The decision to reconstruct and extend the capacity of an already existing biogas plant at the sewerage works of Otrokovice was based on four factors:

• 1. own competent human resources were available to design the technology project
• 2. also a large quantity of biologically decomposable waste was available in relatively close vicinity
• 3. the project is in accordance with the national and regional policy, i. e. to decrease the proportion of biologically decomposable waste placed in dumps
• 4. the availability of EU grants

The whole production both of electricity and heat is used for the energy demands of the sewerage plant, which has a population equivalent of 160 000 people.
The decision to start the project was made in 2005. In July 2006 the biogas plant was put into test-mode operation for one year. Since 1^st July 2007 the plant works in ordinary mode.

TECHNOLOGY

The specificity of the project is the idea of producing energy for the plant’s own needs in conjunction with probably the main reason for starting the project – to produce proteinous material which can be used in the chemical and other industries. The process of energy production is the following: in the first level (hydrolysis) biologically decomposable waste from livestock farming (such as skin and bone waste) and waste from canteens and restaurants is treated and processed. The end products are proteinous products for further use in the industry. During the second level (methane fermentation), the content of the previous end product which cannot be used for the proteinous products, is processed by fermentation. The product of the second level is biogas with 70% of methane and anaerobically stable slurry. This biogas is mixed with the biogas from slurry from the sewerage plant (produced separately by the hydrolysis process) to be used in three cogeneration units. The proportion of biogas from waste of the total biogas production of the sewerage plant is about 30%. The anaerobically stable slurry is in the third level, together with waste of green vegetation, processed to compost. That is, basically there are three kinds of products: proteinous material for industry, energy for the sewerage plant and fertilizer (compost).
Annually about 10 thousand tonnes of waste could be processed in the plant.

In 2006 the biogas plant produced 1.9 GWh of electricity and 9 500 GJ of heat.
The lifetime of the installation cannot be easily evaluated. The whole process used in Otrokovice consists of many different technology parts. The lifetime is different for each one and general or partial repairs are very common.

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ECONOMIC ASPECTS

The total investment amounted to EUR 2 200 000. In addtion to the investor’s (TOMA a. s.) own resources, EUR 800 000 grants from the European Union (administered by Czech ministries) were used.
The calculated payback time of the investment is 6 years.
Based on the production figures of 2006, total annual savings for energy delivered by the biogas plant (and not by the electricity company and heat plant) are about 240 000 EUR.

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SOCIAL EFFECTS

During the whole progress of the project implementation different kinds of information was accessible to the public. The project owner provides basic information on its website and in the form of brochures. Public visits in the factory have not been organised yet, but it should not be a problem to arrange visits with the management.
9 new direct jobs were created due to the reconstruction of the biogas plant. At the same time, waste producers and one logistics company also benefit from the project.

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ENVIROMENTAL EFFECTS

If the amount of 9.5 TJ of heat produced by the plant in 2006 had been delivered – as previously – from the heat plant of Otrokovice, it would have required burning approximately 1 200 tonnes of brown coal. This would have emitted ca. 1 800 tonnes of carbon dioxide (based on 2006 data for energy production and fuel consumption of the heat plant at Otrokovice).
Very probably the biggest environmental effect was achieved by processing the biologically decomposable waste which otherwise would have been placed in dumps.

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DIFFICULTIES, PROBLEMS

During the preparation and implementation of the project, public fear of the risk of bad smells and of the danger of imported waste were expressed. Those fears were communicated to the municipal bodies. But by fulfilling all requested conditions, the plant works today succesfully and without any environmental or other dangers.

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FOLLOW UP

TOMA a. s. plans to extend the number of similar energy producing units. However, because of concerns due to the increased costs of transport, those units will probably be built directly by the producers of waste.

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FURTHER INFORMATION

TOMA a. s.
Tř. T. Bati 1566
Otrokovice
Czech Republic

Web: www.tomaas.cz

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