EnviTec Biogas: Thermal pressure hyrolysis increases efficiency

By EnviTec | February 10, 2017

High pressure plus high temperatures: the recipe for success from thermal pressure hydrolysis (TDH). The optimized process from the R&D division of EnviTec Biogas utilizes high pressures and temperatures to digest biomass even more effectively.

“Like EnviTec itself, thermal pressure hydrolysis is an all-rounder: the technique can be used universally for any biogas plant while also being suitable for any substrate where the breakdown of organic material—typically raw fibre—is not extensive enough in the biogas process,” explains Dipl.-Ing. Jürgen Tenbrink, CTO of the German company based in Lohne in Lower Saxony.

Apart from a long-term increase in gas yield, which can range from 10% to over 60% when renewable raw materials are used, the process also facilitates the use of substrates that have to date been entirely unsuitable for use in biogas plants—or at least not in any quantities worth mentioning.

The process is not itself new, however. “Previously, thermal pressure hydrolysis was used with the input materials—i.e. the raw matter. This is a hugely involved process, however,” explains Tenbrink—since the additional mashing means additional heating or cooling is required, depending on the type of hydrolysed material. Handling unwanted materials also adds to the effort here. EnviTec’s method skips this step, however: the process targets only the difficult-to-degrade raw fibre from the biogas process. Since the technique doesn’t involve any mashing of the input, this significantly reduces heating requirements. Other advantages include the exclusion of unwanted material as well as lower throughput.

The sustainable approach also has a positive effect on the plant owner’s cash flow: compared to a conventional biogas plant, a biogas plant equipped with a TDH system is significantly more economical to run. “Operators can make considerable savings thanks to the more cost-effective use of difficult-to-digest inputs like solid manure,” Tenbrink adds. Depending on the project, input costs can be cut by as much as 35 percent or more.