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How important is it that an additional criteria for ILUC is added to the EU sustainability schemes?
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Tank Storage Canada expo & conference
September 28 - 29
Calgary, Alberta, Canada
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2101 Ethanol Conference & Trade Show
August 02 - 04
Missouri, US |
American Coalition for Ethanol Convention
August 03 - 05
Missouri, US |
NISTM Missouri State Storage Tank Conference
August 19
Missouri, US |
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Volume 3, Issue 9
Feature: The biogas boom |
Small scale biogas plants have been around for 150 years. For farms and food companies producing liquid waste, anaerobic digestion (AD) offers an ideal solution for generating renewable fuel for combined heat and power (CHP) boilers to power their own facilities, and perhaps look at selling any additional power to the national grid to benefit from government subsidies.
Producing biogas through anaerobic digestion has proved so popular that a total of 8,900 biogas plants are destined to be built this year, using manure, food waste or municipal waste to generate 2,700 megawatts (MW) of electricity worldwide. Biogas is produced naturally in oxygen-free conditions at landfill sites over a number of years. Plants simply accelerate the digestion process through the addition of a specific amount of bacteria, constant stirring and temperature control. The gases produced are the same (50-60% methane and 35-40% carbon dioxide) but the yields can be larger and cleaner.
In the medium term biogas can be produced from anaerobic digestion of energy crops and in the long term it can be produced from the gasification of dry lignocellulosic biomass using dedicated biogas plants to produce large amount of renewable power. To produce biogas from lignocellulosic biomass it must be gasified giving a syngas mixture of carbon monoxide and hydrogen. Prior to entering the gasifier solid feedstocks are ground into small particles, while liquids and gases are fed directly. A controlled amounts of oxygen and steam then enters the gasifier, where temperatures reach 760 – 1537oC. The heat and pressure break apart the chemical bonds of the feedstock forming syngas.
The trace levels of impurities are then cleaned up prior to use in power applications. At a biogas plant such as Canada-based StormFisher’s the feedstock is mixed up in the primary digester in a low energy process at 37?C. The heat comes from the process itself. It is stirred and then stored for 22 days in a continuous process. The AD process produces electricity and heat. The former goes to the grid, and the process heat is used to dry the pellet, and the effluent (digestate) is turned into organic fertiliser.
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