on the importance of emission limitation and control
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On the Importance of Emission Limitation and
Control with Methods
Isaac D. Cobb
12.01.2009
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All human activity puts some un-natural chemicals into the air. Most pollution
results indirectly from human activity, the world is so intertwined that arguing the
preceding statement is a fool's errand. Human civilization is awash in a sea of air, which
polluted on a daily basis. Limiting the affect of this pollution is a less desirable option to
treating the problem from the roots. There exist a limited number of options available for
changing emission patterns in the air all must share. Primarily there are three, control
and/or limitation, new technology, and new engineering. The following will attempt to
rationalize the ability of each to alter emission patterns as well as assert foreseeable flaws
in the knowledge presented.
First, examine the chemistry of the air that surrounds all living things. The primary
source of many emissions is transportation. Internal combustion engines are responsible
for a large percentage of nitrogen oxide emissions, in conjunction with the power industry
(3). Major power outages have shown the dramatic contributions of nitrogen oxides to
atmospheric pollution by the dramatic decrease in the oxides, ground level ozone, sulfurous
oxides, and particulate matter. Major power outages result in a loss of industrial
production and vehicular traffic in conjunction with a loss of general modernity. The
complex chemistry of atmospheric pollutants causes them to be cyclic throughout the day.
The addition or subtraction of a relatively small amount of one pollutant can cause a
dramatic shift in the presence of other reactants. This is exacerbated by the fact the
endemic complexity of weather patterns can transport air pollution from one part of a
region to another, perhaps, hundreds of miles away. Below lists a series of reactions, the
direct and indirect responsibility of human activities, causing increased nitrogen oxides in
the atmosphere:
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1. NO2 + UVA NO* + O*2. O* + O2 O33. NO* + O3 NO2 + O24. Olefins + (O2,NO,nitric radicals) aldehydes5. VOCs HOO- or ROO- + NO OH* + NO26. OH* + NO2 HNO3Early in the day, the concentrations of nitrogen oxides are at their lowest because
over the course of the night they largely dissipate. By mid to late morning though
vehicular traffic and general human activity has increase the concentration of NO and over
the course of the late morning the NO in the atmosphere is oxidize to NO2. As seen in the
series of reactions above, NO2 transforms into ground level ozone by a 2-step mechanism
initiated by UV-A radiation. Other reactions that can be important in the broad scheme of
vehicular traffic include this non-comprehensive series:
1. C(s) + NO2 CO + NO2. S(s) + combustion SO2 (g)
Sulfurous emissions are awkward to deal with because, in excess, they can generate acid
rain and sulfur inherently poisons the catalytic converters and scrubbers used to reduce
other emissions. Carbon monoxide is especially toxic to the respiration cycle of mammals
because it effectively binds to the hemoglobin of blood preventing gas exchange in tissues.
The image on the next page, taken from newworldencyclopedia.com, has been
included to show the complexity of the earths atmosphere and the chemistry proceeding
daily. The previous list, remember, was not all-inclusive nor is the diagram. Notice that
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some gases active in the complex chemistry of the atmosphere are natural while others are
anthropogenic. In rural areas, gases involved in atmospheric chemistry can be contributed
by natural sources the majority of the time. However, in urban areas, the contributions of
such natural sources are so low they are negligible. Air currents also play a role in
pollution because some pollutants absent in rural areas help provide a means for
elimination of synthetic gases and emissions. Large natural sources of atmospheric
pollution are volcanoes and other massive geologic events. Many natural processes are in
balance with the surrounding environment but the anthropogenic sources complicate and
throw processes out of equilibrium leading to the formation of products in populated areas,
which would not otherwise occur.
