Update on CWT IPO

A couple of months ago, in response to a story that Changing World Technologies was going to file an IPO to help commercialize their TPD technology, I reposted my story:

TDP: The Next Big Thing

Turns out they decided against the IPO. Bankruptcy seemed the better option:

Renewable Environmental Solutions owner closes plant in Missouri, files for bankruptcy

Changing World Technologies Inc., based in West Hempstead, N.Y., filed for Chapter 11 protection Wednesday in the U.S. Bankruptcy Court for the Southern District of New York.

In a news release, the company, which owns the Renewable Environmental Solutions plant in Carthage, said it was trying to reorganize its business and find new financing “to fund its operations going forward and to move ahead with its expansion strategy.”

The company said in filings with the Securities and Exchange Commission that it had lost $18.8 million for the nine months ending Sept. 30 and had an accumulated deficit of $117.8 million.

They have had a long fall from the cover of Discover magazine, where they were going to be the solution to the world’s energy problems. Let’s review some of the quotes from that initial article, and then consider the fact that the company never made a dime:

“This 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 this pilot plant and has just completed its first industrial-size installation in Missouri. “This process can deal with the world’s waste. It can supplement our dwindling supplies of oil. And it can slow down global warming.”

Pardon me, says a reporter, shivering in the frigid dawn, but that sounds too good to be true. “Everybody says that,” says Appel. “The potential is unbelievable,” says Michael Roberts, a senior chemical engineer for the Gas Technology Institute, an energy research group. “You’re not only cleaning up waste; you’re talking about distributed generation of oil all over the world.”

“This is not an incremental change. This is a big, new step,” agrees Alf Andreassen, a venture capitalist with the Paladin Capital Group and a former Bell Laboratories director. “We will be able to make oil for $8 to $12 a barrel,” says Paul Baskis, the inventor of the process. “We are going to be able to switch to a carbohydrate economy.”

And it will be profitable, promises Appel. “We’ve done so much testing in Philadelphia, we already know the costs,” he says. “This is our first-out plant, and we estimate we’ll make oil at $15 a barrel. In three to five years, we’ll drop that to $10, the same as a medium-size oil exploration and production company. And it will get cheaper from there.”

CWT and their TDP promises are the poster child for the strategy of “overhype your technology to pull in investors, and hope the technological problems are resolved.” They had endorsements from lots of people, and a gushing article in Discover. But reporters and investors didn’t ask the right questions, and they didn’t do their due diligence, and the result was a lot of dollars flushed down the toilet.

The sad thing is, history is repeating itself right now with most of these cellulosic ethanol and algal biodiesel companies. They all have a great story to tell, they are all going to solve the world’s energy problems, and the majority of them will be bankrupt inside of 5 years.

34 thoughts on “Update on CWT IPO”

  1. Sadly this will make it harder for the serious players, as you point out, RR.

    The money quote: We’ve done so much testing in Philadelphia, we already know the costs…
    This from the same people who couldn’t even get their mass and energy balances right! 85% efficiency! My ass!

    And I guess they also didn’t bother to smell the results of all that testing…

  2. Okay, ethanol is dead, as a commercial process, that seems clear,

    However, MIT researchers are reporting a gigantic advance in lithium batteries. Basically, rapid recharge and more storage.
    This looks like another nail in the oil industry’s coffin.

    See below.

    MIT powers up new battery for hybrid cars
    Anne Trafton, News Office
    February 16, 2006

    Researchers at MIT have developed a new type of lithium battery that could become a cheaper alternative to the batteries that now power hybrid electric cars.

    Until now, lithium batteries have not had the rapid charging capability or safety level needed for use in cars. Hybrid cars now run on nickel metal hydride batteries, which power an electric motor and can rapidly recharge while the car is decelerating or standing still.

    But lithium nickel manganese oxide, described in a paper to be published in Science on Feb. 17, could revolutionize the hybrid car industry — a sector that has “enormous growth potential,” says Gerbrand Ceder, MIT professor of materials science and engineering, who led the project.

    “The writing is on the wall. It’s clearly happening,” said Ceder, who said that a couple of companies are already interested in licensing the new lithium battery technology.

    You can read more, just by googling. Yes, I know it is way early, and even MIT scientists can hype something, or get too excited.

    But if you read about it, it looks very promising. Along with several other recent advances, I think we are talking about 80 mile range and 1 hour recharge on PHEVs.

    This is good news, Optimist!

    I may have to change my name to Benny “Perma-glut” Cole

    The future of crude oil gets dimmer every day.

    Wh is going to rely on oil thugs and baboon-states when you can drive PHEVs?

