Plasma Gasification

By Kimia Pourali

Editor-in-Chief

Dear iGlobers,

I wrote this piece nearly two years ago and I thought, following my previous article about sustainable and maintainable society, this would be an interesting read, particularly for those of you gaining more interest in the sciences and other STEM sub-fields, even more so if you are interested in the growing environmentalism of this day and age.

Personally, I love science and math (oh! and, of course, literature; why else would I be part of a newspaper). I thoroughly enjoy researching anything from STEM fields, as I had to do constantly for my projects in Honors Biology, Honors Chemistry, and Honors Physics. Frankly, these, and other advanced classes, take up a lot of my time, plus, I’m not allowed to share those projects; thus, unfortunately, I can’t allocate enough time to research and write specifically for Science Expo.

So, I’ve decided to resurrect this piece from our archives and, as an Editor desperate for a greater dosage of STEM, I am making a call of recruitment for those of you striving to be Science Journalists and those of you who have already built and designed various techie, awesome gadget things! Your homemade ETs are welcomed!

With all of the above stated, I present to you all, and hope you enjoy, another possible solution to the world’s waste problem: plasma gasification.

Plasma gasification has many current and possible uses to benefit the environment. Its practice certainly presents many challenges; however, it also presents opportunities and benefits to the human standard of life.

Before reading on, below is a helpful video that, in essence, summarizes the remainder of this article - it is a concise and helpful introduction to plasma gasification.

The concept of plasma gasification technology was introduced several decades ago.

This technology involves the use of a plasma arc that generates massive amounts of heat to gasify carbon based parts of waste.

Plasma gasification can be applied to waste such as chemical sludge, municipal solid waste (MSW), agricultural waste, and many other forms of waste and toxins.

The term plasma is often referred to as the fourth state of matter (the other three being solid, aqueous, and gaseous - this should be ringing bells back to Physical Science!).

It is a medium which conducts electricity, and ends up with approximately equivalent numbers of negative and positively charged particles, as soon as the atoms of the gas are ionized.

Plasma

A natural form of plasma, which you may or may not see often, is lightning.

However, in an industrial environment, plasma is generated using plasma torches that heat a gas to very great temperature.

At the tip of a plasma torch flame, the temperature can reach up to 7,000 degrees Fahrenheit.

This extremely high temperature would cause the gas, which is typically the air, to ionize - resulting in plasma.

Lightning vs. Plasma Converters/Torches

There are a few important components of a plasma waste processing plant besides the plasma torches.

1) The waste trituration: the waste is grinded into smaller pieces, then sent down to the pyrolysis chamber

2) The pyrolysis chamber: the plasma torch gasifies the waste, and exits into the gas reformer

3) The gas reformer: there are heat exchangers, and creates steam

4) The scrubbers: the gas passes through and hazardous elements are removed

Synthetic gas is the first byproduct of this process.

This synthetic gas may go through other processes to generate ethanol and other chemicals. They may also be sent to turbines and generators, to generate electricity and distilled water.

Magma and rock-like materials are the second byproducts from the plasma chamber. These are separated into two groups; the vitrified glass and the metal nodules.

As for the application of plasma gasification, there are few current uses…

Space programs

Over forty years ago, NASA developed one of the first applications of plasma arcs.

They developed a plasma arc that mimics the temperature during the re-entry of space shuttles into earth's orbit.

The goal was to test the amount of heat the space shuttles’ shields were capable of withstanding.

Environmental usage

o Waste disposal

United States Navy shipboards and certain cruise liners use plasma torches to destroy the solid waste produced daily.

There are also multiple waste-to-energy plants being operated in Japan.

o Remediation of radioactive waste

Plasma gasification can be used to trap radioactive elements in solids.

Any waste that is highly radioactive may be mixed with glass, and then exposed to plasma torches to produce molten glass.

Once this molten glass is cooled down, the product is a stable glass that has trapped the radioactive elements in it.

This will prevent the radioactive elements from moving through the air or leaching into ground water and oceans.

Additionally, there are many future possible applications of plasma gasification technology...

Environmental benefits

o Animal carcass and waste

Plasma gasification can be used to create synthetic gas from animal waste.

This would benefit the environment because one massive producer of the greenhouse gases resulting in problems like climate change is the methane that rises into the atmosphere from animal wastes.

o Agricultural waste

Synthetic gas can also be produced from agricultural waste, like wood chips, by placing the waste in a plasma reactor vessel, and using the waste as feedstock.

o Paper and pulp industry

Wastes created in paper and pulp industries can be placed in plasma reactor vessels to create synthetic gases for electricity and heat.

o Carpet disposal

Plasma gasification technology can also be used for disposing carpets.

Carpets are an extremely challenging form of waste to dispose.

Replacement of current energy technologies (fossil fuels, coal, etc.)...

o Coal gasification

Plasma gasification can use coal as its feedstock to create synthetic gas, the same way municipal solid waste is used as feedstock (as described above).

This can be done instead of incinerating (burning) the coal.

The outcomes of plasma gasification can be divided into the created opportunities, as well as the presented challenges.

