Biogas, as a renewable energy source, is generated through a scientific process called Anaerobic Digestion (A.D.), involving bio-degradable organic materials like agricultural waste, livestock manure, kitchen scraps, and more. This process occurs within Biogas Plants, and the design of these plants is influenced by various factors and the specific feedstock being treated. Biogas is a gas mixture primarily composed of methane (CH4) and carbon dioxide (CO2), along with small amounts of hydrogen sulfide (H2S) and moisture. This gas is created when organic matter breaks down without oxygen, sourced from materials such as agricultural residue, animal dung, municipal waste, plant matter, sewage, and kitchen scraps. Biogas boasts a calorific value of approximately 5000 kcal per m3. Additionally, the residual slurry produced in the Biogas Plants serves as a nutrient-rich organic fertiliser, benefiting agriculture by enhancing crop yields and maintaining soil vitality.
Between April 2021 and January 2022, India’s expenditure on oil imports amounted to $94.3 billion. The nation’s current greenhouse gas (GHG) emissions stand at 2.88 gigatons. Annually, India imports nearly 25 million metric tons of liquefied natural gas. Biogas as a renewable source of energy holds significant potential in India’s energy transition, offering benefits such as energy security, affordability, promotion of entrepreneurship, rural job opportunities, and stimulation of local economies. Shifting towards biogas usage can foster job growth for semi-skilled and skilled labour in various domains such as waste collection, operations, construction, design, engineering, and business establishment. The Indian Government launched the Sustainable Alternative Towards Affordable Transportation (SATAT) initiative to enhance the availability of compressed biogas (CBG) in the automotive and industrial sectors. The initiative envisions investing INR 2 lakh crores ($263 billion) to establish 5,000 CBG plants by 2024, targeting the production of 15 million metric tons of CBG and 50 million metric tons of bio manure. Additional incentives encompass:
Biogas, as a renewable source of energy, consists of approximately 55-65% methane, 35-44% carbon dioxide, and minute quantities of other gases like Hydrogen Sulphide, Nitrogen, and Ammonia. In its natural state, without any refinement, biogas serves as a clean fuel for cooking comparable to LPG, lighting, motive power, and electricity generation. It can act as a substitute for up to 80% of diesel in diesel engines, and complete diesel replacement is feasible using 100% biogas engines. Furthermore, biogas can undergo purification and enhancement to attain up to 98% methane purity. It is a viable green and clean fuel for transportation or high-pressure cylinder filling at around 250 bars, known as Compressed Bio-Gas (CBG).
Initially, biogas plants were primarily designed for processing cattle dung. However, technological advancements have enabled the conversion of various forms of biomass materials and organic waste into biogas through a process known as bio-methanation. These sizes cater to different needs, including households, small farmers, dairy operations, communities, institutions, and industrial or commercial applications. For industrial and municipal waste-based biogas plants, the unit size can expand to produce between 15000 M3 and 20000 M3 of biogas per day.
MNRE has sanctioned a range of biogas as a renewable source of energy plant designs, proving their effectiveness in practical applications. The Indian standards for biogas plants, along with their accessories and appliances, have been established by both MNRE and BIS. This process is ongoing and continually evolving. Within the National Biogas and Manure Management Programme (NBMMP), four fundamental model types and ten designs of biogas plants have received approval. Comprehensive information about these is available in the program’s Guidelines. All these endorsed designs are eligible for consistent financial subsidies and other benefits nationwide. To motivate farmers to utilise nutrient-enriched organic bio-manure, the scheme also encourages the value enhancement of biogas plant slurry by linking it to enrichment units such as vermicomposting, Phosphate Rich Organic Manure (PROM) facilities, and other organic enrichment methods. This integration serves as an additional income source for farmers and aids in reducing their expenditure on chemical fertilisers.
Biogas as a renewable source of energyfacilities, serves as the dependable decentralised source of renewable energy in our country, catering to heating, cooking, electricity generation, and thermal energy needs. The promotion of this form of Decentralized Renewable Energy Source (DRES) for power generation, particularly within the small capacity range (3 kW to 250 kW), as well as for heating and cooling, relies on the utilisation of biogas generated from plants ranging from 30 M3 to 2500 M3 in size. These plants operate based on the availability of suitable quantities of biodegradable organic waste.
