- May 4, 2021
- 2,886
| TYPE | Infrastructure |
| CLIENT | Thailand |
| PROJECT | National Renewable Energy Grid Phase 2 |
| PROJECT COST | 3,552,000,000.00 |
| COMPLETION DATE | 06/04/2025 |
| PROJECT INFORMATION | National Renewable Energy Grid Phase 2 Project Title: National Renewable Energy Grid Phase 2 Project Code: TH-ADP-001 Date of Approval: March 7, 2005 Version: 1.0 Approval and Endorsement Authorities
As part of the National Renewable Energy Grid Phase 2, the Republic Government will be constructing and operating four anaerobic digestion plants for national waste-to-energy conversion that can collectively process virtually all biodegradable waste produced by the Thai permanent population. Each plant will cover 6 hectare (60,000 square meters) constructed near the main highway with access to transportation infrastructure in Surat Thani, Nakhon Pathom, Sukhothai, and Maha Sarakham. Each plant will be equipped with state-of-the-art anaerobic digestion and energy conversion technologies, optimized for biogas production and subsequent electricity generation. The plant is designed to ensure efficient waste processing, high biogas yield, and reliable renewable energy output, adhering to environmental standards and energy policies. Each plant is incorporated with NSST 1.5 Architecture. Each plant will process maximum operational capacity of 15,000 metric tons of biodegradable waste per day, although it is expected that each plant will only process around 10,000 metric tons per day if only domestic waste is input. The waste reception facility will serve as the primary point of incoming municipal solid waste. Waste will be delivered by trucks and unloaded into a controlled tipping area equipped with odor management and dust suppression system. Automated waste sorting systems will utilize mechanical and manual sorting, the system will separate biodegradable material from non-organic and recyclable waste streams. This will include trommel screens, air separators, and conveyor belts to ensure only biodegradable waste enters the digestion process. The biodegradable waste will be shredded to achieve a consistent particle size. Pulpers will be employed to create a homogenous slurry of waste to allow smoother flow through the digestion tanks. The pulping capacity will match the maximum daily input capacity of 15,000 metric tons per day. As each plant is designed to possess the maximum operational capacity of 15,000 metric tons per day, the anaerobic digestion process will rely on a set of digestion tanks designed to accommodate the daily input of waste. Given the expected high volume of waste and biogas production, the digestion tanks are among the largest components of the plant. As the hydraulic retention time (HRT) for thermophilic anaerobic digestion typically ranges between 15 to 20 days, each plant will assume a 20-day HRT requirement for total tank volume, which is 300,000 cubic meters. Each plant will install 30 digestion tanks of 10,000 cubic meters capacity each to provide operational flexibility, allow for maintenance, and ensure continuous operation. These tanks will be constructed from reinforced concrete or steel, with an interior lining resistant to corrosion from the organic acids produced during digestion. They will be insulated to maintain the thermophilic temperature range of 50 to 60 degree Celsius. As the core of each plant is the enclosed anaerobic digestion tanks, where microbial activity breaks down organic matter in the absence of oxygen, each tank will be equipped with internal mixers to maintain uniform conditions and prevent sedimentation. The waste will first pass through a hydrolysis tank, where large organic molecules such as carbohydrates, proteins, and fats are broken down into smaller molecules. This will be followed by the acidogenesis phase, where acids are produced as intermediary products. In the final stage, methane-producing bacteria will convert the intermediate products into methane (CH4) and carbon dioxide (CO2), generating the biogas mixture. Biogas produced from the anaerobic digestion process, primarily composed of methane (60%) and carbon dioxide (40%), will be collected through a gas capture system installed at the top of each digestion tank. Flexible, membrane-based gas holders will be used to store the biogas temporarily before it is sent for energy conversion. Each gas holder will have a capacity of 30,000 cubic meters and they will have the storage capacity to buffer at least 8 to 12 hours of biogas production since biogas production is continuous, which translate to 20 flexible, membrane-based gas holders. Each plant will have around 600,000 cubic meters of storage capacity. Since biogas typically contains trace amounts of hydrogen sulfide (H2S), which is corrosive, desulfurization systems will be integrated to remove H2S from the gas stream. This is achieved using chemical scrubbers or biological treatment units. After desulfurization, the biogas will be compressed and transferred through pipelines to the energy generation unit. The biogas generated by the anaerobic digestion process will be converted into electricity using combined heat and power (CHP) unit, which effectively produce both electricity and heat. The plant will be equipped with high-efficiency gas engines capable of converting biogas into electricity. Each engine will have a capacity of 5 MW, with 20 units installed to meet the plant’s total electricity generation capacity of 100 MW. The engine will be designed to operate continuously, with biogas feeding the combustion process to produce mechanical energy that drives electric generator. Coupled to the gas engines, generators will convert mechanical energy into electricity. The generated electricity will be fed directly into the national grid, with transformers and switchgear controlling voltage and distribution. CHP units are designed to capture waste heat from the exhaust gases and engine cooling systems. This waste heat will be utilized to maintain the thermophilic digestion temperature and can be directed to nearby industrial processes or district heating networks. The organic material remaining after anaerobic digestion, known as digestate, will be separated into solid and liquid fractions. High-speed centrifuges will be used to separate the solid and liquid components of the digestate. The solid fraction, rich in organic matter and nutrients, will be processed further as a soil conditioner and organic fertilizer. The liquid fraction will undergo additional treatment, including aeration and filtration, to meet environmental standards for discharge or reuse as irrigation water in agricultural applications. To mitigate environmental impacts, each plant is equipped with comprehensive systems for emission control, effluent management, and odor suppression. Negative pressure systems within the waste reception and digestion areas will capture odorous air, which will be treated through biofilters or chemical scrubbers to remove volatile organic compounds (VOCs) and sulfurous gases. Wastewater generated from digestate processing and facility cleaning will be treated in an on-site wastewater treatment plant, ensuring compliance with discharge standards before release. For safety purposes, excess biogas that cannot be processed into energy will be safely flared in compliance with environmental regulations. Each plant will operate with a state-of-the-art SCADA (Supervisory Control and Data Acquisition) NSST 1.5-connected system, allowing for real-time monitoring and automation of critical plant processes. Sensors in digestion tanks and gas storage systems will continuously tract biogas volume, methane content, temperature, and pressure. The performance of CHP units, including electricity output and heat recovery, will be monitored to ensure optimal energy efficiency. Automated alarms and shutdown systems will be integrated to respond to critical events such as overpressure, equipment malfunctions, or gas leaks, ensuring plant safety. Transportation systems, including a network of collection vehicles and centralized waste transfer stations, will support the efficient delivery of waste to the plant. Electricity generated will be distributed through high-voltage transmission lines, integrating with the national grid to supply renewable energy. The plant design adheres to all applicable environmental regulations and energy policies to date. The four plants will collectively process near-all biodegradable waste of the Thailand 71.7 million population. These plants will initially process 40,867 metric tons of biodegradable waste per day, yielding approximately 6.13 million cubic meters of biogas per day given that all plants only input daily domestic waste (maximum capacity is 60.000 metric tons of biodegradable waste per day, yielding 9 million cubic meters of biogas per day.). With a conversion efficiency rate of 35% in the CHP units, the plant will generate 12.83 GWh of electricity per day or approximately 4.69 terawatt-hour (TWh) per year (maximum output capacity is 18.86 GWh of electricity per day or approximately 6.9 TWh per of electricity per year.) |
| ENCRYPTED | No |
