Boise Cascade
Boise Environment

Nonwood Alternatives to Wood Fiber in Paper

Throughout history, virtually every sort of plant fiber has been used to make paper — from bamboo to agricultural byproducts such as cereal straw, to industrial crops such as flax and sisal. Use of these fibers has generally been driven by local availability, and the paper they produce has formed an important part of some local economies and niche markets.

Estimates of world paper production attribute 11% to all nonwood fibers. In the United States, use of nonwood fiber for paper is very limited, less than 1% of total capacity. As industries search for more efficient ways to produce products and to conserve natural resources, such as forests, many of these fibers are being explored as wood pulp replacements and major sources of raw material for papermaking.

Like many other companies and research organizations, Boise has also explored the potential for alternative fibers. However, following a review of the research, we, along with others, have concluded that the broad use of such fibers is not a viable alternative to wood fiber. Large quantities of paper that meets customers' quality and cost expectations cannot be produced from alternative sources using available technology. In addition, the use of these fibers presents many negative environmental and land use implications.

This position paper discusses the alternative fibers most commonly used in papermaking today — straw, bamboo, and bagasse — as well as the two materials most often mentioned as potential future alternatives — hemp and kenaf. It examines the advantages and challenges resulting from their use and also reviews other efforts underway by Boise to produce paper more efficiently and to effectively conserve the forests that support the papermaking industry.

Straw

Straw, primarily rice and wheat straw, is an agricultural residue that serves as the major raw material for small paper mills, most of which are in China and India, where the product is plentiful. Straw for paper production was originally used in Europe to make food wrapping papers and newsprint. North American mills used straw to produce corrugated box board until the 1960s.

Pulping of straw requires less steam, energy, and chemicals per ton of paper than does pulping of some other materials. Straw, however, also has a number of serious drawbacks, such as a high percentage of silica, which fouls equipment. It also contains extraneous materials, such as grain, husks, and leaves, that make it generally unacceptable for widespread commercial paper production. The bulky nature of straw, along with its scattered and seasonal availability, increases the difficulty and cost of collection and transportation. Seasonal harvesting means that covered sheds are required to store the plant prior to pulping.

In addition, many existing pulp mills that use straw have serious environmental issues, particularly related to disposal of wastewater. Wastewater from such mills often is more alkaline, carries more suspended solids, bears more bacteria that rob water of oxygen, and is more toxic to fish.

Bamboo

Bamboo, a member of the grass family, grows well under tropical conditions in Asia and South America. Long, thin bamboo fiber makes superior papers of all kinds and is a mainstay raw material for the paper industry in India and China.

The supply of bamboo to mills, however, can be interrupted by sporadic flowering. Pulping of bamboo is complicated by dense nodes and a high percentage of silica. Recently, harvesting bamboo as a nonwood alternative has increasingly come under question by environmental groups who want to preserve bamboo forests, which are home to such animals as the panda in China and the tiger in India.

Bagasse

Bagasse is the remnant of the sugar cane plant following extraction of the juices. Bagasse is used primarily in Latin America and India for the manufacture of newsprint. Bagasse is easily bleached, requires few chemicals for processing, and has low steam and power requirements for cooking.

However, bagasse has a number of disadvantages which limit its use for broad-scale papermaking. It needs longer wood fibers to maintain strength. The bagasse used in papermaking today is generally mixed with imported wood pulp. It is often difficult to maintain an adequate supply of bagasse for papermaking, as bagasse is traditionally burned by the sugar mills as fuel. Consequently, its availability for papermaking is dependent on sugar cane mills switching to alternative sources of energy, most often coal, a challenge to most mills due to the cost of importing coal. Bagasse also requires additional landfill space to dispose of the waste plant matter. The bagasse industry in India has long been subsidized, and many mills are shutting down or moving away from bagasse as a single fiber source. Bagasse is generally not available in the United States because there are few sugar cane mills here.

Hemp

Hemp is a variety of Cannabis sativa, a class that includes marijuana. The hallucinatory chemical THC makes up less than 1% of industrial hemp, though, compared with 5% to 20% of marijuana.

Although hemp is classified as a controlled substance in the United States, making it illegal to grow, use of hemp fiber predates written history. The first recorded cultivation occurred in China, where it was traditionally used in rope, fish net, textiles, and other materials. Migrating peoples likely brought hemp to Europe where, by the 16th century, it was widely distributed and cultivated for fiber and food. Colonists introduced hemp production into New England, and it was later cultivated in some eastern states. Today, the fiber is used in specialty textiles, paper, and composites, and the seed can be used in food or crushed for oil.

Industrial hemp has thousands of uses, including papermaking. A number of U.S. and European companies sell writing paper containing small amounts of hemp fiber, usually blended with less expensive nonwood fibers. However, even in industrialized countries where hemp fiber is legally available, it is used primarily for highly specialized products that are sold at high prices, such as cigarette, tea bag, and currency papers.

U.S. production of hemp, predominantly for cordage and textiles, virtually ceased at the end of the 19th century because of its expense, compared with other fibers. This additional cost is driven by the logistics of handling and storing raw hemp and problems associated with pulping hemp and recovering spent pulping liquors.

