Level Monitoring for Biogas Digester

Biogas plants operate in demanding environments where measurement reliability, safety, and cost control are equally important. From digesters filled with viscous slurry to gas tanks exposed to moisture and foam, traditional level measurement technologies often struggle to deliver stable results over time.

Recently, we received a request from our customer regarding his biogas digester measurement. Other than other customers’ automation level monitoring solution, he requires a power saving solution like this: when the operator presses the IP68 waterproof button, the radar sensor and the display power on and start measuring. After a few seconds, the system can be powered off to conserve battery energy.

The display should be large and easy to read, similar to those used on industrial weighing scales, featuring large red LED digits, and should have an IP68 protection rating for reliable outdoor use. No PLC or external communication is required—only the level sensor, the display, and a power supply—ensuring maximum simplicity and a long service life. They will install the power and the display inside a fully sealed enclosure with an IP68 protection rating. They only needs to open the enclosure, turn on the switch, and immediately read the measurement data.

No cloud connection, no SIM card, and no solar panel are required—this simple and cost-effective local solution is exactly what they need.

Challenges of Measuring Levels in Biogas Tanks

Digestate inside biogas tanks is far from a clean liquid. It is thick, contains gas bubbles and foam, and is constantly moving due to agitators. These conditions can cause frequent signal loss or false readings when using contact-based sensors or ultrasonic devices. In addition, biogas facilities often require explosion protection, as methane may be present in the surrounding atmosphere.

Many operators also prefer simple, local measurement rather than complex automation systems. Continuous power supply, PLCs, cloud platforms, SIM cards, and solar panels increase system cost and maintenance workload, especially when multiple tanks are involved.

Holykell Solution

Non-contact radar level measurement is well suited for harsh biogas environments. Unlike pressure or ultrasonic sensors, radar is not affected by foam, vapor, bubbles, or changes in media density. By using high-frequency technology, reliable readings can be obtained even in narrow tanks or under continuous agitation.

One of the key design goals of this biogas monitoring system is energy efficiency. Instead of running continuously, the radar sensor only operates when a measurement is actually needed.

The working principle is simple:

The operator presses a waterproof IP68 push button. The radar sensor and display power on instantly. It starts measuring. The level measurement is completed within seconds.

The system automatically shuts down to conserve battery power.

This on-demand approach significantly extends battery life while eliminating the need for permanent power or control systems.

Meanwhile, the measurement results are shown on a large, easy-to-read digital display connected to the radar via cable. The display uses bright, industrial-style LED digits similar to those found on weighing scales, making it clearly visible even in outdoor conditions.

The display and power supply are installed inside a fully sealed IP68-rated enclosure. To read the level, the user simply opens the box and press the button. No touchscreen is required, and no configuration is needed during daily operation.

ATEX-Certified Safety for Biogas Environments

Safety is a critical requirement in biogas plants. Since methane gas may be present, all equipment installed near the tank must meet explosion protection standards. The recommended radar level sensor is ATEX certified, making it suitable for installation in hazardous areas and compliant with industry safety regulations.

Recommended Configuration

Our proposed solution consists of:

HR80G 80 GHz radar level sensor, mounted on top of the biogas or digestate tank

LED display

Outdoor-rated power unit

IP68 sealed enclosure for protecting the display and power unit