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Thread: Swedish city replaces fossil fuel with methane from waste

  1. #1 Swedish city replaces fossil fuel with methane from waste 
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    "But Kristianstad has already crossed a crucial threshold: the city and surrounding county, with a population of 80,000, essentially use no oil, natural gas or coal to heat homes and businesses, even during the long frigid winters. It is a complete reversal from 20 years ago, when all of their heat came from fossil fuels.

    But this area in southern Sweden, best known as the home of Absolut vodka, has not generally substituted solar panels or wind turbines for the traditional fuels it has forsaken. Instead, as befits a region that is an epicenter of farming and food processing, it generates energy from a motley assortment of ingredients like potato peels, manure, used cooking oil, stale cookies and pig intestines.

    A hulking 10-year-old plant on the outskirts of Kristianstad uses a biological process to transform the detritus into biogas, a form of methane. That gas is burned to create heat and electricity, or is refined as a fuel for cars...... "

    http://www.nytimes.com/2010/12/11/sc...=1&ref=science

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    It's not entirely a good news story. For example the article puts the initial cost at $144 million and about a $4 million savings per year...that's a long payback. Also the waste is producing methane which is what they burn to power the plant. But methane if not burned entirely, is in itself a potent greenhouse gas.

    Nevertheless it's a promising type of innovation thats gotten them closer to energy independence.


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  3. #2 Re: Swedish city replaces fossil fuel with methane from wast 
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    Quote Originally Posted by Lynx_Fox
    But methane if not burned entirely, is in itself a potent greenhouse gas.
    It's often mentioned that methane has a greenhouse potential of 54 times that of CO2 but this is a bit misleading. Molecule for molecule methane produces less greenhouse forcing than CO2 but the greenhouse effect is a logarithmic function of concentration and since there is far less CH4 in the atmosphere than CO2 it's easier to double CH4 than CO2.

    Note that most of this effect has nothing much to do with any special property of methane, but arises simply because the radiative forcing for most greenhouse gases is logarithmic in concentration, so you sort of get the same radiative forcing for everybody upon doubling their concentration — but if you start with somebody whose concentration is low, it takes many fewer molecules to double. That means that the CO2 equivalent of methane depends on what concentration you are starting with. If you started from a concentration of 10ppm, then the equivalence factor drops to 10. If you start out with equal amounts of methane and CO2 (300 ppm), then the equivalence factor drops further to 0.5. In that sense, methane is, intrinsically speaking, a worse greenhouse gas than CO2, though the crossover is at values that are so high they are only relevant (at most) to the Early Earth.
    Since methane oxidizes to CO2 after a few years its immediate greenhouse impact is short lived. Bottom line is it's still the CO2 emissions we should be focused on.

    http://www.realclimate.org/index.php...ime/#more-5494


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  4. #3  
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    I agree.

    I wonder how well the technology scales up to large city size.

    Imagine New York City or Houston largely powered in this way.
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  5. #4  
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    I wonder if the composting programs that many cities operate, in which yard and kitchen scraps are collected and composted in a central facility, could be developed for biogas production. The logistical infrastructure already exists and energy production might generate cash flow where compost sales barely cover costs. The cost of $114 million for the Swedish plant seems outlandishly high.
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