Innovative Solutions for Cities and Agriculture. Bioenergy via Dry Fermentation

Transcription

1 Innovative Solutions for Cities and Agriculture Bioenergy via Dry Fermentation

2 02 BEKON Dry Fermentation Biogas via Dry Fermentation Until now, biogas technology mainly concentrated on wet fermentation of agricultural and municipal organic waste. Processability of renewables with a high dry matter content (e.g., corn silage) or solid waste were limited. The recently patented BEKON dry fermentation process, on the other hand, allows methane yields from stackable organic matter with a high dry matter content, requiring no conversion into pumpable, liquid substratum. This method renders fermentation of biowaste possible with up to 50 % dry matter content. The BEKON Process Organic matter, or biowaste, is inoculated with substratum that has already been fermented. It is then filled into the digester and fermented under airtight conditions. Continuous inoculation with bacterial matter occurs per recirculation of percolation liquid, which is sprayed over the organic matter in the digester. During the fermentation process, no further mixing, pumping or stirring is necessary inside the digester, nor is further material added. Excessive percolation liquid is collected in a drainage system, temporarily stored in the percolation tank, and then re-sprayed over the biomass in the digester. Fermentation occurs at mesophile (i.e., fermentation friendly) temperatures of C, which are regulated through heated floors and walls. The produced biogas is then pumped into a combined heat and power unit. A biogas engine in the co-generation unit generates electricity. Continuous biogas production is guaranteed by several digesters running simultaneously with progressive biogas production stages. Once the fermentation process is completed, the digesters are emptied and the digested matter either undergoes further composting or is used as high-quality organic compost.

3 03 Batch Process Dry Fermentation The BEKON method is a single-step batch process. The different stages of degradation (i.e., hydrolysis, acid, and methane formation) take place in the same digester. Batch process means that, during fermentation, no further material is added or substracted, and that the biomass is left to ferment in the digester until the end of retention time. In dry fermentation, biowaste needs no liquidation phase, as is with wet fermentation. Instead, it is constantly moistened with its own percolation liquid, thus guaranteeing ideal living conditions for bacteria. Temperatures are adjusted accordingly to each percolation cycle, while additives may be used to optimize process results.

4 04 BEKON Construction Modular Expansion The digesters (i.e., fermenters) are gas-tight, concrete, oblong, garage-like chambers and can be filled and emptied with wheel or front-end loaders. Several digesters may be built next to one another and run simultaneously in progressive biogas production stages, to guarantee continuous biogas production. Since BEKON Dry Fermentation plants treat biowaste with very high dry matter content, the digesters and, hence, overall plants are built in a very compact manner. Given the modularity of construction, the plant s capacity may easily be increased at a later point in time, if desired. The BEKON Dry Fermentation system ideally complements and is easily integrated into existing composting plants. Wheel loaders and front-end loaders at hand may be used to fill and empty the digesters. Heated Floors & Walls Temperatures within the isolated BEKON digesters are regulated via heated floors and walls, thus exploiting the entire contact area between fermenting substratum and digester. Heating tubes are integrated into the cement floor and walls during construction. Accordingly, no intrusive parts bar the digester s interior. In addition, a heat exchanger warms the self-fed percolation liquid. By this means, temperatures are optimally controlled in the digester.

5 05 Gas-tight Gates BEKON Dry Fermentation digesters have hydraulically operated, gas-tight, steel gate-like doors. They have a seal which, when inflated towards the cement entry wall, make the entrance gas-tight. Before the gates are opened, the air in the seal is released. These are then opened top-down, thus preventing the wheelloader from colliding into and damaging them. The inflatable seal lies within the gate s edge and is therefore also protected from damage. The system is run under light overpressure at 20 hpa, thus categorically preventing any potential form of gas-air explosion, even in the case of leakage.

6 06 Plant Operation Operation Efficiency One main advantage of the BEKON Dry Fermentation technology is that constant mixing of the biomass is unnecessary. Pumping and stirring units are not needed. The fermentation substratum rarely requires pre-treatment. The technology is therefore much simpler and robuster that of wet fermentation plants. The BEKON digesters have no moving parts. Therefore, wear and tear costs are low, as well as maintenance costs and staff costs. Process energy consumption is also minimal, making it easy to treat biomass with high dry matter content and interfering substances. Wood, plastic, sand, shrubs, etc. are not a problem. Computer Monitoring The BEKON Dry Fermentation plants are computer controlled and monitored. The various percolation cycle, heating and cogeneration unit parameters are regulated individually per digester. Constant monitoring of the control parameters entails continuous process optimization and, hence, maximum fermentation performance within the digesters.

