Community Research and Development Information Service - CORDIS


Propanergy Report Summary

Project ID: 212671
Funded under: FP7-ENERGY
Country: Germany

Final Report Summary - PROPANERGY (Integrated bioconversion of glycerine into value-added products and biogas at pilot plant scale)

Executive Summary:
PROPANERGY is an EC 7FP collaborative project with partners from Austria, Germany, Greece and Luxembourg. The project aimed at developing a biorefinery process of raw glycerol from biodiesel production to produce the value-added chemical 1,3-propanediol (PDO), biogas and fertilizer, achieving thereby a complete use of the substrate and a zero release of waste material in the production.
For achieving this goal intensive research and development were carried out in iterative way at different levels:
1. Focused laboratory studies for new bioconversion concepts
2. Establishment of a miniplant (reactor up to 30 L) for integrated process development and proof-of-concept of process strategies and
3. Establishment of a pilot plant (M3 scale) for large-scale demonstration of selected processes.
The R&D activities were accompanied by technical feasibility assessment, economical and ecological analyses, marketing and dissemination of the results.
Several progresses beyond the state-of-the-art were first made in laboratory scales. These include for example:
1. Isolation of new and robust production strains
2. Selection and adaptation of microbial communities for combined PDO and biogas production
3. Development of a minimum medium without the expensive yeast extract to simplify the downstream processing (DSP)
4. Non-sterile bioconversion of crude glycerol into PDO with both single strain and mixed culture which strongly reduces operation costs
5. A simple and effective fed-batch process operated continuously over 2000 hours with high productivity and yield.
At the miniplant level different process configurations and control strategies were studied, especially with respect to DSP and its integration with bioconversion. Significant process innovations were made such as improved desalination for more consistent bioconversion and cost reduction, new strategy of pH control for cost reduction, simplified DSP and generation of residue suitable as fertilizer. The optimal processes developed in laboratory and miniplant scales were successfully realized at pilot plant scale. With both pure strain and mixed cultures more than 60 g/L PDO with a yield of 0.5 g/g Glycerol can be produced within 24 h fermentation under unsterile conditions. Highly pure PDO (99.5%) was produced from the fermentation broth by the simplified DSP. The waste from the bioprocess was successfully converted into biogas. The residual from the biogas reactor was proved to be a suitable fertilizer.
Economical analysis showed that PDO can be produced at costs as low as 1.0-1.6€/Kg with the process(es) developed in this project. It has a high potential to replace the chemical processes and the glucose-based process for PDO by using waste glycerine of biodiesel production. This can reduce green house gas and other environmentally harmful emissions and create economic benefits and job opportunities in Europe. The project and out-coming technology fulfils many requirements of the EU policies in environmental, economical and social domains. The concept has in particular a high replication potential for SME and allows demonstrating benefits notably for regions with structural deficits.

Project Context and Objectives:
General information and overall objectives:
The PROPANERGY project is a project carried out within the 7th Frame Programme of the European Commission under the topic Energy (2008-2011, Project No. 212671). It is a multinational consortium with members from Austria, Germany, Greece and Luxembourg. The partners jointly aimed at developing an integrated bioprocess to convert raw glycerol from biodiesel production into value-added products like l,3-propanediol (PDO) along with energy (biogas) and fertilizer from the fermentation residual materials in a Biorefinery approach, achieving therefore a zero waste release in the production.
PDO is a substance of high value for several industrial applications, especially for polymers, resins, coating and synthetic textile fibres. It is presently produced with a chemical process based on ethylenoxide (by the company Shell) and with a bioprocess based on glucose (by the company Dupont). The replacement of the chemical process and the glucose process by PDO from glycerine can reduce green house gas emission and other environmentally harmful emissions and create economic benefits and job opportunities in Europe. The concept has in particular a high replication potential for SME and allows demonstrating benefits notably for regions with structural deficits.
The novel concept for an integrated bioconversion of raw glycerol
Technical glycerine is a by-product of biodiesel production which is growing in Europe and worldwide. New uses of glycerol, especially in the sectors of chemicals and energy, are highly desired. The project PROPANERGY aimed at developing an integrated bioprocess to convert technical glycerine from biodiesel production into PDO and biogas in a biorefinery approach at pilot plant scale. The residual from the fermentation and biogas production should be examined for possible use as fertilizer.
Glycerine water from biodiesel plant is first converted into PDO and by-products (mainly organic acids) in a bioreactor. The by-products after downstream processing of PDO are converted into biogas in a biogas reactor together with waste materials from other sources. The solid residual from the biogas reactor could be used as fertilizer. Furthermore, CO2 +H2 produced in the bioreactor can be introduced into the biogas reactor for biogas production. The biogas generated in the process can be used as energy for thermal separation of PDO. Process water from the downstream processing should be examined for reuse in the glycerine fermentation. This innovative concept will lead to a complete use of glycerine from biodiesel production for a simultaneous production of energy and of two value-added products.
The concept has the potential to produce energy and materials in a very efficient way compared to present standard procedures, because it makes better use of the energy content of biomass residues and explores the optimization potential of chemical and heat enthalpy cascades which are inherent to this specific biorefinery concept.