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In addition to the gaseous emissions, there are also particulate emissions under two
classifications. Those particles which are inhalable, greater than 2.5 micrometers but less
than 25 micrometers, and those which are respirable, less than 2.5 micrometers. The
respirable particles pose a greater health risk because they can readily infiltrate the lungs
and alveoli. However, it is not simply their size posing a danger to humans. While very
small particulate matter within the lungs is expelled very slowly, the greater danger is in
the fact that these airborne particles give a surface for a good deal of very complex, and
possibly, harmful chemistry to take place. While this is worth mentioning, it is not within
the discourse of the current work to cover the complexity of site reactions on airborne
particles. It is sufficient to say that the smaller the particle the more potentially harmful it
is as an exposure risk. Large particles will fall out of suspension at a rate directly related
to their diameter. Thus, once something very tiny is airborne it will have a longer
suspension episode, posing a greater inhalation risk.
Because of the large-scale use of fossil fuels as a mode of transportation and energy
production, it is important to discuss them as something that is not going to go away soon
(9). It is desirable to continue to improve and engineer vehicles, industries and plants with
more fuel efficiency, while maintaining or improving their power output and/or
consumption. The petrochemical industry is large, established, and infiltrates nearly all
facets of modern life. Materials, fuels, and even food owe something to the petrochemical
industry.
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This flow chart of one facet of the petrochemical industry, taken from
Britannica.com, shows how many products come from the distillation of crude oil. Most
first distillation products go through further processing to yield a variety of commercial
goods. Crude oil, coal, and natural gas can all be converted to carbon dioxide and
hydrogen gas through a steam reformation process under heat and pressure. This process
opens up a variety of options for synthesis. The preceding information shows that fossil
fuels have a diversity not seen in many other products or raw materials. Using fossil fuels
responsibly and efficiently simply makes use of an abundant and versatile, if not
renewable, natural resource.
One of the earliest and simplest implementations used to reduce emissions from
vehicles and industry involved the catalytic conversion of harmful byproducts from
combustion of petroleum-based fuels. Simply, a catalytic converter (today) is a three-stage
process (4). The first stage is a reduction stage. Platinum and rhodium reduce potentially
harmful nitrogen oxide emissions to diatomic oxygen and diatomic nitrogen. The transition
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metal chemistry is complex, but simply put the metal complexes with nitrogen to stabilize
the formation of atomic nitrogen, which can then form diatomic nitrogen as a stable
product. The second stage is an oxidation step where the catalyst drives the combustion
cycle to completion. This step drives carbon monoxide formed during combustion to
carbon dioxide. While carbon dioxide is less directly harmful to humans debate rages over
its contributions to the green house effect. Green House Effect is a topic the author wishes
to discuss only as a theory as it potentially relates to emissions. Platinum and palladium
accomplish the oxidation step via another complex transition metal chemistry. The final
stage monitors the exhaust gas and gives the information to the injection and intake system
to help maintain proper stoichiometric ratios for proper combustion. While the three steps
are mentioned sequentially, it does not mean that the steps are not ongoing concurrently
during combustion and emission discharge.
This representation taken from lordgrey.org shows the basic layout of a modern
catalytic converter. The probe monitors the gases entering converter to assure that the
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proper mixture of fuel and air within the combustion chamber. The converter's stainless
steel housing is filled with a porous ceramic substrate layered with metal catalyst. The
porous nature of the ceramic substrate enhances the available surface area utilized as
catalytic sites.
One of the greatest shortcomings to this system is that it is only truly effective at
higher temperatures. Simply moving the converter closer to the combustion block is not
feasible because the hot gases would be a detriment to the converter. The batteries on cars
are not amply robust to heat catalytic converters to light off via a resistance heater. The
inclusion of a battery large enough to do so would likely cause more environmental
consequence than it would eventually solve. The value of the metal catalysts, also present a
target for theft, theft of catalytic converters is becoming epidemic as thieves steal the
converters in hopes of exploiting the precious metals mounted within the ceramic substrate
for profit.
One interesting manner of heating catalytic converters to light off temperatures
more rapidly is called the Spark Ignition Internal Combustion Engine (SIICE). This
engine design uses a rich air/fuel mixture, which causes a higher temperature of
combustion (12). The heat of oxidation for the products of rich fuel combustion may also
help to heat the catalyst to light off temperature more quickly. The excess of oxygen in the
early fuel mixtures can convert hydrogen gas and carbon monoxide to the more innocuous
water and carbon dioxide during the phase of thermal oxidation, and exothermic step
resulting in the release of heat as more stable covalent bonds form. This process supposes
that the increased temperatures may help the catalytic converter reach light off after only a
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few seconds because of the increased temperature of exhaust gases. The increased initial
heat, however, may damage seals inside the engine.
