While the most recent two posts (here and here) on Changing World Technologies’ thermal depolymerization (TDP) process were reposts, this one has not been previously posted here. Regular reader “Optimist” was initially optimistic about the TDP technology. During his investigation, he went through the chemistry of the process, and came away feeling a bit short-changed.
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Perhaps the confusion about reasonable yields from TDP can be addressed by looking at the chemistry, as proposed by Dr. Adams at http://web.mit.edu/10.391J/www/0405SE05adams.pdf (RR: now hosted at) http://ergosphere.files.wordpress.com/2007/04/tdp_0405se05adams.pdf. As I see it, the conversion can be presented as three chemical reactions: hydrolysis, decarboxylation, and product degradation (for lack of a better term).
1. Hydrolysis (aka depolymerization)
H2-C-O-R
…….|
..H-C-O-R + 3H2O => C3H8O3 (glycerol) + 3 CH3-(CH2)14-COOH
…….|
H2-C-O-R
where R = CO-(CH2)14-CH3Of course, there are many different fatty acids that occur, rather than the palmitic acid (C16) shown. However, for the sake of calculating the yield, the choice of fatty acid (typically in the C12 – C18 range) would have a fairly minor affect. Thus, palmitic acid will be used as an example. 2. Decarboxylation CH3-(CH2)14-COOH => CH3-(CH2)13-CH3 +CO2 3. Product Degradation CH3-(CH2)13-CH3 => 7C + 8CH4 Product degradation is necessary to explain the presence of carbon and low BTU gas in the products from TDP. While the actual reactions are likely to be very complex, the balanced reaction shown will suffice for the purpose of calculating yields. Assumptions 1. All available fat/oil undergoes hydrolysis and all the fatty acid thus produced undergoes decarboxylation. 2. Deciding what fraction of the product undergoes degradation is more difficult. From Figure 5, http://ergosphere.files.wordpress.com/2007/04/cwt_genconflasvegas3_3_04.pdf it appears that CWT was originally expecting about a 10:1 mass ratio between oil produced and carbon produced. Using this ratio, it is estimated that about 20% of the product undergoes degradation. The calculation below will illustrate how this leads to the desired 10:1 ratio. 3. The entire feedstock consists of oil/fat. 4. All separations are perfect, i.e. all the fatty acid from the first stage proceeds to the second stage and all remaining product is recovered as TDP/TCP-40 oil. From these assumptions, it would be obvious that the calculated yield would represent a maximum theoretical yield, as separations in a real plant can never be 100% perfect and no waste feedstock is going to be 100% lipid. Calculations The original fat (glyceryl tripalmitate) has a molecular mass of 806, the final oil product 212. Since each unit of fat produces three units of oil, the yield (before degradation) is: 3 x 212/806 = 78.9% Factoring in degradation, the remaining yield (80%) would be: 78.9 x 0.8 = 63.1% Proceeding in this manner the yield of all products can be calculated. The results are summarized below. Note that water is consumed during hydrolysis, hence the negative yield.
| Product | Yield w/o degradation | Yield with degradation |
| Oil | 78.9% | 63.1% |
| Carbon dioxide (CO2) | 16.4% | 16.4% |
| Methane (CH4) | 0 | 9.5% |
| Carbon (C) | 0 | 6.3% |
| Glycerol | 11.4% | 11.4% |
| Water | -6.7% | -6.7% |
| TOTAL | 100.0% | 100.0% |
| Total gas production | 16.4% | 25.9% |
Now let us do some comparison to Figure 5, which Dr. Adams is still holding up as a valid mass balance for the TDP process. On the left we have 92.9 t/d entering the process and on the right we have 69.8 t/d of oil produced, thus allowing for a yield of 69.8/92.9 = 75.1%! As our calculations, show that would only be possible with very limited product degradation.