  3. I thought the EVs and PHEVs were supposed to be of benefit because you could charge them at night when there is spare electricity generation capacity. But if people want to charge their cars in 10 seconds or even 10 minutes, they can’t do that at home even if they had a 220V circuit and 200A entrance. So instead of charging overnight, they’ll have to go to some central charging station, and we could end up making peak demand loads even worse.

  4. I’m new to this blog but I’m really enjoying it. It’s hard to cut through the hype about all these new inventions to figure out what could work and what won’t. I’m struggling now to figure out if gasifying wet sludges (municipal and paper wastewater byproducts) makes financial sense, and one of the big questions is of course the energy balance. But ask 10 people if it will work and you’ll get 10 different answers. As an outsider with a limited technical background but a good grasp of science, it’s maddening.

    Since you say that investors and reporters didn’t ask the right questions, can you tell us what the right questions are when we’re evaluating some of these new renewable energy technologies? Maybe with a bit of insight into how to go about figuring out the answers and to figure out who’s right when you get conflicting answers?


  5. perhaps your message is well understood by some in the industry. would it be true that the obvious powers[XOM, COP,CHEV] do not enter in[purchase these darlings] is because they share your insight?


  6. Since you say that investors and reporters didn’t ask the right questions, can you tell us what the right questions are when we’re evaluating some of these new renewable energy technologies?

    Part of the problem beyond asking the right questions is understanding whether you are hearing spin or not. In a couple of weeks I am going to be on a panel session at the Annual EIA Conference in D.C. I am on a panel called “Energy and the Media.” I am trying to come up with some questions and follow-ups that should help determine the validity of a process. I will probably write something up and post here when I have some time.

    It often requires more than just asking questions, but those are a start. Some of the questions I would ask would be 1). Where was the piloting/experimental work done? 2). What are the patent numbers? (then read them). 3). What challenges to your business model do you foresee? 4). Has anyone independently verified your energy balance?

    Those are just a start.

    Cheers, RR

  7. perhaps your message is well understood by some in the industry. would it be true that the obvious powers[XOM, COP,CHEV] do not enter in[purchase these darlings] is because they share your insight?

    There is a reason the oil industry does not own the ethanol industry. They easily have the capital to scoop up all of the ethanol assets in the country. That’s why I always chuckle when people suggest that the ethanol industry is a threat to the oil industry. These people don’t understand scale. But the oil industry doesn’t want to be involved in something that is entirely dependent upon continued government mandates and subsidies.

    The oil industry is engaged in various ethanol research projects, but so far there isn’t a clear business case. Valero is making a defensive move by acquiring some ethanol assets, but if the government ever changes their ethanol policy those assets will be worthless.

    Cheers, RR

  8. “I’m struggling now to figure out if gasifying wet sludges (municipal and paper wastewater byproducts) makes financial sense, and one of the big questions is of course the energy balance.”

    As RR suggests, ask the right question.

    Start by taking a holistic approach. What are the current best practices? For WWTP, Tacoma, Washington and Milwaukee have excellent programs for finishing sludge by composting and selling as high quality fertilizer. Looking at the energy balance of biosolids, the contained nitrogen is the best use of energy by off setting synthetic fertilzer.

    For sludge from the paper industry, The paper plant at Wallula, Washington also excellent programs for finishing sludge by composting nut uses the product on poplar plantations because dioxin may an issue.

    Any any case, sludges are strictly regulated so information is public.

    Recovering energy from waste is just a step up using a holistic approach. The traditional way to get rid of sludges is in a boiler for process heat or at the closes landfill. Innovative approaches to sludges do not happen when the city WWTP is under the same management the city landfill. Fewer layers are innvolved.

    Do gasifiers make economic sense? It depends on what is in the waste. The number of lawyers you have to hire more than the energy balance.

    The short is answer is no for most cases.

  9. Thanks, Robert and Kit, for your answers. Looking back at my post, I realize that I might have inferred that I’m an investor. I’m not–I work for the EPA to try to help water and wastewater plants use less energy and generate renewables on site.

    We’re definitely taking a holistic approach here. Gasification doesn’t make sense for large areas of the country where energy is cheap and land disposal options are plentiful and less-regulated. But in the coasts, land is expensive and the neighbors are often fighting off land disposal (whether by composting, landfilling, etc.). Many areas incinerate the sludge with no energy recovery, which seems tremendously wasteful and more likely to pollute the air than a good gasification program, and is also very expensive.