Another issue associated with hemp is its low yield per acre. Advocates claim that the plant produces more fiber per acre than trees. But this is misleading, because the entire hemp plant cannot be economically prepared for paper production. While the wood products industry uses nearly 100% of the fiber from harvested trees, only 25% of the dried hemp stem — the bark, called bast — contains the long, strong fibers desirable for paper production. The remaining 75% of the hemp plant is the core, called hurd. Chemical pulp fibers from hemp hurd are comparatively short, weak, and slow-draining — poor fiber quality characteristics for making top-grade papers with modern, high-production processes. Consequently, fiber yields of hemp per acre are from one-half to one-sixth of the tonnage that can be achieved from well-managed tree plantations.

Raising hemp also creates several associated environmental issues. Hemp requires considerable fertilization to reach desirable yields. It removes more nutrients per acre than other crops and requires that cropland be laid bare annually. Land currently devoted to managed forests or to growing food crops would have to be converted to cultivate industrial crops of hemp. An Oregon study, for example, found that the requirement for supplemental irrigation would place hemp in direct competition with the highest-value crops in the Pacific Northwest, limiting available acreage. Additionally, land devoted to hemp production is subject to heavy erosion — nearly twice the maximum level required to maintain soil productivity and 15 times the average erosion levels of timberlands.

Kenaf

Kenaf is a cousin of cotton and okra plants and has been used for centuries to make clothing and twine in Africa and Asia. Kenaf fiber is strong, resists breakage, and lends itself to various processing techniques.

Interest in growing kenaf in the United States developed during World War II, when jute and abaca exports from Southeast Asia were disrupted. Since then, global interest in kenaf has fluctuated. The only commercial papermaking operations using kenaf are in Thailand and North Carolina; it is not the principal fiber source for either mill.

One disadvantage to growing kenaf is its low yield. While the kenaf plant produces about six tons of fiber per acre at test sites, only about 25% to 30% of that fiber is desirable for making standard writing and printing paper, dropping the yield to 1.8 tons per acre per year. In contrast, pine plantations generally produce two tons per acre per year. Repeated cultivation of kenaf also causes soil depletion, which results in the need for very large areas and crop rotation.

Kenaf is a highly expensive alternative. The plant's stem contains two fiber grades that are costly to separate. The outside of the stem produces a fiber that is superior in some respects to pine. However, the interior fiber, the other 70% to 75% of the plant, is profoundly inferior to pine and cannot be used as an effective wood fiber substitute. Additionally, because kenaf is a bulky material, it requires more transportation and warehousing space than an equal weight of wood chips. Seasonal harvesting means that covered sheds are required to store the plant prior to pulping.

In addition, many existing pulp mills using alternative fibers such as kenaf have serious environmental issues, particularly related to disposal of wastewater. Wastewater displays higher pH levels, carries more suspended solids, holds more bacteria that rob water of oxygen, and is more toxic to fish.

Consequently, the only commercially promising use of kenaf at present is as a constituent fiber to make newsprint.

Efficient Use of Fiber Resources

While alternative fibers are not viable sources for production of large quantities of paper today, Boise continues to improve efficiency in papermaking and to manage and conserve our forest resources through several other efforts.

We have made significant strides in using fiber from our 9,800-acre cottonwood fiber farm near our paper mill in Wallula, Washington. The farm was developed entirely from lands previously used for agriculture. Each acre from the farm today is yielding six to eight times the yield per acre per year of natural hardwood acres in the eastern United States. Roughly 20% of the pulp used by our white paper machine in Wallula is made from these fast-growing hybrid cottonwoods.

The forest products industry will always need adequate, dependable harvests from public and private forests for most of the fiber required to make the vast quantity of paper and wood products our society uses, but fiber farming will likely grow as a supplemental source of that fiber.

Boise has produced postconsumer recycled-content paper at its pulp and paper mill in International Falls, Minnesota, for over 20 years. Marketed as ASPEN™ paper, it was first produced using 20% postconsumer recovered fiber. In 1992, the postconsumer recycled fiber content was increased to 30%. In 2002, Boise introduced ASPEN™ 100 paper, a high-quality, 100% postconsumer recycled-content office paper that is also produced at our International Falls mill. Boise also uses postconsumer recovered fiber in the production of forms, envelopes, and offset printing papers.

At Boise, the responsibility to protect the environment is not delegated to one department or a few managers, but is an integral part of every job. We are taking this commitment seriously by searching for ways to reduce, reuse, and recycle the resources needed in our operations and by continuously searching for ways to run our facilities more efficiently.

The company's Standards of Business Conduct, which every employee commits to follow, include specific environmental guidelines. Among other things, these guidelines require regular environmental audits, which we have conducted since 1982. Boise was among the first in our industry to implement this voluntary auditing program.

We are proud of our record in environmental stewardship. We are also committed to improving our performance in the future.

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Boise Cascade Environment
1111 West Jefferson Street
P.O. Box 50
Boise, ID 83728