Assessment of Conversion Technologies for Bioalcohol Fuel ...

HFTA/UC Forest Products Lab, Livermore, California
Organizational Background–Technology invented at the University of California
Forest Products Laboratory (UCFPL) for the purpose of producing ethanol from
cellulosic (primarily forestry) materials continues to be pursued by a private company,
HFTA. Patents covering the technology are owned by the University of California, and
an exclusive option on commercialization rights is held by HFTA, formed in 1994 by
UCFPL staff. Much of the past HFTA/UCFPL research on the technology has been
supported by the U.S. Department of Energy’s National Renewable Research
Laboratory. The UCFPL was a research and graduate teaching facility operated under
the auspices of the University of California, Berkeley, at the Richmond, California field
station. Facilities included a chemical laboratory, a fermentation laboratory, and largescale
chemical processing laboratory equipment, including pulping digesters, wet
oxidation reactor, and a batch biomass/hydrolysis reactor. The University of California
has closed this laboratory and the equipment and staff capabilities are no longer
available in that setting.
Technology Characteristics–The HFTA/UCFPL process utilizes dilute nitric acid as
a catalyst in an acid hydrolysis process to break down cellulosic materials into their
constituent sugars for fermentation to ethanol. The technology was developed
focusing mainly on wood chips, but is said to be generally applicable to all
lignocellulosic feedstocks, including forest thinnings, sawmill residues, waste paper,
urban wood waste, corn stover, switchgrass, rice or wheat straw, and sugarcane
bagasse. The technology can be used in a single-stage or two-stage process, with
residence times of 5-8 minutes in each reactor stage. Lignin collected via filtration is
claimed to be sufficient for all process energy requirements. The HFTA/UCFPL
technology could also be applied as the pre-treatment step for enzymatic hydrolysis
processes.
A key feature of the HFTA/UCFPL technology is its use of nitric acid, rather than
sulfuric or hydrochloric acids used in most other hydrolysis processes. Nitric acid was
selected by HFTA/UCFPL due to several identified characteristics, including its
miscibility with water, allowing low acid concentrations to sufficiently catalyze the
hydrolysis reaction. Nitric acid also “passivates” stainless steels, effectively forming a
protective coating shown to provide corrosion protection at the required operating
temperatures, acid concentrations and abrasiveness of the process. This is said to
reduce the cost of materials needed for processing equipment. The nitric acid-based
process is also claimed to reduce water requirements by affording greater water
recycling, as well as reducing wastewater treatment requirements and solid waste
residuals.
Development Status–HFTA/UCFPL has completed over a decade of research and
development of its technology, through the bench-scale testing phase. Numerous
technical reports and papers have been authored by the project researchers
documenting the results and findings. Economic evaluations have also been
conducted for the process. Since the University of California closed the UCFPL
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