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| A '''biogas powerplant''' is a system where ] is used to generate electricity. The gas which is produced via ] is used to drive an ]. By-products of this process are steam and hot water. The hot water can be recycled in a combined heat and power cycle to increase the temperature of the digesters to optimal conditions. | |||
| == Overview == | |||
| ]s powering electricity generators, ], ], ] ]] | |||
| Biogas power plants are a combination of anaerobic digestion systems with associated electricity generators such as ] or ]. The electricity they produce is classified as ] or ] and if sold into the national grid may attract subsidies (such as ] in the UK). | |||
| Feedstock into the biogas power plants must be biodegradable in order to produce methane. Suitable feedstocks include (but are not limited to): | |||
| *] | |||
| *] ] (primary or raw sludge and/or secondary sludge) | |||
| *] | |||
| *] | |||
| *] | |||
| *Organic component of mixed municipal waste (in ]) | |||
| *Biomass like ] | |||
| There are three stages of anaerobic digestion: ], ], and ]. These stages can occur in the same digestion tank or can be controlled independently and optimised according to the requirements of the different bacterial processes. | |||
| The more complex and efficient a biogas plant the more expensive it will be for the locality. Biogas plants can be simplified to produce gas for villages in countries where organic wastes are available and funds are limited. Alternatively, in more developed countries pressure in the form of legislation and high energy costs is increasing the amount of projects generating renewable energy from waste. | |||
| Biogas plants can be found in countries such as ], ], ], ], ] and ]. | |||
| Advanced processing systems can recover the organic fraction mixed waste streams. These systems are a subgroup of mechanical biological treatment plants. They sort the recyclable elements of the waste and process the organic fraction into a high surface area low solids soup which are then passed into a biogas power plant (anaerobic digester). Advanced systems like this can be found in Israel.<ref> Finstein, M. S., Zadik, Y., Marshall, A. T. & Brody, D. (2004) The ArrowBio Process for Mixed Municipal Solid Waste – Responses to “Requests for Information”, Proceedings for Biodegradable and Residual Waste Management, Proceedings. (Eds. E. K. Papadimitriou & E. I. Stentiford), Technology and Service Providers Forum, p. 407-413 | |||
| </ref>. () and ] and are being widely considered in Europe to meet the EU ]. | |||
| Further energy can be produced by the combustion of the ] which may be classified as a ]. | |||
| ==Principal procedure== | |||
| '''Biogas production''' | |||
| * 1 Preparing the biomass | |||
| * 2 Mixing | |||
| * 3 Digester/fermenter (Heating 40-90 °C) | |||
| '''Gas input''' | |||
| * 4 Raw biogas input 40 °C | |||
| * 5 Liquid gas Separator → condensates | |||
| * 6 Gas dryer (refrigerate) 4 °C → condensates | |||
| * 7 ] about 400] | |||
| * 8 Gas filter (cleaning of dust particles, less than 5 parts per billion by mass of siloxanes) | |||
| * 9 Gas heating (minimum about 10 °C) | |||
| '''Gas combustion → thermal energy''' | |||
| * 10 Gas turbine exhaust output 300 to 400 °C | |||
| * 11 Generator → electric energy | |||
| '''Exhaust output → heat exchange ''' | |||
| * 12 ] heat recovery steam generation | |||
| * 13 Heat exchanger for hot water | |||
| ] might be present in the biogas and must be removed prior to input in the gas engines, as it erodes moving parts. ] may also be produced in the process if there are high levels of ] in the biogas. The exhaust gas must be cleaned up, as sulphur dioxide is toxic. | |||
| ===Plant engines === | |||
| * Gas motor engines | |||
| * Micro–gas turbines | |||
| * ] | |||
| * ] | |||
| === Plant types === | |||
| Plant type depends on the type of biogas and usage of energy. | |||
| * ] combined heat & power or HRSG | |||
| * ] combined heat, cooling & power production | |||
| === Plant sizes === | |||
| {| border="1" cellspacing="0" cellpadding="5" | |||
| ! Size | |||
| ! Power | |||
| ! Plant Size | |||
| |- | |||
| | Small | |||
| | 500W to 5 kW | |||
| | 10 m² | |||
| |- | |||
| | Medium | |||
| | 5 kW to 75 kW | |||
| | 15 to 100 m² | |||
| |- | |||
| | Large | |||
| | 75 kW to 4MW | |||
| | 1 km² | |||
| |- | |||
| |} | |||
| The plant can also be segmented including ]s and ]s. | |||
| == See also == | |||
| {{EnergyPortal}} | |||
| *] | |||
| *] | |||
| *] | |||
| *] | |||
| *] | |||
| *] | |||
| ==External links== | |||
| * | |||
| * | |||
| * | |||
| * | |||
| * | |||
| * | |||
| * (]) | |||
| * | |||
| * (Germany) | |||
| * (Germany) | |||
| * (Philippines) | |||
| * using ] | |||
| * (India) | |||
| === Education === | |||
| * | |||
| * | |||
| * | |||
| == References == | |||
| {{reflist}} | |||
| <br> | |||
| {{Sustainability and energy development group}} | |||
| {{Waste}} | |||
| ] | |||
| ] | |||
| ] | |||
| ] | |||
| ] | |||
Revision as of 09:35, 17 August 2007
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