Scale-Up of Emerging Biofuel Technologies

April 11, 2016 |

By Lorenz Bauer, PhD and William Quapp, MSME, special to The Digest


Bill Quapp

Bill Quapp

Lorenz Bauer

Lorenz Bauer

The continued interest in advanced biofuels has produced numerous exciting technical advances on the laboratory, pilot and demonstration scales. However, attempts to translate these small scale successes into commercial technologies have been less successful.   It is easy to blame lower oil and natural gas prices and opposition from special interest groups. However, nearly all commercialization projects have yet to produce significant quantities of biofuel on a continuing basis.   All parties involved in these efforts would benefit from considering the reasons for these difficulties and the possible methods of mitigating them.

First, as a caveat, the authors have worked with many well known companies under proprietary relationships. As such, the information contained represents an overview of their experience. Attribution of their experience to specific projects or companies is prohibited by their prior confidentiality agreements.

This blog discusses some of the key reasons why new technologies fail technically or economically. The difficulty in scale-up generally involves one or more of the following topics:

  1. Design methods for biofuel projects
  2. Environmental permitting and community acceptance
  3. Surprises associated with chemical processes at larger scale,
  4. Feedstock material handling difficulties,
  5. Seasonal limitations for feedstock
  6. Operational difficulties including process control,
  7. Product qualification testing
  8. Grossly underestimated costs of large plants,
  9. Overly ambitious schedules,
  10. Plant capacity limitations
  11. Product quality and logistical issues

Each of these topics is discussed in more detail in the next section.

These pitfalls are common to new chemical process scale-ups.   The potential positive environmental impacts and financial returns for these new technologies are huge.   The key is to take a measured approach guided by experience to protect the large investments of time and money that implementation requires.

Potential Project Issues for New Technologies

A.    Design methods for biofuel projects

One prescription that almost insures failure is relying too heavily on engineering calculations based on extrapolations from simpler systems or fossil fuel processes. Existing process modeling software often does not include data relevant to biomass derived materials.   Detailed characterization of thermodynamic, rheological and other physical properties of feed stock, products and often poorly characterized intermediate streams does not always exist. The composition of the various process streams needs to be established, including ppm level impurities.

Current models for petroleum based feeds are based on over a century of empirical data which has been used to validate the assumptions used to develop pseudo components used in kinetic and heat transfer calculations.   Designs of separation units are particularly difficult since azeotrope formation is very common due to the non-ideal interactions of the bio derived products.

B.    Site selection, environmental permitting and community acceptance

These three topics are intrinsically related. This is an area where each state is different and the differences are very important. Different regions within the same state may also have critically different regulatory processes. It is critically important to have early meetings with local officials, local regulators, and other community groups to asses the acceptance before large financial commitments are made. A more demanding regulatory environment can be a better regulatory environment providing that the regulatory staff are technically competent and that the applicant has its facts developed and supporting data available.

As an example, a project for a renewable energy generation project in California garnered the attention of an environmental group that opposed the issuance of an air permit after it had been issued. The entire permitting process involved several types of permits with the air permit being the final one before construction began. In appealing the air permit, the opposition was allowed to claim that the data and permit technical work was in error and did not have to establish their basis for those claims. The opposition preyed on public’s emotions and had no qualms about using distortions. The review board established under California regulations consisted five members of the community including one attorney, one physician, one engineer, and two members of the public at-large. In this case, the members consisted of a pediatrician, a retired mosquito district manager, a civil engineer, and one other member of the public. The original attorney recused himself after the first hearing due to a conflict of interest. While all were respectable professionals in their own field, they knew essentially nothing about the complex technology of air pollution control issues under review. They had no technical ability to challenger either side of the debate.

After a protracted 6 months of hearings (2 to 3 days per month), the air permit was rescinded by the review board. The rescinding decision was challenged in court. After about another 6 months and a million dollars in legal and other costs, the air permit was reinstated by the court. But the extensive regulatory delays were effective in killing the project in that location.

Similar projects were expediently permitted in both Texas and Nevada where the regulatory process required that any objectors demonstrate solid technical bases for their objections. These objections would then be reviewed by professionals in the field — not laymen without appropriate training.

This area can be particularly problematic for developers that desire to be located near their feedstock supplies in small rural communities. Small communities often have less experienced regulatory staff and their skill in communicating to the public can be limited to more traditional industries. Furthermore, small community members often want to their community to stay small. They want zero emissions even if estimated emissions are within state regulatory guidelines. Often, they are not swayed by the promise of jobs as they do not necessarily believe the job promises will benefit them.

Books have been written on these topics. No one location is like another when it comes to regulatory permitting and public acceptance. Using experienced project development professionals will reduce project risk. The experience they have gained or the mistakes they have witnessed will help others avoid the same pitfalls.

