Agricultural Residues:
A Promising Alternative to Virgin Wood Fiber
 

Agricultural residues are a promising alternative to virgin wood fiber as an industrial feedstock. Residues are abundant, cheap, and their use will yield economic as well as environmental dividends. We must, however answer some pressing questions and take action before the full potential of this fiber source can be realized.

by Meghan Hayes (formerly Meghan Clancy-Hepburn)

TABLE OF CONTENTS

Abstract

The Problem

Benefits of Using Residues

Tree Crisis, Agricultural Residue Solution

Types of Agricultural Residues

Concerns About Agricultural Residues

Case Studies

Conclusion

Endnotes


Abstract


The facts about wood use and deforestation are bleak, but one solution to the problem can be found in abundance across the United States. Using agricultural residues, wheat, rice, barley and other cereal grain straw, and corn stalks and stovers, as industrial feedstock for the construction material and pulp and paper industries will allow those industries to move away from the current reliance on virgin wood fibers.

There are between 140 and 350 million tons of agricultural residues produced annually in the United States. Although some of these residues must be left in the field for soil conservation purposes, the bulk of the residues are available for industrial use. Using a conservative conversion factor of 50 percent yield(i) of pulp from agricultural residues, the United States could produce between 70 and 175 million tons of pulp per year. The higher value represents far more pulp than is used annually by U.S. industries to produce paper.

Agricultural residues are an excellent alternative to using virgin wood fiber for many reasons. Aside from their abundance and renewability, using agricultural residues will benefit farmers, industry and human health and the environment. Wheat straw, for example, is being grown at yields of between 1-3 tons per acre. The manufacturers currently using wheat straw as an industrial feedstock pay up to $45 per ton. This income is a boon to farmers. In fact, one manufacturer, Agriboard Industries, claims that local farmers stand to make more from selling the wheat straw than from selling the actual crop.

In lieu of full cash payments, some farmers have agreed to acquire stock in the industrial enterprise to which they sell straw. This ensures that the farmers add value to their crops in the short term, but then continue to receive dividends in the future. It also allows cash-poor start-up industries to save capital, funneling much needed funds to initial expenditures rather than to resource suppliers.

Using agricultural residues for industrial purposes is a much more environmentally friendly practice than many residue disposal methods currently in use. Until recently, many farmers disposed of agricultural wastes by burning or landfilling them. The burning of straw created 56,000 tons of carbon monoxide annually in California alone. In some states, most notably California, Washington, and Oregon, the practice of burning has been all but eliminated by legislation mandating phase down. Using agricultural residues as an industrial feedstock is a critical channel for making these phase downs successful. In addition, because agricultural residues can be pulped using much more benign processes than can wood fibers, the effluents from the mills will be less toxic than those from traditional mills. This will serve to protect water quality in the United States.

Many questions remain about how to proceed with using agricultural residues as an industrial feedstock in the United States. The USDA and other entities should provide accurate reports of how much residue is created each year in the United States, how much of that residue can safely be removed from fields without diminishing soil health, and which regions can support local mills to process locally produced residues.

Transportation of residues can be expensive, and not highly energy efficient. The USDA, possibly in conjunction with the U.S. Department of Transportation, should commission studies on the best ways to move residues from field to factory. The technology that has been developed to process residues is constantly being improved. However, since the industries using residues as feedstocks tend to be capital intensive (particularly the paper industry), incentives and subsidies will be useful to start-up mills and the engineers who work to streamline residue-processing technologies. Finally, the public needs to be educated about the benefits of using agricultural residues as an alternative to virgin wood fiber.

The Problem

Amid the contentious debate over logging and the global wood supply, one of the most important questions has long gone unanswered: what are the alternatives? According to the International Institute for Environment and Development, "in 1993, the total world harvest of wood for all purposes was 3.4 billion m3,"(ii) 160 million tonnes (176 million tons) of which went to producing paper and paperboard. In the United States alone, estimated annual tonnage of wood fiber consumed is close to 200 million. Some of the best known impacts of logging on such volume are soil erosion, damage to water supplies, loss of habitat, diminution of biodiversity, loss of wilderness, and increased air pollution. Additionally, logging mars the landscape and the natural amenities which have become the economic base of western communities;(iii) it creates jobs only temporarily, and then undermines local economies by moving on when the wood supply is gone; and it costs millions of dollars in tax subsidies every year.