    So gasification could work financially for plants in some areas of the country because two of their biggest costs are disposing of sludge and purchasing energy, and this addresses both costs. The real questions are the energy balance, the startup capital and operating costs, and the emissions, as I see them.

    It’s just that when we ask different people about those three things (energy balance, costs, emissions), we get wildly different answers. So I’m trying to refine my questions so that I can better cut through the spin and figure out if this will work or not.

    BTW, for most US municipal sludges, the energy content when the sludge is dried is roughly equivalent to some sort of coal. Exactly what grade of coal will depend on what happened in the process leading up to the sludge. But since this stuff starts out very wet, there is a lot of energy required to make it dry. And that’s where I’m hearing disagreements over the energy balance.

    Also, composted sludge is an OK fertilizer, but most of the nitrogen and phosphorous pass through treatment plants. There are legions of people who would argue that to market composted sludge as “high-value fertilizer” requires a lot of spin. And industrial composting processes require a tremendous amount of energy for heat, aeration, and turning the piles. After last year’s energy spike, I think many municipal facilities are rethinking composting.

  10. To be fair, start ups have about a 50% chance of staying alive 4 years, and only 30% after 10 years. Start ups ARE risky, period.

    The problem for investors, is that some pretty crazy sounding ideas become successful. In this case, RR showed the business model of these companies was seriously flawed. So I guess the message for investors is that you need an objective analysis by an industry insider, but not one who is wedded to the industry.

    In some ways it is satisfying these start ups fail, at least it shows our understanding of science is correct!

  11. Jason

    It is nice to hear someone at the EPA thinking about cost effective solutions.

    I know of one gasifier technology that can be economically used to safely take sludge to produce process heat to directly dry food fro human consumption. I would never consider that in the US because of regulations. However, it is practical to take a dewatered waste (food processing waste) and dry the waste with boiler exhaust, feed it into the gasifier and take the heat to produce process steam for the food processing plant and make electricity.

    Starting Monday can you get everyone at the EPA to not say 'land disposal'. Biosolids is a very beneficial product and dry land what farmers can not get enough.

    One of the primary unit process to remove N & P is anaerobic digestion which produces energy. Both a mass and energy balance needs to be performed with the goal of maximizing N & P recovered. If you understand the emissions from producing N&P, then it is obvious that energy efficiency secondary. EPA has a series of documents with information. (AP-42 Chief?).

    Most of WWTP were built when energy was cheaper, so the energy to pump air into aerobic processes was cheaper than the cost of more anaerobic processes. We need to rethink WWTP to make them resource recovery plant.

    WWTP can produce great fertizer. However, the energy is pretty close to worthless like a ton of low BTU 'equivalent to some sort of coal'.

    Give me biosolds or biogas from a WWTP and I can make electricity a lot cheaper than solar. Give me enough subsides and I can show a profit. That does not mean it is a good idea environmentally however. Because of the absence of scientific decisions at the EPA based on political pressure from loons, too may choices by industry are made based on the cost of attorneys.

    Jason my assumption is you are not a policy maker at the EPA so do not take any of this as an insult.

  12. Kit, I don’t want to get into a long discussion about biosolids on this site. That’s a battle other people fight all the time and I have no interest in it. Not trying to be rude, but I am deeply involved in the world of sludges and biosolids and don’t need any more education about most aspects of that topic.

    My purpose here is to try to evaluate the efficacy of a particular technology -gasification- as a method that can cost-effectively handle wet sludges from municipal and industrial wastes, especially if you take into account the high disposal costs that treatment plants in my region are now paying, and so far I haven’t really gotten any more info.

    There are a number of plants in the US that are very close to being able to be net-zero energy consumers using sludge as an energy resource, and my goal is to make that much more common. Anaerobic digestion has lots of drawbacks but it’s easy for us to evaluate it because we know a lot about it and have hundreds of reference installations. But there are plenty of places where anaerobic digestion is just not an option.

    What I am trying to find out is will gasification work at all with wet sludges as a feedstock, and if it does will it be cost-effective? In spite of all the other things you can do to biosolids (composting, landfilling, incinerating, digesting, etc., etc., etc.) they still present a very expensive and difficult disposal problem for hundreds of facilities in the US and I need to find out if gasification can play a role in helping those facilities.

    And yes, I do agree that we need to rethink wastewater treatment and make our plants become resource recovery units. That’s the main focus of my job. But a huge part of those resources is the energy bound in the sludges and in the heat contained in the effluent, and you can’t just dismiss that energy out of hand. It is most definitely not “close to worthless” as you suggest. In fact, energy derived from sludge vio biogas is saving individual plants millions of dollars a year each right now in energy cost. The question is whether gasification might generate even larger savings or help plants where anaerobic digestion isn’t a viable option.

