A teacher of mine once said, "There are always two ways to look at a situation, the optimistic way and the pessimistic way." He went on to say that he preferred the pessimists' way, because an optimist is too easily fooled, and constantly being disappointed that things didn't work out as well as expected. The pessimist, on the other hand, always expected the worst, so was constantly being delighted with the things that did work out better than expected, while never suffering dissatisfaction when things did not work out. Indeed the pessimist can take consolation in having presumed a negative outcome in the first place.

I have often tried to adopt this stance myself, but I find that I derive too much enjoyment from the anticipation of positive results despite frequent disappointments to give up my optimist's view of the world.

My teacher, unfortunately, is far from alone in his stance, especially when it comes to the future of biofuels. Bioethanol in particular, but all the strategies that use edible crops are under attack these days by some rather vocal opponents. A healthy dose of scientific skepticism is not a bad thing, but these folks sound more like crusaders with a cause in their hearts than scientists, despite the fact that they don the cloak of scientific justifications for their negativity. To be fair, we need to allow these voices to be heard, and if you are interested, the web site at www.biofuelwatch.org.uk will be happy to give you an earful of negativity about biofuels of all stripes.

Another vocal, if highly surprising, critic of the biofuels future, and of American biofuels strategies in particular turns out to be Fidel Castro. Back from the brink of his own demise, Castro, the elder, recently attacked US global energy strategy as American Imperialism that imperils the well being and health of developing nations, and threatens to bring starvation to more of the world's poor people than already face death daily from lack of food. Producing ethanol from food crops theatens the availability of food in poorer nations, because developed countries can afford to buy those crops when poor locals cannot, Castro reasoned in an editorial that reportedly appeared in the Communist Party newspaper in Havana. The Boston Herald reports that, "The headline read: 'Condemned to Premature Death by Hunger and Thirst more than 3 Billion People of the World.'"

Castro (no longer "President," by the way, his brother Raul, also a party stalwart since the revolution, now holds that office, at least temporarily) would seem to qualify as a pessimist under my teacher's definition, I guess. It seems that he is inclined to ignore the proposals to turn Cuba's sugar refineries into self-sustaining co-generation facilities by pyrolysis of the cellulose discarded from the sugar refining process. Typically this "bagasse" is burned, as are cane fields themselves. Cellulosic ethanol is a possibility, but that is not even what is proposed for these facilities. This is a straight up, cellulose to gases as fuels process. The pyrolysis (chemical breakdown under relatively high heat) of the cellulose is used in gas fueled turbines to generate electricity, while the exhaust heat is used to generation additional electricity plus steam to power the sugar refining process.

I will leave cellulosic ethanol's further discussion for another time. I promised more details on Thermal Depolymerization, and Catalytic Deploymerization.

In truth the terms are somewhat deceptive. Both processes involve heating to relatively high temperatures, though somewhat below what most pyrolysis processes use. Whether catalyized or not, the first step in both processes essentially amounts to a pyrolysis of the long chain hydrocarbon/carbohydrate molecules.

For a more complete discussion of thermal depolymerization, see the Wikipedia article by that name. The first stage heats the feedstock to 250 °C. It is then flash dehydrated so that water and volatile gases evaporate. Early descriptions of the process indicated that this was the source of the majority of the gases to fire the process. That fraction of the feedstock was quoted as 9%, originally, but now the available energy used to fire the whole process is being quantified at 15% (of the Low Heat Value)(assuming dry feedstock, which the feedstock is NOT). There is also substantial energy recovery from this stage. The hot steam is used to pre-heat the feedstock after being separated from the methane and butane (and other lesser percentage gases). The flash evaporation happens in a vacuum vessel so that although the feedstock was initially isolated from oxygen (to prevent combustion or even partial combustion) and air by allowing the steam to displace any air in the process chamber, it remains in an "anaerobic" state when this evaporation under low pressure occurs.

As you probably realized, 250 °C is well above the boiling point of water, so that this rise in temperature results in significant pressure in the reaction chamber. Wikipedia reports this pressure at 600 psi. Exactly how this brew goes from 250 °C and 600 psi to something less than atmospheric pressure in a "flash" has not been revealed in any detail, but clearly this step in the process results in significant releases of energy. When the gases and other light gases have been evacuated from this chamber, the remaining feedstock is passed to another heating stage.

In thermal depolymerization this stage raises the temperature even higher. By heating to about 500 °C remaining long chain bonds are broken to release short and medium length hydrocarbon molecules. The result, separated by differential distillation are water, carbon (and some other chemicals depending on the composition of the feedstock) and a medium grade fuel oil. In the case of the Carthage, Missouri plant built in partnership with ConAgra to process waste from turkey packaging and processing, the output is about 500 barrels a day from 200 tons of turkey parts. The some of the oil is classified as #2 diesel and another fraction, reportedly, is a lower grade #4 diesel.

Now that description conforms to Wikipedia's description, however, Terry Adams, PhD. of Changing World Technologies, described it this way in a paper authored by himself and others: "The process temperatures for the initial slurry phase of processing are between about 200 °C to 300 °C (392°F to 572°F). For the second processing stage the temperatures are near 500°C (932°F)."