Now look at the fuel gas production, listed as 7.5 t/d for a yield of 8.1%. As our calculations show, even with no product degradation you will produce twice as much gas as that. With product degradation, we expect to see THREE times as much gas. Did CWT forget to factor in the CO2 that would be produced? Note that a lipid feedstock would contain oxygen which would not be present in the hydrocarbon product, and would have to the report to the fuel gas. At the same time the oxygen would limit the fuel content of the fuel gas. If the oxygen is in the form of CO2, it would have NO fuel value. If it is in the form of CO, it takes valuable carbon from the oil product. Keep in mind, these are theoretical maximum yields. Look at the four assumptions. Most importantly, we have not factored in the fact that any protein in the feedstock is effectively lost as amino acid fertilizer. According to the label on the turkey, the feedstock is 2/3 protein. If true, yields would significantly below what has been shown above. [Proteins are polymers constructed out of 20 different monomers, a.k.a. amino acids, as discussed at Wikipedia: http://en.wikipedia.org/wiki/Amino_acids. Of the 20, only 9 are nonpolar, i.e. hydrophobic or fat soluble. While this does not mean that only 45% of hydrolyzed turkey protein would dissolve in fat (turkey protein may contain a greater/smaller fraction of the fat soluble amino acids), it does point to a limited contribution of protein to the hydrocarbon product. Especially if one bears in mind that each amino acid contains at least one -COOH group (which would convert to CO2), at least one -NH2 group (which would be released as ammonia) and two contain sulfur which would be released as H2S.] Let us now consider the actual plant performance (300 bbl/d from 270 t/d of waste). 300 bbl/d x 42 gal/bbl x 7.05 lb/gal / 2,000 lb/ton = 44.4 t/d oil. Assuming CWT got the make-up of the feedstock (left hand side of Figure 5) right, 270 t/d of feedstock would consist of 44% organics or 119.4 t/d. Based on the maximum theoretical yield (with degradation), the feedstock must include at least 44.4/0.631 = 70.4 t/d of fat. Thus, in spite of what the label claims it appears that the feedstock is at least 70.4/119.4 = 59% fat. Bottom line: CWT’s original mass balance of the TDP process is a flight of fantasy, most likely because they forgot about the CO2 that the process produces. By continuing to present this mass balance as representative of plant performance, they are deliberately misleading people. Specifically, they are claiming a conversion efficiency that simple chemistry proves impossible to achieve. They should by now be able to factor in the correct gas production, carbon production and unconverted organics reporting to the “fertilizer” stream. The fact that they are reluctant to do so speaks volumes.
As for the actual conversion efficiency, I think most people will agree that the main product of interest is the oil. Yes, energy in the gas and carbon products can be recovered, but the main excitement is about the oil. Energy in the high-quality fertilizer (all water soluble monomers) are effectively lost, as this energy will not be recovered by the TDP facility. (The energy in that fertilizer may save a plant using the fertilizer some energy, thus increasing the yield of such a crop plant.) Assuming the reported conversion (300 bbl/d from 270 t/d of waste) is correct, that would mean 158 MM BTU/h in the feedstock and 63.3 MM BTU/h in the oil, for a conversion efficiency of 40%. MUCH below the original claim of 85%!
“As for the actual conversion efficiency, I think most people will agree that the main product of interest is the oil.”
As an engineer, I do not care what most people think. If fact if you are an engineer making cell phones. I am not too interested in your thoughts about energy.
The main product of plants is food and fiber. Energy is the byproduct. The natural world of plants and bacteria are very efficient with phosphorus but energy is plentiful and can be wasted. If the life cycle of phosphorus has more environmental impact than energy production, should we be focusing on energy efficiency?
The second problem with biomass and efficiency is the feed stock. What is in it. Fossil fuels have the same issues. Is your process concentrating arsenic or making dioxin, your non energy byproduct may have to be sent to a hazardous waste treatment facility. Very expensive!
It is really a marketing issue. If fertilizer is the more valuable product of an energy how do you explain this to people who are only thinking about energy. Like RR, I am skeptical of the fertilizer value of TDP. In any case they did a bad job of marketing it.
