From Wikipedia, the free encyclopedia
Thermal depolymerization. Thermal depolymerization (TDP) is a depolymerization process using hydrous pyrolysis for the reduction of complex organic materials (usually waste products of various sorts, often biomass and plastic) into light crude oil. It mimics the natural geological processes thought to be involved in the production of fossil fuels. TDP stands for Thermal Depolymerization Plant, which is “a solution to three of the biggest problems facing mankind,” says Brian Appel, chairman and CEO of Changing World Technologies, the company that built a pilot plant and has just completed its first industrial-size installation in Missouri. “This process can deal with the world’s waste.
Thermal Depolymerization (TDP)is a process using hydrous pyrolysis for the reductionof complex organic materials (usually waste products of various sorts, often known asbiomass and plastic) into light crudeoil. It mimics the natural geological processes thought to be involved inthe production of fossilfuels. Under pressure and heat, long chain polymers of hydrogen, oxygen, and carbon decompose into short-chain petroleumhydrocarbons with a maximum length ofaround 18 carbons.
|
Similarprocesses
Thermal depolymerization is similar to other processes that usesuperheatedwater as a major step in their processing to produce fuels,such as direct Hydrothermal Liquefaction[1] .Thermochemical conversion (TCC) can mean conversion of biomass tooils using superheated water, although it more usually is appliedto fuel production via pyrolysis.[2][3] TheThermal Conversion Process is another name for thermaldepolymerization. A company called Renewable EnvironmentalSolutions (RES) was formed as a joint venture between ConAgra Foods andChanging World Technologiesto operate the plant at Carthage, Missouri and the name ofthe process was changed to Thermal Conversion Process(TCP), which is patented.[4][5]
EnerTech operates the 'SlurryCarb' process,which uses similar technology to decarboxylate wet solid biowaste,which can then be physically dewatered and used as a solid fuelcalled E-Fuel. The plant at Rialto, California is said to beable to process 683 tons of waste per day.[6]
The Hydro Thermal Upgrading (HTU) process was originallydeveloped by Shell, and is now operated by BiofuelBV. It uses superheated water to produce oil from a range ofbiomass and domestic waste.[7] Ademonstration plant is due to start up in the Netherlands said tobe capable of processing 64 tons of biomass (dry basis) per dayinto oil.[8] Thermaldepolymerization differs in that it contains a hydrous processfollowed by an anhydrous cracking / distillation process, althoughupgrading of the raw HTU product is also possible.
History
Thermal depolymerization is similar to the geological processesthat produced the fossil fuels used today, except that thetechnological process occurs in a timeframe measured in hours. Until recently, the human-designed processes were notefficient enough to serve as a practical source of fuel—more energy was required than wasproduced.
Many previous methods which create hydrocarbons throughdepolymerization used dry materials (or anhydrous pyrolysis), which requiresexpending a lot of energy to remove water. However, there has been work done on hydrouspyrolysis methods, in which the depolymerization takes placewith the materials in water. In U. S. patent 2,177,557, issued in 1939,Bergstrom and Cederquist discuss a method for obtaining oil fromwood in which the wood is heated under pressure in water with asignificant amount of calcium hydroxide added to themixture. In the early 1970s Herbert R. Appell and coworkers workedwith hydrous pyrolysis methods, as exemplified by U. S. patent 3,733,255 (issued in1973), which discusses the production of oil from sewer sludge and municipal refuse byheating the material in water, under pressure, and in the presenceof carbonmonoxide.
An approach that exceeded break-even was developed by IllinoismicrobiologistPaul Baskis in the1980s and refined over the next 15 years (see U. S. patent 5,269,947, issued in1993). The technology was finally developed for commercial use in1996 by Changing World Technologies(CWT). Brian S. Appel (CEO of CWT) took thetechnology in 2001 and expanded and changed it into what is nowreferred to as TCP (Thermal Conversion Process), and has appliedfor several patents (see, for example, published patent applicationUS 2004/0192980). A Thermal Depolymerization demonstration plantwas completed in 1999 in Philadelphia by Thermal Depolymerization,LLC, and the first full-scale commercial plant was constructed inCarthage,Missouri, about 100 yards (100 m) from ConAgra Foods' massive Butterball turkey plant,where it is expected to process about 200 tons of turkey wasteinto 500 barrels (21,000 US gallons or 80 m³) of oil per day.