Specific objectives: Progress beyond the state-of-the-art
European research groups and industries have had a long lasting interest and extensive experience in exploring the use of glycerine for microbial production of PDO. In addition to the glycerine surplus problem and the very promising properties of PDO as mentioned above this is also because of the fact that glycerine is the only known natural substrate for the biosynthesis of PDO.
Recently, technical glycerine from biodiesel production has also been successfully tested for PDO production. However, previous work has been mainly focused on improving the product yield and productivity with pure culture. The accumulation of the unavoidable but toxic by-products such as acetate limits the final product concentration and the productivity of the whole process. The limited product concentration also causes a relatively high cost for product recovery by thermal process which has a high energy consumption. In 1990s a fermentation and downstream processing concept was developed by a German chemical company together with the former German Research Center for Biotechnology (GBF) in Braunschweig. This process was the starting point for many other developments. However, no pilot plant demonstration has been made, not to mention an integrated process from fermentation to purification of PDO. Economical analysis suggest that to make PDO from glycerine economically competitive to the chemical processes especially the costs of the downstream processing should be significantly reduced.
Another important issue of bioconversion of raw glycerine from biodiesel production is the possible inhibition of cell growth by methanol, salts and other impurities from the process. Methanol is used for the esterification of plant oils. Normally, it is necessary to remove residual methanol by energy consuming evaporation and distillation before fermentation. Also the inorganic salts (K+, Na+) and oleic and stearic acids in the raw glycerine could be problematic.
The specific objectives of the project PROPANERGY are as follows:
1. Use of raw glycerin from biodiesel production
2. Non-sterile fermentation with a simple medium to reduce production costs
3. Byproducts converted to biogas for complete substrate utilization
4. Integrated downstream processing and energy reuse
5. Demonstration of the technical feasibility of process(es) developed in laboratory scale at pilot plant scale.
The overall target of the Propanergy project is a pilot plant scale demonstration of an integrated process which should have at least a reduction of production costs by at least 20% compared to present production processes.

Project Results:
The realization of the project concept was effected in several levels in an iterative way:
1. Focused laboratory studies for process development
2. Miniplant trial and optimization of process strategies and
3. Pilot plant demonstration of selected and promising processes.
The process development was backed-up by accompanying technical feasibility assessment and economical and ecological analyses. Each specialized partner elaborated results which were communicated in time to enable the collaboration with a high level of synergy.

Detailed S & T results are given in the description of the deliverables, especially those updated as parts of the final report:
1. Deliverable Nr.6: Marketing concept for PDO
2. Deliverable Nr.8: Final plan for use and dissemination of foreground
3. Deliverable Nr.11: Selected and adapted production strain/culture
4. Deliverable Nr.12: Criteria and protocol for glycerine quality control
5. Deliverable Nr.13: An integrated bioconversion concept
6. Deliverable Nr.15: A miniplant for integration of propanediol and biogas production
7. Deliverable Nr.17: Construction and start up operation of the pilot plant
8. Deliverable Nr.18: Data from pilot plant for new approaches in miniplant
9. Deliverable Nr.19: First analysis after receipt of delivery of residual material
10.Deliverable Nr.20: Final evaluation report after one year of testing
11.Deliverable Nr.21: Results of technical feasibility analysis
12.Deliverable Nr.22: Results of economical and ecological analyses
13.Deliverable Nr.23: Optimized production concept

The deliverables 6 and 8 are open to the public and available on the web site.

In the following, a concise description of the major S & T results is given:
Laboratory results
Within this project, the focus of laboratory experimental work was on the development of a novel bioconversion concept, choice of an appropriate strain of bacteria for the conversion.

Screening of an optimal production strain
For the selection of optimal production strains or cultures, two parallel approaches were taken. One approach tested the performance of pure strains. In a first approach 84 bacterial strains were screened using glycerol as carbon source. After initial trials, 12 strains were revealed capable of consuming raw glycerol under anaerobic conditions. Based on further comparison, the strain Clostridium butyricum VPI 1718 was selected for further study. The strain C. butyricum VPI 1718 showed several interesting physiological properties such as a lower generation of hydrogen during glycerol fermentation. This is important for achieving a high PDO yield since the reducing power NADH2 which is needed for PDO formation will not be lost as hydrogen. With a special fed-batch approach and with an optimized medium composition a hereto highest PDO concentration (> 90 g/L) in fermentation of commercial glycerol was first achieved with the VPI 1718 strain under sterile conditions. Typical PDO concentration in glycerol by C. butyricum was reported to be in the range of 60-75 g/L in literature. It should be mentioned that a relative large amount of yeast extract has to be added in the culture medium to achieve a high final product concentration. Yeast extract is expensive and makes trouble for the downstream processing.

