Could biochar be the solution for AD plants with minor gas yields? 4CleanTech, a joint venture between Biogas Clapton and CleanTech Leasing, shares its findings.
After investing in an AD plant, the majority of operators are confronted with the fact that the gas yield is not nearly as high as previously calculated. UK-based 4CleanTech sees biochar as a way to significantly increase the gas yield from a given feedstock.
Asked about the reasons for the often-disappointing performances, Guenther J. Schulz, one of the directors of 4CleanTech, addresses as a major problem the design of the plant’s digester(s): “In many AD plants, especially the bigger ones, the retention times for feedstock such as grass or maize are far too short, which is due to the digesters being too small,” he said.
“The result of this is that the substrates are not broken down properly and energy is wasted.”
To support this view, 4Clean Tech refers to the KTBL calculator, a widely recognised data evaluation tool used by major biogas research institutes in Germany. According to this calculator, for example, a maize...