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By Robert Rapier on Apr 5, 2012 with 16 responses

Poet, KiOR, and Waste-to-Heat — R-Squared Energy TV Ep. 17

In this week’s episode of R-Squared Energy TV, I answer questions about POET’s Project Liberty, about why KiOR might need a natural gas pipeline, and whether there are better options out there for utilization of waste heat from electrical generating plants.

Some of the topics discussed this week are:

  • POET’s prospects for success with their cellulosic ethanol venture
  • The synergy of co-locating a cellulosic ethanol plant next to a corn ethanol plant
  • Why a renewable energy company might require natural gas
  • Options for utilizing energy from waste hot water

The Project Liberty site that I referenced in the video is here.

Readers who have specific questions can send them to ask [at] consumerenergyreport [dot] com or leave the question after this post (at the original source). Consider subscribing to our YouTube channel where you’ll be able to view past and future videos.

Link to Original Article: Poet, KiOR, and Waste-to-Heat — R-Squared Energy TV Ep. 17

By Robert Rapier

  1. By Rick on April 5, 2012 at 5:36 am

    A couple of adds:

    KIOR may be using NatGas as a source of hydrogen to make a hydrocarbon fuel from biomass, which is typically short of hydrogen. The alternative is to use biomass to make the hydrogen, but that uses up a lot of the feedstock and dings output.

    The heat that comes out of a power plant is generally at very low temperature, perhaps 50C, 122F, hence not very useful for anything other than space heating – power plant designers do their best, subject to the laws of thermodynamics, to wring the last drop of electrcity from the heat flow. River/sea water cooled power plants usually have an upper limit on output temperature to protect the enviroment; during the big European heat wave a few years back, French nuclear plants were constrained off becuase they could not dump their waste heat without violating the temperature limit.


    • By Robert Rapier on April 5, 2012 at 12:32 pm

      KIOR may be using NatGas as a source of hydrogen to make a hydrocarbon fuel from biomass, which is typically short of hydrogen.

      I almost mentioned that, but my understanding is that they are shipping their oil off to a refinery for finishing. Nevertheless, they claim that their oil is partially upgraded from conventional pyrolysis oil, in which case it would presumably require some hydrogen during processing.


  2. By Karl O on April 5, 2012 at 1:03 pm


    Congrats on publishing your first book. I plan to pick up a copy.

    My question is about the waste heat from power plants. I’ve always been mystified why it isn’t used more often. Would it be possible to operate an ethanol plant using the waste heat from a coal fired power plant? There are lots of coal plants here in corn country so I would think it would be ideal to use that heat energy for fermentation and distillation.


    • By Robert Rapier on April 5, 2012 at 3:00 pm

      I’ve always been mystified why it isn’t used more often. Would it be possible to operate an ethanol plant using the waste heat from a coal fired power plant?

      The biggest problem is that the ethanol plants — and chemical plants and refineries in general — require high pressure steam. The waste heat from the power plants is either very low pressure steam or is just hot water. There is some energy that could be captured by using the hot water as boiler feed water, but the ethanol plant would need to be next door to the power plant — and the savings would not be huge unless they can actually get steam from the power plant (which the power plant needs to produce power).


      • By Karl O on April 7, 2012 at 12:19 pm

        My (admittedly limited) understanding of the ethanol process is that the temperatures required are below the boiling point of water. Would it be possible to use, or redesign the process to use, hot water instead of steam? Lets assume that the ethanol plant is sited properly and corn supply is no problem. Energy efficiency is much less of an issue since waste heat is being used so the cost is much lower – costs are primarily equipment maintenance and pumping energy to move the hot water. At what temperature is the waste heat coming out of the steam condenser of a typical coal fired power plant?

        The reason for these questions is that I just read a report on ethanol from one of the national laboratories that examined the energy return on energy invested using alternative heat sources instead of natural gas. Using waste heat was not investigated. I suppose this would be another form of cogeneration if it worked. My thought is that it would be less expensive than biomass or solar to improve the energy balance of ethanol.