  13. batogrClee-
    If lithium batteries work as these MIT profs and researchers think they can, we will be a much richer and cleaner nation in about 10-15 years. Peak load is of little concern if we can save trillions of dollars in import costs, and have cleaner air (and emit less CO2’s for the global warming crowd).
    Sheesh. If we can obtain rapid recharge on lithium batteries, and extended range, we are looking at a game changer, something that will make the world, especially in the US, a much better place.
    We are also looking at obsoleting the oil industry. The oil industry faces a dilemma; It can keep oil cheap, or it can face the world passing it by.

  14. Jaon – I will try to answer your question. Although not the technical expert, I build gasification plants for a living, and at the first of my career I was responsible for a 10 MGPD waste water treatment system.

    Yes you can use wastewater sludge in a gasifier. There are a couple of reasons why you wouldn’t want to do it.

    First, a gasifier converts the carbon, hydrogen, and oxygen in the feedstock into synthesis gas. Everything else is produced as a byproduct or waste stream. Municipal wastes contain relatively high amounts of nitrogen, sodium, phosophorous, and other things we don’t want. The nitrogen can be converted into ammonia (NH3)which you can sell as fertilizer. Or you can combine it with the sulfur to convert to ATS (ammonium thiosulphate). The refinery that RR used to work at does that. Municipal sludge just isn’t a very good feedstock.

    Second problem, cost. Bitumunous coals currently cost about $45 per ton for a 11,000 BTU/lb heating value. Lignites sell for about $15 for 7,000 BTU/lb. I MIGHT be able to pay you $5/ton for your municipal sludge, depending on the quality of it. For comparison, most biomass is around 7,000 BTU/lb. By the time you transported to my gasifier, it would be cheaper to landfill it. Building a gasifier to get rid of it may cost you more than landfilling too.

    Gasifiers use lots of water, that is where the hydrogen comes from in the syngas. It may just be easier and cheaper to sell me your untreated raw water. Then you bypass the cost of treatment alltogether.

  15. Occasionally I have wondered in these posts what would happen if the two largest oil-consuming nations adopted measures to reduce oil consumption.

    Now this word from China. They may subsidize alternative-fuel or electric cars:


    This, combined with rapid advances being made in batteries, may mark the end of the oil era.

    I would not say that conventional crude oil has a bright future at this point. With oil supplies controlled by thugs and baboons, and with alternatives popping up, and with China and the USA pushing alternatives–oil may be a dinosaur industry.

    No sane nation wants to rely on KSA, Iraq, Chavez or Putin.

  16. KingofKaty-

    Thanks, that was helpful. I guess I wasn’t clear enough in my description. We’re actually looking at building small gasifiers on site at some medium or large wastewater plants. So the plant operators wouldn’t be trying to sell the sludge to large commercial gasifiers offsite–they would be using it onsite to create energy to run the plant. Wastewater plants tend to be massive energy consumers and they are currently spending a good deal of money to dispose of sludge, so if they can eliminate or greatly reduce those two costs there is a sound financial reason to try it.

    In other areas with many small plants, it might make sense to build a central gasification unit at one of the larger plants and have it accept sludges from nearby plants. Right now, those plants would probably PAY to have the sludge go there, but they would be paying less than their other options so it would still be a net win.

    Interesting comment that the water provides all the hydrogen–I hadn’t realized that, although it makes sense. That certainly opens up some new avenues of thinking–there may be instances where it would make sense to build a gasifier near a treatment plant and have it use the influent or effluent as a water source. I’ve seen power plants that use treated effluent as a cooling water source and I’ve also seen effluent used for building and industrial cooling processes, but haven’t seen anyone try to use the raw wastewater for their process. I’ll have to pursue that option further.

    As for the nutrients, we’re also working at ways to recapture those earlier in the process so they don’t end up in the sludge or effluent where they become a hazard. But wouldn’t the nitrogen get converted to N2 gas and the phosphorous end up in the ash where it could be recovered?

    You say you build gasifiers for a living–would you be available to chat on the phone or via email? My email is turgeon DOT jason AT epa.gov.

  17. Jason – gasifiers don’t make ash. They make a glass like material called slag. The slag contains any inorganic material with boiling points less than about 2000 degrees F. So, sodium, phosphorous go out with the syngas. Iron, nickel go out with the slag. Nitrogen in the sludge is usually in the form of various nitrates. The gasification reaction operates at a high enough temperature to break the nitrogen-oxygen bonds. In an excess of hydrogen, the ammonia reaction is favored.