Logging has had a profound effect on the environmental and economic health of our country. Although some progress has been made to protect forests in the name of environmental health, it seems that the growing timber shortage will force those who use wood to look quickly and seriously for alternatives rather than face the economic costs. Fortunately, there are people acting regionally to develop alternative fiber sources that can substitute fully or partially for wood products. Some of the most plentiful and environmentally benign nonwood fibers can be found not too far down the road on the family farm.

A century ago, before wood became the raw material of choice for making paper, people used straw and other nonwood fibers for pulp. To this day, many countries use straw and other agricultural residues for papermaking, although the technologies have advanced a great deal in the last 100 years. There are over 140 million tons of agricultural residues produced annually in North America, and while to date, high grade copier and printing paper cannot be made entirely out of straw pulp, a good percentage of straw pulp could be used in combination with recycled pulps or other nonwood fibers to make paper.

Agricultural residues have industrial uses beyond paper making. They can be used to make construction materials and biofuels. Environmental Building News offers the following assessment of the immense possibilities for using agricultural residues:

If we used all of [the] available straw for the exterior walls of straw-bale buildings, 2.7 million 1,000-ft2 (93 m2), single-story houses could be built each year. If we turned that straw into structural compressed-straw panels, they could provide the exterior walls, roofs, interior partition walls, and floors of 1 million 2,000 ft2 (186 m2), two-story houses per year. Or, that straw could be used to produce 22 billion ft2 (2.1 billion m2) of 3/4" (19 mm) particleboard, which is five times the current total U.S. production ofparticleboard and medium-density fiberboard (all thicknesses). Clearly, the potential is significant.(iv)

Faced with all of these options, one of the challenges ahead is to determine how best to use straw to protect forest health in this country and to build up our important rural economies.

Benefits of Using Residues

The advantages to using agricultural residues are three-fold: economic, environmental, and technological.

A. Economic

For the farmer, agricultural residues can be a cash crop. Traditionally farmers have harvested grain and burnt or otherwise disposed of straw and other residues (stalks, stover, etc.), but the heightened interest in making paper out of agricultural wastes means that farmers can reap a "second harvest" from grain plantings. One papermaker has estimated that a farmer could expect to see a 20 percent increase per acre in net farm income from selling wheat straw. Farmers will also amass environmental dividends: studies have shown that the burning of agricultural wastes causes air pollution, soil erosion, and a decrease in soil biological activity, which eventually leads to soil crusting and may lower yields.(vi)

In addition, because of the high cost of transporting agricultural residues to be processed into pulp, it is likely that mills will have to be built in rural areas, near the farms that supply the residues. This will boost local economies by providing jobs, services, and a higher tax base. There has also been talk of encouraging farmers to obtain stock in local mills, so that their earnings increase both through the sale of agricultural residues and through dividends from industrial ventures.(vii)

As with any commodity, the cost of agricultural residues is likely to fluctuate. Currently, data is available for the cost of wheat and rice straw, although it varies by region and season. Wheat straw sells for up to $45/ton (delivered) and rice straw sells for about $40/ton (delivered). Some states have made available predicted amounts of straw produced per year: California, Washington, and Oregon combined are expected to produce close to 6 million tons of straw that can be used for commercial purposes;(viii) Idaho alone produces close to 2.9 million tons of wheat, barley, and oat straw (net available) per year.(ix) Iowa is producing more than 34 million tons of recoverable corn stover each year.(x) These yields could represent significant increases in annual income.

An increase in farm earnings will diminish the need for farm subsidies, which will eventually save money for taxpayers and reduce farmers' reliance on the government for support. Regionally, the use of agricultural residues is proving to be a boon to businesses. In California, firms using rice straw in products and services are eligible for a $15-credit per ton of straw used. The limit on the credit is $400,000 for 11 years. Furthermore, there are numerous examples of enterprising companies making profits by using straw and other agricultural residues in their products.

