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Is the US EISA production target of 36 billion gal/year of biofuels by 2022 realistic?
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Biofuels International expo & conference
May 05
Barcelo Hotel, Prague, Czech Republic
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BioEnergy Expo
February 04 - July 02
Verona, Italy |
National Biodiesel Conference and Expo
February 07 - 10
Texas, US |
F.O. Licht's 3rd Annual Developing and Commercialising Next Generation Biofuels
February 09 - 11
London, UK |
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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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