I was an engineer making cell phones. They made me take a year of chemistry and I can follow along pretty good.
I realize I don’t have a palm oil plantation in Malaysia and I didn’t do my thesis on sticking my elbow in cow stomachs but I don’t have an agenda either.
So who is Kit P and why should I care what your thoughts are either.
Kit,
I think you are missing the point about TDP. Some important implications:
1. With all due respect, Kit: as an engineer you often don’t make a lot of sense. Here you seem you miss the fact that food and fiber are both sources of energy. To people interested in the statement that TDP is going to free us from foreign oil, the product of interest from a TDP facility is the oil. Same for the economics. I doubt the byproducts will make a dent on the bottom line.
2. The fact that water-soluble monomers end up in the “fertilizer” stream means NO carbohydrate can be converted into fuel. The main product of plants (by mass) would be fiber (aka cellulose) and certainly that would be the main product freely available for biofuel production (waste paper, woodchips, crop residue, etc.) TDP is not able to recover ANY energy from a fiber feedstock.
3. I don’t think the quality of the fertilizer is an issue. With my limited knowledge of fertilizers I can see that amino acids may be a great fertilizer. I doubt that a TDP plant can be profitable thanks to fertilizer production. I suspect that is some of the most expensive fertilizer available today. The issue here is that more organics to fertilizer means less organics to the fuel product.
Again, I suspect CWT figured much of this out only after the Carthage plant was in operation. Look at the mass balance they presented before start up (Figure 5), it shows glycerol and ammonia (NH3; as part of ammonium sulfate, (NH4)2SO4) in the effluent. Seems like they expected the organic part of the amino acid to be converted into fuel. OOPS!
Now look at their energy balance (Figure 6). Note that they assign no energy value to the effluent, even though they show it containing glycerol! With amino acids that hidden energy value increases.
Another energy output overlooked: the water vapor coming out of the mineral drier. It takes a fair amount of energy to convert water into vapor.
Add it all up, and CWT is either grossly incompetent, or willfully dishonest. For the prospective investor, I don’t think it matters which…
Just for the record, I can’t follow any of this. I am just glad we have cchemcial engineers, in this world.
Oil is going to $10 a barrel.
“Here you seem you miss the fact that food and fiber are both sources of energy.”
Optimist is a rich guy. He goes to the lumber store and buys 2×4’s for firewood. Not very good at nutrition however. Sugar is energy not food.
“With my limited knowledge of fertilizers …
Among other things. Look at the holistic picture, for double jeopardy name the primary product of the process. What is turkey, Alex? Holistic picture for $1000! Name an important part of growing food. What is fertilizer, Alex?
In the middle of the process of delivering that that processed price of turkey breast to my house, there is some waste. For those really interested in efficiency, I give you turkey soup.
So now in the context of producing food and processing waste, what is the best way to do it. I would suggest the efficiencies related to converting waste to transportation are a simplistic part of the picture .
It is not that RR did not do a fine job of calculating thermal efficiency. He is worried about his children having enough energy without them being in debt to OPEC. He should be worried about them having phosphorus to grow food.
So Optimist, look at Table 4 in your link. Consider for a moment that those nutrient are important.
From CNN today:
“This report is a bearish one, and it’s confirmation of a trend we’ve expected,” said Chris Lafakis, economist at Moody’s Economy.com. “Even amid production cuts, supply is far outpacing demand.”
Crude oil inventories were above the upper limit of the average range for this time of year, the report said.
“If this level remains, we’re going to have a glut of oil and prices will stay low,” Lafakis said.
Gasoline: The EIA report also said stockpiles of gasoline rose by 300,000 barrels last week, with the total supply being in the upper half of the average range. Analysts were looking for an increase of 1.3 million barrels.
“Gas demand is weak, and this gives operators a tough time because profit margins are so low,” Lafakis said. “If that continues, the U.S. could be drowning in crude oil.”
