Autohydrolysis – A Simple, Low Capital, Financeable Bioethanol Process Using Proven Process Equipment and Technology

Autohydrolysis has been long studied but often abandoned as a financially viable bioethanol process.  Generally, developers have been deterred by relatively low yields of fermentable sugars and have focused on higher yielding, but more complex technologies.

Autohydrolysis economics are substantially improved by implementing any or all of the following:

(1) Process technology and equipment proven in the pulp and paper industry for decades, reducing technological risk;

(2) Increasing enzyme hydrolysis yield by over 30% through mechanical refining using techniques and equipment common to pulp and paper manufacture;

(3) Improving the value of unhydrolyzed residue by drying and pelletizing;

(4) Co-locating the autohydrolysis bioethanol process in an operating kraft pulp mill, taking advantage of infrastructure and assets already in place.

Applying items (1) – (4) result in favorable investment economics, ~ $0.50 per Liter Minimum Ethanol Revenue to achieve a 12% Internal Rate of Return in the best case.

Using Autohydrolysis plus refining strategy, sugar conversion is slightly lower compared to dilute-acid process, but the level of inhibitory compounds is significantly lower due to the low severity.

We report results of four options: Greenfield and Co-Location, each with optional power sales or fuel pellet sales.  Results are based on supporting laboratory studies, material and energy balances, capital investment estimates, and investment financial analysis.