B. Environment

The current debate in California about rice-straw burning is a prime example of the type of environmental problem that can be solved by commodifying agricultural residues. In 1991, Governor Pete Wilson signed the Rice Straw Burning Reduction Act, which was intended to restrict burning annually until the year 2000, when burning would be completely phased out. California farmers, particularly in the Sacramento Valley, have typically burned the rice straw on close to 500,000 acres to prepare fields for future crops and control rice diseases. However, burning yields smoke and other pollutants which adversely effect air quality, visibility, and human and environmental health. In fact, more than 1 million tons of California straw were burned every autumn at the start of this decade. Scientists have estimated that this resulted in the release of 56,000 tons of carbon monoxide annually.(xi) The Act was intended to reduce the environmental impacts of burning, while investigating viable alternatives to burning.

Recently California rice growers have cited undue hardship under the Act, claiming that it is too expensive to plow rice straw under instead of burning it. In addition, according to a July 18, 1997 article in the Sacramento Bee, "industry advocates have said farmers need to burn the straw to protect crops from disease and because no alternative markets exist for the straw."(xii) An amended bill (SB 318) approved by the California Senate would allow more leniency in burning and would provide $5 million to fund demonstration projects for alternative rice straw uses. Oregon lawmakers have also mandated a phase-down of burning of straw in the Willamette Valley.

Using rice straw as pulp for paper could prove to be an ideal solution to the California and Oregon rice burning conundrum. There are ongoing trials at the Canadian Flax Pulp, Ltd. Mill in Vulcan, Alberta, Canada using rice straw as pulp for paper (See section VI.A.1). These trials have demonstrated that turning rice straw into paper removes the burden of an agricultural waste product from the shoulders of farmers, protects local environmental quality and health, and may even benefit the printing industry by serving as a low-cost alternative to high newsprint and paper prices.

As a cautionary note, it must be stated that straw might prove to be an excellent pulp, but there are environmental restrictions to the amount of straw that can be harvested. Some straw is often left on fields to resupply nutrients to the soil and retain soil moisture. To take all of the straw off of a field would cause erosion, poor soil nutrition and reduced crop yields, hence negating the net environmental benefits of reducing wood use. For this reason, unless otherwise indicated, the figures on straw availability in this paper do not represent the actual amount of straw produced, but rather the net available straw, calculated as a percentage of the gross tonnage per year, some of which is left in the fields or used elsewhere on the farm.

C. Technology

Current research and testing indicate that pulping of agricultural residues is best achieved at small, local mills. The rice straw trials in Alberta, Canada are being carried out at a relatively small mill, which was built for the express purpose of processing agricultural residues. This local-scale production process will offer a number of jobs to the region at the same time as it reduces transportation costs and provides affordable paper to users. In fact, a recent study shows that it is 15 percent cheaper to make newsprint from agricultural residue pulp than it is from conventional pulps.(xiii)

Unlike wood pulps, agricultural pulps can be produced using more environmentally benign processing and bleaching methods. For example, scientists have had great success with pulping and bleaching methods that use oxygen or enzymes to remove lignin from straw and free up the cellulose fiber that is necessary for paper production. While most wood pulp is bleached using chlorine or chlorine-based chemicals, straw can be treated with minimal additions of chlorine-free chemicals. Absence of chlorine or chlorine-based chemicals in the pulping and bleaching stages means that there is no production of adsorbable organic halides (AOX), the most famous and harmful of which are dioxins and furans.

One method for manufacturing pulps from agricultural residues uses potassium chemicals, which can be recycled at the end of the process to make potassium-enriched fertilizer and natural fungicide products. Therefore, not only does the process not produce highly toxic chemicals, it also may protect environmental quality in the areas outside of the mill, a promise that most wood fiber mills cannot make since they release such large volumes of effluents. Another process, called the Organosolv Process, uses water ethanol for pulping. At the end of the process, technicians redistill the ethanol out of system and are left with sugar and lignin, which can be burned as fuel in the boilers or used as fertilizer. Yet another process uses ammonium sulfite to pulp straw. This process fixes the ammonium to lignin, which can be returned to the soil in pelletized form.

In addition to the technological reasons that have already been discussed for using agricultural residues, there are also chemical and mechanical reasons. For example, agricultural fibers are much more porous than wood, and have much lower lignin levels. Both of these factors make straw easier to pulp. Most agricultural fibers are shorter than softwood fibers, and are therefore well suited for the manufacture of certain specialty papers.

