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E-M:/ Trash (and much more) Gasification......Re: Out of state trash/Granholm/waste incineration



I guess the word is that the Granholm initiative on trash to
energy will not be Detroit Incinerator style trash combustion/heat
recovery for steam/electricity approach.

It will instead by production of synthetic gas and synthetic
liquids from trash using gasification units.

This is a technology in which trash is input to a high temperature,
high pressure gasification vessel to produce "syngas" which
is mostly hydrogen and carbon monoxide, plus several other
substances, including hydrogen sulfide, carbonyl sulfide,
carbon disulfide, hydrochloric acid, nitrogen
oxides, ammonia, phosgene, methane and, of course,
the greenhouse gas carbon dioxide.   Syngas also will have
mercury, toxic metal particulates and other products of
incomplete combustion.

Syngas must be cleaned by use of sulfur recovery units and
tailgas treatment similar to what is used in a petroleum refinery or
sour gas plant.   If there is no backup sulfur recovery unit, the
gasifier will flare acid gas in the same manner as would
occur at a petroleum refinery.   Syngas plant gasifiers will have
elevated waste gas flares much like a petroleum refinery or
petrochemical plant.

In addition to cleaning out the hydrogen sulfide, carbonyl sulfide
and carbon disulfide, the gas must be cleaned of metal compound
and toxic organic compounds (i.e. polycyclic aromatic hydrocarbons)
that are present in the gas as generated by the gasifier.  

Gasifiers of this nature will also generate mercury in process
gas that is present in consumer items found in trash.   The mercury
can be cleaned from synthetic gas using a carbon bed, but care
must be taken in disposing or regenerating that waste to
avoid mercury air emissions by toxic transfer.

Scrubbing out other materials, such as the ammonia and hydrogen
chloride, will have to potential to produce wastewater that must
be disposed.  Such wastewater may also contain some of the
inorganic mercury compounds formed in the process.

Gasifiers generate a lot of slag that contains the non-toxic
and toxic metals plus silicates.  Such slag is generally considered
as a vitrified waste, allegedly inert and non-leachable as characterized by the industry, although
I have not personally seen any toxic extaction procedure leaching
tests on such material to determine how much lead, cadmium, nickel, etc.
will leach out.   Apparently such slag can be marketed as
an aggregate for building materials.

Because a gasifier features injection of solid materials at
atmospheric pressure into a high pressure vessel, the point
at which such injection is made using "lock hoppers" has the
potential to be an emission source of raw gasifier releases unless
carefully designed, operated and maintained.

The most fundamental objective with gasification plants is to
utilize the carbon monoxide and hydrogen to make methanol and
other higher order C2-C4 hydrocarbons, either for fuels or
as an industrial feedstock.   Other gasification units burn all or part of
their synthetic gas in  a combined cycle combustion turbine.

Last week, Dow Chemical submitted an application to MDEQ Air Division for a gasification
unit to be constructed in Midland, MI.   I do not yet know what
they plan as the feedstock for this gasification unit.

Gasification units can be combined with combustion turbines to produce
electricity.   Michigan DEQ is currently taking public comment on whether
"Integrated Gasification Combined Cycle" power plant technology should be
always be considered as a potentially valid control technology option
compared to traditional pulverized coal electric power plants.  See
this:  Public Comment Period Extended Through 9/14/07 Although sequestration of carbon dioxide is technically
feasiable with gasification, most of the gasification units
that have been installed in the United States do not
incorporate any carbon dioxide sequestration control
technology.   So far, establishment of stand-alone
gasification/turbine electricity generating units  has at times
required significant public taxpayer subsidies from the
Department of Energy as demonstration projects.

Although the present discussion is of trash gasification,
such technology must be understood as multiple waste/fuel
based input technology.    What is fed to these units will
be whatever material is available that contains hydrogen and
carbon and has limited amounts of non-combustibles and water.

For example, a proposed
Integrated Gasification Combined Cycle power plant I
dealt with in Lima OH would charge the gasifier with
"briquettes" made out of trash, sewage sludge and
Ohio high sulfur coal.   At the time of permitting, the
sponsors of that project said they would take up to
20% of all of the trash generated in Ohio and they
would be utilizing the absolute cheapest 4+% sulfur dirtiest
coal available.

I'm sure that some sponsor of a gasification unit will
ultimately want to feed it materials which would otherwise
be hazardous wastes, such as petroleum wastewater treatment
sludge, coke oven tar sludge or processed autofluff (a waste which is not a legally
designated hazardous waste but which has hazardous properties).

Bringing large amounts of trash and substances like
sewage sludge to a single location poses certain
management, transportation and odor control problems.   Large
trash transfer stations would be needed and such
facilities, like the one next to the Detroit Incinerator,
have traditionally been very significant odor sources.

Gasification units could be charged with large amounts
of urban waste wood and utility/tree crew wastes, although
this might draw such materials away from lower tech
composting and other methods of management.

A gasification unit in Michigan's northern, forested areas
and utilizing public forest resources poses significant
public trust, forest policy/forest management, land use and forest products
market conflict problems. 

Trash/sludge/waste/dirtycoal/etc. etc. gasification is a highly
centralized technology and is not the kind of smaller scale
energy utilization/generation technology that might offer more
promise (i.e. an integrated space heating/water heating/electric
generation device at a home or neighborhood scale).   We might
get more bang for the buck out of municipal or neighborhood
district heating/combined energy/power proposals.    We
also need to take energy conservation technology and developments
more seriously than we presently are, instead of always
focusing on supply side energy approaches.  

On the gasification approaches I'll be interested to see whether
they will involve significant taxpayer expense and subsidy as was
put into the trash to energy plants like the one in Detroit.   

I'm not sure, however, that encouraging trash importation to Michigan
because we would ultimately have trash gasification plants as the
recent press spin on Granholm's recent announcement really passes
the "sniff test.".....especially if a tipping fee is charged that is any
higher than common landfill disposal tipping fees.

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Environmental Enforcement, Permit/Technical Review, Public Policy,
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