Criteria and methods for quality control of raw glycerol, medium optimization
The use of raw glycerol/raw glycerol waters for the fermentation is a major aim of the project. Raw glycerol water can contain impurities like methanol, fatty acids and inorganic salts. These impurities can impair bacteria growth and product formation. Therefore quality guidelines for the raw glycerol have to be set. For this purpose, laboratory experiments were carried to investigate the influence of methanol, different inorganic salts (K+, Na+) and oleic and stearic acids. With C. butyricum VPI 1718 it was found that a high presence of methanol (up 1% w/v) and NaCl (up 20-30 g /g glycerol) in raw glycerol can significantly impair cell growth and PDO production, whereby the effects of Na and K phosphate salts are significantly lower. NaCl seems to be the most inhibitory salt amongst others that can be found in crude glycerol. Whereas oleic acid (up 2% w/w, of glycerol) is very inhibitory, stearic acid is much less inhibitory. Further studies revealed that the double bond of the mono-unsaturated fatty acid is the main inhibiting factor for C. butyricum.
As mentioned above, yeast extract is normally needed to be added into the medium for glycerol fermentation, especially for achieving a reasonable cell growth and PDO production of trypical PDO producers like Klebsiella peumoniae and C. butyricum. However, it represents a significant cost factor and complicates the downstream processing using thermal separation processes. Efforts of completely omitting yeast extract for the cultivation of C. butyricum VPI 1718 was not successful. However, we succeeded in developing a complete synthetic medium without yeast extract for an adapted mixed culture and a new isolate of Clostridium pasteurianum from the mixed culture (see below).

Selection and adaptation of a mixed culture for the production of PDO
One of the objectives of the project was to develop process control strategies to couple PDO production from glycerol with methanogenesis (biogas production) of the fermentation byproducts in one bioreactor. For this purpose, microbial communities from sewage sludge were selected and adapted to grow on raw glycerol as mixed culture. Several fermentation strategies using microbial communities were performed with different parameters and feeding strategy. The goal of the work was to find out whether a mixed culture could be selected which is comparable to or even better than the pure strain in performance. One advantage of the mixed culture is that it can produce PDO from glycerol and biogas from the byproduct organic acids as well. Such a mixed culture of strains was initially successfully selected and adapted for growth on raw glycerol. The performance of this mixed culture was later on significantly optimized (see Section below: Unsterile processing as a low cost process ).
The composition of the adapted microbial consortium was determined by DGGE (Denaturing Gradient Gel Electrophorese), which separates DNA fragments according to their mobilities under increasing denaturing concentrations. Firstly, DNA was extracted from the samples by PowerSoil® DNA Isolation Kit (MoBio Laboratories, Inc.) according to the manual provided. The extracted DNA was further subjected to PCR to amplify the gene sequences. The amplify DNA was now ready for DGGE. To determine the most dominant species of microorganisms for the glycerol fermentation, the mixed culture was subjected to a selection process by consequently inoculating the culture. After DGGE, some bands were excised for sequencing. Not every excised band were able to be sequenced, either because the DNA materials were too few or the DNA were overlaying, which mean more than one strains exist even though only one band was feasible in the DGGE gel. Most of the detected microorganisms were still uncultured. The difficulty to isolate, culture and identify each of these microorganisms could be because they can only grow in consortium. However, a dominant PDO producer could be identified in this case as Clostridium pasteurianum.

Unsterile processing as a low cost process
One major achievement of this part of the work was the development of a fermentation process under unsterile conditions which significantly reduces the costs for equipment investment and for operation costs because it is not necessary to ensure aseptic conditions.
After a first proof-of-concept in laboratory fermentation the feasibility of such a unsterile process was further studied extensively, especially with respect to protection of contamination, degradation of the final product PDO and the process stability. Unsterile fermentation of glycerol could be successfully run in different modes of operation (batch, fed-batch and repeated fed-batch) over long time period. In particular, C. butyricum VPI 1718 culture was tested in relation with its ability of converting glycerol into PDO under non-sterile fermentation conditions. For this purpose, batch experiments were carried out with new raw glycerol feedstock, deriving from Greek biodiesel industries. Initial concentrations of 20 and 50 g/L were tested, with final PDO production and the respective PDO yield achieved found to be similar with those reached under sterile conditions (0.56-0.60 g/g). Furthermore, batch trails were performed with increment of initial glycerol concentrations up to 80 g/L and in every case the respective PDO yield were satisfied (between 0.52-0.56 g/g). Additionally, a continuous fermentation was done in order to investigate the sustainability of the system under non-sterile cultivation conditions. Indeed, a continuous culture of nearly a month was achieved, while the system was running in a steady-state mode for more than 15 days, with a dilution rate (D) of 0.06 h-1 and a glycerol concentration of 25 g/L in the feed. PDO concentration was 12.9 g/L inside the chemostat, while the respective PDO yield was 0.52 g/g. The PDO yield achieved with C. butyricum VPI 1718 is very close to the theoretical maximal PDO yield (0.53-0.60 g/g).

Combined PDO and biogas production
To combine the PDO and biogas production an integrated bioconversion concept was studied. Extensive experimental work in batch, fed-batch and continuous fermentations demonstrated that it is possible to produce PDO and biogas simultaneously with a selected microbial community. More importantly, this integrated process can also be carried out under unsterile conditions. This represents a major achievement of the consortium which is beyond the originally envisaged process with a mixed culture operated under sterile conditions. However, the biogas production rate was still not high enough for a technical application of the new concept and problems with process stability was encountered. Further studies were therefore necessary to investigate the population dynamics, to increase the biogas production rate and process stability. This was done in close collaboration with the industrial partners. Considering the technical realization a two-stage process was suggested for further study of the integrated process.