C.    Surprises associated with chemical processes at larger scale

The smaller the development scale of a new process before getting to commercial scale, the higher the risk. Some of the process kinetics may be misunderstood, inadequately modeled or measured in small lab and pilot scale. Second order effects may be small and un-noticed at small scale but be significant or devastating at large scale. Mixing of process ingredients at small scale may be very efficient but not so at larger scale. Catalytic processes may work at small scale but have heat removal issues at large scale. If heat removal is not well controlled adequately, catalyst bed damage may occur and result in higher operating costs.

Overly optimistic interpretation of performance based on the “best” experimental results is a common fault of human nature.   A rigorous statistical approach to data collection and analysis with tight quality control is needed to eliminate bias. The scientific method needs to be applied. Results are only valid if they can be repeated.   Often external review of the methods and calculations may reveal assumptions that could lead to inflated predictions and disappointments.

There are cases of half billion-dollar petrochemical processes being shut down and require significant retrofits due to a coproduced impurity that was present below analytical detection level in the product stream from small scale demonstrations.

D.    Feedstock material handling difficulties

Generally, traditional chemical manufacturing starts with commercially available feedstock materials with known and controlled characteristics. The chemical manufacturing process then can be designed around those known physical and chemical characteristics. In contrast, many of the biofuel technologies start with some type of biowaste as the feedstock. This type of feedstock may vary physically, by the season, local sources, chemical composition, etc. Moving and storing solid feedstocks is the most problematic but liquids can present problems as well. If a feedstock has compositional variability (municipal solid waste), the feed rate for a process may require near real time chemical analysis in order to adjust the feedrate as needed. This is often difficult for biomass products which can vary widely in moisture and physical properties.

E.    Seasonal limitations for feedstock availability

A somewhat obvious requirement is the year round availability of feedstock. Plants must operate year round for efficient capital utilization. However, crop residues are seasonal and available only a few months of the year in close proximity to their consumption. Transportation over longer distances might make feedstock available but cut severely into the profitability. On site storage of a seasonal feedstock for 6 to 8 months or more adds to the capital costs. Preserving the feedstock during storage may also add new technical difficulties. Forest residues used for feedstock may also have seasonal availability in parts of the country due to severe winters.

Feedstock moisture may vary throughout the year and might be an economic problem with some technologies if the feedstock moisture is too high. Drying is an expensive process.

F.     Operational difficulties including process control

There are often operational problems which are not found in short term pilot testing. These include the more typical scale up concerns of mixing and heat transfer. However, others are less expected, like the build-up of deposits on distillation packing. These deposits can plug heat exchangers, foul columns, and reduce the effectiveness of heaters. The process performance can decrease with time due to catalyst deactivation which changes the reactor heat profile. It is difficult to predict long term catalyst stability. This leads to much shorter than expected run lengths.   These frequent turn arounds (outages) can significantly affect the through-put of the process and thus the economics.

Plants are often designed without these issues in mind.   A plant using a new technology may require additional clean out points, manways, sample points and storage for off spec product that are not included in the design.

Using feedstock with widely varying composition may require real time analytical methods for process control. On line analytical methods used for petroleum will need to updated and modified. In many cases new methodology will need to be developed.

G.    Product qualification testing

New processes for transportation fuel production have taken many years to be commercialized. Sometime new fuels need to be demonstrated to satisfy regulatory authorities or potential customers. Bio based jet fuel is one example. When this occurs, it may be difficult to generate enough fuel at small scale to satisfy the demonstration requirements. Yet investment capital may not be available to build larger scale plants to generate larger demonstration quantities “hoping for approval” or market acceptance. Likewise, analogies with existing products may not be sufficient to satisfy environmental regulations without further work.   There was one case in which the goal was to produce a drop-in fuel. By using normal analytical methods, the product contained only the molecules found in current fuels. However, the regulatory agency required development of which new more sensitive analytical methods for measuring specific off gas components in the parts per billion range which were needed for current products containing the same components.

H.    Grossly underestimated costs of large plants

Technology developers are often the poorest ones to develop good project cost estimates. Their optimism leads to an overly simple flowsheet and poor project costs. Costs to develop good engineering cost estimates by credible engineering and construction firms is often unaffordable in early project stages. Furthermore, these estimates can also be compromised by incomplete development data. At the development scale, developers focus on the technology and often neglect some of the institutional costs of a full scale installation. Examples of such costs include feed materials acquisition (waste is often thought to be free), feed material handling and storage, storage tanks for on-spec product and off-spec product, loading facilities, on-site electrical substations, reagent gas supply and storage, etc.  Even the professional engineering firm’s estimates can be misleading. The assumption that existing equipment and technology will work without modification often proves to be wrong.

Some sites have the needed utilities such as electrical power and natural gas. For other sites, bringing in these energy sources could add tens of millions of dollars to a plant’s cost if long distances are involved. Similarly, if gaseous reagents such as oxygen or hydrogen are needed for the project, these reagents may not be locally available. These gases are supplied by pipeline in the US Gulf Coast at reasonable costs but in the northern US, they must usually be trucked in at very high costs or on-site plants must be built adding to the overall capital.

