Imagine a process that can turn any kind of organic waste into high-grade oil. It sounds too good to be true. But that’s the promise of the thermal depolymerization process (TDP), outlined in the May issue of the respected popular science magazine Discover (from which most of the following information is drawn).
Naturally occurring oil comes from one-celled plants and animals that died in the oceans, settled to the floor, decomposed, and were eventually crushed underneath the planet’s sliding tectonic plates. The pressure and heat far underground broke down the creatures’ long chains of hydrogen, oxygen and carbon-bearing molecules, called polymers, turning them into petroleum hydrocarbons, which have much shorter molecular chains.
Scientists have tried to recreate this process for years. The usual approach has been to superheat organic feedstock in an attempt to drive off any water it contains and break down the molecular chains at the same time. This takes so much energy that you almost burn a barrel of oil for every barrel produced.
In the late 1980s Paul Baskis, an Illinois microbiologist and inventor, suddenly realized how to improve the process. TDP doesn’t drive off water; it uses it. In fact, it adds more. The water conveys heat throughout the feedstock, causing its molecules to begin to break down at a much lower temperature (about 260 degrees C) and pressure (about 45 atmospheres) than with previous methods. Then the slurry is quickly dropped to a lower pressure, causing 90 percent of its free water to flash off as steam (which is then used to heat the incoming feedstock).
Minerals settle out and are shunted to storage tanks, while the remaining liquid pours into a reactor similar to that used in an ordinary refinery. The liquid is heated up to 480 degrees C to further break down the long molecular chains, and the resulting hot vapour rises up into a tall distillation column. Different substances condense at different heights: gas is captured at the top, light oil flows out of the upper middle, heavier oil out of the middle, water out of the lower middle part, and powdered carbon collects at the bottom.
With a little tweaking, the process can turn waste into other things besides oil. Polyvinal chloride (PVC) can be turned into the valuable chemical hydrochloric acid, for example. TDP can also destroy hazardous waste such as PCBs, dioxins, heavy metals and medical infectious waste, process agricultural waste and human sewage, process the noxious discharges from pulp and paper making, and recycle tires, among other things.
TDP is being championed by Changing World Technologies (www.changingworldtech.com) which has been running a pilot plant at the Philadelphia Naval Yard in partnership with the Gas Research Institute since 1996. Now a $20 million commercial facility is coming online in Carthage, Missouri, where every day it will turn 200 tons of turkey-processing waste–feathers, organs, blood, etc.–from a Butterball Turkey plant into 600 barrels of high-quality oil, 21,000 gallons of water, and 11 tons of minerals, mostly from bones, which make excellent fertilizer.
The oil should cost only $15 U.S. a barrel to make; in three to five years, that’s expected to drop to a very competitive $10 a barrel; it should get even cheaper after that. The U.S. government provided some funding for the Butterball plant and has also provided grants for demonstration plants to process chicken offal and manure in Alabama and crop residuals and grease in Nevada. There are also plans for plants to process turkey waste and manure in Colorado and pork and cheese waste in Italy.
Oil companies, despite the potential competition, like TDP too: it can convert heavy crude oil, shale and tar sands into light oils, gases and carbon, and convert the heavy solid waste produced by refining petroleum into natural gas, oil and carbon. TDP can also clean up coal, extracting stuff like sulfur and mercury–which are valuable, but bad for the environment when burned–leaving coal that burns hotter and cleaner and can be more easily crushed for use in electricity-generating plants.
Turning the U.S.’s annual production of agricultural waste into oil and gas via TDP would yield the energy equivalent of 4 billion barrels of oil–within spitting distance of the amount of oil the U.S. imports every year. Or imagine a local plant that turns your garbage into the fuel that eats your home. The possibilities are mind-boggling.
As more and more TDP plants come on line, we’ll soon know if this technology is really too good to be true–or maybe, this time, both good and true.