Theory andprocess
In the method used by CWT, the water improves the heatingprocess and contributes hydrogen to the reactions.
In the Changing World Technologies(CWT) process,[9] thefeedstock material is first ground into small chunks, and mixedwith water if it is especially dry. It is then fed into a pressure vesselreaction chamber where it is heated at constant volume to around 250 °C. Similar to a pressure cooker (except at much higherpressure), steam naturally raises the pressure to 600 psi (4 MPa) (near thepoint of saturatedwater). These conditions are held for approximately 15 minutesto fully heat the mixture, after which the pressure is rapidlyreleased to boil off most of the water (see: Flashevaporation). The result is a mix of crude hydrocarbons andsolid minerals. The mineralsare removed, and the hydrocarbons are sent to a second-stagereactor where they are heated to 500 °C, further breaking down thelonger hydrocarbon chains. The hydrocarbons are then sorted by fractional distillation, in aprocess similar to conventional oil refining.
The CWT company claims that 15 to 20% of feedstock energy isused to provide energy for the plant. The remaining energy isavailable in the converted product. Working with turkey offal as the feedstock, the processproved to have yield efficiencies of approximately 85%; in otherwords, the energy contained in the end products of the process is85% of the energy contained in the inputs to the process (mostnotably the energy content of the feedstock, but also includingelectricity for pumps and natural gas or woodgas for heating). Ifone considers the energy content of the feedstock to be free (i.e.,waste material from some other process), then 85 units of energyare made available for every 15 units of energy consumed in processheat and electricity. This means the 'Energy Returned on Energy Invested' (EROEI) is(6.67), which is comparable to other energy harvesting processes.Higher efficiencies may be possible with drier and more carbon-richfeedstocks, such as waste plastic.
By comparison, the current processes used to produce ethanol and biodiesel from agricultural sources have EROEI in the 4.2range, when the energy used to produce the feedstocks is accountedfor (in this case, usually sugar cane, corn, soybeans and the like). These EROEI values arenot directly comparable, because these EROEI calculations includethe energy cost to produce the feedstock, whereas the above EROEIcalculation for thermal depolymerization process (TDP) doesnot.
The process breaks down almost all materials that are fed intoit. TDP even efficiently breaks down many types of hazardousmaterials, such as poisons anddifficult-to-destroy biological agents such as prions.
Feedstocksand outputs with thermal depolymerization
Feedstock | Oils | Gases | Solids (mostly carbon based) | Water (Steam) |
---|---|---|---|---|
Plastic bottles | 70% | 16% | 6% | 8% |
Medical waste | 65% | 10% | 5% | 20% |
Tires | 44% | 10% | 42% | 4% |
Turkey offal | 39% | 6% | 5% | 50% |
Sewage sludge | 26% | 9% | 8% | 57% |
Paper (cellulose) | 8% | 48% | 24% | 20% |
(Note: Paper/cellulose contains at least 1% minerals, whichwas probably grouped under carbon solids.)
Carthageplant products
As reported on 04/02/2006 by Discover Magazine, the Carthageplant was producing 500 barrels per day(79 m3/d) of oil made from 270 tons of turkeyentrails and 20 tons of hog lard. This represents an oil yield of22.3 percent. The Carthage, Missouri plant produces API 40+, a highvalue crude oil. It contains light and heavy naphthas, a kerosene, and a gas oil fraction, withessentially no heavy fuel oils, tars, asphaltenes or waxes. It canbe further refined to produce No. 2 and No. 4 fuel oils
Output Material | % by Weight |
---|---|
Paraffins | 22% |
Olefins | 14% |
Naphthenes | 3% |
Aromatics | 6% |
C14/C14+ | 55% |
100% |
The fixed carbon solids produced by the TDP process havemultiple uses as a filter, a fuel source and a fertilizer. It canbe used as activated carbon in wastewater treatment, as a fertilizer, or asa fuel similar to coal.
