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Wood to Wing: The Northwest Advanced Renewables Energy Alliance
By Colleen Walker, PhD and Charles Burke, PhD
The forest products industry has spent many years evaluating forest biorefineries for the production of energy, fuels, and chemicals from biomass. While replacing fossil fuels with bio-based wood materials seems like a great idea, to date there have been few commercial successes.
The Northwest Advanced Renewables Alliance (NARA), a public-private partnership led by Washington State University, represents a new approach to speeding up the commercialization process. It began in 2011 as one of six Coordinated Agricultural Projects (CAPs) within the Sustainable Energy challenge area currently funded by the USDA National Institute of Food and Agriculture (NIFA) Agriculture and Food Research Initiative (AFRI).
NARA's goal is to establish sustainable production of bioenergy and bioproducts in the Pacific Northwest. By drawing upon a network of companies, universities and other organizations, it leverages expertise and resources.
NARA's basic task is to develop a viable integrated pathway for commercially producing a bio-based aviation fuel (biojet). Towards this end, NARA's five specific goals include:
To accomplish its goals, NARA is organized into five teams:
Sustainability Measurements Team
Weyerhaeuser provides support in both project leadership and management as well as in feedstock sourcing evaluations and other lignin co-products. Teams are also evaluating applications for the lignin-rich by-product stream that results from the conversion process.
Catchlight Energy is evaluating a new wood pretreatment option called Mild Bisulfite Pretreatment which works well on the wood chips already used by the pulp and paper industry. Optimization of this process is underway as the team tries to enhance accessibility of the polysaccharides to the hydrolyzing enzymes.
Gevo's role is to convert the sugars into isobutanol and separate it from the fermentation broth by use of their proprietary GIFT® process--Gevo's Integrated Fermentation Technology. The conversion of primary sugars into isobutanol is performed by specialized yeast that import the glucose and other simple sugars into the cell and then secret isobutanol. Gevo works to optimize the strain of yeast for optimum performance, and also evaluates multiple pretreatment processes through other NARA's partners for efficiency. Gevo is also providing key input on cost so that an economically feasible operation is developed.
REDUCING FEEDSTOCK TRANSPORTATION COSTS
Feedstock cost, handling, and transport were found to represent up to 20 percent of the overall manufacturing costs for the wood-based biojet fuel. To burn woody biomass for energy or heat, dry biomass is preferred, and burning efficiency increases with lower moisture content. Alternatively, conversion of woody biomass for jet fuel does not require drier feedstocks as water is actually needed in the conversion process. Regardless of whether the objective is to burn or convert, it is still desirable to maximize the amount of woody biomass per truckload to reduce transportation costs.
A recent publication from John Session at Oregon State University, one of NARA's team members, addressed how moisture content in wood residuals contributed to transportation costs. Results from this study found that the moisture content of recently cut forest residuals can range from 60 percent (wet basis) to below 30 percent. Also, it was found that chipped feedstock packed more densely than ground, and that using a blower increased load density over conveyor systems that dropped chips into the trailer. Wood species also affected load density, with Douglas -fir chips weighing more per unit volume when compared to other lower specific gravity species like White fir and ponderosa pine.
The ultimate goal of this work is to increase the amount of biomass per trailer load by 20 percent over today's standards. This will be done by developing moisture management strategies and models to recommend the best time to haul forest residuals, and further evaluation of chipping versus grinding strategies.
THE BEST BIOMASS FEEDSTOCK FOR BIOJET FUEL
Pulp chips typically contain the lowest bark content, but this feedstock has a higher price point. However, moving to forest residuals which can be obtained at a lower cost, would result in compromises in eventual sugar yields due to the bark content and fines losses.
According to NARA team member Gevan Marrs from Weyerhaeuser, the most promising feedstock supply strategy is to use forest residuals while trying to minimize the bark content and fines losses. The goal for a near-term target feedstock would be Douglas-fir forest residuals at relatively low bark content (3 percent to 5 percent).
Feedstocks collected and processed for this study are now being evaluated by Gevo for isobutanol conversion, which will provide additional valuable data to evaluate feedstocks.
A TALE OF TWO INDUSTRIES
The forest products industry in North America has undergone some dramatic changes in the last ten years, with the closing of pulp and paper mills due to global competition. Traditional forest products companies are looking towards transformational strategies to revitalize the industry.
The aviation industry has faced serious issues due to changes in fuel pricing. In 2011, jet fuel was the biggest expense for airlines representing one-third of their total costs--jet fuel prices rose at a blistering rate of 47 percent in the past year. At the same time, concern over greenhouse gas emissions has changed how the aviation industry views its dependency on petroleum-based fuel. According to NARA Team Leader Dr. Andrew Hawkins from Gevo, "The airline industry as a whole is interested in biojet because they want to find an alternative supply to petroleum's price volatility and to reduce their greenhouse gas emissions."
NARA is helping these two industries find a sustainable path forward that brings jobs and economic development to rural communities that value their forests, and provide a cleaner solution to the aviation industry. Leveraging the knowledge of the experts in these two great industries with the resources that both have to offer can lead to substantive change for all.
To learn more about NARA or to become directly involved, there are a number of options:
Colleen Walker, PhD, is Project Manager and Technical Lead at TAPPI. She can be reached at [email protected]. Charles Burk, PhD, is NARA Communications and Publicity Director at Washington Sate University and can be reached at [email protected].
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