It is possible to process agricultural residue pulp in existing mills by adding additional pulping lines and increasing recovery boiler capacity through verified retrofits. Currently, some of the larger paper companies are experimenting with the addition of nonwood fiber pulping lines, although at this time, none of the lines operate at the commercial level.

Tree Crisis, Agricultural Residue Solution


Paper can be made from any and all types of fiber, ranging from an old pair of bluejeans to a lawn full of grass clippings. Papermakers have relied on trees in the last century to provide fiber in bulk, but many regions of the United States are facing wood shortages. Current estimates reveal that only five percent of U.S. virgin forests remain standing, and consistent over-logging has left some areas of this country devastated both economically and environmentally.(xiv) Washington and Oregon have experienced a particularly dramatic shortfall of virgin wood fiber for use in pulp and paper, a shortage estimated to be close to 2.5 million tons in 1997-1998.(xv) It has also become increasingly more profitable for the timber industry to sell logs for sawn lumber than for pulp furnish.

In sharp contrast, agricultural residues are plentiful, widespread, and easily accessible. Estimates vary on the amount of agricultural cropping residues produced in North America annually, with figures ranging from 140 million tons (128 million tonnes) to 282 million tons (260 tonnes)(xvi) to 350 million tons (320 million tonnes).(xvii) It is predicted that between 123 million tons (112 tonnes) and 214 million tonnes (235 million tons) of these residues are produced in the United States.(xviii)

In addition to being faced with regional paper shortages, the paper industry has resisted pressure to make its processes more environmentally benign. The relatively recent discovery that pulp and paper mills were releasing dioxins and furans directly into rivers, resulting in unprecedented fish kills, was hailed as an environmental catastrophe. Recent debate over the hormone-mimicking properties of dioxins, furans, and other chlorinated compounds has fueled public pressure on mills to eliminate chlorine and chlorine-based chemicals from manufacturing processes. A conversion to effluent-free mills would fully recycle all process chemicals and reduce effluents to zero.

The technologies required for turning agricultural residues into pulp for papermaking are the types of innovation the industry needs to embrace. Processes for pulping agricultural residues require minimal chemical inputs, do not form persistent toxic compounds, and produce compounds that can be recycled at the end of the process into useful farm additions. Some processes are effluent-free, reflecting a previously unheard of efficiency in pulp production. The Organosolv method being tested now by the Fiber Futures Project (See section VII.A.2) is one such effluent-free process.

Types of Agricultural Residues


There are numerous types of agricultural cropping residues. For pulp and paper purposes, only those with cellulose (fiber) content are of real interest. Corn stalks, leaves, and sheaths; wheat straw; rice straw; barley straw; oat straw; seed grass straw; and bagasse from sugar cane are all examples of agricultural cropping residues. When sugar cane is grown for the bagasse, it is called an intentional or on-purpose crop and is no longer considered to be a residue.

A. Wheat straw

Wheat is harvested across the United States and its straw is an ideal agricultural residue for use in paper and paper products. Its lignin content is comparable to hardwoods and it has one of the highest cellulose contents of all of the agricultural fibers. When farmed intensively, wheat straw can be produced at a rate of 50 bushels/acre, yielding 1-3 tons per acre (depending on whether it is dry land or irrigated), and sold at a price of $20-45/ton.

Wheat straw is clearly the most abundant nonwood plant material available for pulp and papermaking in the United States. The amount of wheat straw available for pulp production varies depending on the type of wheat grown, the harvest efficiency and the amount that must be left on the field to comply with the residue management provisions of the Farm Bill.(xix) The conversion figure tends to be in the range of 1.0-1.1 tons of straw produced per ton of grain. However, estimates do have to be made with an eye to the specific type of residue used. Wheat, for example, tends to have a much higher straw residue yield than barley.

Straw papers are known to possess good printing qualities and are made from pulp requiring low energy relative to that required to process wood pulp. Technicians have found that wheat straw must be pulped under conditions of less energy and fewer chemicals than wood pulps to maximize pulp yields. To make the strongest product, papermakers will likely combine some stronger hardwood, kenaf, or hemp pulp with straw pulp.

