3.5 What is biological methane potential, and why is it important?

Biological Methane Potential (BMP) refers to the highest possible quantity of methane gas that can be generated from a specific quantity of organic material.

Understanding the BMP of organic matter is crucial for designing effective anaerobic digestion systems. It helps appropriately size the digester and gas storage and determine the retention time for specific feedstock. Moreover, this information is essential for comprehending the project’s feasibility, conducting economic analysis, and identifying potential benefits. Additionally, BMP aids in selecting feedstock for co-digestion and determining the optimal ratio for combining various feedstocks.

The BMP can be assessed using different approaches. One method is to conduct experimental measurements in controlled laboratory conditions. Another method is to estimate the methane potential using empirical models based on known organic matter characteristics. Alternatively, methane potential can be tested directly in the field to account for real-world conditions; however, it would be referred to as methane yield in this case. Additionally, existing literature sources can provide valuable data on methane potential for specific types of organic matter.

Published studies and research papers often provide methane potential values for various organic materials, allowing for comparisons and reference. However, it’s crucial to consider that the empirical models and literature values are specific to certain conditions, feedstocks, or experimental setups.

It’s important to note that the accuracy of documented gas measurements can vary depending on the specific parameter being used. The following list is arranged in increasing order of accuracy, indicating that the error rate increases from the top to the bottom.

• m³ Biogas/t fresh substrate
• m³ Biogas/t Total Solids
• m³ CH₄/kg Total Solids
• m³ CH₄kg Volatile Solids
• Nm³ CH₄ / kg Volatile Solids

The N stands for Norm, and it accurately describes the volume of biogas under the standardised condition considering a temperature of 0°C, pressure of 1.01325 bar, and relative gas humidity of 0%, as the volume of gases is affected by temperature and pressure.

Please keep in mind that the empirical models were created under specific experimental conditions and may not precisely forecast BMP in diverse operating situations.