Thermal depolymerization
Thermal depolymerization (TDP) is a process for the reduction of complex organic materials (usually waste products of various sorts, often known as biomass) into light crude oil. It mimics the natural geological processes thought to be involved in the production of fossil fuels. Under pressure and heat, long chain polymers of hydrogen, oxygen, and carbon decompose into short-chain petroleum hydrocarbons with a maximum length of around 18 carbons. The process has been referred to with various names, including thermochemical conversion (TCC) and thermal conversion process (TCP).
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2 Theory and process 3 Skepticism 4 External links 5 References |
This is not a new technology; it is similar to the process that produced the fossil fuels used today. The difference is that where the geological process occurs over millions of years, the technological process occurs in a timeframe measured in hours. Until recently, the human-designed processes were not efficient enough to serve as a practical source of fuel—more energy was required than was produced.
A new approach that exceeded break-even was developed by Illinois microbiologist Paul Baskis in the 1980s and refined over the next fifteen years. The technology was finally developed for commercial use in 1996 by Changing World Technologies. A demonstration plant was completed in 1999 in Philadelphia, and the first full-scale commercial plant was constructed in Carthage, Missouri, about 100 yards (100 m) from ConAgra Foods' massive Butterball Turkey plant, where it is expected to process about 200 tons of turkey waste into 500 barrels (21,000 gallons or 80,000 liters) of oil per day.
Similar methods to create hydrocarbons use a lot of energy to remove water from the materials. This method instead uses water to improve the heating process.
The feedstock material is first ground into small chunks, and mixed with water if it is especially dry. It is then fed into a reaction chamber where it is heated to around 250 °C and subjected to 600 lb/in² (4 MPa) for approximately 15 minutes, after which the pressure is rapidly released to boil off most of the water. The result is a mix of crude hydrocarbons and solid minerals, which are separated out. The hydrocarbons are sent to a second-stage reactor where they are heated to 500 °C, further breaking down the longer chains, and the resulting petroleum is then distilled in a manner similar to conventional oil refining.
Working with turkey offal as the feedstock, the process proved to have yield efficiencies of approximately 85%; in other words, the energy required to process materials could be supplied by using 15% of the petroleum output. Alternately, one could consider the energy efficiency of the process to be 560% (85 units of energy produced for 15 units of energy consumed). Higher efficiencies may be possible with drier and more carbon-rich feedstocks, such as waste plastic.
By comparison, the current processes used to produce ethanol and biodiesel from agricultural sources have energy efficiencies in the 320% range when the energy used to produce the feedstocks is considered (in this case, usually sugar cane, corn, soybeans and the like).
The process breaks down almost all materials that are fed into it. TDP even efficiently breaks down many types of hazardous materials, such as poisons and difficult-to-destroy biological agents such as prions.
The process, if it actually works as advertised, represents a very significant step forward in the processing of biomass into fuel energy. Any such leap in technological ability is initially greeted with skepticism, and TDP is no exception. While the plant in Carthage, Missouri now appears to be up and running, little new information has been released since an article in Discover was printed in 2003. According to recent press releases, the Carthage plant is currently producing between 100 to 200 barrels of crude oil No. 4, a lower grade oil used in industrial heating.
History
Theory and process
Skepticism
External links
References