For Prelims: Biogas, Sustainable Development Goals, compressed biogas (CBG), liquefied biogas (LBG), hydrogen, methanol, and Sustainable Alternative Towards Affordable Transportation (SATAT).

For Mains: Significance of Biogas, advantages, and disadvantages. 

Why in News?

Countries worldwide are inclined towards biomethane and biogas to raise their energy security. 

What do we need to know about biogas?

  • Methane (50–65%), carbon dioxide (30–40%), hydrogen sulfide (1-2.5%), and a very small amount of moisture make up the majority of biogas. This fuel can be produced again by anaerobically breaking down organic feedstock.
  • In addition to assisting in developing many sustainable transportation fuels, it contributes to the United Nations' Sustainable Development Goals.

Variants:

  • Compressed Bio Gas (CBG): Compressed biogas (CBG) is a fuel made from upgraded or high-purity biogas that has been compressed at 250 bar pressure after being stripped of unwanted substances like carbon dioxide, hydrogen sulfide, and moisture. 
  • It can share similar features as that of CNG to power CNG engines. 
  • Its gaseous nature increases the cost and complexity of transportation. 
  • Although large engines have traditionally powered short-distance driving, it is more suitable for small-sized vehicles.
  • Methane derived from biogas that has been liquefied by cooling it to -162 degrees Celsius is known as liquefied biogas (LBG). It requires less storage space because it has a higher energy density.
  • The energy density of liquid methane at atmospheric pressure is roughly 600 times greater than that of gaseous methane and 2.5 times greater than that of methane at 250 bar.
  • The fact that it has a relatively high energy density makes it a potential replacement fuel for heavy-duty road transportation.
  • In addition to being used in heavy-duty vehicles, it is starting to attract the attention of the shipping industry.

Applications:

  • Biogas can be used to create a variety of eco-friendly transportation fuels.
  • Along with being used as fuel, biomethane can also be converted into other fuels like hydrogen and methanol. 
  • The primary method of producing hydrogen encourages reforming light hydrocarbons, mainly methane, which makes up a significant portion of biogas.
  • Limiting the amount of oxygen and steam present in the reaction while raising the temperature of the bio-methane to high levels (typically over 600°C) is known as gasification.
  • This process results in the production of syngas, a mixture of hydrogen and carbon monoxide. Fuel cells could be powered by the hydrogen that is left over after carbon monoxide is removed.
  • Syngas can also be used to produce methanol. 
  • Methanol emits less nitrogen oxide (NOx) and particulate matter than gasoline, making it a more efficient fuel. 
  • As a substitute for or in addition to gasoline, it can also be used as a transportation fuel. It is more inexpensive than LNG. 

What is India's current state of biogas and methanol?

CBG is the only transportation fuel derived from biogas for which commercialization efforts have been made.

The main reasons why biogas cannot currently be converted into LBG, hydrogen, or methanol in India are

  • Lack of bulk biogas availability for such derivatives and infrastructure for selling and manufacturing these fuels. 
  • Research and development efforts to improve process economics need to be more comprehensive to address the shortcomings of modified automobile engines or their lack of effectiveness.
  • Initiatives from the government: The Sustainable Alternative Towards Affordable Transportation (SATAT) program, introduced in 2018, encourages private companies to build CBG plants and supply CBG to oil marketing firms for sale as automotive and industrial fuels.
  • The Indian government and Niti Aayog have also developed a roadmap to promote LNG, hydrogen, and methanol and speed up the switch to greener fuels.

Source: DTE