    Small scale gasifiers are extremely expensive on per ton basis. You will need to build an oxygen purification plant, (or buy liquid oxygen) gasifiers (at least 2), and depending on what you want to do with the syngas, you may need to shift some of the CO and steam to H2. You can then burn the gas in a turbine or convert it to some other product. It takes a lot of kit.

    Don’t forget too that gasifiers are high maintenance items. They are steel reactors lined with refractory operated at conditions that slowly breaks down the refractory and other internals.

  18. “Wastewater plants tend to be massive energy consumers “

    WWTP use lots of electricity and only a small amount of heat is needed to maintain AD temperature.

    Converting the heat from poor quality fuel to electricity is capital and labor intensive.

  19. KingofKaty-

    Thanks for the extra info. My fault for the slag/ash mixup. I knew that already, just got confused. The marketing for gasifiers often mentions that the metals are either recoverable or are bound in an inert form and won’t leach out. The marketing also states that the slag can be sold for use as an aggregate substitute in roadbed applications. Have you found that these claims are true?

    Good thoughts on the maintenance. I expect that gasification will only be feasible at some of the larger facilities. It might also make sense in areas where MSW or coal gasification is being proposed nearby–the excess heat from that process could be used to dry the sludge and the dried sludge could be mixed with the other fuel source. Treated effluent could also be used for cooling/process water.

    Kit P-

    When you say “poor quality fuel,” are you referring to the Btu value, the particular pollutants in the fuel (P, N, S, etc.), or both? What would you consider good quality fuel from a Btu perspective?

    As for your other comments–wastewater plants are expensive to build and operate already. Individual plants routinely spend tens or even hundreds of millions of dollars on sludge management practices including digesters, and these digesters only capture a fraction of the energy in the sludge and reduce the volume of the sludge by perhaps 50%. So if a gasifier could be built for roughtly the same money that captured a higher percentage of the energy and resulted in a 95% reduction in volume, I’d think that would be a net win.

    Consider that in my region there is a plant that digests sludge to produce 17% of its power from biogas and still spends $15 million on electricity and $20 million a year on sludge disposal. The sludge disposal in this case involves using natural gas to dry the sludge to pellets that are 92% dry, perfect for gasification. This plant-like many large wastewater plants-already produces pure oxygen onsite for its process, and presumably there is extra capacity in that equipment for the periods of high flow the plant is designed to handle occasionally. The plant already has gas-burning equipment to make electricity, currently fired on biogas.

    Seems to me with $35 million in potential avoided costs and the potential of some kind of carbon credit income, it would be worth a very thorough investigation of switching from digestion to gasification. Not saying that it would work, but that we should do a very thorough analysis. So far, I still see evidence that this process could work cost-effectively and produce some environmental benefits if we can nail the details. But I don’t think it’s a slam dunk or a cure-all.

    Thanks again to everyone for their help.


  20. Jason,
    I think you are onto something. Keep up the good work. Unfortunately, the wastewater industry, being dominated by government agencies and the like tends to be risk-averse and insensitive to costs, to the point were innovation gets suppressed.

    Did you start out talking about wet gasification? What ever happened to that technology? Seems like USDA was working on wet gasification, but I get the impression they stopped working on it. What is the status of this technology?

    Also, if you are looking for a gasification expert, I would suggest you give one of these guys a call. I went to a presentation where one of them claimed their gasifier likes water, whatever he meant by that.

    BTW King, it seems like they use steam in lieu of oxygen, if I scanned the patent correctly. Refer to the section: Oxygen-Free Driver Gas and Reactor Operation.

    Seems like it should be feasible to recover both energy and nutrients from wastewater. Currently energy recovery is low (WWTPs should be power plants) and nutrient recovery is almost non-existent. The city of LA is being forced to shut down their own farm, where they have been land-applying the sludge.

    Gasification would be a good way to produce sterile fertilizer and fuel.

  21. Optimist-

    Thanks, those links were helpful. I’ll have to investigate that patent more–I’m not quite sure I grasp all of the technical aspects of it yet but it looks interesting.

    I only know of one wet gasification project, at UC Riverside. They were looking at building a large wet gasifier to handle the municipal sludge but couldn’t provide enough sludge from the local plant. As an extra feedstock, I think they were going to mix in green yard waste and other compostable plant wastes. The end product was to be some sort of synthetic diesel, if I recall. See http://jcwinnie.biz/wordpress/?p=1497

    I know that LA has been forced to look for alternatives to land application, but I can’t remember off the top of my head what they were looking at for alternatives. One of the larger LA area plants is very nearly energy self-sufficient (using extra sludges as a feedstock imported from other area plants) and could soon be a net energy producer. I’m with you–WWTPs should be power plants and I think they will be soon.