Advantages
The process can break down organic poisons, due to breakingchemical bonds and destroying the molecular shape needed for thepoison's activity. It is likely to be highly effective at killingpathogens, including prions. Itcan also safely remove heavy metals from the samples by convertingthem from their ionized or organometallic forms to their stableoxides which can be safely separated from the other products.
Along with similar processes, it is a method of recycling theenergy content of organic materials without first removing thewater. It can produce liquid fuel, which separates from the waterphysically without need for drying. Other methods to recover energyoften require pre-drying (eg. burning, pyrolysis) or produce gaseous products (eg.anaerobic digestion).
Potential sources of wasteinputs
The United StatesEnvironmental Protection Agency estimates that in 2006 therewere 251 million tons of municipal solid waste, or 4.6 pounds generated per day per personin the USA.[12] Muchof this mass is considered unsuitable for oil conversion.
Limitations
The process only breaks long molecular chains into shorter ones,so small molecules such as carbon dioxide or methane cannot be converted to oil through thisprocess. However, the methane in the feedstock is recovered andburned to heat the water that is an essential part of the process.In addition, the gas can be burned in a combined heat and power plant, consistingof a gas turbinewhich drives a generator to create electricity, and a heatexchanger to heat the process input water from the exhaust gas. Theelectricity can be sold to the power grid, for example under a Feed-in Tariff scheme. This also increasesthe overall efficiency of the process (already said to be over 85%of feedstock energy content).
Another option is to sell the methane product as biogas. For example, biogas canbe compressed, much like natural gas, and used to powermotor vehicles.
Many agricultural and animal wastes could be processed, but manyof these are already used as fertilizer, animal feed, and, in some cases,as feedstocks for papermills or as boiler fuel.Energy cropsconstitute another potentially large feedstock for thermaldepolymerization.
Currentstatus
Reports in 2004 claimed that the facility was selling productsat 10% below the price of equivalent oil, but its production costswere low enough that the plant produced a profit. At the time itwas paying for turkey waste (see also below).
The plant then consumed 270 tons of turkey offal (the fulloutput of the turkey processing plant) and 20 tons of eggproduction waste daily. In February 2005,[13] theCarthage plant was producing about 400 barrels per day(64 m3/d) of crude oil.
In April 2005 the plant was reported to be running at a loss.Further 2005 reports summarized some economic setbacks which theCarthage plant encountered since its planning stages. It wasthought that concern over mad cow disease would prevent the use ofturkey waste and other animal products as cattle feed, and thusthis waste would be free. As it turned out, turkey waste may stillbe used as feed in the United States, so that the facility mustpurchase that feed stock at a cost of $30 to $40 per ton, adding$15 to $20 per barrel to the cost of the oil. Final cost, as ofJanuary 2005, was $80/barrel ($1.90/gal).
The above cost of production also excludes the operating cost ofthe thermal oxidizer and scrubber added in May 2005 in response toodor complaints (see below).
A biofuel tax credit of roughly $1 per US gallon (26 ¢/L) onproduction costs was not available because the oil produced did notmeet the definition of 'biodiesel' according to the relevantAmerican tax legislation. The Energy Policy Act of 2005specifically added thermal depolymerization to a $1 renewablediesel credit, which became effective at the end of 2005, allowinga profit of $4/barrel of output oil.
Companyexpansion
The company has explored expansion in California, Pennsylvania,and Virginia, and is presently examining projects in Europe, whereanimal products cannot be used as cattle feed. TDP is also beingconsidered as an alternative means for sewage treatment in theUnited States.[14]
Smellcomplaints
The pilot plant in Carthage was temporarily shut down due tosmell complaints. It was soon restarted when it was discovered thatfew of the odors were generated by the plant.[15]Furthermore, the plant agreed to install an enhanced thermaloxidizer and to upgrade its air scrubber systemunder a court order.[16] Sincethe plant is located only four blocks from the tourist-attractingtown center, this has strained relations with the mayor andcitizens of Carthage.