It is a fact that the lower combustion temperatures of diesel engines cause less
nitrogen oxide emissions (3). Naturally, diesel has its own set of problems. Diesel fuel
combustion forms more particulate emissions and diesel fuel generally contains more
sulfurous compounds because sulfur tends to migrate to heavier hydrocarbon fractions.
Sulfurous emissions are harmful to the environment, but are also a detriment to the
catalytic converter. Other problems with diesel include the particle trap. While this
reduces the emission of particulate matter, it forms a site for the active oxidation of
elemental carbon, soot, by nitrogen dioxide to form carbon monoxide and nitric oxide.
Diesel is also somewhat problematic in colder climates because of the long chain paraffin
residues within the fuel raise the cloud point and pour point of the fuel (6). For this reason,
diesel formulations must be regional and the blends often sacrifice combustibility (cetane
rating) to allow for cold weather performance. Cetane rating relates to the ability of the
fuel to attain auto ignition under pressure and has a widely accepted fuel rating of greater
than 40 with a performance plateau of about 55. Strategies for blending diesel fuels to
achieve a proper cetane rating and have cold weather performance should be investigated.
Despite the en vogue thing, fuel cells, automakers continue to research new forms of
internal combustion engines that run on petrol distillates (9). One attractive approach to
solving the emission dichotomy between diesel and gasoline fuels is the Homogenous
Charge Compression Ignition (HCCI) engine. The design incorporates diesel like efficiency
with the clean burn of traditional American unleaded gasoline (Popular Mechanics). The
technology has been in existence since the late 1970s. At the time of its conception, the
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engine designers lacked the computing equipment to control the precision timing required
of the HCCI engine. HCCI is only one of many technologies under exploration behind the
closed doors of industry and academia alike since primary personal propulsion systems will
likely fall under the domain of petrochemical fuels for decades to come. Thus,
investigations into practical solutions for petrol based fuel engines are imperative.
Research involves the digital control of fuel systems, thermal regulation of exhausts,
exhaust recycling, and improving cylinder design.
HCCI is one of the oldest technologies under development for modern use. The idea
is simple, but does require a good deal of new engineering to include all the control sensors
and other systems vital to timing. The HCCI engine uses exhaust gases to help maintain
engine temperature at levels sufficient for the ignition of gasoline. HCCI engines are able
to maximize the efficiency of gasoline at lower temperature burns. Using high pressures,
HCCI engines achieve ignition but keep their temperature below 2000 degrees Kelvin,
above which the formation of nitrogen oxides is favored via a thermal oxidation
mechanism. While computing and engineering of these engines has come a long way,
timing the cycles properly at high RPM remains a difficulty. At modest speeds, the cycle is
somewhat easy to maintain but as the vehicle requires power for acceleration, the timing
issue becomes problematic. There remain, however, other engineering ideas that may
improve the overall efficiency of internal combustion engines, thus lowering overall
emissions.
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See the differences between the cylinders in the three types of engines in an image
taken from wired.com. Diesel is ignited by increasing pressure to the air/fuel mixture,
gasoline is ignited causing a higher temperature burn by the spark plug, and HCCI engines
have a better air/fuel mixture that is ignited by the high-pressure compression. These
engines actually achieve a lower burn than diesel engines. The low fuel burn temperature
and homogenous nature of the fuel/air mixture achieve a reduction in nitrogenous
emissions as well as particle emissions.