7 07 Safety The BEKON Dry Fermentation plants are subject to a sophisticated, high-security concept. Explosions during the methane-to-air transition phase, when the digester is emptied, are impossible. Methane-air mixtures are excluded. During filling and emptying, a vacuum system ensures that the digester is constantly furnished with fresh air. The facility control room ensures a direct view of the digester entrance at all times. BEKON biogas plants are highly reliable, due to their robust construction. BEKON has developed and patented various technologies, to ensure the operation and safety of its plants. The BEKON technology therefore guarantees its customers that highest safety standards are met.

8 08 Economic Advantages Operation Efficiency One main advantage of the BEKON Dry Fermentation system is that constant mixing of the biomass is unnecessary. Pumping and stirring units are not needed. Fermentation needs little or no pre-treatment. The technology is therefore much simpler and robuster than that of wet fermentation plants. The BEKON digesters contain no moving parts. This has a positive effect on operating costs: Wear and tear costs are low, as well as maintenance and staff costs. Process energy consumption is much lower than that of wet fermentation. Biomass with high dry matter content is easily processed, as well as interfering substances, such as plastic, wood or fibrous materials. Gas Yield & Exploitation With dry fermentation, gas yields are similar to those of conventional liquid fermentation systems. The low sulphur and high methane contents in biogas from dry fermentation are a particularly interesting feature of the dry fermentation system. Research to date has shown that no desulphurization of the biogas is necessary. The biogas obtained in the BEKON Dry Fermentation process is dried, and gas quality and volume are measured. The biogas is then pumped through a gas regulating device into a combined heat and power unit. The cogeneration unit is adjusted depending on the biogas yield, making costly external gas storage unnecessary. Only the gaseous space above the fermenting substrata in the digester is used for temporary storage. The cogeneration unit converts the biogas to electricity and heat. The current is fed into a grid at a respective local price. A minor part of the heat is recycled, to heat the digesters. The majority of the heat is made available to external heat consumers. A further alternative for biogas, besides being fed into the combined heat and power unit: Once upgraded and adjusted to natural gas standards, it can be used in natural gas driven vehicles or fed directly into natural gas supply networks.

9 09 Composting and Compost Use Once the fermentation process is completed, the digested matter is hauled out of the digester with a wheel loader. Since the BEKON system runs on solid waste, no costly pressing or separation of liquid from solid waste is needed. Instead, the residues can be directly stacked onto heaps, where they are left to compost. Depending on local legislation and construction regulations, the substrata can also be spread onto fields directly, e.g. if derived exclusively from renewables. Hygienization is an alternative and facilitated through the substratum s selfheating process. The highly valuable compost can be used as a quality fertilizer by farmers and private or commercial gardening operators. The exact composition and quality of the compost depend on the initial feedstock. Entering a quality assurance system for compost and biowaste residues promotes sales to public and private gardeners, in particular, and existing compost plants can continue to market their products successfully. BEKON Technology Advantages Highly developed, computer monitored system Robust, simple technology Low maintenance costs Low investment costs Low staff costs High-quality gas High gas yields High safety & emission standards

10 10 Selected References Munich Green & Biowaste 25,000 t/p.a. Electrical Power 570 kw In Operation as of 11/07 Saalfeld Biowaste 20,000 t/p.a. Electrical Power 1,100 kw In Operation as of 11/07 Kusel Renewables 7,500 t/p.a. Electrical Power 330 kw In Operation as of 01/07 Rendsburg Biowaste 30,000 t/p.a. Electrical Power 1,000 kw In Operation as of 10/08 Cesena (I) Biowaste 30,000 t/p.a. Electrical power 1,200 kw In Operation as of 12/08 Naples (I) Renewables 30,000 t/p.a. Electrical power 1,000 kw In Operation as of 12/08

11 11 Vechta Biowaste 10,000 t/p.a. Electrical power 330 kw In Operation as of 12/08 Schmölln Renewables 16,000 t/p.a. Electrical Power 1,000 kw In Operation as of 10/08 Ostrhauderfehn Renewables 12,000 t/p.a. Electrical Power 500 kw In Operation as of 11/08 Göhren Renewables 14,000 t/p.a. Electrical Power 625 kw In Operation as of 06/08 Melzingen Renewables 11,000 t/p.a. Electrical Power 500 kw In Operation as of 05/08 Erfurt Biowaste 20,000 t/p.a. Electrical power 660 kw In Operation as of 11/08

12 Contact + 49 (89) (89) contact@bekon.eu BEKON Energy Technologies GmbH & Co. KG Feringastraße Munich, Unterföhring Germany