  3. By Ed Reid on April 6, 2012 at 9:13 am


    Please note that combined-cycle power plants are significantly more efficient than typical Rankine cycle power plants. In the case of natural gas CCT plants, the efficiency is ~55-60% (HHV). In the case of IGCC coal plants, the efficiency is ~40-45%.

    Many cities have, of had, district heating and cooling systems, which utilized the thermal energy rejected by power plants located in the downtown area of the city to provide either hot water or chilled water seasonally.

    There is also renewed interest in on-site co-generation systems in industrial, institutional and commercial facilities. These systems can achieve efficiencies of up to ~80% with proper integration into the facilities energy systems. The uses of the thermal energy rejected by the generator include process water heating, space heating, space cooling and dehumidification, included process drying. 

  4. By Tim C. on April 6, 2012 at 11:15 am

    Thanks for your insights on KiOR, RR. 

    KiOR’s use of natural gas may or may not be an issue, depending on how much they use.  If their process will consume more than 0.5 MMBTU of NG for every MMBTU of product, then I have to question whether their product is really renewable.  Note that the product basis for this calculation should be the fuel coming out of the refinery, not the oil coming out of the KiOR plant. 

    I wonder why KiOR doesn’t address these sorts of questions on their website?  I’m sure they must have done a LCA on their process.  Why don’t they say that their process makes lots of fuel with minimal fossil inputs, if that’s the case? 

  5. By ben on April 7, 2012 at 9:24 am

    Ed Reid’s comments on the efficacy of combined-cycle for industrial/institutional CHP applications are right on money. .  The specter of lower long-term Ng prices, more efficient conversion technologies and a greater emphasis on waste streams has contributed to marked increases in planning for combined cycle applications.   It will be interesting to see to what extent distributive networks become a part of mixed-use PUD projects as the economy recovers and much greater consideration directed toward to the combination of energy costs and carbon footprint in jursidictions aiming to be part of the systemic transition to communities of progress/independence.   Thanks for the emphasis.





  6. By Tom G. on April 8, 2012 at 1:32 am

    I am sure almost everyone on this site has heard the old saying – the cheapest energy is the energy we don’t have to create.  Or how about this one –  Prior, Planning, Prevents, Poor Performance [the 5 P's], and the last; the environmentalist who said – we should first pick the low hanging fruit which I believe means we should work first on those systems with the biggest possible return for the least amount of effort.     

    On any given day in the U.S. we have about 100 nuclear power plants and maybe about another 500 or so coal and natural gas plants online and most of these power plants waste about 70% of all of the heat energy we put into them.  Even our latest Combined Cycle Turbine [CCT] natural gas plants are only about 45-60% efficient.  And forget our next generation III+ nuclear plants; they are lucky to muster up about 35% efficiency. 

    So how do we justify this terrible waste in our minds?  Do we justify this waste by saying; well when we built the nuclear plants back in the 80′s we thought nuclear power would be too cheap to meter.  Well how about now – checked your electric bill lately.  How about the price of coal – looked at the cost of a ton of coal lately?  Even our current glut of natural gas is not going to last forever and its price will go up gradually over time until it becomes expensive.  From what I read, if the trucking industry starts using natural gas on a large scale some people have projected that we could even burn up most of our excess natural gas in as little as 30-40  years.      

    I have worked at or visited virtually every type of power plant over my last 20+ years of work in the public utility sector of our economy.  What we have been doing is going to the grocery store, buying $100 dollars worth of food, going home and promptly throwing $70 of that food in the trash.  That is basically what we are doing with our power plants.  A terrible waste of heat energy.  If there was ever a time for our country to be using some Prior Planning to Prevent Poor Performance it might be now.  

