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Thread: Does Biogas contribute to global warming?

  1. #1 Does Biogas contribute to global warming? 
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    Does Biogas release carbon dioxide and methane into the atmosphere (contributing to the greenhouse effect)? Or is it more ecologically friendly because any carbon released is from plants which lived recently?
    I'm slightly confused because the burning of trees (for example) to clear land during deforestation is said to emit a high amount of CO2 into the atmosphere. However, if the trees have lived recently doesn't that make them fairly carbon neutral?

    Thank you


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  3. #2  
    Forum Isotope Bunbury's Avatar
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    Any time you burn carbon based materials, including biogas, carbon dioxide is released, but if you burn it in an engine and use the engine to turn an electric generator you might reduce the need to burn coal or oil elsewhere.

    The biogas was made from waste that would have produced CO2 and methane without the benefit of producing useful energy if left to decompose in a landfill so on balance the biomass to electric power process should result in a net reduction of greenhouse gases in the atmosphere.


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  4. #3  
    Forum Radioactive Isotope skeptic's Avatar
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    Also, if biogas, or other biofuel, is made from trees or crops that are replanted, the CO2 emitted is compensated for by the CO2 that is absorbed by the new growing crop.
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    If the so-called biogas were produced from material that would have been land filled, it does speed the emissions of global warming gases - esp. carbon dioxide. Land fills are designed to slow biodegradartion and are effectively entomb the great percentage of waste, not unlike petroleum deposits.

    Production by frementation consumes more fiel that it produces.
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  6. #5  
    Forum Isotope Bunbury's Avatar
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    Quote Originally Posted by Jorge1907
    If the so-called biogas were produced from material that would have been land filled, it does speed the emissions of global warming gases - esp. carbon dioxide. Land fills are designed to slow biodegradartion and are effectively entomb the great percentage of waste, not unlike petroleum deposits.

    Production by frementation consumes more fiel that it produces.
    Gases emitted from landfills are approximately 50% methane and 50% CO2(?). Methane is a far stronger greenhouse gas than CO2 so it is advantageous to burn it to produce energy while at the same time converting it to CO2.

    Covering a landfill may delay the release of gases, but AFAIK they are still released eventually. There are experiments with biological covers that convert CH4 to CO2, which I don't know much about. If this is what you are referring to I'd appreciate a little more info.

    Better yet, compost household organic waste so it never goes to a landfill.
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  7. #6  
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    Thank you for the information. I am also wondering about the carbon emissions of hydrogen gas, methanol and ethanol as fuels (in regard to finding a future and more ecologically friendly alternative to fossil fuels). Which one is better and has the lowest greenhouse gas emissions? Am I right in thinking that ethanol (that has not been produced from plants which contain alot of cellulose) consumes more energy in its production than it actually saves in emissions, methanol recycles CO2 so could therefore be viable in reducing the net production of greenhouse gases and hydrogen gas would be viable providing it is not produced using energy from fossil fuels? I hear that hydrogen is considered the least viable. Why is this? To me, it sounds like a good, clean alternative (though maybe dangerous).
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  8. #7  
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    Quote Originally Posted by emetzner
    I am also wondering about the carbon emissions of hydrogen gas
    Don't worry, it does not burn hot enough to cause fusion :wink:
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  9. #8  
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    Landfills are designed to minimize biological activity so production of methane and carbon dioxide is relative slow and a signficant percentage of each are fixed and metabolized within soil.

    There are no carbon emissions from hydrogen fuel.
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  10. #9  
    Forum Isotope Bunbury's Avatar
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    Quote Originally Posted by Jorge1907
    Landfills are designed to minimize biological activity so production of methane and carbon dioxide is relative slow and a signficant percentage of each are fixed and metabolized within soil.
    Nevertheless landfills are the largest source of methane emissions in the USA, according to the EPA.

    http://www.epa.gov/methane/sources.html
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