B. Rice straw

Rice straw is another of the so-called "cereal straws," and contains a low concentration of lignin. Rice straw has a higher silica content (as high as 18 percent in "clean rice straw," and 19-24 percent including silica from field dust)(xx) than other cereal straws, which makes pulping somewhat more costly due to increased chemical recovery difficulties and costs. Recent developments in pre-pulp cleaning and pulping techniques have yielded much higher precipitation of silica from the pulping waste (also called black liquor), making chemical recovery more viable, and thereby diminishing pulping costs. Researchers have also identified new uses for the recovered silica, which can be made into bricks, ceramic articles, and glassware, thus completing the recovery cycle.

China currently has the greatest capacity for pulping rice straw, and to date there are no rice-straw pulp mills in the United States, although an engineer/entrepreneur named Al Wong (see section VII.A.1 for more details on Mr. Wong's projects) is proposing to build one in California. Should this happen, Mr. Wong will have a great deal of furnish at his disposal. The California average of recoverable and/or burnable rice straw is 3 tons/acre. During the 1996-97, California growers farmed close to 500,000 acres of rice. This means that, particularly if the Sacramento Valley rice straw burning phase down continues apace, there are a possible 1.5 million tons of rice straw available for post-harvest use.

C. Corn waste

Iowa State University is experimenting with the manufacture of a stressed skin panel made from a number of different fibers, including corn stalks. Heartland Fibers, a midwest company, has also announced that it intends to produce pulp from cornstalks. Little information is available on the efficacy of using corn wastes, a problem which requires a remedy.

D. Others

Other agricultural residues that are being researched to determine their utility as industrial feedstocks include grain sorghum, cotton stalks, and amaranth, to name just a few.

Concerns About Agricultural Residues


Although agricultural residues are likely substitutes for the use of wood pulps for the manufacture of paper and other materials, there are still obstacles to their use. The high collection, transportation, and handling costs associated with agricultural residues are the foremost obstacles to the production of paper and building materials from these wastes. Whereas logs have high volume density, straw is hard to pack, has low volume density, and is difficult to store. Agricultural residues are also available only seasonally, and their cultivation is limited to certain geographic regions.

Case Studies


A. Pulp and Paper

1. Agri-Pulp

Al Wong is the president of Canadian Flax Pulp, Ltd. of Vancouver, Canada which operates an Agri-Pulp processing mill in Vulcan, Alberta, Canada that turns wheat straw into paper. Mr. Wong's company combines the wheat straw pulp (which he calls agri-pulp) with post-consumer wastepaper pulp to produce a high quality office paper.

To date, the company has focused its efforts in Canada, buying wheat straw from Alberta farmers, but Wong says this could change within the next six months. Plans are in the works to build an Agri-Pulp mill in the Sacramento Valley. Executives are investigating several potential mill sites in Colusa County, and are working with the Rice Producers of California to find potential suppliers of agricultural wastes. Wong expects to collect wastepaper from the Sacramento/Bay area to be repulped and mixed with the wheat straw pulp to make paper. As it is conceived now, the Sacramento Valley mill would be the largest of its kind. Capable of producing 40,000 tonnes (44,000 tons) of pulp per year, this mill could supply the pulp for 80,000 tonnes (88,000 tons) of paper per year.

There are two options for the paper plant. Either Wong's company will build an integrated mill in the Sacramento Valley that could produce both pulp and paper, or the company will build a pulping facility in the Sacramento Valley and buy an existing paper manufacturing facility in the Los Angeles region which would process the pulp from the Sacramento Valley.

Mr. Wong reports that in the Sacramento Valley, farmers are producing three tons of rice straw per acre. The first Agri-Pulp mill in California will purchase approximately 100,000 tons of straw per year. At $40 per ton delivered, farmers in the region will make a combined total of $4,000,000each year. In the wake of the Sacramento Valley rice straw burning phase down, this represents a windfall for farmers who are being forced to dispose of their straw in new ways. Mr. Wong reasons that in the case of Sacramento Valley rice farmers, the driving force behind selling the straw is environmental and political, but his company gives farmers a cost-attractive option to plowing the straw under. The building of new mills will also provide jobs to the region. An estimated 50 jobs would be created within the pulp mill in Sacramento Valley, 150 people would be employed in the paper mill, and if the company builds another tissue mill, that will create another 150 jobs.

