Rewiring Anaerobic Digestion
October 27-28, 2016
Washington, D.C.

Rewiring Anaerobic Digestion Workshop Summary

ARPA-E held a workshop on “Rewiring Anaerobic Digestion” on October 27-28, 2016 in the Washington, D.C. area. The workshop brought together experts in the fields of anaerobic digestion, microbiome science, microbial consortia engineering, electrocatalysis, and chemical engineering (catalytic hydrogenation and liquid-liquid separations), to identify feasible research pathways forward for the development of disruptive technologies that can enable enhanced hydrolysis, prevention of methanogenesis, volatile fatty acid (VFA) separations, and downstream upgrading to hydrocarbons. By adding reducing power to the system, the overall carbon yield of rewired AD is theoretically 100%; all carbon entering the system is fixed. A program in this direction would additionally serve as a strategic integration of past and ongoing efforts, with macroalgae feeding in as an alternative feedstock, and downstream conversion using elements of Electrofuels, REMOTE, and REFUEL.

ARPA-E is interested in control mechanisms for anaerobic microbial consortia focused on enhanced hydrolysis and prevention of methanogenesis, and technologies for VFA separations and downstream upgrading.

Areas of interest and targeted outcomes include:
• Identification of key substrates for initial conversion demonstration in a FOA and longer-term implementation;
• Identification of consortia engineering approaches for cost-effectively enhancing hydrolysis rates;
• Identification of consortia engineering approaches for preventing methanogenesis;
• Determination of intermediate compounds of interest and identification of cost-effective separations technologies;
• Identification of downstream upgrading technologies for cost-effective reduction of VFAs to hydrocarbons, through the addition of hydrogen or electricity;
• Understanding the current state of technology regarding analysis of mixed/syntrophic microbial communities; and
• Identification of opportunities for process intensification and capital cost reduction in anaerobic digestion.

Day 1: Thursday, October 27

8:30 am Eric Rohlfing, ARPA-E Deputy Director - Technology
Welcome and Introduction to ARPA-E

8:45 am Marc von Keitz, ARPA-E PD
Workshop Motivation & Goals

9:05 am Luca Zullo
Anaerobic Digestion Industry Overview and Opportunities for Process Intensification

9:30 am David Chynoweth
Anaerobic Digestion Feedstocks and Opportunities for Macroalgae Conversion 

9:50 am Marc von Keitz Breakout #1 Instructions

10:15 am Breakout Session #1 Challenges and Opportunities for Intensification of the AD Process
Group A Reactor design and feedstock pretreatment: Opportunities for enhanced hydrolysis and process intensification
Group B Monitoring and process control
Group C Feedstock, co-products, and upgrade pairing considerations

11:45 am Breakout Session #1 report out

12:45 pm Marc von Keitz Breakout #2 instructions

12:50 pm Lars Angenent
Microbiome Shaping of Anaerobic Fermentation and Chain Elongation to Increase Product Specificity

1:10 pm Paul Weimer
The Ruminant Microbiome, Biomass Conversion, and Carboxylate Production

1:30 pm Breakout session #2 Engineering & modulating the product portfolio of the AD microbiome 
Group A Microbiome analysis & tools to prevent methanogenesis
Group B Metabolic pathways and target intermediates
Group C Reactor design and lessons from ruminant conversion systems

3:00 pm Breakout Session #2 read out & Instructions for Breakout Session #3

3:30 pm Ned Jackson
Electrocatalytic Upgrading Opportunities and Challenges 

3:50 pm Glenn Lipscomb
Separations Opportunities and Challenges 

4:10 pm Breakout session #3 Product upgrading and process integration 
Group A Biological product upgrade strategies
Group B Catalytic/electro-catalytic upgrading and best pairings with biological intermediates
Group C Separations unit operations required to facilitate upgrading strategies

5:30 pm Breakout Session #3 read out & Day 1 closing remarks

Day 2- Friday, Oct 28

9:00 am Marc von Keitz
Welcome to Day 2

9:10 am Mark Holtzapple
History of the MixAlco Process and Future Challenges

9:40 am Marc von Keitz
Strawman FOA & Instructions for Breakout Session #4

10:15 am Breakout session #4 ARPA-E funding opportunity – Key topics, target metrics & boundary conditions
Group A Key technical problems/ risks for FOA focus
Group B/C Target metrics & benchmarking against competitor conversions

11:45 am Breakout Session #4 read out

1:00 pm Marc von Keitz
Closing Remarks

Supplemental Information:

Michael R. Schuppenhauer
Feedstocks for Biogas and How It Replaces 50% of US Transportation Fuel