Residual materials as raw materials for bioenergy – PFI develops new analysis method

The biogas industry is undergoing change: instead of traditional energy crops, biogas plant operators are increasingly turning to residual materials and agricultural by-products. This is due to changes in the Renewable Energy Sources Act (EEG), which limit the use of maize and have abolished the bonus for renewable raw materials. This is shifting the focus to cost-effective alternatives such as green waste, straw, manure, poultry manure and flowering plants.

However, many of these substrates have hardly been studied to date. There is a lack of reliable data on the degradation rate and methane formation potential.

Challenge: Existing processes are expensive and time-consuming

The tests currently available for substrate characterisation are predominantly designed for traditional energy crops. Methods from feed analysis can only be applied to a limited extent. Gas yield tests do exist, but they are expensive and time-consuming:

• 5–6 weeks for static methods
• several months for continuous trials

This is a clear disadvantage for operators who need to make quick decisions about substrate use.

New solution: Enzymatic tests for residual substances

In the BiomassValue research project, the PFI is developing a completely new process for quickly and reliably assessing the suitability of residual materials for biogas production.

The approach:

• Development of special enzyme blends to measure the degree of degradation of various substrates
• Creation of models for gas yield forecasts based on enzymatic hydrolysis
• Validation through static and dynamic biogas tests in the PFI technical centre

The goal: a universally applicable test procedure that delivers practical forecasts on methane formation within a maximum of three working days – significantly faster and more cost-effective than previous methods.

Relevance for operators and consultants

It is not only biogas plant operators who benefit from the new analysis method. Numerous companies offering consulting and analytical services for the industry also gain a tool for evaluating residues efficiently and reliably.

Demand is growing not only in Germany: internationally too – in France, for example – markets are increasingly focusing on the fermentation of residual and waste materials.

Research framework

The BiomassValue research project is being carried out as part of the INNO-KOM programme under the project management of Euronorm and with financial support from the Federal Ministry for Economic Affairs and Energy.