Opportunities:

Environmental benefits

o Reduced usage of landfills

The U.S. EPA's records show that an average of 4.5 pounds of solid waste was produced daily by each U.S. resident in 2001.

60% to 90% of solid wastes were sent to landfills, which means greater than 650,000 tons of solid waste is produced every day in America.

Through the usage of plasma gasification technology, all of this waste that would go to landfills could be used to generate synthetic gas, electricity, plastic, and metal nodules.

Landfills

o Safe disposal of hazardous waste

If the operators of a plant have a permit, under extremely careful monitoring, merely all forms of hazardous wastes can be used as a feedstock for a plasma gasification chamber.

When the hazardous waste is destroyed in the chamber, it will not leave ashes that would need to be buries in landfills.

o Oil replacement

The synthetic gases created by plasma gasification can replace the need for oil

Ultimately, synthetic gases can be used as fuel and a source for generating electricity.

They can also be used to power other devices to generate things like gasoline, butanol, ethanol, methanol, diesel, plastic, and multiple other carbon-based products that are usually generated from oil.

Pumpjack at an Oil Well

Economy and jobs

o Usage of the byproduct (in the form of molten lava or magma)

Cooled down - forms a solid like a rock - can be used in different industries

ex. crushed and used for ceramics, bricks, and gravel for roads

Can be cooled down in a variety of shapes, and in molds.

ex. artificial reefs

These artificial reefs can be placed in parts of the ocean that naturally do not have any habitat for sea creatures.

Can be used to attract sea creatures and form new underwater colonies

Can also apply to areas closer to shore - would allow for easier access for fisherman - can result in boost in one small area of the economy and business.

Separation of nodules - done by cooling magma while immersed in water, rather than naturally...

Metal nodules can be recycled in metal refineries

Examples of Artificial Reefs (Note: these are not specifically made from plasma gasification’s rock-like byproduct – they just show how the byproduct can be molded and used)

Challenges:

Lacking standards for plants

Rules and regulations are needed for building and operation of plants

Plasma gasification technology does not have regulations on government level

Lacking a criteria for quality of gas and byproducts

The cost, and uncertainty regarding how much plants will return (worth of investments)

There is doubt over investing in building and maintaining the plants and equipment

Overall, the cost of a modern natural gas power plant is less than a plasma gasification plant

The difference between plasma gasification and incineration seems to be unclear

There is a difference between incinerating solid wastes and using plasma gasification to gasify it

Incinerating - simply burning the waste

It results in toxic ashes and fumes

Once these toxins are created, they remain toxic forever

Will most likely be buried in a landfill

With toxic ashes underground, there is a risk of contaminating underground water, or floods or hurricanes moving toxins to other locations

Gasifying, on the other hand, produces the rock-like material that would not leach hazardous elements

To conclude, plasma gasification technology can be applied to both benign and hazardous waste. The synthetic gas generated can replace other means of natural gas and oil, meanwhile, the non-carbon parts of the waste can be used for reusable metal and glass. Plasma gasification can create environmental benefits, including avoiding the effects of burning fossil fuels, greenhouse gas emissions, and the frequent need to and consequences of searching for oil.

All of the facts of plasma gasification technology that have been explained show how greatly it would benefit the environment and the human standard of life if it were to be put in common use.

Please share your thoughts on plasma gasification and let us know if this great technology has been implemented in your country!

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Sources:

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Circeo, Louis, John Nemeth, and Robert Newmson. Evaluation of Plasma Arc Technology for the Treatment of Municipal Solid Wastes in Georgia. Atlanta, Georgia: Georgia Tech Research Institute, 1997. eBook.

Circeo, Louis., and M.S. Smith. Plasma Processing of MSW at Coal-Fired Power Plants. Atlanta Georgia: Georgia Tech Research Institute, 2008. eBook

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Leal-Quiros, Edbertho, and Carlos R Villafane. "An Assessment of the Power Generated with Plasma Processing of Sludge From Wastewater Treatment Plants." IEEE Transactions on Plasma Science. 35.6 (2007): 1622-1627. Web. Feb. 2012.

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—. “Plasma Market Solutions.” ALTERNRG. Alter NRG Corporation, 2012. Web. Feb. 2012

—. “Plasma (state of matter).” Britannica Encyclopedia. —, Sep. 2008. Web. Feb. 2012.

—. “Region 7 Solid Waste Program.” Solid Waste Program Index. U.S EPA, 15 Apr. 2011. Web. Feb 2012. <http://www.epa.gov/region07/waste/solidwaste/>

—. “Technology.” Westinghouse Plasma Corporation Projects. Westinghouse Plasma Corporation (a division of Alter NRG Corporation), 2012. Web. Feb. 2012.

—. The Reef Ball Foundation. Reef Ball Foundation, Inc, 1993. Web. Feb. 2012. <http://www.reefball.org/>

Young, G. C. "From Waste Solids to Fuel." Pollution Engineering 2008: 45-49. Print.

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Young, G. C. “Zapping MSW with Plasma Arc, An Economic Evaluation of a New Technology for Municipal Solid Waste Treatment Facilities.” Pollution Engineering 2002. Print.

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