Inventor Eddie Struman believes that to way to improve overall efficiency is to
micro-manage airflow coming into the engine. In his cam less engine, he replaces the
overhead cam with digitally controlled valves, which optimize airflow for a variety of
driving situations and fuels. This system also allows for the deactivation of piston cylinders
during times of idle driving where not acceleratory power is required. This will help
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maximize fuel economy in much the same way that a 4-cylinder engine gets better fuel
economy than an 8-cylinder engine. The cam less engine also utilizes exhaust gases to help
initiate the fuel burn helping keep engine temperature below that of the temperatures seen
in traditional internal combustion engines.
Another idea, which claims to have a 25 percent increase in efficiency accompanied
by a 50 percent decrease in NOx emissions, is the split-cycle-combustion engine. The split-
cycle-combustion engine (SCCE) separates the 4 cycles of the traditional internal
combustion engine (intake, compression, combustion, exhaust) across two different
cylinders designed to work together. The combustion cycle is optimized by igniting the fuel
mixture after the piston crosses dead top center, the point where the piston begins its
downward stroke. By incorporating this energy usually sapped by continuing the upward
stroke, or sending it in reverse, is eliminated. The cycles are divided over the 2 cylinders in
a manner where the intake/compression and combustion/exhaust are split between 2
cylinders. The compressed air from the first cylinder is transferred to the second cylinder
as the fuel mixes with the air. The increased efficiency is due to the turbulent flow across
the cylinder exchange bridge. The turbidity of the fluid more intimately mixes the air and
fuel leading to a more comprehensive burn.
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The image above, taken from thefraserdomain.com, gives a simple diagram of how a
split cycle engine cylinder pairing might be set up.
M.I.T. has also developed a technology it calls Turbocharged Ethanol Boost (TEB).
This idea claims to be as efficient as a hybrid without the need of a battery. While cars
with large batteries may burn less fuel it is not ridiculous to think that a batter
manufactured by the lowest bidder in a developing nation has a carbon foot print as large
as the car itself. Batteries also pose difficult environmental disposal problems. The TEB
also boast potential savings of about 2000 dollars over price of a hybrid. The engine works
by injecting ethanol into the combustion chamber to vaporize and reduce overall
combustion temperature while at the same time reducing knocking which can be associated
with traditional gasoline. Computer models estimate a 20 percent increase in efficiency
though at the time of the article a full-scale working prototype had not been tested. This is
similar to a technology Ford has been working on for a new generation of engine to move
beyond its new EcoBoost series (1). The technology Ford is using dates back to the 1970s
and is pictured below in an image taken from green.autoblog.com
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The Ford Bobcat engine is a twin turbo/twin fuel engine that works by mixing fuel and air
in the intake manifold and adds the E85 to the combustion chamber to prevent premature
ignition associated with high-pressure turbocharged engines. The direct injection of the
ethanol directly into the combustion chamber raises the octane rating of the fuel mixture to
about 150, from the low 90s. This allows the engine to run on a lean fuel mixture without
increasing thermal oxidation of atmospheric nitrogen. In addition to the decrease in NOx
emissions, Ford promises a 5 to 10 percent increase in fuel economy and power
performance increase similar to that of their current production Turbo Diesel Engines
without the addition of costly diesel particle filters. One foreseeable problem with this
engine design is the increased number of working parts leading to increased incidences of
break down.
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The last engine technology to discuss is not new but is finding new utilization in the
commercial auto industry. Turbo-compounding converts heat from the combustion cycle
into mechanical power (9). By using exhaust heat, turbo-compounding is able to increase
the power generated by smaller engines. Currently, large trucks employ this technology
and they have seen a power increase of about 5 percent with a similar decrease in fuel
consumption. The idea is similar to conventional turbo charging. However, instead of
using a turbine to force more air into the combustion chamber the turbine is located
somewhat further down the exhaust stream and creates a mechanical power used to turn
the crankshaft.
All of these technologies do not necessarily effect the formation of nitrogen oxides or
other vehicular emissions. These new engine designs only hope to decrease overall
emissions by increasing the efficiency over current technologies. The new designs may be
somewhat costly to implement but the idea is that by increasing efficiency the operating
cost is significantly lowered so any additional costs associated with initial cost should be
offset by operating costs.