I like that. Drowning in crude oil.
Kit,
You are really not making a lot of sense here. I don’t mind a difference of opinion, but I have a hard time following your logic. So do me a favor, as the lawyer (Denzel Washington) in Philadelphia said: Explain it to me like I’m a six year old.
Sugar is energy not food.
?!? I guess I’m just imagining people eating it, then!
Look at the holistic picture…
The holistic picture is this: replacing crude oil with waste (turkey guts) is a great idea. If you can make it work. For the investor the question is how much does it cost? Do you have customers for the product? As Discover magazine reported, it’s not looking so good in that department, with CWT only being able to sell 24% of the product it produced, and that at between 60 and 70% discount. Not an attractive investment, is it?
In the middle of the process of delivering that that processed price of turkey breast to my house…
Forget the turkey, Kit. This is about TDP, not the Butterball plant.
He should be worried about them having phosphorus to grow food.
You are missing a key difference between crude oil and phosphate-bearing rock: the energy in crude oil can only be used once, whereas the P in phosphate can be recycled indefinitely between man and his food. Why isn’t it happening yet? Phosphate-bearing rock is still dirt cheap. As you suggest, that may change.
So Optimist, look at Table 4 in your link. Consider for a moment that those nutrient are important.
1. I take it you meant Table 3 (top of page 5).
2. This gets confusing, because CWT is using the term “fertilizer” for more than one output stream. What is shown in Table 3 is the make-up of the “Dry mineral” stream (bottom on the righthand side of Figure 5; 8.2 tpd). However, they are now saying that the “Water + Glycerol + (NH4)2SO4” stream (third from bottom on the righthand side of Figure 5; 33.6 tpd) contains amino acids [and no (NH4)2SO4 I guess] and is a great liquid fertilizer.
3. You are missing my point completely: I am not saying that recycling the nutrients is a bad idea. I am saying that I doubt it counts for significant income. On top of that, carbon makes a far better fuel than fertilizer. From a profit-maximizing POV (again exactly what a potential investor would be interested in), you’d rather want the carbon in the amino acids (and glycerol) to report to the oil product, than to the effluent. Note that without the carbon, you’d still have the nitrogen, i.e. the fertilizer value would still be there.
Hint: the (NH4)2SO4 shown in the effluent stream in Figure 5 suggests that CWT were expecting the carbon in the amino acids to report to the oil product, leaving only the ammonia to report to the effluent. OOPS!
@ Optimist
Hint: the (NH4)2SO4 shown in the effluent stream in Figure 5 suggests that CWT were expecting the carbon in the amino acids to report to the oil product, leaving only the ammonia to report to the effluent. OOPS!
Your use of the word ‘report’ seems odd to me, so I wonder if you could clarify: This was the ‘bleeding edge’ element, engineering wise ?
And when it ‘reported’ differently they had to decide to adapt (to the reality) or mislead ?
RBM
RBM,
I use report here to mean arrive at.
As far as I can tell it was mainly an engineering blunder. If you understood that the first step produced monomers (fatty acids and glycerol for lipids; amino acids for protein) you should have been able to predict where a lot of those amino acids would have ended up.
My theory is that CWT subbed out the engineering work, and failed to communicate the details with their sub.
I suspect that’s how the sub came up with the low estimate on gas flow: he treated the feedstock as if it was pure hydrocarbon (like crude). Small difference, big effect…
“Explain it to me like I'm a six year old.”
Optimist I do not expect a six year old to understand. I am not trying to defend CWT because they have not provided enough data to evaluate.
To correctly perform any engineering problem the boundaries must be properly defined. Start with the product. The product is turkey which is food. The product of a dairy farm is milk which is food. If we add an energy project to the turkey producing facility or a dairy farm, the main product does not change: turkey and milk. A similar analogy can be made for lumber and paper.
