In his letter to The Sun (“Waste to energy is more complicated than The Sun lets on,” Dec. 18) Sidney Rankin points out the shortcomings in the logic of current thinking on waste to energy (WtE) projects and facilities. And he correct, as far as he goes.
Landfills, even when operated to stringent standards, generate tons of greenhouse gasses. The basic biology and chemistry of the bacterial breakdown produces polluting and odiferous fumes that are released into the atmosphere. As received, municipal solid waste is a poor fuel for combustion. Its heterogeneous nature, high moisture content and physical morphology make mass combustion or incineration problematic and inefficient, in the extreme. High maintenance combustion units (moving grate) and auxiliary fuel are often necessary to maintain and complete combustion. The required introduction of combustion air (oxygen) and the unavoidable thermal inconsistencies within the combustion unit lead to the formation of unacceptable hazardous compounds such as dioxins and furans.
Now, I readily admit to a strong bias in these next comments and statements:
All of these serious drawbacks can be avoided with the application of proven, well controlled processes. Employing innovative preparation of the waste (to provide an easily handled and processed feedstock) coupled with close control of the reactor temperatures, mixing and residence times, will produce an extremely valuable non-polluting fuel with near zero emissions. This fuel closely resembles natural gas and can be used to generate renewable electricity, steam, liquid fuels such as diesel and high octane gasoline, and valuable chemicals (methanol, DME).
At the same time the landfill operation can be eliminated.The water is removed from the incoming waste, treated to the desired specification and reused or discharged.
Each integrated sub-process is clearly defined and proven effective in multiple applications with unquestioned historical performance. Other by-products, in addition to those listed above, are possible along with the renewable energy that together make a facility a profitable asset with long term viability.
There are no technical barriers or environmental drawbacks.
In comparison with older technologies such as mass burn and incineration, the advantages are dramatic and the advancement potential more than substantial. All of the barriers are political and emotional. These are caused by and are the result of a lack of educated, informed decision making and a lack of will.
Doug Shackelford, Washington
The writer is the director of business development for D4 Energy Group, a waste-to-energy company.
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