    I also agree that it should be possible to recycle the nutrients and the energy. One way of recycling nutrients is by producing struvite, which is nitrogen, phosphorous, and ammonia. The Ostarra process that is up and running in Portland, OR, is doing that, I haven’t heard yet how well it works. Lots of plants produce struvite where they don’t want it (like in the pipes or in the biogas, where it clogs up the works), so producing it at a controllable stage of the process makes sense. Then you can more easily use the remaining sludges as a fuel feedstock.

    One other thing to note is that primary sludges (the raw excrement) are easier to dry out and much higher in energy content than secondary sludges (the excess bacteria that have consumed the wastes in the water and thus used some of the energy for their own life functions). And it takes a lot of energy to grow those bugs by adding oxygen, too. So if we can tweak the system to produce more primary sludges and fewer secondary sludges (or even get to a point where there is NO secondary sludge), we can really start to tip the energy balance in our favor.

  22. The problem you run in to when gasifying any kind of municipal waste is scale.

    Unless you are willing to employ children to do the maintenance on your gasifier, you need units with a diameter at least 6′ or so in diameter. Remember your gasifier is lined with refractory that fits together like a 3D jigsaw puzzle with no morter holding it together. Gasifiers operate at well above the melting point of steel.

    That takes a whole lot of sludge to run. Bigger is better, more cost effective, and cheaper on a per unit basis. But with NYMEX gas today at $3.83 / million BTU, your sludge gasifier would be big money loser – wouldn’t really matter about the size.

  23. One way of recycling nutrients is by producing struvite, which is nitrogen, phosphorous, and ammonia.
    You mean magnesium, phosphorous, and ammonia.

    Ostara has more projects I believe. Seems like the first full scale was Edmonton, Alberta.

    Anyway, for Ostara’s process to work (well) we need to do more biological phosphorus removal. The EPA should be able to help with that…

    So if we can tweak the system to produce more primary sludges and fewer secondary sludges (or even get to a point where there is NO secondary sludge), we can really start to tip the energy balance in our favor.
    Sounds like you’re familiar with the IMANS process.

  24. King,
    You make some sobering comments. Nonetheless, with coastal cities having to pay more and more to get rid of sludge, it seems inevitable that gasification will eventually pan out. Especially if you use it to replace anaerobic digestion, which is expensive to build with an HRT of 15+ days.

    1. You mention a min. diameter of 6′. How much throughput would such a unit need? What would make the most sense to rate: wet tons/d, dry tons/d, BTU/d?
    2. You say that P and N would leave the gasifier with the gas. That implies that it can be recovered, right?
    3. Does a modular approach make sense for processing the syngas?
    4. You said: Gasifiers use lots of water. Surely a dewatered sludge cake (~20% dry solids) would have more than enough water? Too much? What would be optimum?

  25. Optimist-

    You’re right about struvite, of course–this is what happens when I get tired! And I wasn’t thinking about IMANS, although that looks like it could work. I was thinking of something more like Micro Media Filtration or maybe a fixed film mobile carrier process that produces no sludge at all.


    Good info–this is the kind of stuff I need to hear and find out more about. I guess the questions then become–would the gasification process lose *more* money than our current methods of energy purchase and sludge disposal? Remember, it only has to provide an incremental savings over a paradigm where spending $35 million a year AFTER energy recovery and sludge volume reduction through Anaerobic Digestion is considered OK. And a follow up would be at what gas price would this become cost-competitive? Since wastewater plants are going to be around for a long, long time, this might work out in their favor if (when?) we see another spike in energy prices. I’d like to see a couple of sludge gasification plants get up and running now so that we can have the technology sorted out and ready for when we eventually need it.

    Of course, it might be that the solution is to pursue more research on advanced fast-throughput anaerobic digesters like the BioTerminator (PDF link). That system only seems to work on primary sludges, but if we switch to a system that produces little or no secondary sludge, that’s OK.

  26. For a single 6′ gasifier you need 500-1000 tons per day of feed at 7,000 BTU/lb. I don’t know how much sludge the typical wastewater system might generate.

    That’s why I think co-firing with a conventional coal or biomass reactor would work better.

    I can’t answer the wetness question because it is one of those – it depends – answers. We add just enough water to the ground up coal to make it a slurry, about the consistency of pudding. Ideally you would dry fire the gasifier and just inject steam. The problem with liquid water is that you lose the heat of vaporization and any sensible heat getting the water to the 2500 F or so reaction temperature. There is more than enough waste heat rejected from the syngas and further downstream reactions.