Properly engineering or formulating fuels may also reduce emissions. New
formulations of gasoline incorporate oxygenated products, which help force the formation
of carbon dioxide over carbon monoxide (3). This helps reduce CO emissions even before
the catalytic converter reaches its light off temperature. Even after the converter has
reached is light off temperature the incorporation of the oxygenated products allows the
converter to have less work to do. This may mean longer catalytic life for the converter.
Another innovation in fuel design is Shells Nitrogen Enriched Gasoline which incorporates
nitrogen into the fuel which helps reduce and remove engine sludge build up in cylinders,
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injectors, and valves (8). The gasoline works because the incorporation of the nitrogen
helps to induce a thermal stability in the gasoline. The increased thermal stability means
that the fuel will not degrade and deposit inside the engine before combustion. By reducing
and removing engine-sludge users can expect increased efficiency from their internal
combustion engines.
The process of refining the hydrocarbons that go into gasoline formulations can also
be complicated (10). Essentially, all gasoline formulations are the same coming from the
refinery. Different service station franchises include their additives after the production
process. They may be added directly to the transport tanker or to the underground tank at
the service station. Fluid Catalytic Cracking (FCC) of coal, oil, and other chemical
manufacturing processes is a major source of sulfur oxide emissions. Sulfur contained in
many petrochemical feedstocks forms a coke containing sulfurous deposits on catalyst
active sites. After leaving the reactor, product and catalyst are separated and the catalyst
goes for regeneration. The FCC can form mixtures of hydrocarbon products. Often, FCC
processes generate gasoline and diesel fuels.
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During regeneration of the cracking catalyst, the coke is burned off along with any
sulfur forming SOx gases. Flue gas scrubbing is a mature technology that is capable of
removing much of the SO2 emissions in FCC regeneration processes (11). However, the
current methods of flue gas scrubbing teach a one size fits all approach toward removing
SOx emissions via flue gas scrubbing while different FCC units may be more effectively
scrubbed using different sorbents and additives depending on the degree of combustion
and oxygenation of the flue gases. Investigations into new scrubbing additives for
proprietary purposes include one or more sorbents and oxidation catalysts. Using new
scrubbing technologies fitted specifically to individual FCC units, emissions will be more
effectively scrubbed while also maximizing the efficiency of the catalyst in a low oxygen
environment. Investigations into varying sorbents, oxidants, and catalyst structure show
that the ability of the catalyst to substantially reduce SOx emissions in different conditions
at low levels of oxygen.
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One other trouble with gasoline is the incorporation of sulfurous compounds in the
catalytically cracked gasoline itself (10). Upgrading hydrocarbon streams for gasoline
production is one way to limit sulfur content in gasoline. Hydrotreating of heavy gasoline
fractions, including naphtha, is a way of forming H2S gas, easily fractionated and
sequestered. By working to decrease the sulfur content of fuels it can be assumed that
lower CO and NOx emissions can be achieved by maximizing catalyst activity that could
have been lost due to catalytic poisoning. The hydrotreating process can be problematic
because it also attacks olefin double bonds lowering octane numbers. Overcoming this
problem involves first forming heavy and light petrol fractions because the majority of
sulfurous compounds in hydrocarbon streams migrate to the heavy petrol fractions. An
additional step incorporated takes desulfonated heavy fractions to reformation over a
platinum catalyst to induce aromacticity. These new aromatic compounds then undergo an
alkylation step because of the carcinogenic effects of benzene. This reforming introduces
the octane boosting affect of aromatic compounds while the alkylation gives the liver a site
for metabolism. Regardless, whether the heavy fraction is reformed or simply recombined
with the lighter fraction the result is a highly desulfonated gasoline.
ExxonMobil has created a licensable process in which naphtha is fractionated,
hydrotreated, and selectively cracked over a size exclusion zeolite to boost octane.
Blending the new fraction with the lighter fraction and subjecting the mixture to an
extractive process for sulfur removal gives another method of forming greatly sulfur free
gasoline. This process works best with streams heavy with naphtha because the decrease in
yield is substantially lower using those streams.