According to a company spokeswoman, the plant has receivedcomplaints even on days when it is not operating. She alsocontended that the odors may not have been produced by theirfacility, which is located near several other agriculturalprocessing plants.[17]
In December 29, 2005, the plant was ordered by the stategovernor to shut down once again over allegations of foul odors asreported by MSNBC.[18]
As of March 7, 2006, the plant has begun limited test runs tovalidate it has resolved the odor issue.[19]
As of August 24, 2006, the last lawsuit connected with the odorissue has been dismissed and the problem is acknowledged asfixed.[20] Inlate November, however, another complaint was filed over badsmells.[21] Thiscomplaint was closed on January 11 of 2007 with no finesassessed.[22]
Status as of February2009
A May 2003 article in Discover magazine stated, 'Appel has linedup federal grant money to help build demonstration plants toprocess chicken offal and manure in Alabama and crop residuals andgrease in Nevada. Also in the works are plants to process turkeywaste and manure in Colorado and pork and cheese waste in Italy. Hesays the first generation of depolymerization centers will be upand running in 2005. By then it should be clear whether thetechnology is as miraculous as its backers claim.'[23]
However, as of August 2008, the only operational plant listed atthe company's website is the initial one in Carthage, Missouri.[24]
Changing World Technology applied for an IPO on 12 Aug 2008, hoping toraise $100 million. [25]
The unusual Dutch Auction type IPO failed possiblybecause CWT has lost nearly $20 million with very littlerevenue.[26][27]
CWT, the parent company of Renewable Energy Solutions, filed forChapter 11 bankruptcy. No details on plans for the Carthage planthave been released.[28]
SimilarTechnologies
- Plasma Converters use powerful electricarcs to reduce and extract energy from waste.
See also
References
- ^'Biomass Program, directHydrothermal Liquefaction'. US Department of Energy. EnergyEfficiency and Renewable Energy. 2005-10-13
. http://www1.eere.energy.gov/biomass/pyrolysis.html#thermal . Retrieved2008-01-12. - ^Demirba, Ayhan (2005-10-07). 'Thermochemical Conversion ofBiomass to Liquid Products in the Aqueous Medium'. EnergySources (Taylor Francis) 27 (13):1235–1243. http://www.ingentaconnect.com/content/tandf/ueso/2005/00000027/00000013/art00005. Retrieved2008-02-05.
- ^Zhang, Yuanhui; Gerald Riskowski andTed Funk (1999). Thermochemical Conversionof Swine Manure to Produce Fuel and Reduce Waste.University of Illinois. http://www.age.uiuc.edu/bee/RESEARCH/tcc/tccpaper3.htm. Retrieved2008-02-05.
- ^'Biomass Program.Agricultural mixed waste biorefinery using Thermal ConversionProcess (TCP)'. U.S. Department of Energy. 2006-08
. http://www1.eere.energy.gov/biomass/pdfs/agricultural_waste.pdf . Retrieved2008-02-05. - ^'Chronology of a ProvenTechnology Using Thermal Processing'. Renewable EnvironmentalSolutions LLC. http://res-energy.com/press/pdf/Chronology%20of%20a%20Proven%20Technology.pdf. Retrieved2008-02-05.
- ^Sforza, Teri (2007-03-14). 'New plan replaces sewagesludge fiasco'. Orange county register.http://www.ocregister.com/ocregister/news/local/article_1620010.php. Retrieved2008-01-27.
- ^de Swaan Arons, Jakob; H. van derKooiand Wei Feng. 'Hydrothermal Upgrading ofBiomass'. Delft University ofTechnology. http://www.dct.tudelft.nl/ttf/biomass.htm. Retrieved2008-02-05.