Development of a novel and simple repeated fed-batch fermentation process
Upon discussion with the industrial partner and in view of a simple operation in the pilot plant repeated fed-batch approach was chosen for the production of PDO from crude glycerol. We successfully developed a repeated fed-batch process in laboratory (at 2 L scale) with a mixed culture under unsterile conditions. The experiment was started in a batch mode with 25 g/L of crude glycerol. Before the substrate was completely consumed, the feeding was started. Crude glycerol without dilution was used as feed and it was fed continuously into the reactor. After each fed-batch, 90% of the fermentation broth was discharged and fresh medium was added to 1.5 L total volume. A PDO concentration as high as 70 g/L was obtained on the first and third fed-batches. The PDO yield was in the range of 0.5 g/g Glycerol.
This very promising repeated fed-batch process was further adapted to the requirement of a simple operation without the need of skilled personnel and with minimal supervision. The reactor was harvested by 2/3 every 24 hours and refilled at a constant rate for about 10-12 hours. It was successfully carried out in more than 75 runs by such a simple scheme. A semi-continuous operation was achieved with a PDO concentration between 40-50 g/L, a yield around 0.5 mol/mol and a productivity of 1.5 g/l.h. Study of the repeated fed-batch process at very different fermentation conditions showed the stability of the process in laboratory scale. Pilot plant try of this repeated fed-batch process was also successful (see below).

Results at the miniplant scale
Beside the laboratory studies the Propanergy project included the construction of a Miniplant for proof-of-concept of processes developed in laboratory scale and for integrated development of fermentation and product downstream processing (DSP). The Miniplant also delivered basic data for the pilot plant construction and operation.
The Miniplant was first tested in different operation modes of glycerol fermentation with culture of C. butyricum VPI 1817. Unfortunately, from December 2010 C. butyricum was classified as pathogen (safety level L2) and it cannot be longer used for miniplant and pilot plant studies. A new strain isolated from the mixed culture was then used for further Miniplant and pilot plant studies. The strain was classified as C. pasteurianum, a safely level 1 microorganism.
Development and construction of the Miniplant
Starting from a basic but not technically proved DSP concept intensive simulations of the thermal separation processes were carried out for concept development and for the dimensioning of the equipment such as evaporator and rectification columns. An electrodialysis step had to be added to the DSP due to the high salt loading of fermentation broth from raw glycerol. Based on experimental study it turned out that it is more adequate to place the electrodialysis step before the fermentation. This ensures a more consistent substrate feed, a more stable fermentation and reduced DSP costs. The originally proposed centrifugation and precipitation steps were replaced by microfiltration and ultrafiltration respectively. A further process improvement is the replacement of NaOH with ammonia for pH control. This resulted in better separation of organic acids, avoiding of salt fouling and significantly reduced production costs.
The components of the miniplant were purchased, installed and put into operation. The following picture shows the established minioplant in the pilot bioplant at TUHH.

Process optimization in the miniplant and production of highly pure PDO
With the setup of the Miniplant it was able to study technical feasibility of different process strategies such as desalination before fermentation, replacement of precipitation and centrifugation by ultrafiltration and the change of pH control method which were all successfully implemented. The Miniplant was also used to test the possibility of water recycle. Whereas it was demonstrated possible, stability problem was encountered in long-term operation.
The Miniplant was used to proceed fermentation broth (PDO recovery) from different fermentation processes using pure cultures (such as C. butyricum VP1718 and our own isolate) and mixed culture. In all these cases 99.5% pure PDO can be obtained from fermentation of raw glycerol from biodiesel plant. Several liters of pure PDO were also produced from fermentation broth of pilot plant studies. It can be used as samples for application tests.

Miniplant studies for scale-up in the pilot plant
The Miniplant was used to accompany scale-up studies in the pilot plant, for example for the development of culture seed train. Precultures for fermentation experiments at pilot plant were provided by the partner TUHH. To develop a suitable seed train scale-down studies at lab and miniplant scale were carried out. With a 2mL kryo culture 100mL media were inoculated and incubated at 37°C. Every 8h the culture was transferred to 10x larger volume in unsterile containers at controlled temperature of 37°C. At 100L scale cultures were divided in 3 fractions for better handling. The culture seed train was finally successful.

Pilot plant demonstration
Planning, detailed engineering, construction and start-up of the pilot plant
The pilot plant established at the industrial partner BKW includes a bioreactor of up to 8 M3, a reactor of 1 M3 for inoculation and corresponding unit operations for ultra- filtration, electrodialysis and evaporation. The1 M3 reactor was also used as for biogas production. After planning, detailed engineering and construction the individual unit operation was tested for their function and put together.

