Log in   •   Sign up   •   Subscribe  feed icon

Plasma Gasification Transforms Garbage into Clean Energy

It sounds too good to be true: a machine that can get rid of almost any kind of waste at a fraction of the cost of today's disposal techniques, eliminate existing landfills, and produce an excess of clean energy to be sold back to the grid. This very realistic process is called plasma gasification.

One of the leading companies that is developing plasma gasification is called Startech. The company was founded in 1988 by Joseph Longo, the engineer behind the invention of the trash compactor in the ‘70s. As Longo explains, plasma gasification works somewhat like the big bang in reverse, as you get nothing from something.

A sealed, stainless steel vessel is filled with a stable gas, such as pure nitrogen. When a 650-volt current passes between two electrodes, electrons are ripped from the air, converting the gas into plasma. As current continues to flow, it creates an intense energy field with plasma arcs, which are like lightning. The radiant energy of the 30,000˚F plasma arcs disintegrates trash into its basic elements by tearing apart the materials' molecular bonds.

Tile, wood, nails, glass, metal, plastic, diapers-almost any material can be broken down with Startech's technology, eliminating the time-consuming, tedious and costly process of sorting waste by hand. (Nuclear waste is an exception due to its indestructible isotopes.)

Only two by-products come out the opposite end of the machine: an obsidian-like glass and "syngas," which is a mixture of hydrogen and carbon monoxide. The glass can be recycled as a raw material for applications such as tiles and asphalt.

The syngas is one of the biggest attractions of plasma gasification. The 2,200˚F mixture can be cooled to generate steam for electricity, or converted into fuel such as ethanol, natural gas or hydrogen. About two-thirds of the fuel powers the plasma machine to make it self-sustaining, and the rest could be used for onsite electrical use or sold back to the grid for profit.

The power of plasma gasification makes it not only an environmentally clean technique, but also economic. Longo says that a Startech machine that costs about $250 million could break down about 2,000 tons of waste daily-enough to accommodate the needs of a city of a million people. Such an investment could pay for itself in about 10 years, not even including the money made from selling the excess electricity and syngas.

With the rising transportation prices and concerns about the environment, countries and organizations are taking notice. Three waste-disposal executives who recently formed a partnership called U.S. Energy plan to build the first plasma gasification plant on Long Island, New York.

New York City currently pays about $400 million a year to get rid of its trash, due to many closed landfalls around the city, incinerators being banned, and the city having to transport its trash to Virginia and Pennsylvania. A few Startech machines could reduce the current cost of $90 per ton to $36 per ton-and after generating surplus electricity, the city would actually make $15 per ton.

U.S. Energy's Paul Marazzo has one concern, though. Many landfill operators are politically well-connected, and enjoy getting a million dollars a month out of debris. With a plasma gasification converter, these businessmen would lose much of their revenue.

Besides New York, plasma gasification machines could be built literally all over the world. The National Science Foundation might install a system at McMurdo Station in Antarctica, the Vietnamese government may build one to get rid of stockpiles of Agent Orange left behind by the US military, and an assortment of investors from China, Japan, Romania, Poland, Italy, Russia, Brazil, Venezuela, the U.K., Mexico and Canada are interested. In Panama, overflowing landfills are polluting groundwater and drinking water, causing outbreaks of cholera and hepatitis A and B.

With so much disease being caused by pollution-much of which comes from excessive waste-many countries could benefit from a plasma gasification system.

Lisa Zyga
Science Blogger
InventorSpot.com

via: Popular Science