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One component of combustion exhaust often over looked is the fact that all engines
must use a lubricating oil (5). In all combustion cycles, there is a risk that the fuel mixture
is contaminated with a small amount of lubricating oil. Lubricating oils are not under as
stringent governmental regulation as are fuels. Thus, there is still a component of sulfur
and phosphorous in the lubricating oil that can be burned and poison the catalyst. The
burning of the lubricating oil also forms ash and other engine deposits, which can hurt
engine efficiency and oil performance. The loss of efficiency can lead to increased
emissions because of wasted fuel. The loss of oil performance can lead to engine wear and a
degradation of engine life.
Advances in particulate emission control only make the increase use of diesel
engines more attractive. The incorporation of a closed crankcase in diesel engine design
has greatly reduced particulate emission from diesel engines (7). Most of the blow by gases
from engines using open crank cases, which are prevalent in mass transit, marine, and
industrial applications, have large amounts of particulate emissions of which half can be
less than 1 micrometer (deeply respirable). By incorporating a blow by gas collector for
these engines, these emissions can be reincorporated into the combustion cycle. The
incorporation of the blow by gas collector working in tandem with an oxidation/reduction
catalyst, flow filter, and particle filter can greatly reduce diesel emissions. A turbo charger
can offset any additional air resistance induced by the inclusion of an air filter. The
exhaust emissions or even the blow-by-gases can power the turbo charger.
Diesel performance in cold climates is also an important issue to tackle because of
the inherent efficiency of diesel engines (6). It is also important because the Fischer-
Tropsch Process (FTP) makes the formation of sulfur free diesel fuels a reality. The
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paraffin wax content of FTP diesels increases the cloud point and pour point of Fischer-
Tropsch diesel fuels. The cloud point is essentially the point where paraffin wax residues
begin to come out of solution making the diesel fuel appear cloudy. The pour point is the
point where the diesel fuel begins a gelation process and is no longer acceptable for use as a
fuel. Blending of fuels sufficiently free of sulfur can give sufficient cetane numbers while
also giving the desirable low cloud point and pour point. It is important to find acceptable
blends of FTP products lies because feedstocks for the FTP can come from pretreatments
of biomass from agricultural and municipal wastes. There are still many complications to
overcome with the FTP including the lack of selectivity in the catalysts as well as the water-
gas-shift, which results in the formation of carbon dioxide, especially using iron catalysts.
By tackling catalyst design and optimizing the partial pressures of carbon monoxide and
hydrogen gas used as FTP feed stocks along with optimal temperature it may be possible to
minimize carbon dioxide formation and achieve more narrow hydrocarbon product
distributions of exit streams from Fischer-Tropsch reactors.
One of the most environmentally responsible ways of reducing emissions is to
harness them. One of the most overlooked ways in which humans form potentially harmful
emissions is the accumulation of organic wastes and their impending decay (2). Currently,
some municipal wastes are disposed of using an incineration process. These incinerations
produce dinitrogen oxide, nitrogen oxide carbon monoxide, nitrogen dioxide, as well as
sulfur dioxide and sulfur trioxide. These are all gases under regulatory concern and are in
addition to the potential production of VOCs and other hydrocarbons. One of the most
common gases produced from organic municipal waste decay is methane. Methane is a
gas, which is of a concern for the theory of global warming because it has its largest
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absorbance at lower wavelengths (3. Low wavelengths means higher energy, thus any
energy absorbed by methane can be emitted in the form of heat back to the earth. Methane
gas also poses a potential safety risk because if not properly contained, or eliminated, it
may be an explosion risk.
Proper landfill design should be incorporated into city planning as it allows for the
entrapment and harvesting of methane gas for point source power generation. Landfill
design is also important because it helps create a safe landfill based on environmental risk,
not simply the risk of explosion. By trapping the methane gas under a combinatorial layer
of clay, sand, soil, or polymer the risk of explosion decreases so long as the top membrane
remains intact. The same is true for the membrane at the bottom of the landfill. Any
environmental contaminants leeched through the landfill via water transport can be
collected and processed for safe disposal. Below is a diagram of a landfill design to safely
trap and harvest methane gas for power generation and capture leechate for safe disposal
as it collects at the bottom of the landfill. The diagram of the cutaway landfill is taken
from pollutionissues.com.