    Just think about it for a minute – if we could find some way to use just 1000 of the 2000 Mwt of the waste heat from each nuclear reactor in America it would be like building 100 new nuclear power plants.  If each new nuclear power plant costs $10 billion to build and we didn’t need to build them; just how much money could we save [100 X $10 billion].  Now lets add in another 500+ coal plants and some gas peaking units and you get some idea just how much potential money there is in waste heat.  So, if you have some idea[s] on how to use the low temperature waste heat from our power plants you might just become very wealthy very quickly.  

    The only individual I know of who has surfaced with a reasonable plan is Robert McGinnis,PhD. who is the chief technical officer of Oasys.  His new and fresh idea is to use a new membrane material which can desalinate and/or purify contaminated water using the low temperature waste heat from a power plant.  Here is a recent presentation he made on the subject www[DOT]youtube[DOT]com/watch?v=R63zYZZuRvQ]. Replace the [DOT] with a period .  

    Please let me know what you think of the presentation.


    • By Ed Reid on April 10, 2012 at 9:14 am

      When you take into account the energy remaining in the “spent” nuclear fuel, the overall process efficiency is greatly reduced. Failure to reprocess and reuse ”spent” fuel is the largest efficiency loss in nuclear power generation.

      Desalination as a bottoming cycle for nuclear power plants will have to wait until our demands for fresh water exceed the available supply sufficiently to increase the price of water above the cost of desalination.  

  7. By mac on April 9, 2012 at 6:04 pm

    Use the waste heat….

    We all agree on this ..

    Now what ?

    • By Tom G. on April 9, 2012 at 7:27 pm

      I was hoping to generate some discussion but that never happened since it was posted too late in the week.  

      So you asked; Now what? – just ignore the posting I guess.  Unless there is some action you would recommend?


      • By mac on April 9, 2012 at 8:49 pm



        I just suggested that heat transfer through binary fluids might be something to look into.  It’s certainly not the only way excess heat can be profitably used (recycled) ? and the heat energy put to use.

      • By Robert Rapier on April 9, 2012 at 10:17 pm

        I was hoping to generate some discussion but that never happened since it was posted too late in the week.  

        Tom, just FYI, based on my StatCounter a comment can be read hundreds of times for every time someone responds. So don’t be disheartened that there was not a lot of discussion. Happens on my comments a lot, and even on my articles.

        In fact, the funny thing is that I can spend 5 hours writing something only to have it get 4 comments, and then something I put together in 20 minutes gets 200 comments. 

        Regarding your post, I think the biggest challenge is that most of this hot water is a long distance from a user. We put our nuclear and coal plants in the middle of nowhere. Plus, coal is still cheap so there isn’t a premium on efficiency. Yet. But I always imagined that the low grade heat could possible be used to evaporate a refrigerant, which could be used to produce electricity itself.


        • By Ed Reid on April 10, 2012 at 9:33 am

          Robert, you are correct that a refrigerant-based bottoming cycle could be used to convert the residual energy in the discharge steam from a back-pressure steam turbine to electricity. In fact, the discharged steam is the vapor state of the world’s best refrigerant – water. NG CCT plants use HRSGs and condensing steam turbines in their bottoming cycles to achieve their higher efficiencies.

          However, in a coal or nuclear power plant, any heat removed from the turbine discharge steam, beyond that necessary to condense the steam before it is returned to the boiler as feed water, reduces the overall efficiency of the steam cycle.

          There is no such thing as a “free lunch”; and, the better lunch is, the more it costs. (First and Second Laws of Thermodynamics restated.)

  8. By Tom G. on April 10, 2012 at 11:19 am

    Lots of good comments here but it is time to move on to the next story.  

    However before I leave, I encourage anyone interested in energy efficiency and water resources to go view at least part of the recommended video.  Desalination and purification of water without a phase change is quite an accomplishment.    

    www[DOT]youtube[DOT]com/watch?v=R63zYZZuRvQ].   Replace the [DOT] with a period . 


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