Also a fascinating insight that is rarely discussed is this equation:

INPUTS are Electric 3.6 MM Btu/hr power, Natural gas 0.0 MM Btu/hr,

and Organics equal to 122.9 MMBtu/hr (from 210 tons/day dry)(ignoring Water, Mineral and Ammonia content of feedstock).

OUTPUTS are Fuel-gas 1.4 MM Btu/hr (recycled and used in process) TDP-40 oil 99.5 MM Btu/hr, Carbon 6.4 MM Btu/hr.

But also rarely identified is INPUT of 3.6 tons/day of H2SO4, and output of 33.6 tons/day of combined Water+Glycerol+(NH4)2SO4.

This is still based on 210 tons/day of feedstock which includes 108 tons of water, 92.9 tons of "organics", 8.2 tons of "minerals" and 1.0 ton of ammonia. The other outputs (in addition to the 33.6 tons of the water-glycerol-(NH4)2SO4) are the 7.5 tons of "fuel gas" (recycled to process), 8.2 tons of water vapor, 8.2 tons of minerals, 79.7 tons of water (distilled), 6.7 tons carbon, and 69.8 tons/day of their oil product (they call it "TDP-40").

The Wikipedia article has an interesting, ironic, historical note that in the 1970's a man named "Appell" was granted a patent (along with his colleagues) for a thermal deploymerization process. The founder of Changing World Technologies is named Brian Appel. It is just one of those little oddities of the world that one often sees people who "grow into" their name, like my cousin's husband, Doctor Blood. (no joke, really!)

Catalytic Depolymerization is a very similar process. One of the interesting differentiations is that rather than more traditional heating methods, Dr. Koch, the inventor of the currently leading version of the process has chosen to use turbines to heat the brew. Not the kind of gas turbines that CWT/RES use for their process heat, but mechanical turbines that actually churn the broth to impart heat by friction. At least one of Dr. Koch's models shows 8 such turbines attached to the main reaction vessel. These electric turbines are noted in one drawing to be 22 kW rated, but whether that is for one or for all 8 is not clear to me. It appears to be the former, because some of those drawing are clearly simplified process outline drawings, not intended to act as construction plans.

Dr. Koch states that he uses 3 (or more) catalysts, a different one for each type of feedstock. It may be true that these are "catalysts" but he also says that the catalysts are "consumables", and shows that they form reactions with other constituents to form the slag of the process. No form of recovery of the catalysts is indicated anywhere in any of the drawings (in the patent or otherwise) or descriptions. While they don't appear to be expensive chemicals (not as compared to the platinum filters used in some gas separation processes) just potassium, calcium, sodium and magnesium-aluminum silicates, they are reported as having a nano-particle size to facilitate maximum surface area. That may or may not be expensive, or they may be planning on licensing only if you commit to buying their proprietary brand of catalyst. Essentially these mechanical turbines impart heat to 750 °F, and dried feedstock is input in a slurry with a "carrier oil". (There are recent reports that they now can do this without the oil as "carrier", but those reports are unconfirmed at this time [more about that later].) The hyrdocarbon vapors, along with CO2 rise into a cyclone cleaner (you know, like a Dyson vacuum, spin the particles [dirt] to the edges so the gases continue to flow), and from there into a distillation column that condenses out the water and the diesel fuel. It is marginally more complicated than that, but the problem is that Dr. Koch is playing it very close to the vest in terms of exactly how his process works, and he came to America to form a partnership with a man convicted of fraud in Germany. Dr. Koch has since separated from that partner, who now claims to be building an $80 million plant in the US that produces 2000 gal/hr., but as someone pointed out, even if the plant operates for 7000 hours a year, and one assumes an amortization period of 10 years (10% is a poor return on an unproven technology investment, but we're being kind here) that means that you have $0.57 per gallon in capital cost to pay back on every gallon for 10 years, and that says noting about operating costs, including catalyst (remember, that's a consumable, according to Dr. Koch) which although Greenpower, the promoter, quotes $0.05/gal others estimate it at more like $0.50/gal. Beyond that, Dr. Koch's reluctance to reveal some of the details of his process have lead to some hardline skeptics. (If you take that link you might want to backtrack a little, too, though you may not want to wade through all 52 pages of the discussions/arguments.)

With respect to capital costs, I received a comment from a gentleman who said that $0.57/gal is not unreasonable (despite the fact that this applies to every gallon produced for the first ten years). For comparison, however, I have received a quote of $0.50/gal/year capacity (paid once for construction) for a biodiesel "factory". On the other hand, last time I checked they were getting about $0.57/liter for the feedstock oil (at 3.7 liters = 1 gal.)(which is about $1.71/gal. for oil feedstock alone, not counting the methanol required, energy, labor or disposal of glycerol).

The "biodieselnow.com" web site also has some posts that claim that the CDP process "MUST" be "magic" because you can't get diesel without starting with fatty acids. That claim, sadly, or happily depending on your point of view, is nonsense. You can get oil from coal, or from straw. Rumplestiltskin gave the whole turning straw into anything valuable an undeserved bad reputation.

love

Stafford "Doc" Williamson