Feasibility study on biowaste digestion at the Pirmasens Energy Park: Potential for sustainable biowaste recovery

The Pirmasens Testing and Research Institute (PFI) was commissioned by the Südwestpfalz district to carry out a feasibility study on the anaerobic digestion of biowaste. The aim of the study is to analyse the technical, economic and organisational requirements for the sustainable recycling of biowaste in the region.

The study focuses on several key issues: in addition to the economic viability of a biogas plant within the framework of an inter-municipal partnership, it also examines the integration of existing logistics structures, suitable technologies, the use of the energy generated, and the utilisation of the resulting digestate. Furthermore, the study encompasses the development of a technical concept with a particular focus on the local utilisation of the resulting material flows, as well as a detailed site analysis for the Pirmasens Energy Park.

Inter-municipal cooperation in the region

The feasibility study examines a potential partnership between the towns of Pirmasens and Zweibrücken and the districts of Südliche Weinstraße and Südwestpfalz. In this region, which has a population of around 270,000, approximately 28,000 tonnes of organic waste are collected from organic waste bins each year.

To date, this bio-waste has mainly been managed by external service providers following a tendering process (outsourcing). The current Rhineland-Palatinate Waste Management Plan (AWP 2022) stipulates that, in such cases, a combined approach involving both energy recovery and material recycling – in the form of a cascade solution – must be adopted.

Furthermore, the AWP sets out clear targets: by 2035, 100% of organic waste is to be treated in facilities with upstream anaerobic digestion. At the same time, it calls for the subsequent material recovery of the digestate, in compliance with high emission standards and with high efficiency levels in biogas utilisation.

Climate protection potential through regional biogas production

At present, the organic waste from the participating local authorities is processed over relatively long transport distances, resulting in annual emissions of over 600 tonnes of CO₂ equivalents. The majority of the waste (around 23,000 tonnes per annum) is currently composted.

However, the results of the feasibility study indicate significant scope for improvement: by processing the bio-waste at a regional anaerobic digestion plant in the Pirmasens-Winzeln Energy Park, annual greenhouse gas emissions could be reduced by up to 2,700 tonnes of CO₂ equivalents.

The potential analysis carried out also highlights the need for further measures to improve the quality of the raw material used. The focus here is particularly on:

• the reduction of impurities to below 3%
• increasing the biogas yield to around 120 Nm³ per tonne of biowaste

Technological options and site assessment

As part of the study, three different fermentation processes for biowaste were developed. All the fermentation processes examined can, in principle, be implemented at the Pirmasens-Winzeln Energy Park site.

The legal framework has also been analysed in detail. The findings show that, from a regulatory perspective, there are no fundamental concerns regarding the implementation of the project at the proposed site.

Next steps in the feasibility study

The findings contained in the interim report, together with specific recommendations for action, will be discussed with representatives of the participating local authorities in March 2026. On this basis, subject to the funding body’s approval, the next phase can be initiated.

According to current plans, the feasibility study is set to move into the design and planning stage from April 2026. The funding is provided by the Federal Ministry for Economic Affairs and Climate Action (BMWK)