to produce plastics, ply-woods, explosives and paints. [2][3]

As a fuel, methanol has had a very rough journey. It quickly rose to become the alternative fuel in the United States in the 1990s during the oil crisis. However, it quickly went out of fashion when oil prices plummeted a few years later. Engines were designed by several auto OEMs to run on either pure methanol or methanol blended with gasoline. [6] Fuels with 15% methanol can be used in cars without modifying the engine. 85% methanol blends require slight modifications of the engine. Volvo was the first to design flexible engines which could run on pure methanol or methanol blends. [4] Also, pre-catalytic chambers were designed to reduce tail pipe emissions. The pre-catalytic chamber is metallic instead of ceramic and is heated by electricity. This pre-chamber ensures that there are very less unburned hydrocarbons in the exhaust. China is the largest user of methanol in their daily usage of fuels. They use the 15% and 85% blends and annual usage is more than 1 billion gallons of methanol. [6]

Lastly, direct methanol fuel cells are proton-exchange fuel cells which are emerging as a good alternative in portable applications. In these cells, methanol is oxidised over a catalyst to form carbon dioxide. Water molecules are consumed at the anode and the protons are transported across the exchange membrane where they react at the cathode with oxygen molecules to form water. The electrons produced at the anode pass through an external circuit through the appliance, powering it up. The equations are:

• ${\mathit{CH}}_3\mathit{OH}{+H}_{2}O={6H}^{+}+{6e}^{–}+{\mathit{CO}}_2 \left(\mathrm{ANODE}\right)$
• ${}_2{}^3{O}_2+{6H}^{+}+{6e}^{–}={3H}_{2}O\left(\mathrm{CATHODE}\right)\mathrm{ }$
• ${\mathit{CH}}_3\mathit{OH}$

  + ${}_2{}^3{O}_2={2H}_{2}O+{\mathit{CO}}_2 \left(\mathit{OVERALL}\right)$

 Though they are not very efficient, they are used in applications which require energy and power density more than efficiency. This means they can provide a small amount of power over a longer period of time. This makes them ideal for small scale applications like chargers, forklifts, tuggers and military tactical equipment.[2] 

Technological/Legislative challenges

The primary problem with methanol is that it is toxic and can affect human health and the environment quite highly. As a fuel, it has certain drawbacks too. It is not easily flammable, making it challenging to ignite it during cold starts. It burns cooler than gasoline and has a colourless flame. So, it is almost impossible to detect a fire from methanol. [1][2]

The low calorific value of methanol is also a large factor standing on its way to be chosen as the best alternative. Since production of methanol is more expensive than gasoline, customers will end up spending much more to run their vehicles on methanol. Also, methanol corrodes aluminium parts inside the engine, reducing its lifetime. The chemical reaction equation is as follows:

$6\mathit{ C}{h}_3\mathit{OH}+{\mathit{Al}}_2{O}_3=2{\mathit{Al}\left({\mathit{OCH}}_3\right)}_3+3H_{2}O$

This reaction shows how methanol removes the protective coating on the surface of aluminium parts. Once this protective layer is gone, the aluminium is exposed to be attacked by methanol.

$6\mathit{ C}{h}_3\mathit{OH}+2\mathit{Al}= 2{\mathit{Al}\left({\mathit{OCH}}_3\right)}_3+3H_2$

This is highly undesirable in engines. But this process can be inhibited by using certain solvents and anti-corrosive layers on the aluminium parts. [2]

Methanol affects the lifetime of birds, animals and plants and can lead to death with prolonged exposure. It also inhibits growth in plants. [3]

The vital reason why the United States chose ethanol over methanol for mass production is due to the fact that methanol can be consumed as an alcohol with vary high health hazards. During the period of Prohibition in the United States, methanol was being consumed resulting in a high number of permanent blindness and death of consumers. During the Oil Crisis, although OEMs started producing flexi-fuel cars running on methanol, American lobbyists pushed ethanol upfront as this was easily produced from corn and boosted the agricultural industry in the United States. [6]

Critical Analysis

After viewing all pros and cons of methanol, it is found that it is a god substitute for gasoline and diesel in vehicles. Though certain technical drawbacks exist, they can be overcome with modifications. For instance, corrosive properties of methanol can be reduced by using other materials to make oil and seal rings which are not attacked by methanol.

Specialized tanks can be built for on-board storage which would be safer and prevent leakages. Electrically heated pre-catalytic chambers were already introduced by Volvo in early 90s to reduce tail-pipe emissions.

Manufacturing of methanol is still an expensive process because it involves using non-renewable sources of energy as the feedstock. However, if excess energy produced by solar, wind and geo-thermal power plants is used to produce methanol, then it reduces costs of large-scale manufacturing by a great extent. When that happens, methanol will be easily available for wide-spread usage. This will help to reduce overall air pollution and control greenhouse effects.

Conclusion

Methanol certainly is a strong candidate as the fuel of the future. Its drawbacks can be overcome with slight effort but the benefits reaped from it would be very high. Considering its widespread use in the chemical industry, it can also become predominant in the fuel industry as well.

References:

1. Lazonby, J. (2019). Methanol. [online] Essentialchemicalindustry.org. Available at: http://www.essentialchemicalindustry.org/chemicals/methanol.html
2. Targetstudy.com. (2019). Methanol invented by Robert Boyle in year 1661. [online] Available at: https://targetstudy.com/knowledge/invention/35/methanol.html
3. The Chemical Company. (2019). Methanol – The Chemical Company. [online] Available at: https://thechemco.com/chemical/methanol
4. Holusha, J. (2019). Technology; When Clean-Air, Methanol-Powered Cars Hit the Road. [online] Nytimes.com. Available at: https://www.nytimes.com/1991/07/28/business/technology-when-clean-air-methanol-powered-cars-hit-the-road.html
5. Afdc.energy.gov. (2019). Alternative Fuels Data Centre: Methanol. [online] Available at: https://afdc.energy.gov/fuels/emerging_methanol.html [Accessed 8 Jan. 2019].
6. Fuel Freedom Foundation. (2019). Why aren’t we using methanol? — Fuel Freedom. [online] Available at: https://www.fuelfreedom.org/why-arent-we-using-methanol