Test and modifications of the pilot plant
The pilot plant was originally designed for batch fermentation. Due to the change in concept to repeated fed-batch strategy the pilot plant was modified in spring 2011 to run unsterile fed batch fermentations for PDO production. These modifications included a rearrangement of buffer and feed tanks as wells as its connections, establishment of a pH-control system and incubation system for the pre-cultures. After successful modifications PDO production was stated at the pilot plant site. Initially, a batch-mode test fermentation was successfully carried out to demonstrated the proper functionality of the equipment. However, difficulties were encountered in fed-batch and repeated fed-batch mode operations. Also instability in the quality of the substrate was observed. A series of trouble-shootings was necessary.
The trouble-shooting involved reexamination and scale-down studies in laboratory and miniplant scales and modification of the pilot plant based on such knowledge. For example, the substrate glycerol for PDO production was desalinated before fermentation as proposed in the optimized production concept. The desalination was carried out with electrodialysis. For the desalination glycerol had to be diluted to a concentration of 50% (w/w) with water to reduce viscosity. General desalination performance of this operation in the pilot plant was acceptable but showed unexpected product losses as well as glycerol dilution. A large amount of glycerol was transferred over the membrane with the salts and also water was moved into the glycerol stream possibly due to osmotic effects. Therefore glycerol concentration was reduced to min 32% (w/w). This performance was not acceptable and did not correspond to data from the miniplant study. The desalination was therefore reexamined in the miniplant regarding possible reasons for the discrepancy such as difference in membrane material, problems with the cell tightness and the glycerol quality. Finally the desalination step worked also at the pilot plant.
Another example of pilot plant modification was related to the temperature control. Several fermentations in the pilot plant failed initially. Analysis of collected process data then gave a hint on the problem: An increase of reactor temperature due to limited heat transfer and bad mixing. According to calculations considering an exponential cell growth and substrate consumption the reactor temperature may rise to a maximum of 43°C during the fermentation if heat transfer is severely limited in the large bioreactor. The negative effect of temperature increase was confirmed by the partner TUHH in laboratory. Due to the smaller ratio of surface to volume in large scale compared to lab or miniplant scale heat transfer in large scale bioreactor could be therefore a problem. A more active cooling system was therefore added to the bioreactor at the pilot plant site. Also mixing performance was improved.

Successful pilot plant-scale fermentations
After implementation of the necessary modifications, overall successful fermentations were achieved in the pilot plant scale. With the isolated strain C. pasteurianum in batch culture a final concentration of 56g/L PDO was reached with comparable productivity, titer and yield as in the laboratory study. The yield was 0.47 g PDO per g glycerol at a productivity of 2.33g/L h PDO.
As mentioned above, we developed a very promising non-sterile repeated fed-batch fermentation process (harvest of 2/3 the bioreactor content every 24 hours) with a mixed culture and successfully operated it in more than 2000 hours. Study of the repeated fed-batch process at very different fermentation conditions showed the stability of the process in laboratory scale. The repeated fed-batch process was also successfully implemented at the pilot plant scale. A simple and robust strategy for preparing the seed culture was developed for this purpose. The pre-culture was started from a 1-liter bioreactor (or flasks) inoculated with a 2mL kryo culture. Unsterile plastic containers of 50 liters could be used for further inoculation as long as the temperature was somewhat controlled (e.g. at 37°C). Three consecutive repeated fed-batch cultivations were successfully demonstrated. The cultivations gave excellent results with stable operation. More than 60 g/L PDO can be obtained within 24 hours, the yield and productivity of these fermentations were about 0.5 g PDO/g glycerol and 2.5 g/l.h respectively. The productivity is much higher than values reported in literature for fed-batch glycerol fermentation (ca. 1.6 g/l.h which reduces to less than 1 g/l.h when considering the time for preparing and re-starting a new fed-batch.). It is worthy mention again that we have implemented a very simple linear feeding strategy and a regular harvesting period of 24 hours. The operation of our process requires thus litter supervision and low man power.

Biogas production from fermentation residual
To demonstrate the feasibility of biogas production from the fermentation residual the fermentation broth from the pilot plant scale was first filtrated and used for biogas production in a pilot plant scale. The biogas production from the fermentation residue was also successful at the pilot plant.
The specific production rate was 83 m³ biogas or 46 m³ CH4 per ton input of fermentation broth. In the above test PDO was also degraded. If the contribution of PDO is deducted, the whole specific gas production will be reduced by about 44 m³/t to about 39 m³ biogas (or 21 m³ CH4) per ton input. With a caloric value of about11 kWh/Nm³ CH4, approx. 230 kWh can be gained per ton residual from PDO fermentation.

