Biogas: Advantages and Challenges – Explained, pointwise

Introduction

The Union Budget 2023-24 has given a new push for clean energy. Apart from providing INR 35,000 crore for priority capital investments towards energy transition and net zero objectives, the Budget has earmarked INR 10,000 crore for establishing 500 new ‘Waste to Wealth‘ plants under GOBARdhan (Galvanizing Organic Bio-Agro Resources Dhan) scheme for promoting circular economy. Of the 500 new plants announced, 200 will be Compressed Biogas Plants (CBG), including 75 in cities and the remaining 300 will be community or cluster-based plants. Biogas is an environment friendly solution to ensure energy security as well as a small step towards reducing dependence on fossil fuels.

What is Bio-gas and how is it produced?

Biogas is a mixture of Methane (CH₄), Carbon-dioxide (CO₂)and small quantities of other gases. It is produced by anaerobic fermentation of organic matter in an oxygen-free environment. The precise composition of biogas depends on the type of feedstock and the production method used. The organic matter to produce biogas can be biodegradable waste such as agricultural waste, animal waste like dung and segregated organic fraction of municipal solid waste.

Generally, the fermentation goes through four stages to turn the organic material into biogas. In the first step (Hydrolysis), bacteria break down carbohydrates. In the second stage (Acidogenesis), acidogenic bacteria turn sugars and amino acids into carbon dioxide, organic acids, hydrogen, and ammonia. In the third stage (Acetogenesis), these organic acids are transformed into acetates. In the final stage (Methogenesis), methanogens break the components (acetates) to obtain methane and carbon dioxide.

Anaerobic digestion yields a variety of products in three different forms. The slurry obtained from the process is used to extract liquid fertiliser and the fermented organic manure (FOM) in solid form.

The solid part of products is used as soil conditioner and fertiliser.

The gaseous products are known as Biogas. It contains about 55-65% Methane, 35-44% of carbon dioxide and traces of other gases such as hydrogen sulphide, ammonia and nitrogen.

Compressed Biogas (CBG): Biogas can be purified and upgraded up to 98% of purity to make it suitable to be used as a green fuel for transportation or filling of cylinders. The process relies on a high pressure of ~250 bar and hence is called Compressed Biogas (CBG).

Bio-Methane: It is also known as ‘renewable natural gas’. It is a near-pure source of methane produced either by ‘upgrading’ biogas or through the gasification of solid biomass followed by Methanation. Upgradation refers to a process that removes any CO₂ and other contaminants present in the biogas.

What are the various initiatives taken by the Government with respect to Biogas?

First, Under the Sustainable Alternative to More Affordable Transportation (SATAT) programme (launched 2018), the Government of India has been encouraging private businesses to establish Compressed Biogas (CBG) plants and provide CBG to oil marketing companies so that it can be sold as an automotive and industrial fuel.

Second, Galvanizing Organic Bio-Agro Resources (GOBAR)-Dhan was launched by the Government of India in April 2018 as a part of the biodegradable waste management component under the Swachh Bharat Mission-Gramin.

Third, the Waste to Energy Division of the Ministry of New and Renewable Energy’s (MNRE)  has notified a five-year-long National Bioenergy Programme (2021-22 to 2025-26).

Fourth, the Government of India and NITI Aayog have devised road maps to speed up the country’s transition to environmentally friendly fuels and to boost the use of liquefied natural gas (LNG), hydrogen, and methanol.

What are the advantages of Biogas?

Environment Friendly: It is a renewable and environmentally friendly energy source. Less energy is required to produce Biogas compared to extracting natural gas.

Moreover, Methane has higher greenhouse/warming potential than carbon-dioxide. Hence, capturing and combusting methane to produce carbon-dioxide reduces the overall global warming, compared to a situation where methane is allowed to escape to the atmosphere.

Energy Diversification: Biogas production reduces reliance on fossil fuels such as oil and coal.

Renewable: The raw materials used in biogas production are renewable, as trees and crops will continue to grow. Manure, food scraps, and crop residue are always available raw materials, making it a highly sustainable option.

Reduce Soil and Water Pollution: Producing biogas from waste reduces dumping of wastes in landfills. Overflowing landfills not only emit foul odours, but also allow toxic liquids to enter underground water sources. As a result, another advantage of biogas is that it may improve water quality. Furthermore, anaerobic digestion deactivates pathogens and parasites, making it effective in reducing the prevalence of waterborne diseases.

Similarly, waste collection and management improve dramatically in areas with biogas plants. This, in turn, leads to improvements in the environment, sanitation, and hygiene.

Organic Fertilizers: The byproduct of the biogas generation process is enriched organic digestate, which is an excellent supplement to or replacement for chemical fertilisers. The fertiliser discharge from the digester can accelerate plant growth and resistance to diseases, whereas commercial fertilisers contain chemicals that are toxic and can cause food poisoning, besides other harmful effects.

Promotes Circular Economy: It is a simple and low-cost technology that promotes a circular economy. The technology used to generate biogas is relatively inexpensive. It is simple to set up and requires little investment when used on a small scale. Small biodigesters can be used at home, utilising kitchen waste and animal manure. After a while, a household system pays for itself, and the materials used in generation are completely free.

Biogas can also be compressed to the quality of natural gas and used to power automobiles in large plants. Such plants require little capital investment and create green jobs.

Healthy Alternative for Cooking Fuel: Biogas generators relieve women and children of the laborious task of gathering firewood. As a result, more time is available for other productive activities. More importantly, cooking on a biogas rather than an open fire keeps the family safe from smoke in the This aids in the prevention of deadly respiratory diseases.

Achieving SDGs: According to the Linköping University’s Biogas Research Center report, Biogas contributes to all 17 of the United Nation’s Sustainable Development Goals.

What are the challenges in Production and Use of Biogas?

Lack of Technological Advances: According to some experts, the systems used to produce biogas are inefficient. There is lack of a new technology that can simplify the process, make it accessible, and reduce the cost of doing so. This means that large-scale production to meet the needs of a large population is still impossible. Although current biogas plants can meet some energy needs, many governments are unwilling to invest in the sector.

Impurities: Impurities remain in biogas after refinement and compression. Use of Biogas in automobiles can corrode the engine’s metal parts. Corrosion would result in higher maintenance costs. The gaseous mixture is far more appropriate for kitchen stoves, water boilers, and lamps.

Temperature Limitation: Biogas generation, like other renewable energy sources (such as solar and wind), is influenced by the weather. The ideal temperature for bacteria to digest waste is around 37°C. Digesters in cold climates require heat energy to maintain a constant biogas supply. Hence its use is limited to warm regions.

Suitability for Metropolitan Areas: Another disadvantage is that industrial biogas plants only make sense where raw materials (food waste, manure) are abundant. As a result, biogas generation is much better suited to rural and suburban areas. The material used in biogas generation emit bad smells. Hence it is necessary that the plants are sufficiently far from the inhabited areas

To power a 1MW power plant, at least 300 hectares of land is required, as minimum usable area. Large quantities of land must therefore be available, which poses a challenge in urban areas.

Transport: If the plant is located far away, suitable means of transport will be needed to transport the raw materials and the final product. This will add to costs and emissions.

Conclusion

Biogas can prove to be a sustainable alternative to fossil fuels. It is an ideal source to ensure energy security in the rural areas. It can also contribute to decarbonization of the agriculture sector through conversion of methane. There is a need to invest in new technologies that can help scale up the use of Biogas in urban areas. This can help in achieving the climate targets in the long run.

Syllabus: GS III, Infrastructure: Energy; GS III, Conservation.

Source: Down to Earth, SBM, IEA, Outlook