When an waste to energy project is added to an exiting process, the energy project must be evaluated in the context of the primary product. The correct comparison is different processes that treat turkey possessing waste to recover energy and the N, P, & K. To focus on just the energy is mostly an indication of your focus rather than the merits of the process.
I am not trying to defend CWT because they have not provided enough data to evaluate.
The data is out there, altrhough CWT does not seem particularly interested in sharing it. Considering what the data shows, I am not surprised.
For example, we have this from Discover magazine: Three tanker trucks arrive here on peak production days, loading up with 500 barrels of oil made from 270 tons of turkey guts and 20 tons of pig fat. Compare that to CWT’s mass balance: 210 tpd of waste in, 68.9 tpd (~470 bbl/d, assuming diesel density) oil out.
So there you have it: CWT predicted they can get 2.24 bbl/ton of waste. In the real world, they are only getting 1.72. That 23% drop in production hurts the bottom line.
When an waste to energy project is added to an exiting process, the energy project must be evaluated in the context of the primary product.
I completely disagree: why complicate the analysis by trying to estimate the efficiency of the primary production process? How is that relevant to energy recovery?
The primary production process continues, with or without energy recovery. The waste simply goes somewhere else. People are still going to eat turkey, drink milk, use paper and wooden products, with minimal regard for the efficiency of the production processes. So why get into that? It makes more sense to assume the primary products will be produced regardless, and the waste… eh, byproducts get churned out accordingly. The sensible thing to do is to ignore the primary product, and set the system boundaries accordingly. Butterball may be highly efficient in converting live turkeys into the frozen product, or they may be highly inefficient. Either way, that does not affect the efficiency (or feasibility) of the TDP process.
The correct comparison is different processes that treat turkey possessing waste to recover energy and the N, P, & K. To focus on just the energy is mostly an indication of your focus rather than the merits of the process.
Excuse me, Mr. Know-it-all, but the N, P, & K are not going anywhere. The N reports mostly to the liquid effluent ("fertilizer" if you must) and the P & K report to the "Dry minerals". No process can make the P & K disappear. N may, under certain process conditions, be released to the air as off-gas. So TDP is doing about as well as can be expected ito nutrient recovery. What is there to analyze?
You seems to have forgotten that we are talking about an IPO here. For the potential investor the question is: Is TDP potentially profitable? What are the risks? On both counts, I'd say the answers are troubling.
“Excuse me, Mr. Know-it-all, but the N, P, & K are not going anywhere.”
Sorry I did not post my name last time. I am a really smart guy Optimist and I certainly know what I do not know. N, P, & K goes somewhere. N, P, & K is a much more significant pollutant than CO2.
The traditional place N, P, & K goes is into the environment. In the US, the CWA requires water discharges to be treated. So the next place N, P, & K is the sewer or a lagoon. If N, P, & K blows away that is fine too. Waste treatment generally uses energy.
Finally N, P, & K can be recycled back into growing the product that is the feedstock to produce fuel. Generally speaking, renewable energy advocates ignore the environmental impact of producing renewable energy. So Optimist if you choose to put on blinders and only look energy, I will keep pointing out that you are missing an important part of the picture.
“You seems to have forgotten that we are talking about an IPO here.”
My interest is energy and the environment. Never the less I did look at the web site for the offering and it does fall into the category of not providing sufficient information.
N, P, & K is a much more significant pollutant than CO2.
That is your opinion. You’re entitled to it.
The traditional place N, P, & K goes is into the environment. In the US, the CWA requires water discharges to be treated.
Then I guess you know that we are seeing strict regulations on N in some places such as Chesapeake Bay. P regulation is much more limited. I don’t know of any place where K is directly regulated, do you?
So Optimist if you choose to put on blinders and only look energy…
You can call it blinders, I’d call it focus: if TDP is going to make commercial sense, it would be thanks to energy. The fertilizer is an afterthought, ito the economics.
You may wish it was different, but that does not make it so.
BTW, I actually support the idea of recycling nutrients. TDP would also be a great way to do it. But so would most waste -> energy processes.