The integrated forest products biorefinery by Gerrard Closset ... - Pyne

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In order to provide focus and to take advantage of the unique ability of trees for carbon fixation throughphotosynthesis, only the production of transportation fuels and chemicals is examined here. Theproduction of electric power has been reported in detail by Larson et al (1) .III. The Value PropositionThe overall financial objective is to more than double the return on manufacturing assets. Thetransition to forest biorefineries is enabled by economic returns from on-going pulp and paper production,but also requires sustained and substantial efforts by public-private partnerships to address criticaltechnology and policy issues.It will be important to carry out a thorough evaluation of the potential economic benefits the forestbiorefinery would bring to an existing chemical pulp mill. A rigorous study of the potential of biomassgasification power generation in the pulp and paper industry was recently completed by Larson et al (1) .An equally detailed study for the production of fuels and chemicals is being carried out by the samegroup, for completion in January of 2006. In its absence at this time, simplified economic evaluationshave been carried out by Ben Thorp with assistance from industry academic experts (2) (3) (4) and aresummarized in the Table below. The “model mill” used in the Larson report was used here. (The inputwas 2089 tpd bone dry hardwood, 1122 tpd bone dry softwood, 318 tpd bark which produced 1580 BDtpd unbleached pulp. If this were a freesheet mill, one would reduce solids by ~9%, add ~13% forfiller/size and add ~6% moisture to get a 1722 tpd mill).Results are summarized in Table 2 and provide an illustration of the potential of the forest biorefinery. Forexample, installing processes A and C in an existing Kraft pulp mill would add totally new product lines tothe traditional pulp and paper products. Case B is extracted from the Larson study and, therefore, carriesa high degree of accuracy. Cases A and C are more preliminary and should be viewed as such.Table 2: Economic Impact of IFB OptionsCaseABConditionsEthanol Production Prior toPulpingBLG syngas to Power;Incremental Capital*IncrementalCapital,$MMNetRevenuePer year$MMSimple PayBack,Years33 33 170 38 1.9CBLG Syngas to RenewableTransportation Fuels;Incremental Capital*– 5 –83 55 1.5(*) Incremental capital indicates the recovery boiler is at the end of its useful life, replacement isrequired and there is little added return for replacementThe value propositions for each area of the biorefinery technology platforms are discussed in more detailbelow. Further details regarding the calculations used can be found in the attached Appendix.Sustainable Forest Productivity – Annual harvest from private forests in the U.S. is around 250 milliondry tons of wood and bark. About 40 percent of this material is used for energy. Estimated 1990 energyyield from wood residues in the forest products industry alone was equivalent to 300 million barrels of oilworth $8.8 billion. Applying biorefinery technology to creating new value streams will more than doublethis value by 2030 through systematic improvements in forest productivity and biomass conversiontechnologies.As another example, lets consider the total industrial loblolly pine land base in the South. It is about 40million acres, which has a conservative annual NPV of $200 per acre. It is also very conservative to saythat clonal forestry will add 20% value to each acre planted; and the value attributed to the industry forclonal forestry would be equal to the following calculation: 40,000,000 (total acres) * $200 (NPV per
acre) * .20 (value added) * = $1.6 billion. This amount accounts only for the value added to the industrialland base and does not take into account any energy savings associated with clonal forestry.Extracting Value Prior to Pulping – Ethanol and Acetic Acid production from wood chips in a Kraft millThis example consists of extracting the hemicelluloses from wood chips before the pulp digester and theirconversion to ethanol and acetic acid. Specifically, Case 1 consists of installing hot water extractionvessels (low pressure digesters), extracting the soluble hemicelluloses, separating the acetic acid andfermenting the sugar to fuel grade ethanol, all using known processes. The impact of removing the"sugars" on the downstream process is not totally clear and needs further investigation. In this case, noimpact is considered. Higher value-added products may be attained by additional fermentation and otherconversion steps to manufacture products such as polymers and chemicals.Using the Larson (1) reference Mill (produces 1580 tpd BD unbleached pulp; raw material consumed:2089 tpd BD hardwood, 1122 tpd BD softwood and 318 tpd bark), the following stream of new products iscreated:• 19 million gallons ethanol• 6 million gallons acetic acidA preliminary estimate indicates that the required capital (vessels, distillers, membranes & controls), is ofthe order of $33 million, with an operating cost of approximately 35 cents/gallon. An initial, simplifiedestimate shows a yearly net revenue increase of $33 MM, yielding a one-year simple payback. This is anexcellent return, increasing the mill revenue by 60%. Granting that the calculations are simplified, theyshow enough promise to warrant the development of more in-depth conceptual estimates in the very nearfuture.New Value from Residuals and Spent Pulping Liquors - renewable transportation fuelsThis example considers the production of renewable Fischer-Tropsch transportation fuels from spentpulping liquor residuals. Of several possible alternatives, the Fischer Tropsch process is selected as acase study to illustrate overall economics (2) (5) . This would be a totally new product line to the forest andpaper industry. The innovation is derived from the fact that low-value renewable energy (spent pulpingliquor residuals) is indirectly converted to high-value fuels through BLG.Specifically (5) , this case consists of: install a black liquor gasifier to the Larson reference mill, add aFischer-Tropsch unit and convert all the BLG syngas to renewable transportation fuels for sale to thepetrochemical industry. Convert the old chemical recovery unit to a biomass boiler, procure additionalbiomass to run the mill and install a condensing turbine to convert excess steam into the same powergenerated in the Larson case. This is a very crude way to configure a mill. However, data are available toestimate this configuration. Higher values can be obtained by configuring a mill with a propersteam/electrical balance and by adding distillation columns to produce finished transportation fuelsinstead of mixed fuels that require further separation by the petrochemical company. The renewableFischer Tropsch fuel is worth much more than its Btu value due to the flexibility the multi molecular weightproduct provides to refineries. A figure of $62 per 42 gallon barrel (bbl) has been used in other studiesand will be used here pending further studies.Using the Larson reference mill, approximately 1,090,000 million barrels of renewable Fischer-Tropsch fuel is produced, for an incremental capital cost expenditure of $83 million and additionaloperating costs of $19 MM. An annual net revenue increase of $55 million is produced for the mill,yielding a simple payback of 1.5 years. This is an excellent payback that warrants consideration ofimplementation in a mill with a recovery boiler nearing the end of its useful life.This example is predicated on the replacement of conventional kraft recovery by high pressuregasification of kraft black liquor. For mills facing Tomlinson recovery boilers replacement,implementing black liquor gasification (BLG) is an option that affords flexibility to export power inareas where power value is high ($50+/MWhr) or produce liquid fuels or chemicals when/wherethose product values are high. Furthermore, the opportunity exists to gain global advantage overnew mills built with Tomlinsons and mills with recent Tomlinson replacements (30+ yearadvantage).– 6 –
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