Karl-Heinz Kettl

Process optimization for efficient biomediated PHA production from animal-based waste streams.

Conventional polymers are made of crude oil components through chemical polymerization. The aim of the project ANIMPOL is to produce biopolymers by converting lipids into polyhydroxyalkanoates (PHA) in a novel process scheme to reduce dependence on crude oil and decrease greenhouse gas emissions. PHA constitutes a group of biobased and biodegradable polyesters that may substitute fossil-based polymers in a wide range of applications. Waste streams from slaughtering cattle are used as substrate material. Lipids from rendering are used in this process scheme for biodiesel production. Slaughtering waste streams may also be hydrolyzed to achieve higher lipid yield. Biodiesel then is separated into a high- and low-quality fraction. High-quality biodiesel meets requirements for sale as fuel and low quality is used for PHA production as carbon source. Selected offal material is used for acid hydrolysis and serves as a source of organic nitrogen as well as carbon source for PHA-free biomass with high production rate in fermentation process. Nitrogen is a limiting factor to control PHA production during the fermentation process. It is available for bacterial growth from hydrolyzed waste streams as well as added separately as NH4OH solution. Selected microbial strains are used to produce PHA from this substrate. The focus of the paper is about an overview of the whole process with the main focus on hydrolysis, to look for the possibility of using offal hydrolysis as an organic nitrogen substitute. The process design is optimized by minimizing waste streams and energy losses through cleaner production. Ecological evaluation of the process design will be done through footprint calculation according to Sustainable Process Index methodology.

Regional Optimizer (RegiOpt) – Sustainable energy technology network solutions for regions

Abstract Developing energy strategies for the future is an important strategic task for regions and municipalities. Renewable based technologies and decentralized energy supply based on regional resources have the potential to locally and regionally increase added value, provide new jobs, decrease the dependency on limited fossil resources as well as on external energy providers and may have a positive impact on ecological stability. Regional Optimizer (RegiOpt) software tool is based on the concept of Process Network Synthesis (PNS) (Friedler et. al, 1995 and Halasz et. al, 2005) and of the Sustainable Process Index (SPI) (Kotscheck et. al., 1996 and Sandholzer et. al., 2005). Both methodologies are combined in RegiOpt to enable the user to create economically optimal sustainable energy technology networks and at the same time evaluate them with respect to environmental sustainability. Inputs to the software are (renewable) resources (e.g. amount of crops available for energetic use, biowaste, waste heat, etc.) and regional energy demand profiles. Both resource provision and energy demand can be provided in time dependent form. On top of that the user may supply contextual information like costs and prices of particular resources and services. Result of the calculation with RegiOpt is the economically optimized technology network that fulfils the energy needs defined by the user and renders the highest regional added value. RegiOpt also provides the ecological footprint according to the SPI methodology. The user is able to calculate different scenarios based on different input data. RegiOpt software tool will be provided in two versions. Web based “Conceptual Planner” as a simple analysis for regional stakeholders and an “Advanced Designer” for a more detailed technology network scenario generation meant for expert use.

Economic and Ecological Potential Assessment for Biogas Production Based on Intercrops

Biogas production is discussed controversially, because biogas plants with substantial production capacity and considerable demand for feedstock were built in recent years. As a consequence, in most cases corn becomes the dominating crop in the surrounding and the competition on arable land is intensified. Therefore biogas production is blamed to raise environmental risks (e. g. erosion, nitrate leaching, etc.). Furthermore it is still discussed, that a significant increase of biogas production could threaten the security of food supply. The way out of this dilemma is simply straight forward but also challenging: to use preferably biogenous feedstock for biogas production which is not in competition with food or feed production (e. g. intercrops, manure, feedstock from unused grassland, agro-wastes, etc.). However, the use of intercrops for biogas production is not that attractive since current biogas technology from harvest up to the digestion is optimized for corn. Additionally current reimbursement schemes do neither take the physiological advantages and higher competitiveness of corn into account nor compensate lower yield potentials of intercrops which are growing in late summer or early spring. Higher feed-in tariffs for biogas from intercrop feedstock, as they are provided for the use of manure in smaller biogas systems, would not only be justified, as shown below, but also stimulating. Beyond that, the plant species used as intercrops as well as the agronomic measures and machinery used for their growing seem to provide lots of opportunities for optimization to increase achievable yields. Moreover, adaptations of biogas production systems, as discussed in this chapter, facilitate biogas production from intercrops.

Ecological and economic evaluation of biogas from intercrops

BackgroundBiogas made from main crops (e.g., corn) is commonly used for producing electricity and heat. Nevertheless, the production of energy from monocultures is highly unsustainable and not truly renewable. Since neither monocultures nor food competition are desirable, intercrops can be used to increase the yield per hectare instead of leaving agricultural fields unplanted for soil regeneration. The extra biomass can be used for biogas production. In a case study, the economic as well as the ecological feasibility of biogas production using intercrops, cattle manure, grass and corn silage as feedstocks for fermenters was analyzed.MethodsThe set-up for the case study included different feedstock combinations as well as spatial distributions of substrate supply and heat demand for modeling and optimization. Using the process network synthesis, an optimum structure was generated representing the most economical technology constellation which included transport of substrates, heat and biogas (when applicable). The ecological evaluation was carried out by using the sustainable process index method.ResultsThe application of both methodologies to different scenarios allowed a constellation to be found which is economically feasible while entailing low ecological pressure. It is demonstrated that the production of intercrops for producing biogas has so far not been regarded as a viable option by the farmers due to a variety of barriers. Sensitization is needed to emphasize that planting intercrops holds many advantages like positive effects on soil regeneration and raised nitrogen fixation, as well as increased biomass output per hectare and, last but not least, it allows the production of energy without conflicts between food and energy production.ConclusionsUsing intercrops for the production of biogas has the potential to decrease the ecological footprint decisively while still offering opportunities in the lucrative biogas market. The transfer of know how regarding this option should be taken up by agricultural training.