I.      Overly ambitious schedules

Entrepreneur or project developer often set unrealistic expectations especially to their funding sources.   They are anxious to prove the profitability of their ideas. But it is a mistake to set these unrealistic expectations.   Failure to meet the stated milestones for production will make future investment difficult and possibly kill otherwise promising technologies.   Permitting activities are highly uncertain as discussed previously. Equipment availability and suitability must be carefully determined and extra time for unforeseen delays must be included.   Delays are also costly as staff must be supported when a project falls 3 to 6 months behind. Gas compressors are an example of equipment that can take in excess of a year to obtain. Thus, neglecting to get good bids and delivery schedules for key equipment can lead to project failure.

J.    Plant capacity limitations

The spread between the observed plant output and theoretical yields is assumed to be comparable to that of existing fuel and chemical processes. However, these mature technologies have benefited from generations of practical experience.   It is likely that a new process will take a significant time to achieve the expected performance.   A recent paper from Hazen Research, reported that for first of its kind technologies in the mining and chemical industries about 30% failed to reach 80% of design capacity after 3 years   The successful projects were closely aligned with existing technologies and used mature technology in applications similar to those in prior work. First of its kind technology scale ups had a much poorer record. Those that were successful were thoroughly pilot plant tested. In today’s environment tight budgets often do not allow for generous design margins and or account for the possibility of significant revamps.

K.    Product quality and logistical issues

The assumption that existing methods will work with a biomass derived material needs to be confirmed. The necessity to achieve the maximum yields from least expensive feeds typically leads to intermediates and products that are complex mixtures. The difficulty of separation products is often not appreciated. There are often issues with impurities not present in mature technology models used to predict performance. In one chemical process, the need to add an additional feed clean up step to remove ppm levels of an impurity can add very large costs to the total plant capital. Sulfur impurities are commonly a major problem for most catalysts. Yet removal to very low levels is costly.

Recycling off-spec materials can also be a problem. If a product does not meet customer’s specification, it must be either recycled or disposed. If technically feasible, recycling is preferred but it may not be possible or may require more plant unit operations and capital. If disposed, the revenue potential is lost and the disposal cost can be huge depending on its hazardous characterization under RCRA Regulations.

There can be unexpected logistical issues.   For example, are their sufficient clean trucks or rail cars available to transport product. It will likely be necessary to produce and store off spec product during commissioning.   Storage and/or disposal methods should be planned.

In Summary

Great patience and objectivity is needed to carefully plan and test all aspects of the integrated process in as realistic manner as possible.  A staged approach can be used to control investment costs with testing at the lab, pilot and demonstration scales is strongly recommended (see “Scaling Up Step by Step” by Zeton for a discussion).   A design and build philosophy which pushes starting construction of commercial scale equipment before completing a demonstration program is very risky.

Advice should be sought from a variety of sources with process scale up experience. For a small start-up company this likely requires outside partners or consultants to form technology review panels.  Fresh eyes can see problems and solutions that may escape those more closely associated with the project.   Detailed planning using an approach like Six Sigma, that includes process mapping, cause and effect analysis and sensitivity and risk analysis, can greatly improve the chances for success.

These pitfalls are common to new chemical process scale-ups. However, the potential positive environmental impacts and financial returns for these new technologies are huge.   The key is to take a measured approach guided by experience to protect the large investments of time and money that implementation requires.


Zeton Corporation Articles, Biofuels Commercialization: Scaling Up, downloaded from, 4/1/2016

Dennis Gertenbach and Brian L. Cooper, Hazen Research, Paper 509f, presented at the AIChE National Meeting, November 12, 2009, Nashville, TN, downloaded from, 4/1/2016

About the Authors

Lorenz Bauer – Lorenz has PhD from Washington University. He is a catalysis, oil refining and biomass conversion expert with over 30 years of experience with UOP and KiOR.   He is an inventor on 20 patents.   His projects have ranged from food additives, off gas treatment, upgrading unconventional feeds and waste recycling.   Most recently he worked on fast pyrolysis of biomass and upgrading products to fuels and chemicals. He is Six-sigma black belt trained in project management. He is currently an independent consultant based in Houston evaluating new technologies in biomass conversion, renewable chemicals, catalysis and material science.

William Quapp – Bill has a Masters Degree in Mechanical Engineering with extensive project experience in plasma gasification, chemical, mechanical and nuclear engineering. Most recently he has been developing and analyzing gasification projects. He also has additional experience in the conversion of biomass, municipal and other low value wastes to energy. He has prepared air permits and interfaced with the cognizant regulatory authorities. He is knowledgable of RCRA, TSCA, CERCLA and other regulatory requirements. He holds four patents in the fields of waste destruction, chemical conversion, and nuclear shielding fields. He has published over 75 reports and papers in his fields of experience.

Contact the team here.



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