Question 1

What is biogas?

Accepted Answer

Biogas is a combustible gas generated when organic waste is decomposed through an anaerobic digestion process. Its main components are methane (CH₄), carbon dioxide (CO₂), and trace amounts of hydrogen sulfide (H₂S), nitrogen (N₂), ammonia (NH₃), etc. It is used for fuel or electricity production.

Question 2

What are the main facilities of a biogas plant?

Accepted Answer

Feedstock reception and pre-treatment facility Anaerobic digestion facility Gas purification and storage facility Power generation facility Liquid fertilizer (digestate) production and storage facility Compost (solid fertilizer) production and storage facility

Question 3

What are the main raw materials for biogas?

Accepted Answer

The representative feedstocks are as follows: Livestock manure Food waste Sewage sludge Agricultural by-products (corn stalks, rice husks, etc.) Organic waste (slaughterhouse waste, food processing factory waste, etc.)

Question 4

What by-products are produced in a biogas plant and how are they utilized?

Accepted Answer

The digestate remaining after biogas production can be used as liquid fertilizer or compost. These by-products are rich in nutrients and are recycled as agricultural fertilizers.

Question 5

What are the methods of energy production?

Accepted Answer

Combined Heat and Power (CHP): Produces electricity and heat simultaneously using biogas as fuel Boiler: Direct combustion to produce heat Upgraded biomethane production: Purified to natural gas quality and used as city gas or vehicle fuel Hydrogen can be produced using methane reformers

Question 6

What is the economic feasibility? What is the revenue structure?

Accepted Answer

The main revenue sources of a biogas plant are: Electricity sales Heat energy sales Sales of purified biogas as city gas or vehicle fuel Waste treatment fees Sales of liquid fertilizer and compost Carbon credit sales

Question 7

What are the environmental benefits?

Accepted Answer

Reduction of greenhouse gases Mitigation of waste disposal issues Odor reduction Resource recycling Reduction of fossil fuel use

Question 8

What are the major risks to consider during operation?

Accepted Answer

Instability in feedstock supply Risk of gas leakage and safety accidents Equipment failure and maintenance issues Odor management challenges Excessive digestate generation and disposal difficulties

Question 9

What permits are required for installing a biogas plant?

Accepted Answer

Approval for installing waste treatment facilities Environmental permits related to air and water quality Building and civil engineering permits Energy generation-related permits (including grid connection with KEPCO) Permits for producing liquid fertilizer and compost

Question 10

How many personnel are required to operate a biogas plant?

Accepted Answer

It varies depending on the plant size, but for a small to medium plant (100 tons/day), 15–20 on-site staff are needed. Main tasks include feedstock input and monitoring, equipment maintenance, digestate management, and safety inspections. Automation systems can reduce staffing needs.

Question 11

Why can a biogas plant cause conflicts with local residents?

Accepted Answer

The most common causes of conflict are as follows: Odor emissions Increased traffic and noise due to transport vehicles Concerns about soil pollution from digestate management

Question 12

How is biogas production volume predicted?

Accepted Answer

Biogas generation varies depending on the type and characteristics of the feedstock. Volatile solids (VS) content of the feedstock Hydraulic retention time (HRT) and temperature in the digester Digestion efficiency

Question 13

How can odor be effectively reduced?

Accepted Answer

To effectively reduce odors, structural design and odor treatment systems must be comprehensively considered from the design stage to minimize complaints during operation and maintain stable facility performance. 1) Structural design elements 2) Apply a combined odor treatment system A multi-stage system combining a scrubber (chemical washing) as the first stage and a biofilter as the second stage can effectively remove both low and high concentration complex odors. Design feedstock inlets, digesters, and storage tanks as sealed structures to prevent odor leakage. Install local exhaust systems at odor emission points. Install sealed collection lines in odor-prone areas to prevent external dispersion. Maintain negative pressure in odor zones to prevent outward odor leakage. Control airflow to prevent odors from moving to clean areas. Combine natural and mechanical ventilation to promote indoor air circulation.

Question 14

What is the installation cost and investment cost per ton for a biogas plant?

Accepted Answer

Minimum USD 300,000 per ton ~ Maximum USD 600,000 per ton The installation cost per ton varies greatly depending on plant size, type of feedstock, technology, equipment configuration, automation level, and conditions of each country.

Question 15

After the plant is completed, the investor may find it difficult to operate due to lack of technical expertise. How is post-construction operation handled?

Accepted Answer

Since the facility requires professional operation and management even after completion, the technology provider usually operates the plant directly for a certain period after construction. For investors without operating experience, contracting an O&M specialist company initially is the safest option. After 2–3 years of stable operation, it is possible to transition to technology transfer and direct operation. In other words, “completion ≠ the end”; an operation plan must be included in the business model.

Question 16

What is the minimum and maximum processing capacity for constructing a biogas plant?

Accepted Answer

Biogas plant capacity does not have a fixed minimum or maximum specification. It varies depending on feedstock type, operation method, installation purpose, and the capability of the technology provider. However, based on actual domestic and overseas cases, the typical minimum capacity is around 100 tons, and there is no upper limit.

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