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Point energy sources are becoming increasingly popular and pragmatic because it
would lower the loss of electrical potential over long transmittance (2). Not only is the
operation of small-scale power production becoming more popular the processes by which
harvest waste gases have become more effective. By creating solid organic waste enclosures
with conditions favoring bacterial growth, the desired methane can be produced more
efficiently and even in greater quantities. One problem with this form of power generation
is the mixture of gases formed by organic decay. As the methane gas formed by the organic
decay permeates up through the biomass, it picks up contaminants that can form SOx and
NOx as well as some VOCs after combustion. These gases are not only of a regulatory
concern but may also be odorous, if not harmful, for anyone down wind. It is vital to
develop a way of separating the gases in the complex mixture. One method of
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accomplishing this separation may be the use of polymer membranes or some kind of wet
scrubbing process utilizing the differences in polarity between oxides and methane.
Combinatorial separation processes generally work best for complex mixtures.
Should the purification of the gas stream become a reality the use of organic decay
as a source of renewable and responsible energy will become a reality. The gases produced
are useful for generating electricity and also heating or cooking. The electricity generated
can be used or sold back to the grid to raise funds for municipal programs. Utilizing the
power for water purification and sewage treatment is another use for the energy created.
Another source of methane can be wastewater treatment facilities where anaerobic
microbes under water produce methane by processing organic wastes. This means that the
water treatment plants and point power production could work in unison to prevent and
utilize potentially harmful emissions. The largest problem outside of purifying the gas
stream is likely the capital required to start large-scale methane gas collection and power
generation operations. The modification of existing landfills for utilization could also pose
a costly engineering dilemma.
The world must acknowledge that pollution problems exist and mitigating the
pollution produced by everyone is going to be a costly undertaking. The afore mentioned
problems cost not only dollars but also man-hours to devise solutions to problems at hand.
Hopes of imagining and creating technologies that can offset cost incurred as an initial
expense or as a maintenance expense are really more than hopes but are becoming realities.
With all new technologies, there are problems. However, as humanity advances what was
once inconceivable becomes mundane. The body of this work has sought to show that
common human activity creates waste and pollution, but there is much to be done and
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much that is being done to diminish the amount of waste and pollution. By utilizing new
technologies currently under development, it is possible to achieve sustainability on fossil
fuels for much longer than experts estimate. By utilizing waste from human activity, it is
possible to realize a truly renewable resource. Research will turn todays problems into
tomorrows solutions. Much as children of the 1960s wanted to be astronauts children in
the 90s and 2000s grow up wanting to be engineers and scientists to tackle the problems of
the future. The dreams of children often become realities and the hope of humanity hangs
on the dreams of today.
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Works Cited
1. Abuelsamid, S. (2009, June 8). Ford's New Bobcat. Retrieved December 1, 2009, from AutoblogGreen:
http://green.autoblog.com/2009/06/08/update-on-fords-new-bobcat-ethanol-injected-turbocharged-
v8/
2. Augenstein, D. (2008). Patent No. 11/975,234. United States.
3. Baird, C., & Cann, M. (2008). Environmental Chemistry(4th ed.). New York: W.H. Freeman and
Company.
4. Catalytic Converter - how it works. (2005, August 3). Retrieved December 1, 2009, from Ford Scorpio:
http://www.fordscorpio.co.uk/cats.htm
5. Jackson, M., Arters, D., MacDuff, M., & Mackney, D. (2008). Patent No. app 11/869,944. United Sates.
6. O'Rear, D. (2008). Patent No. 7,354,462. United States.
7. Schmeichal, S., Schmidt, F., Imes, J., & Dushek, R. (2007). Patent No. 7,257,942. United States.
8. Shell Launches New Nitrogen Enriched Gasolines. (2009, February 3). Retrieved December 1, 2009,
from Shell.com:
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