Why producing CBG, LBG, hydrogen, methanol from biogas can be beneficial

Subject :Environment

Biogas, a renewable fuel produced using the anaerobic digestion process from organic feedstock, is primarily composed of methane (50-65 per cent), carbon dioxide (30-40 per cent), hydrogen sulfide (1-2.5 per cent) and a very small fraction of moisture.
It was predominantly thought of as a rural economy product.
Biogas contributes to all 17 of the United Nation’s Sustainable Development Goals. Furthermore, biogas can also be converted to produce numerous sustainable transportation fuels.
The removal of unwanted components like carbon dioxide,hydrogen sulphide and moisture from raw biogas yields pure methane (over 97 per cent content).
Some of the common methods to purify biogas include water scrubbing, membrane separation,pressure swing adsorption and adsorption.

Compressed biogas (CBG)-

This upgraded or high-purity biogas compressed at 250 bar pressure results in a fuel called compressed biogas (CBG). This has properties similar to compressed natural gas (CNG) and could be directly used to power CNG engines.
Drawbacks of CBG-
- Its existence in the gaseous form
- Demands bigger volumes for transportation.
- Considered more suitable to power small-sized vehicles, though heavy engines have been used for short-distance driving.

Liquified biogas (LBG)-

If the biogas-derived methane is liquefied by cooling it at -162 degrees Celsius, the fuel thus obtained is liquefied biogas (LBG). It has a higher energy density that lowers storage space requirements.
Advantage of LBG-
- LBG has become a viable alternative fuel for heavy-duty road transportation.
It has-
- High energy density (1 litre of LBG against 2.4 litres of CBG)
- Low sulphur content
- Lower life cycle greenhouse gas emissions than diesel.
LBG is also becoming attractive to the shipping industry in addition to being utilised in heavy-duty vehicles.

Hydrogen and Methanol-

Biomethane can also be transformed into other fuels such as hydrogen and methanol.
Gasification process produces Syngas, a mixture of hydrogen and carbon monoxide. Methanol can also be generated from syngas.
The hydrogen produced after the removal of carbon monoxide could be used in fuel cells to generate power.
Advantages of Methanol-
- Methanol is an effective fuel with an octane rating of 100. It emits less particulate matter and NOx than gasoline and doesn’t produce SOx because it doesn’t contain sulphur.
- It can be used also as a transportation fuel by blending or entirely replacing gasoline. Methanol, which is more affordable than LNG or marine oils with virtually no SOx or NOx emissions.

Leading country-

Presently, China leads the methanol-based automobile sector with vehicles running on different blends of gasoline and pure M100.

India’s scenario-

In the Indian context, CBG is the only transportation fuel from biogas for which commercialisation efforts have been made.
Currently, LBG, hydrogen and methanol are not produced from biogas in India. The main reasons are-
- the unavailability of biogas in bulk for such derivatives
- the absence of infrastructure to generate and market these fuels
- the deficiency of modified automobile engines
- the lack of effective research and development

Government initiative-

The Indian government has been encouraging private businesses to set up CBG plants and provide CBG to oil marketing companies for sale as automotive and industrial fuels under the Sustainable Alternative Towards Affordable Transportation (SATAT) scheme launched in 2018.
It has set a goal to produce 15 million tonnes of CBG from 5,000 plants by 2023–24.

As of August 2022, a total of 37 plants have been commissioned with an average capacity of 5 tonnes per day.