Introduction
Biomass power generation is attracting attention as a key source of clean energy. However, did you know that it also poses a major fire risk?
The number of biomass power plants in Japan is on the rise, and expectations for replay energy are also rising. However, wood biomass fuel comes with invisible risks.
As experts are actively discussing this issue, the Ministry of Economy, Trade and Industry issued a groundbreaking notice on February 1, 2024. The notice is titled "Request for thorough safety measures at biomass power plants and reporting of accidents."
This article introduces the actual fire risks at power plants and an innovative monitoring system aimed at reducing those risks.
For details, click here (Ministry of Economy, Trade and Industry)Request for safety assurance and accident reporting at biomass power plants
In response to the recent spate of fires and explosions at storage and transportation facilities for biomass fuels, this notice calls for the following three measures:
1. Safety measures tailored to fuel characteristic
Since the quality of fuel varies depending on the place of production, it is necessary to take appropriate safety measures according to characteristic of each fuel. In particular, we conduct thorough patrols, inspections, and cleaning of facilities where accidents have occurred in the past.
2. Prompt reporting of accidents
In the event of a fire or other accident, even if it is not required by law to be reported, we will promptly report it to the relevant Industrial Safety and Health Supervision Department. This is to promote early response and information sharing.
3. Preventing recurrence through information sharing
After reporting, we will investigate the cause and share measures to prevent recurrence through industry associations in an effort to prevent similar accidents from occurring.
This notice is intended to call on each operator to strengthen safety measures and promptly share accident information, in order to maintain social trust as well as comply with legal obligations.
Biomass fuel ignition risk and accident examples
Why does it ignite?
Wood pellets and wood chips pose a fire risk due to microbial fermentation, oxidation, and heat accumulation.
Heat generation mechanism
- Heat is generated by internal fermentation and oxidation
- As heat accumulation progresses, the risk of spontaneous combustion increases.
Explosion risk factors
- Accumulation of flammable gases (e.g. methane, carbon monoxide)
- Dust explosion caused by wood dust
- Static electricity and heat from friction can cause ignition
Actual accident cases
Below are some examples of accidents that have occurred in Japan and around the world.
| Accident Number | Location of occurrence/Plant name | Year of occurrence | Cause of the accident | Time from outbreak to extinguishing | Estimated damage amount | Current situation |
|---|---|---|---|---|---|---|
| 1 | Chiba Sodegaura Biomass Power Plant | 2023年 | Ignition due to spontaneous heating of wood pellets | Approximately 4 months (fire broke out on January 1, 2023, and was confirmed to have been extinguished on May 1 of the same year) | Not published | Fuel removal completed, measures to prevent recurrence implemented |
| 2 | Kyoto/Kansai Electric Power Maizuru Power Plant | 2023年 | Heat generation due to fermentation and oxidation, accumulation of flammable gases, spontaneous combustion | The exact time the fire was put out is unknown. | Not published | Fuel management methods reviewed, monitoring equipment added |
| 3 | Tottori Yonago Biomass Power Plant | 2023年 | Possibility of flammable gas generation and dust explosion due to natural fermentation of wood pellets | Approximately 3 hours and 50 minutes (fire broke out at 9:22 on September 9, 2023, and was extinguished at 1:15 p.m.) | Not published | Measures to prevent recurrence are currently under consideration. |
| 4 | Aichi JERA Taketoyo Thermal Power Plant | 2024年 | Dust explosion caused by pulverization of wood pellets and frictional heat | Approximately 5 hours (fire broke out at 15:11 on January 31, 2024, and was extinguished at 20:04) | Not published | Measures to prevent recurrence are being implemented |
| 5 | Case study: Texas, USA | 2017年 | Fire caused by spontaneous heating of wood pellets | The exact time the fire was put out is unknown. | Not published | No information |
| 6 | Yamagata / Yamagata Biomass Energy Power Plant | 2019年 | Explosion of a hydrogen gas tank (insufficient performance of backfire prevention device) | Instant explosion, time to extinguish fire unknown | Not published | After the accident, the design and construction company began bankruptcy proceedings |
Functional requirements for a surveillance system
To deal with the risk of fire, it is important to monitor the condition of fuel and equipment in real time and detect abnormalities early. Conventional fire alarms only sound an alarm after detecting smoke or flames, so a mechanism is needed to detect temperature increases in advance.
The temperature of fuel storage facilities and transportation facilities is monitored in real time 24 hours a day.
It detects abnormal heat before smoke or flames appear, enabling rapid initial response.
Automatic alarm when the set temperature is exceeded. Immediate notification is given via on-site buzzer, control room display, email and SMS.
Temperature data from multiple locations can be centrally managed and remote operation is also possible. It will also support centralized monitoring between plants in the future.
Accumulate temperature data and use it for trend analysis and report creation. Use it as reference for predictive maintenance and inspection planning.
Proposed solution
The proposed solution is a non-contact heat detection system that uses high-performance thermal imaging cameras. Fixed cameras are installed at key points within the power plant and managed with dedicated monitoring software, enabling rapid detection and response to abnormalities.
High-resolution cameras are installed at key points. Thermography with a resolution of 640 x 480 pixels and a temperature accuracy of about ±2°C ensures that even small abnormalities are detected.
By overlaying thermal images and visible light images, it is possible to simultaneously grasp temperature abnormalities and on-site conditions.
Click here for more information on CPA-L3
It is an integrated platform that centrally manages data from various sensors and measuring devices, and is equipped with a wide range of functions such as threshold monitoring, alarm notifications, and remote viewing.
Real-time temperature values and heat map images allow you to immediately identify abnormalities.
For more information about CISAS, click here
In addition to thermal images, a temperature cable sensor is installed inside the silo to detect abnormalities from both the inside and outside, improving reliability.
Click here for information on silo temperature measuring cables
You can set alarm levels such as "Caution," "Warning," and "Emergency." When an alarm occurs, the thermal image is automatically saved and can be used for later analyzing.
system configuration diagram
The entire process of temperature detection, alarm, recording, and notification is automated. Data acquired by the thermal imaging camera is sent to the monitoring PC via the network and display in real time on CISAS.
Alert Levels and Response Flow
| Alert Level | Example Conditions | Notification Method | Examples of support |
|---|---|---|---|
| Note | Fuel surface temperature exceeds 50°C | Pop-up display on the person in charge's PC | Strengthening surveillance and checking the situation |
| caveat | Fuel surface temperature exceeds 70°C | Email notifications to field workers and managers | Fuel mixing and cooling in the relevant section |
| emergency | Fuel surface temperature exceeds 90°C | Global emergency bell activation, SMS notification | Fuel removal, fire notification |
Preventive maintenance using data
CISAS accumulates temperature data as logs and enables trend analysis and report generation, allowing you to understand temperature rise trends in specific silos and use this information to make decisions about routine inspections and planned shutdowns.
In addition, by linking with visible light camera footage, it is possible to simultaneously record the on-site situation when temperature abnormalities occur. In the case of a dust explosion, the footage immediately prior to the occurrence can be useful in identifying the cause.