Various organic waste materials like cattle dung, animal waste, kitchen scraps, poultry droppings, and agro-industry waste are utilised as feedstock for these biogas plants. They hold advantages for fulfilling off-grid power needs in individual dairy and poultry operations, dairy cooperatives for dairy equipment operation, and other electrical, thermal, and cooling energy demands. The installation of such biogas systems replaces the use of diesel in DG sets, reducing electricity bills for individual farmers, beneficiaries, entrepreneurs, and dairy cooperatives, ultimately increasing their income. Additionally, nutrient-enriched organic bio-manure generated from these projects becomes an additional income stream and aids in reducing chemical fertiliser expenses, promoting ventures like organic farming. Biogas plants established under this scheme meet the electricity and thermal necessities of beneficiaries, dairy farmers, and other organisations. They find applications in milk chilling, pumping, lighting, irrigation, and cooking and can even be shared with neighbours in off-grid settings. Biogas primarily consists of methane and carbon dioxide, with trace amounts of hydrogen sulphide, moisture, and siloxanes. Methane, hydrogen, and carbon monoxide within the gas can be combusted or oxidised using oxygen, allowing biogas to serve as fuel for heating and cooking. Gas engines can also use it to convert its energy into electricity and heat. Family-sized biogas plants generate biogas from materials like cattle dung, other organic matter, farm biomass, gardens, kitchens, and night soil waste. This process, known as anaerobic digestion (AD), brings forth several benefits, such as:
Biogas, as a renewable source of energy, can be harnessed to fulfil heating needs on farms by burning it in boilers, heaters, or engines. Furthermore, it can address electrical requirements, and any excess electricity can potentially be sold to a local utility provider.
Regrettably, in most instances where full-scale anaerobic digestion is employed, the energy cost savings and potential revenue from electricity sales do not typically cover the capital and installation expenses, resulting in a negative cash flow. To counter this, producers often explore options like cost-sharing, grant funding, or other forms of supplementary support to offset a portion of the initial costs for setup. The residual material from the digestion process can undergo solid-liquid separation, with the liquid portion utilised as fertiliser. The separated solid fraction can be composted to stabilise it and transform it into a more usable product.
Various types of biogas plants are categorised based on the digested substrates they handle, the technology they employ, or their size. Biogas plants that primarily process manure are classified as agricultural biogas plants, often combining manure with other suitable organic materials, many of which originate from agricultural sources. Agricultural biogas plants can be divided into two main categories:
The distinction between these categories is not always strict, as technological aspects from one category can also be observed in the other.
The utilisation of biogas is in the following ways:
The specific documentation requirements can vary across different categories of renewable energy enterprises. Nevertheless, certain standard documents are essential:
Biogas stands as a prominent and promising renewable source of energy with multifaceted benefits that extend far beyond its energy generation capabilities. Its versatility in providing clean cooking fuel, lighting, power generation, and even transportation fuel showcases its potential to transform energy landscapes on local and global scales. By harnessing the natural decomposition processes of organic materials, biogas not only produces energy but also mitigates waste management challenges, reduces greenhouse gas emissions, and promotes sustainable agricultural practices through nutrient-rich bio-manure. The significant strides made in technology, government initiatives, and public awareness have propelled biogas into a key player in the quest for cleaner and more sustainable energy solutions. As we navigate the challenges of energy security, environmental preservation, and socio-economic development, biogas emerges as a beacon of hope, exemplifying how nature’s processes can be harnessed to power a brighter and greener future for generations to come. It is recommended to take expert advice for ensuring the documents that would be required for setting up a business on biogas as a renewable source of energy.
Biogas is a fuel that burns at a gradual pace, necessitating an engine with an elevated compression ratio to ensure effective combustion. Efficient ignition of the compressed mixture of air and biogas is achieved using a high-energy spark plug. The ignited biogas and air blend undergoes rapid heating, causing expansion, and subsequently propels the piston downward, generating torque that powers the engine’s rotation.
In the process of enhancing biogas to Renewable Natural Gas (RNG), the methane concentration is heightened by extracting moisture, carbon dioxide, hydrogen sulfide, and other contaminants. After this purification, injecting and transporting the upgraded gas through existing natural gas pipelines becomes possible, serving as a viable replacement for conventional natural gas.
The tank would probably include one or two sizable, hermetically sealed containers with ample storage volume to accommodate approximately one to two days’ worth of generated biogas.
Hence, the ratio is such that 1 kg of biogas is produced from 10 kg of fresh green leaves, while 1 kg of biogas requires 40 kg of fresh dung. Approximately 90% of the dung is discharged as slurry.
Various technologies and primary mechanisms can transform biogas into electricity and sustainable fuels. The methods involve utilising prime movers, such as gas and steam turbines, diesel engines, Otto cycle engines, Stirling engines, and direct conversion within fuel cells, to facilitate power generation from biogas.
In theory, biogas has the potential for direct conversion into electricity using a fuel cell. Nonetheless, this procedure demands exceptionally purified gas and costly fuel cell technology.
Every cubic meter of biogas contains an energy content equivalent to 6 kWh of heat energy. When this volume of biogas is transformed into electrical power, it generates 2 kWh, with the remaining energy being released as heat, which can be captured and utilised for various purposes.
In a laboratory setting, when processing 10,000 tons of human excreta using this method, approximately 6.25% would result in biogas production, while the remaining 93.75% would transform into digested within 20 days.
Microorganisms convert biomass into gas. The majority of the organic material is decomposed into biogas, which comprises methane and carbon dioxide, within about three weeks.
Biogas is generated through the bacterial digestion of organic matter (biomass) in an environment devoid of oxygen. This biological process is referred to as anaerobic digestion and takes place naturally in various settings, ranging from digestive systems to the depths of effluent ponds. It can also be replicated artificially within specially designed containers known as digesters.