Lightning Protection of Biogas Plants

Biogas plants are facilities where a type of flammable gas is produced for the purpose of energy generation. Unlike natural gas and other flammable gases, Biogas is produced through the intensive processing of animal and plant-based raw materials. In biogas plants, both electricity and heat are generated. Biogas is a gas mixture released as a result of the anaerobic fermentation of organic waste materials; it is lighter than air, has a density ratio of 0.83 compared to air, an octane number of 110, burns with a bright blue flame, and consists of 54–80% methane (CH4) and 20–46% carbon dioxide (CO2).

The gases produced during the process in biogas plants are hazardous and flammable. Therefore, specially designed systems must be used when protecting biogas plants against lightning and overvoltage. Using a lightning rod system as a external lightning protection system will increase the lightning risk. Lightning rod systems are active components and emit ions. This situation creates an explosion risk. The correct external lightning protection system is to perform a risk analysis in accordance with the IEC 62305 Standard and calculate the rolling sphere radii for the facility.

Internal Lightning Protection Systems

Internal lightning protection surge protection systems must also be installed in biogas plants against internal overvoltages and lightning surges. Coordinated protection against overvoltage surges should be implemented using Class B+C surge protectors in main panels and Class C surge protectors in sub-panels. Sensitive systems must also be protected with Class D surge protectors. Biogas plants contain heavy processes, and such sensitive devices are frequently present and exposed to surges. These systems include;

• Flow meters
• Level sensors
• Measuring devices
• LAN lines
• Telecom lines

Another important issue is ensuring that grounding is fully implemented throughout the entire facility and equipotential bonding is achieved.