Small Anaerobic Digestion Plants

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A presentation from Enerwaste Summit - Abu Dhabi - 18-19 March 2013 aboutSmall Anaerobic Digestion Plants, benefits, design guide, case study in Batroun - Lebanon

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<p>BY Samer Al-AyashMechanical Engineer Environmental Consultant</p> <p>Target1- Benefits of Small Waste-to-Energy Plants on: -Recruiting local expertise to design &amp; build WTE plants - Recruiting local manpower for construction &amp; operation - Rural Development - General Sustainable Development 2- Economical &amp; financial needs 3- Simple design &amp; engineering guides</p> <p>Anaerobic Digestion Basicsoxygen - the process occurs in one of two temperature ranges: 30-40C (mesophilic) or 50-60C (thermophilic) - System influent: animal manure, organic household wastes, sewage - System effluent: biogas (65% methane + 35% carbon dioxide), nutrient rich digestate (fertilizers, land conditioners) Benefits: - waste management and landfill reduction - improvement of agriculture - providing clean alternative energy source-Is the process in which microorganisms break down biodegradable material (organics) in the absence of</p> <p>EXAMPLES</p> <p>Domestic Solid Waste Management Centre QatarBy: Keppel SeghersClient: Project Type: Project Value: Plant Capacity: Key Features: Ministry of Municipal Affairs and Agriculture, Qatar 20-year Design-Build-Operate (DBO) contract approx. $1.7 billion Up to 2,300 tons of mixed domestic solid waste and 5,000 tons of construction and demolition waste per day Integrated solid waste management facility providing waste sorting and recycling facilities, land filling, composting plant and a 1,500 tons per day waste-to-energy (WTE) plant Steam Turbine Generators, estimated 30MW exported to National Grid Waste Sorting / Separation, Recycling, Incineration, Anaerobic Fermentation and Land Filling</p> <p>Energy Output: Processes:</p> <p>Sewage Treatment Plant Leonberg (near Stuttgart) - GermanyIn operation since September 94 Total investment: 3.22M Euro Annual Incomes: 280,000 EU Simple Payback: 10.6 years</p> <p>Bran Sands AAD Plantby</p> <p>Northumbrian Water - UKpeople - Advanced Anaerobic Digestion (AAD) system added to existing plant to reduce 500,000 tons of sludge to 60,000 tons and generate 4.7 MWe &amp; 2 MWth - Annual incomes:-$ 3.5 millions from electricity sold to national</p> <p>- Sewage Water treatment plant serving 2 million</p> <p>grid -$ 5 millions operational savings -$ 2.4 millions Renewable Obligation Certificate</p> <p>- Carbon Dioxide reduction = 62,000 tons/year -Construction cost: 50 million USD -Construction works consumed:-10,000 tons of concrete -4000 meters of pipes -100,000 meters of cables</p> <p>CASE STUDY</p> <p>AD TECHNOLOGYBiogas</p> <p>Boiler</p> <p>C</p> <p>1500 MWh/y</p> <p>Engine</p> <p>Organic Solid Waste32 ton/day + 15 m/day Sewage</p> <p>CLiquid Fertilizer</p> <p>AD PLANT1600 m dig. 1000 m area</p> <p>42,000 m/y</p> <p>Storage</p> <p>120,000 m/y</p> <p>Ponds</p> <p>Distilled Water Compost Fertilizer</p> <p>Dewatering115 tons/y</p> <p>SORTING DRUM &amp; CONVEYOR</p> <p>ADDITIONAL SYSTEMS PLASTIC RECYCLING LINE METAL BALERS GLASS RECYCLING LINE</p> <p>WATER DISTILLATION / SOLAR DESALINATION- Designed by Innovative Concepts and developed with Promex</p> <p>Environmental Solutions&amp; Alberto Fernandez Architects -Produces Distilled Water and cold air by completely clean &amp; renewable energy sources (solar, wind &amp; geothermal) - Completely self sustainable. - 200m diameter Solar Collector - Annually: 47,000 m of distilled water - 200,000 m/hr of cold air</p> <p>Batroun AD Plant Components 4 x 470m concrete digesters 1 x Preheating biogas boiler: 500KWth 4 x heat recovery biogas boiler: 120kWth each 2 x biogas electric generator: 200 kWe each 1 x sorting system: 100 tons/day 1 x metal baling system</p> <p>Batroun AD Plant Balance Inputs: 32 tons/day Organic Wastes + 15 tons/day sewage Sources: household wastes, dairy farms, agriculture wastes, Outputs: Biogas 2300 m/day Net Electricity: 1,750,000 kWh/year (enough for 200-300 houses) Liquid &amp; Solid Fertilizers: 6500 m/year Distilled Water: 9700 m/year Recyclable material: 5500 m/year</p> <p>Batroun AD Plant Costs &amp; Revenues Construction cost: 1.8 Million USD Annual Running Costs: 750,000USD Annual Revenues: 1.85 Million USD Simple Payback period: 1 years Complex Payback Period: 3.5 years</p> <p>Rules of thumb</p> <p>Consider the ratio of organic waste to the total wastes Consider Total Solids (TS) of the organic waste Digester maximum allowed load: 70% of total volume Maximum allowed TS: 13% of digester loading 50% of TS shall be converted to biogas Biogas calorific value = 25 MJ/m Electric production: 2-3 kWh/m biogas</p> <p> i.e.: for 1 ton of households 640 kg of organic wastes TS = 13% of organic wastes = 83 kg Biogas produced = 36 m Electricity produced = 100 kWh</p> <p>Plant Capacity Investment Cost ($/t) Operation Cost ($/t)</p> <p>6000 ton/year 700-900 80-120</p> <p>20,000 ton/year 200-500 40-120 Large 1MW 5000 cows</p> <p>25,000 ton/year 200-400 35-100</p> <p>50,000 ton/year 50-350 30-90</p> <p>Small 25kW 125 cows $ 500,000 $9000 $ 0.06 $ 0.01</p> <p>Capital cost Annual Operating Cost Power Sale ($/kWh) Heat Sale ($/kWh) Solids Sale</p> <p>$ 9million $ 643,000</p> <p>$ 700,000</p> <p>$ 20,000</p> <p>Large vs. SmallLarge AD Plants Lower initial cost/ton Lower running cost/ton More taxes paid to government More staff to be recruited Complex design &amp; technologies High skilled &amp; professional</p> <p>Small AD PlantsHigher initial cost/ton Higher running cost/ton Less taxes paid to government Local Staff to be recruited Simple design &amp; technologies Local professionals are able t0 design, construct &amp; operate the plant. And many components might be manufactured and/or assembled locally Suitable for small cities, group of villages, etc.. </p> <p>international companies needed for design, construction &amp; operation Suitable for large cities or nation wide</p> <p>SMALL AD PLANTS Can be designed, constructed and operated by local professionals and experts. Recruits local manpower =&gt; saving transportation over long distances. Collecting wastes from surrounding villages or cities =&gt; less transportation cost. Can provide cheap power (electric &amp; thermal) and fertilizers for rural &amp; agricultural communities. Improve sense of environmental responsibility within the surrounding community.</p> <p>THE END</p> <p>THANK YOU</p>