- ^Goudriaan, Frans; Naber, Jaap and vanden Berg, Ed. 'Conversion of BiomassResidues to Transportation Fuels with th HTU Process'
. http://www.nvrd.nl/nvrd/proceedings/downloadProceedings.asp?filename=618085%20Paper.pdf&filesize=85441 . Retrieved2008-01-12. - ^The description of the operation of the process, includingtemperatures, pressures, and time, has been adapted from thedescription in Brad Lemley (May 2003). Anything Into Oil.Discover. See also the description of the operation of the processin Appel et al., published U. S. patent application US 2004/0192980, publicationdate September 30, 2004.
- ^The data on the outputs for the various feedstocks, exceptfor cellulose, is taken from Brad Lemley (May 2003). Anything Into Oil.Discover. The same data, with additional data for cellulose, isfound in Appel et al., published U. S. patent application US 2004/0192980, publishedSeptember 30, 2004.
- ^'A PONA classification of the TDP 40 oil is shown below inTable 2.[..] The oil classification is useful for predicting fuelperformance when used in combustion, e.g. as a diesel fuelreplacement. The classification is also a useful prediction forfuel refiners or blenders in determining product distribution in arefinery or specialty chemical plant.' Converting turkey offal intobio-derived hydrocarbons oil (pdf) (Accessed January 7,2008)
- ^Municipal Solid Waste - BasicFacts
- ^Spragins, Elyn (1 February 2005). 'A Turkey in your Tank'(in English). Fortune Magazine (Time Inc.)
. http://money.cnn.com/magazines/fsb/fsb_archive/2005/02/01/8250633/index.htm . Retrieved2008-10-15. - ^Kantor, Andrew (2004-01-23). 'Killing germs, reducingwaste, making oil: TDP might be the next big thing'. USA Today
. http://www.usatoday.com/tech/columnist/andrewkantor/2004-01-22-kantor_x.htm . Retrieved 2007-02-21. 'TheCity of Philadelphia currently turns a lot of its sewage sludgeinto landfill. (All together now: Eww.) But working with ChangingWorld, the city is planning a TDP project to divert that sludge —and whatever pathogens are living in it — away from the land andinto oil.' - ^Reported by the Kansas City Star, April 12, 2005. The Kansas CityStar website has since archived this article: Kansas City: Searchresults
- ^In the circuit court of Jaspercountry, Missouri, at Carthage
'The company said it has finished installation of a thermaloxidizer and upgraded odor scrubber system that were ordered aspart of a consent agreement with the city and the Missouri attorneygeneral's office.' City questions RES - ^'A plant spokeswoman, Julie Gelfand, tells the Pitch thatrepeated odor complaints have been lodged on days when the plantwasn't in operation or when wind conditions were inconsistent withthe complaints.' Fowl & Crude
- ^'A foul-smelling plant that turns turkey byproducts into fueloil was ordered closed by the governor Wednesday until the companyfinds a way to clear the air.' Turkey-oil plant closed due to foul odors.
- ^'An experimental plant that turns turkey byproducts into fueloil can resume normal operations for 15 days to test whether newequipment solves a problem with bad smells that prompted the stateto shut it down in December.Kansascity.com
- ^'The last lawsuit left from a dispute over odors from a plantthat converts turkey waste into fuel oil was dismissed Thursdayafter the facility fixed its odor problems.' Last lawsuit dropped inCarthage turkey plant odor case
- ^Belleville.com
- ^News Release 012 -MoDNR
- ^Anything Into Oil.Discover magazine
- ^Changingworldtech.com
- ^News.Cnet.com
- ^Earth2tech.com, changingworld IPO is a no go
- ^UK.reuters.com
- ^'Breaking News: RES parentcompany files for bankruptcy'. Carthagepress.com
. http://www.carthagepress.com/news/x1362397575/BREAKING-NEWS-RES-parent-company-files-for-bankruptcy . Retrieved2009-03-07.