Evaluation of fermentation residues as fertilizer
One of the objectives of this project is to examine the possibility of using residues from the PDO fermentation and biogas production as fertilizer. The following aspects were analyzed regarding the aptitude of fermentation residues out of the PDO production as fertilizer. First the demand on nutrition and fertilization of important crops was analyzed by considering wheat, maize and sugar beet. Due to the fact that the availability of fermentation residues in appropriate quantities for practical testing was delayed, the analysis was first carried out by theoretical consideration through extrapolation of results from laboratory studies. The ingredients of fermentation residues of the fed-batch PDO production process were extrapolated to usual quantities of application to land (30 m³). Through this it was possible to analyze if the needs of plants and soil could meet respectively if specific legal threshold values were exceeded.
The composition of fermentation residues and the projection based on usual quantities of application to land (30m³/ha) were estimated. The major conclusions based on this study are as follows:
• Fermentation residue with NaOH for pH buffering and control is less suitable as fertilizer due to high sodium residues.
• Fermentation residue with ammonium for pH control is only possible if there is a reduction of application quantity per ha to meet legal specifications.
• Furthermore it is recommended that the fraction from the electrodialysis unit should not be added to the residue to avoid salination of soils due to high quantities of chlorine and salts.
To gain experimental information about the aptitude of fermentation residues as fertilizer practical indoor and comparative field studies about the impact of fermentation residuals were carried out on different crops using biogas slurry, glycerine and sewage slurry from other sources.
For the practical indoor test an examination of the intensity of blowing and germination was carried out. Therefore we added the incoming fertilizer fractions (=fermentation residues out of the PDO production) to slurry and a fermentation trial took place. We evaluated the fertilization effect of received fraction and investigated the effect on different crops, like rape, winter wheat, sun flower and rye regarding different parameters. These parameters were germination capacity, intensity of blowing, health and height of the crops. Therefore four variants were tested. One test was carried out without fertilization, one was with 10 m² slurry/ha, one with 30m²/ha and one with 100 m²/ha.
The results showed that there was no negative effect on the health of the crops from fertilisation with fermentation residues out of the PDO production. Variants with higher quantities of fertilisation had a slight higher intensity of blowing. Therefore we can assume that fertilisation in the analysed quantities are suitable for the health and growth of the crops.
For out-door field study, cares were taken to meet the envisaged testing conditions as close as possible. The effects of different types of fertilizers on plant growth, plant health and harvest quantities were evaluated.
The experimental studies revealed that
• No significant difference of the analysed parameter, e.g. health conditions, yield per hectare etc. due to fertilisation with glycerine-containing residue
• Fertilisation with biogas slurry (with or without glycerine) causes higher weed infestation
In summary we conclude that fertilisation with glycerine in quantities used in the trial had no negative effects on the parameter examined. The residue from the PDO fermentation and biogas production can be used as fertilizer.
Potential Impact:
Economical and ecological impact

PDO and biogas production processes
The technical feasibilities of different strategies of PDO production and separation developed in the project were analyzed. The most promising ones which were also demonstrated at miniplant and pilot plant scales were selected for more detailed economical and ecological analysis. First a basic concept was assessed. The results of the economic and ecological analysis of the basic concept were described in details in previously submitted report. Based on the results of basic concept, the concept was adopted and optimized in two major directions: 1. saving operating costs by searching for substitute of major cost factors, 2. increasing the product concentration in the fermentation broth in order to reduce the downstream costs by decreasing the amount of water to be separated. Concretely two major improvements were made after the development of the basic concept:
- Substitute of caustic soda by ammonia for buffering and pH control
- Higher fermentation efficiency and volumetric productivity

A renewed economical analysis was made for the optimized process. It should be mentioned that the process analyzed was not the finally optimized process at pilot plant scale. In the results summarized below only a fermentation with a PDO concentration of 55 g/L under unsterile conditions and in a medium without any yeast extract was used as “the optimized” process. In the final stage of the pilot plant study unsterile fermentations with more than 60 g/L PDO were achieved in relative short time. This represents a further 10% increase in the product concentration compared with the “optimized process” analyzed.

The effect of higher product concentration in the fermentation broth is significant. Up-scaled to the large scale (corresponding to a PDO unit for a large biodiesel plant), the improvement becomes even more clear (see tables below). The production costs for an assumed plant scale of 8200 t PDO/y (glycerol price scenario: neutral) can be reduced from 1.80 €/kg PDO to 1.55 €/kg PDO when the PDO concentration was increased from 44 g/L to 55 g/L.

A further cost reduction was achieved in this project by changing the strategy of pH buffering and control. The economical analysis of the basic concept showed that the use of caustic soda for pH control is the third highest cost factor. Thus the optimization for implementation on industrial scale aimed at a substitute for caustic soda as buffering substance. The choice was ammonia which is available at moderate prices worldwide. With the application of ammonia, the costs for pH buffering and control could be reduced from about 3.3 million EUR to 561 thousand EUR per year. The total production costs were further reduced from 1.55 €/Kg to 1.45 €/kg PDO.

The cost structure of the different processes was calculated and compared. The process developed and optimized in the Propanergy project can reduce the product costs by about 30% in comparison to the basic process. A total cost below 1.5€/kg PDO is possible, with a payback time in the range of 3-4 years.

As can be seen in the cost structure of the process, thermal separation takes a major part of cost factors, that is
- heat energy
- electric energy
- process water
- waste water
- capital costs for separation equipment

If the Propanergy process is integrated into a biodiesel plant where raw glycerol solution (about 20%) without concentration can be directly used as waste stream (thus with strongly reduced substrate cost) PDO can be produced at a price lower than 1€/kg PDO. Alternatively, if the Propanergy process is integrated into an existing biogas plant where waste heat energy can used also a PDO production cost lower than 1€/kg PDO can be achieved. In both these cases the Propanergy process will be very competitive to all the other existing routes of chemical or biological production processes for PDO.

