Photo of David A. Sievers

David Sievers

Researcher IV-Mechanical Engineering

Orcid ID

Research Interests

  • Thermochemical pretreatment residence-time distribution measurement and control

  • Solid-liquid separation and fractionation of bioprocess slurries

  • Reactive separations: continuous enzymatic hydrolysis

  • Sugar fractionation and concentration

  • Specialized instrumentation development for real-time measurements

  • Big data analysis and communication of results through multimedia forms

Affiliated Research Programs

  • Separations Development and Application

  • Biochemical Process Integration

Areas of Expertise

David launched his career as a biopharmaceutical industry consultant and has been advancing next-generation biofuels research and development as a research engineer at NREL since 2007. His goal is to reduce the projected costs of  biofuels through the development and refinement of process technologies at the bench and pilot scales. David is an expert at scaling up and demonstrating technologies at the pilot scale, including feedstock handling, pretreatment, enzymatic hydrolysis, fermentation, solid-liquid separation, concentration, and distillation. A few of his interests are in the separation and fractionation of process intermediate streams and the scale-up of pretreatment processes. He currently leads a core research group studying reactive separations and has led several successful industrial partnerships at the pilot scale, including demonstration of a complete corn-cobs-to-ethanol process, scale-up of an n-butanol fermentation process, and demonstration of a malonic acid and fermentation and refining process. One of his favorite topics is in the design and commissioning of custom research equipment. His areas of expertise include:

  • Project management

  • Process design, equipment design, and fabrication

  • Instrumentation and controls design and programming

  • Data analysis and presentation

  • Flocculation, filtration, and membrane-based separation including reactive separations

  • Computeraided design (CAD)

  • Process hazard analysis

  • Graphic design


  • B.S., Chemical Engineering, Colorado School of Mines, 2004

Professional Experience

  • Licensed Professional Engineer since 2010

  • R&D Engineer, National Renewable Energy Laboratory, 2007–present

  • Process Engineer, ZAP Engineering, Lakewood, CO, 2006–2007

  • Pharmaceutical Engineer, JM Hyde Consulting, Boulder, CO, 20042006

Featured Publications

  1. "Effects of Dilute-Acid Pretreatment Conditions on Filtration Performance of Corn Stover Hydrolyzate,"  Bioresour. Technol. (2017)
  2. "Online residence time distribution measurement of thermochemical biomass pretreatment reactors," Chem. Eng. Sci. (2016)
  3. "A low-cost solid–liquid separation process for enzymatically hydrolyzed corn stover slurries," Bioresour. Technol. (2015)

  4. "Performance and techno-economic assessment of several solid–liquid separation technologies for processing dilute-acid pretreated corn stover," Bioresour. Technol. (2014)

View all NREL Publications for David A. Sievers.