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Garbage in, MWatts out

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  • Garbage in, MWatts out



    MIT link....

    Garbage In, Megawatts Out
    Ottawa will build the first gasification facility in North America to make energy from waste.

    This week, city counselors in Ottawa, Ontario, unanimously approved a new waste-to-energy facility that will turn 400 metric tons of garbage per day into 21 megawatts of net electricity--enough to power about 19,000 homes. Rather than burning trash to generate heat, as with an incinerator, the facility proposed by Ottawa-based PlascoEnergy Group employs electric-plasma torches to gasify the municipal waste and enlist the gas to generate electricity.

    A few waste-to-energy gasification plants have been built in Europe and Asia, where landfilling is more difficult and energy has historically been more costly. But PlascoEnergy's plant would be the first large facility of its kind in North America. The company's profitability hinges on its ability to use a cooler gasification process to lower costs, as well as on rising energy and tipping fees to ensure strong revenues.

    PlascoEnergy's approval marked the latest in a string of positive developments for waste gasification projects in recent weeks. Last month, Hawaii okayed $100 million in bonds to finance a waste-to-energy plant using plasma-torch technology from Westinghouse Plasma, based in Madison, PA, that is already employed in two large Japanese waste processing plants. Meanwhile, Boston-based competitor Ze-gen reported the successful ramp-up of a 10-metric-ton-per-day pilot plant in New Bedford, MA, that uses molten iron to break down waste.

    Most gasification plants work by subjecting waste to extreme heat in the absence of oxygen. Under these conditions, the waste breaks down to yield a blend of hydrogen and carbon monoxide called syngas that can be burned in turbines and engines. What has held back the technology in North America is high operating costs. Plasma plants, using powerful electrical currents to produce a superhot plasma that catalyzes waste breakdown, tend to consume most of the energy they generate. As a result, the focus of plasma gasification plants has been to simply destroy hazardous wastes. "There was really no thought of being able to produce net power," says PlascoEnergy CEO Rod Bryden.

    PlascoEnergy started looking at gasification for municipal solid waste five years ago, when it determined through simulation that cooler plasma torches could do the job. "The amount of heat required to separate gases from solids was much less than the amount being delivered when the purpose was simply to destroy the material," says Bryden. PlascoEnergy tested the models on its five-metric-ton-per-day pilot plant in Castellgali, Spain (jointly operated with Hera Holdings, Spain's second largest waste handler). In January, the company began large-scale trials in a 100-metric-ton-per-day demonstration plant built in partnership with the city of Ottawa.
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    Dr. Mordrid
    ----------------------------
    An elephant is a mouse built to government specifications.

    I carry a gun because I can't throw a rock 1,250 fps

  • #2
    I've been promoting the use of garbage for electricity generation for many years.

    Attached is the raw text for an article I wrote for the E&T magazine (Institution of Engineers and Technologists). The conclusions are:

    The technology used by the Tridel company is usable in many places worldwide and can best be summarised into lists of advantages and disadvantages.
    Advantages:
    • Sustainable supply of renewable fuel
    • Much reduced greenhouse gas emissions
    • Virtually no pollution
    • Recovery of precious and other valuable metals
    • Landfill volume reduced by about 90 per cent
    • No landfill pests, odours or emissions
    • Able to recycle paper/plastics into energy where material recycling is impractical
    • Energy available as electricity and heat
    • Energy efficiency typically about 50 per cent for a combined heat and power plant
    • Flexible, according to the type of available waste
    • Can be adapted for large cities with economy of scale
    • Known and mature technology with long experience
    • Cost-effective
    Disadvantages:
    • Relatively high capital cost (national or international grants or subsidies may be available)
    • Requires waste to be partially pre-sorted (recyclable and non-combustible materials removed)
    • Less suitable for sparsely populated rural areas

    Can't attach the pdf article as too big for MURC

    Further reference: http://www.cypenv.org/worldenv/files/tridel.htm

    There are advantages and disadvantages of direct combustion and gasification processes. Gasification is cheaper but more polluting and there is less value obtained out of it.
    Attached Files
    Brian (the devil incarnate)

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