The Propanergy process has the following ecological impact:
- Maximizing the value of a waste stream
- Replacing chemical processes with a bio-based technology for a large-volume chemical (PDO)
- Zero-waste release production process

Regarding other environmental requirements, it can be assumed that the process meets the requirements for sustainable technology. As a result of the use of renewable energy sources, it is CO2 neutral. As a result of the decentralized location and the reduction of volume, it considerably cuts transport costs and have a beneficial impact on the CO2 balance too.

Residual materials as fertilizer
The residual material from the biogas production is a high valuable fertilizer, as the analysis of incoming fertilizer fractions from biogas plant showed. It contains organic carbon, important macronutrients, like nitrogen, phosphor, potassium, magnesium and calcium as well as micronutrients, like copper and zinc. Analysing the nutritional needs of different crops, it became apparent that the fertilizer fraction of the PDO production is highly suitable as substitute of mineral fertilizers.
Through the substitution of energy intensive produced mineral fertilizer CO2 can be reduced. For example one ton of nitrogen inclusive production, transport and application correlates with an energy content of 2 tons crude oil. Therefore per hectare the usage of 240 litre crude oil (based on the average N-demand of wheat: 120 kg/ha) can be reduced and in the following approx. 600 kg CO2 saved (assuming that 1 l crude oil causes 2.44 kg CO2) per hectare.
Farmers depend on highly fluctuating prices for mineral fertilizers. Fertilizers from the PDO production would be a valuable source for nitrogen and other macro- and micronutrients. Calculations with actual market proices (2011) and real analysis data of the residuals we found that the ca. 47 kg/m³ nitrogen in 1 m³ fertilizer fraction from PDO production has a financial value of € 56. If we summarize the values of all macronutrients per m³ fermentation residuals we show that it has a financial value of about € 60 at current market prices. For usual application quantities of 30 m³ it means a financial chance of approx. € 1809,98/30 m³ fertilizer fraction of PDO production considering only the macronutrients nitrogen, potassium and phosphor.

Socio-economic impact and societal implications
The Propanergy project contributes to the expected impacts of the Area Energy 3.3 Biorefinery by maximising the value of a waste stream (glycerine water) derived from biodiesel production by using all of its components during bioconversion. By producing PDO, a very promising basic chemical for a wide range of applications, biogas and fertilizer simultaneously from the glycerine waste stream the project expands the range and volume of bioproducts on the market. It can also improve the profitability of biorefinery plants aiming at the use of plant oils, while optimizing their energy and environmental performance to enhance the cost competitiveness of biodiesel production. Moreover, by producing biogas from the residual of glycerine bioconversion this project directly contributes to the expected impact of the topic “New uses for glycerine in biorefineries”, namely maximising the renewable energy output from biodiesel plants, thereby optimising the profitability of the biodiesel process.

To bring about these impacts, closely concerted research and development activities in laborarory, miniplant and pilot plant scales were carried out in both research institute and industrial settings. A co-operation on a European level supports the dissemination of this innovative concept. An energy and material flow efficiency strategy cannot be successfully implemented without the cooperation and support of a wide variety of actors.

The integrated bioprocess to convert technical glycerine from biodiesel production into biogas and two value-added products PDO and fertilizer in a biorefinery certainly supports the EU objective to strengthen the position of EU companies in the export sector.

The participation in the FP 7 is a way of increasing the innovation potentials of the industrial partners (especially SMEs) in our consortium and it improves our competitiveness and facilitates transnational cooperation. Under these conditions of stronger competition every firm must be innovative. The main objective of the project was to open a new market for SMEs in the field of innovative bioenergy facilities.

The Propanergy process is simple and has a particularly low personnel (about 1% of the total costs) and operation costs. The major costs are substrate (ca. 44%), other materials (16%), energy (27%) and capital /maintenance costs (16%).

The project enables SMEs, especially those from the consortium to gain better regional and national market positions because of the experience and results of the project. This helps the SMEs to respond to the pressures for continuous innovation and technological adaptations that are exacerbated by the completion of the European internal market and the intensification of competition. To survive and grow, SMEs must constantly innovate, which means either developing new technologies themselves or gaining access to technology developed by others, in this case by the RTD performers. The composition of the international consortium facilitates the transnational co-operation between SMEs research institutions and other organizations, which is essential to SMEs competitiveness and international strategy. The co-operation leads to the development of transnational networks from which the SMEs in the consortium can benefit in many different ways.
The development and improvement of such systems will also a positive impact for the creation of new jobs in the EU.