    The question on nitrogen, sodium, phosphorous, chlorine, and other stuff that leaves with the syngas also depends on what you are making from the syngas.

    I think it could work, it won’t be a panacea though. You need to find the right place. Gov’t credits would help.

    South of Philadelphia there are a couple of goal fired power plants – convert one to a gasifier and then deliver sludge by barge from all the treatment plants on the Delaware. Co-fire coal with biosludge.

    But I doubt Philadelphia has much of a disposal problem – being so close to New Jersey. (That is a joke.)

  27. In the last post I meant to say that we use the downstream heat recovery to generate steam. It is better to dry fire the gasifier and then use steam to provide the hydrogen for making syngas than to inject liquid water. Liquid water reduces the overall heat recovery making the process less efficient. Injecting too much water turns a gasifier into an extremely expensive waste heat boiler.

    I have been playing around with the idea of a biomass gasifier thought experiment, similar to what RR did last year on PV Solar. Perhaps we could do a biosludge thought experiment too.

  28. For a single 6′ gasifier you need 500-1000 tons per day of feed at 7,000 BTU/lb.
    Depending how you operate the aeration basin, that would be roughly 500 – 1,000 million gallons a day (MGD). That’s a big plant, there are probably only a handful of those in the US. Of course, pooling the sludge from all of a large city’s plants would make a gasifier feasible for (most) NFL cities.

    Metcalf and Eddy (an industry handbook) lists the energy content of wastewater sludges as follows:
    Primary, undigested: 10 – 12,500 BTU/lb; Typical: 11,000
    Primary, digested: 4 – 6,000 BTU/lb; Typical: 5,000
    WAS (secondary, presumably undigested): 8 – 10,000 BTU/lb

    So, as Jason pointed out, primary sludge (esp. undisgested) would work a lot better than secondary. Now if someone would just launch an anti-secondary treatment jihad at USEPA…

    King, other than BTU content, quantity of sludge and %water, what information do you need for the thought experiment?

  29. Jason if you are trying to convince me that using sludge for energy is a good environmental or energy choice; then you are barking up the wrong tree. I will be glad to read any research that suggest differently.

    “What would you consider good quality fuel from a Btu perspective?”

    How about U-235 is very good. For the east coast, high BTU coal is plentiful. Large power plant produce $300 million a year in electricity.

  30. I think I have enough info.

    You can make small gasifiers, even the size of a barbeque grill. I’ve seen 1 MW size units. That isn’t the issue. It is just a lot cheaper to dispose of the sludge other ways and then make power from something else. If ti was that easy somebody would be doing it by now.

    I could easily generate power using PV solar or install a ground effect HVAC. But neither of those investments would pay me a very good rate of return. I’m better off buying my electric power for 11 cts/kWh and using my money on something else.

    Sludge to power probably falls into that category, even if you could use cheap tax-free municipal bonds to do it.

  31. I’ve enjoyed following this civil exchange on WWTP and gasification. I don’t really want to interrupt it with an off-topic question, but I will anyhow.

    Benny, what is “batogr”? Is that “battery-to-grid”, a bit like V2G? That would be interesting. I suspect utilities will find it cheaper to build a new natural gas peaker plant than to buy a lot of batteries. But maybe that will change as natural gas prices rise and battery prices drop.

  32. King and Optimist-

    Thanks for your help here, I’ve learned a lot. FYI, I’m trying to work with a program we have to verify technologies to answer some of the lingering questions, including whether the technology will be financially viable in some configuration. Fortunately, I’ve found that we have a contractor with considerable gasification experience. My feeling is that we need this kind of technology assessment because so many gasification vendors are trying to sell their products as solutions to sludge disposal and MSW waste disposal problems. Having an independent 3rd party analysis could go a long way towards settling the differing viewpoints we’re seeing in this comment thread.

    Keep in mind that under the current paradigm, “financially viable” simply means COSTING LESS than our current methods, not turning a profit. Eventually, of course, I’d like to see wastewater plants be profit centers, providing enough energy to run their operations and selling excess; selling nutrients, and selling tertiary quality water for non-potable reuse. We’re a long way away, but we’ll never get there if we don’t take the first steps.

    I don’t think anything is off the table–if it makes more sense to cofire dried sludges with other feedstocks, I think that could work very well, especially in areas where the gasifier could be built close enough to the treatment plant to use waste heat for the sludge drying process. We might also find a way to radically improve the anaerobic digestion process, too, getting much better sludge destruction and much more biogas out of the digesters at faster retention time.

