This post is a part of BioBiz’s Bio-CNG Perspectives.
BioBiz, a division of EAI, is a leading market intelligence & strategic consulting firm for the Indian bio-based sectors.
This blog post uses the terms bio-CNG and renewable natural gas (RNG) interchangeably.
Bio-CNG or bio-compressed natural gas, also known as sustainable natural gas or biomethane, is a biogas which has been upgraded to a quality similar to fossil natural gas and having a methane concentration of 90% or greater. As the gas is derived from natural and renewable sources, it is also termed renewable natural gas (RNG).
Introduction
Anaerobic digestion is a well known technology and have been practiced for years at smaller scales as domestic and select industrial plants. As the capacities of these plants are small, not much conditions are required in site selection. Moreover, the biogas from these plants are used for captive consumption.
However, as the plant scale increases say from 10 TPD and more, the plants cannot be considered captive and becomes a centralized system. In such cases, certain regulations are required in choosing the plant location to avoid any political challenges owing to the odour emanating from the feedstock such as food waste or other operational activities. It is hence required for large scale potential investors to first understand the criteria for setting up a large scale biogas or bio-CNG in a state in order to have successful operations.
This blog post provides some highlights on the guidelines for site location for a biogas plant. It is to be noted that these guidelines have been provided based on an understanding of the existing biogas plants and discussions with industrial experts.
Guidelines for site location for setting up biogas plants
The highlights are provided for different scales of biogas plants set up typically in business establishments. Domestic plants are not covered in this section.
1. Captive plants
Captive biogas plants are those which are set up within the premises of any commercial or business establishment. These biogas plants are small ranging from 100 kg per day to 1 ton per day and typically set up in commercial sectors and individual business establishments. The commercial sector includes restaurants, large hotels, hospitals etc. These plants usually use food waste, kitchen waste, and sometimes cow dung as the feedstock. The biogas being produced is used as a cooking fuel. As the capacity is small, segregation and pre-processing can be carried out within the premises. Digestate would be used internally.
2. Community plants
These plants are usually in the range of 1-10 TPD and set up in communities, residential apartments or large IT parks. The feedstock used is predominantly food waste and kitchen waste. The biogas or RNG generated is distributed among the residents of the community, apartments or IT sector as a cooking fuel. Some companies also use the biogas to upgrade to bio-CNG and use as transport fuel or generate electricity. The segregation and pre-processing is carried out within the premises. Unless the residents or related segments have issues with setting up the plants, major challenges are not met with at these scales.
3. Medium-large scale plants
Biogas plants of scales beyond 10 TPD fall under medium and large scale plants. These plants can be collocated (as in the case of industries) or a centralized facility (close to the feedstock sources within a radius of 20-30 kms).
In the case of collocated plants, the model is typically being used by industries who have ample space near the facility for setting up a biogas plant. The size of the biogas plant varies according the size of the company. Commonly used industrial sources as feedstock for biogas and RNG production include effluents from paper mill, cow dung, poultry waste and more.
In the case of centralized facility, the biogas plant should be at a radius of minimum 30 kms from the city, and 20-30 km radius from the feedstock source. However, it is suggested to locate the plant within 20 kms from the feedstock source, to reduce the logistics cost.
The biogas produced can be upgraded to renewable natural gas and supplied to commercial, industrial and transport (OMCs) segments, only within a 20-25 km radius.
In this case, while the segregation and pre-processing are part of the biogas facility, considering the large scale of the plant, primary source segregation is essential to remove major impurities, and at the processing facility, secondary or tertiary segregation unit can be set up, to quickly screen the impurities and a pre-processing unit needs to be set up to make the feedstock into a slurry form.
Thus it is essential for prospective investors looking to set up large scale plants to optimally locate the plant such that it is close to the source of feedstock and end user markets, thereby reducing logistics cost, at the same time far from the residential areas to avoid political challenges.
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