Main dissemination activities and exploitation of results
Our dissemination activities and exploitation of results during the project period were manifolds and at different levels.
The first dissemination activity was the creation, installation (within the first 6 months) and maintain of a project website with up-to-date information for internal and external communications. The website address is: The website will be remained active after the end of the project by the coordinator.
The next dissemination activity was an active one with in-time publication of the results achieved in the project in form of peer-reviewed journal and book publications (12), oral presentations (16) and poster presentations (13) at national and international conferences, workshops and invited seminars. A list of the scientific publications is submitted to the on-line reporting tool SESAM and will be make public available.
The Propanergy coordinator Prof. Zeng organized 2009 an “International Conference on Biosystems Analysis and Engineering” in Hamburg. Most of the project partners participanted in the conference and presented their results of the Propanergy project.
At another international conference organized by Prof. Zeng 2011 in Frankfurt results of Propanergy was presented as example of new bioproduction systems.
Further more direct dissemination and exploitation of the results from the project can be further described as internal and external ones.
Internally the consortium mutually benefited from the collaboration and each participant increased its experience related to the technical design, management, construction, and operation of Propanergy units. All project partners are experienced in exploiting the results of the process developments. In particular, the engineering companies (Agraferm, HF Biotec, and BKW) have their own departments for the marketing of results related to the Propanergy process. Additionally the institute TUHH presented the projects progress and the improvements, made during the projects processing time, on its Internet page. LFS Tulln held different workshops where also information about the project Propanergy was given to participants to disseminate the activities of the project. In public rooms of the LFS Tulln posters give information about the project. Throughout this in a short movie made by students of the LFS the project is introduced to the public. Also on the LFS homepage information about the project Propanergy is available as well as background information.
The operator of the plant, the BKW Fürstenwalde, supported by Agraferm and the coordinator, presented the finished unit to invited visitor groups, for the first time by the “public put into operation” on 25th October 2011in Fürstenwalde, Germany. We invited people to public put into operation of the pilot plant.
Public put into operation of the Propanergy Pilot Plant on 25th October 2011
Externally, we have identified and contacted potential users of our technologies world-wide. For this purpose we prepared special reports, data sheets of the best approaches and flyers. The recipients included scientific contacts such as universities, institutes, technology consultants, networks and scientific associations. We reached also out to recipients of commercial interests such as producers of biodiesel and biogas, trade associations and networks. The coordinator and major participants of the project visited respective institutions and companies in Europe and countries outside Europe such as Poland, Slovakia, China, Thailand, Indonesian and Brasilia.
The coordinator of Propanergy Prof. Zeng visited a Biodiesel plant in Thailand and discussed about possible application of Propanergy technology with the plant owner.
Another major dissemination activity was the organization of a joint “International Workshop on Innovative Uses of Glycerol from the Biodiesel Process”, 13th December 2011, 1000 Brussels organized by the management teams and coordinators of the three glycerol valorization research projects SUPERMETHANOL, GLYFINERY and PROPANERGY supported by EC under the same FR7 Program. The workshop aimed to bring together industry and research partners from across Europe, with an interest in the research issues involved and the practical aspects of applying glycerol for innovative high-value purposes. Propanergy was presented with brochure, poster walls and two specific presentations and round table discussion led by Dr. Follmann (CEO of HF Biotec). Nearly hundred people participated in this workshop.
The project Propanergy was well covered in popular media in forms of press releases, articles published in the popular press and news paper. Propanergy was selected by the German Federal Ministry of Education and Research as a model project of biorefinery supported by EC:,did=99194.html
Other major activities of dissemination and exploitation of the results are market research and development of marketing concept. The project partner HF Biotec was very active in this regard throughout the project. The activities included studies of market situations for glycerol and PDO and analysis of position of the Propanergy process in comparison to other competing technologies. It was observed that the situation with the availability of raw glycerol from biodiesel production has changed in the past few years due to unfavorable economical conditions for biodiesel production in several Europe countries and the increased applications of glycerol in other sectors such as pharmaceutical and chemical industries. The price of glycerol in the last years was very fluctuating, with a slightly increasing trend. This makes the marketing of glycerol bioconversion technologies such as the Propanergy process presently not an easy task. On the other hand, the forecast for the PDO market development is very encouraging. The present PDO market volume of about 200000 t/y and the PDO price (ca.1.8-2.0 €/kg) are predicted to increase to about 700000 t/y and above 2.1 €/kg by 2014 respectively. Internationally, there is a high and faster growing demand on materials based on biologically produced PDO.
We believe that in a long term glycerol from biofuels (biodiesel, bioethanol and algae-based biomass) and generally from processing of oil plants will be an attractive substrate for bioconversion. The integrated process of biorefinery of glycerol into 1,3-proanediol, biogas and fertilizer successfully developed and demonstrated at pilot plant in the Propanergy project has the following attractive advantages for future dissemination and exploitation of the results:
- Use of raw glycerol directly
- Fermentation byproducts into energy and fertilizer, resulting in a closed process with zero release of waste
- Unsterile operation and minimal medium, thus low investment and running costs
- Simple repeated batch process, no skilled personnel needed
- Suitable for small volume and decentralized operation
- Ideal for integration into biodiesel and biogas plants
- PDO production costs below 1.0 €/kg possible when integrated into biogas or biodiesel sites. This is very competitive to all the other existing technologies.

We will actively disseminate the Propanergy results world-wide also after the end of the project. The demonstration of the feasibility of such a sustainable biorefinery technology with the above mentioned advantages at the pilot plant paves the way for a successful dissemination. We will especially continue to disseminate the Propanregy technology to the following potential users:
- Biogas producers
- Suppliers of biogas technology
- Biodiesel producers
- Suppliers of biodiesel technology
- Producers and/or users of 1,3-propanediol

A reference list of publications and dissemination activities is part of the Final Report and can as well be found in detail within the Final Publishable Summary Report.

Related information


Monica Schofield
Tel.: +49 40 766296351
Fax: +49 40 766296359
Record Number: 196156 / Last updated on: 2017-03-23
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