    Optimist, thanks for the numbers on energy content. I’d seen them before but couldn’t find them again when I needed them. I should really get a copy of that book. I’m always trying to get treatment plant operators to maximize their production of primary sludge. Not only do they have a better energy source that dewaters more easily, but the more solids they remove up front, the less air they have to strafe into the system to remove the remainder biologically. I have seen a system that claims to produce only primary sludge and I’m hoping we can get enough reference installations to really put it through its paces.

    As for specifics–we produce somewhere on the order of 7.2 million dry tons a year of biosolids nationally, although it’s very difficult to know exactly how much energy that represents because there are so many different ways of handling this stuff and it’s not reported consistently between states. But still, it’s not inconceivable that a 100-ton per day unit like Plasco could work for a medium sized metro area that collected sludge from several plants. A 1000-tpd unit fired solely on sludges would probably be impractical in most places, but might be viable in the largest cities, especially areas like NYC and Boston which are currently pelletizing sludges with fossil fuels and sending those pellets thousands of miles by rail to get rid of them.

    Finally, to Kit: biosolids are already a proven energy resource at hundreds of treatment plants across the country via anaerobic digestion. The question throughout this thread has always been whether gasification might be a more cost-effective way to get the energy out while also solving the disposal problem that is a very real (and costly) issue for many facilities. And with the info I’ve gotten from King and Optimist and RR, along with other research, I’m still inclined to say it’s worth pursuing in certain areas. Will it work everywhere? Obviously not, but there’s no one-size-fits-all solution for any of our energy problems.

    King, this gets back to your comment that “It is just a lot cheaper to dispose of the sludge other ways and then make power from something else. If ti was that easy somebody would be doing it by now.” That may have been true in the past, but in large parts of the country the economics have changed significantly–it’s now shockingly expensive to get rid of sludge in many parts of the northeast. And those areas happen to be the same areas that have much higher prices than they did a couple of years ago. And as a result, there is now one small sludge gasifier in Sanford, FL and another larger unit seeking financing in Stamford, CT. And not for nothing, almost all of our public works projects, especially in water and wastewater, are somehow publicly subsidized, so no reason gasifiers can’t be as well if they work as promised and deliver environmental and financial benefits over the long term.

  33. Thanks Jason,
    I had forgotten about the Stamford project, I have heard about it.

    I suspect you’ll find it an interesting read. Some excerps: The team is completing its assessment and beginning the design of a 15-MW power plant — the first in the country to turn human biomass pellets into energy. The power plant will supply enough electricity to operate Stamford’s wastewater treatment plant — approximately 1 MW — and sell the rest. The plant appears to generate 15 x as much power as the wastewater treatment plant needs! A power plant indeed.

    Fournier noted that waste gasification is not the most efficient way to make energy, but, he added, “it’s revolutionary in the management of our oldest waste.” With gasification, biosolids mass is reduced 95%, he explained. “Waste management is moved from cost to income.”

    The greatest savings may be that energy-intensive anaerobic digestion, which reduces the volatile content of waste activated sludge, can be eliminated from the wastewater process, Brown said. While any biomass containing carbon can be used for gasification, high volatile content is needed to generate the highest Btu product. I think this proves you were right, King. Not so much viable energy, as viable waste disposal, with energy as a valuable byproduct.

    The process also uses “virtually zero energy” to reach the high temperatures, all that is required is a 1.5-hp blower, Fournier said. “No external heat sources is required, and the working temperature of 900 degrees Celsius is easily achieved with a small blower or vacuum.” The blower pulls air through the system during gasification so that the reactor reaches the desired temperature. “And that’s the amazing part,” he added. Does that make sense to you, King?

    “Our goal is to use everything beneficially,” Brown said, explaining that her team looks at the wastewater process holistically, and adding gasification reduces the city’s carbon footprint. I know you care about the carbon footprint, King…

    Brown is hopeful that grant money will be available to help finance construction of the 15-MW plant — a $60 million project — so the city can sell its energy at a low cost. Does that sound reasonable? I know $60 million won’t buy you much WWTP capacity these days.

    Of course, high electricity prices help: Stamford sits in an electrical congestion zone, where power costs are high.

  34. King,
    I think I agree that co-firing sludge and a dry MSW (waste paper would work well) would probably make the most sense.

    If you’re looking for info on MSW, this should be helpful. Such as 37.8 million tons (per year) of paper and paperboard that would be available (after recycling) for gasification.

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