Farmers in the region are pleased to have an end use for the straw that they are prohibited from burning, and Mr. Wong reports that they have been happy just to break even on costs. As a result, there has been discussion of paying the farmers only $30 per ton, and putting the remaining $10 per ton in a trust fund, thereby making the farmers shareholders in Agri-Pulp California. This works well for both sides because it costs the new company less in cash at a time when its start up costs are high, and it gives the farmers both equity and the opportunity to comply with the straw burning phase down. Mr. Wong reports that many of the farmers would really like to see this business thrive, and some look forward to participating in what they see as one solution to extensive logging in California.

The pulping process that Agri-Pulp uses for agricultural residues is remarkably simple. Engineers cook the straw under pressure with potassium sulfite. This process yields cellulose fibers and potassium sulfate, which can be converted into fertilizer. Generally, an Agri-Pulp mill would contract off site to recycle the potassium sulfate, either with private groups or with farmers cooperatives, who then mix the potassium sulfate with nitrogen and phosphorus to make fertilizer. Additionally, whereas conventional kraft pulping mills would experience enormous difficulty with the high silica content of rice straw, the pulping process that Agri-Pulp mills use for rice straw yields potassium silicate, which is a naturally occurring fungicide.

Agri-Pulp has taken an unconventional approach to pricing its products. Although the paper industry usually operates in extremely pronounced pricing cycles, Agri-Pulp California has chosen to set one price for its products and to maintain that set price over a period of years. This goes directly against the tradition of commodity pricing for paper, and has led to complaints by customers who want rock bottom prices for paper. Mr. Wong explains that by setting a standard price, which he can guarantee for five years, he is trying to even out the price cycling.

Agri-Pulp papers meet a barrier in the form of the federal government. President Clinton's Executive Order no. 12873 mandating government procurement of paper with recycled content does not include agricultural residues-based paper as an alternative paper. Although Downtown Paper meets the requirements for recycled content, and can therefore be put up for bid under the Executive Order, paper made with agricultural residues is still not included as an acceptable "alternative fiber" paper under government procurement rules. An amendment to the Executive Order that would support agricultural/ farm-based fiber paper as an acceptable alternative would be a significant boost for straw-based papers.. Until this happens, paper made from agricultural fibers are not considered by the U.S. government to be environmentally preferable papers.

Nevertheless, there are many more customers than there is Agri-Pulp paper. Mr. Wong thinks there is a future market for his paper in California, and that the company may be able to start meeting the skyrocketing demand for his paper within the next few months if all goes well with the Sacramento Valley mill. There is also some interest in building mills in Iowa. Furthermore, the California legislature has passed AB84, which is a procurement bill that gives paper containing agricultural residues an environmentally preferable status. This bill is currently awaiting the governor's signature.

Mr. Wong believes his product will be a viable alternative to paper made from virgin wood pulp. He has calculated that if 50 million tonnes (55 million tons) of straw (in Canada) were converted to papermaking pulp at an average yield of 50 percent, then the potential agri-pulp production would be 25 million tonnes, (27.5 million tons), a number which is equal to the 1995 Canadian production of all wood pulp. Wong has done an analogous calculation for lumber, writing that "if 50 million tonnes (55 million tons) of straw can be converted to a construction-grade lumber [substitute], then the equivalent volume of solid wood would be about 136 million cubic metres."(xxi) All told, using 50 million tonnes (55 million tons) of residue straw could save about a half of a million large Douglas fir trees or about 35 million smaller white spruce trees each year. At this point, Mr. Wong feels that if his company can achieve 10 percent of US market (3M tons), it can be a big influence on the paper market. He thinks that a full 1 percent of the market can be achieved in California alone.

2. Future Fiber Partners (FFP)

The University of Minnesota is currently working as part of a broad midwestern coalition, called Future Fiber Partners (FFP), to study the feasibility of using agricultural wastes for papermaking. Other groups in the coalition include Blandin Paper Company, the Minnesota Wheat and Barley Growers, the Nature Conservancy and the Agricultural Utilization Research Institute (AURI). Two paper companies and some individual farmers have also expressed peripheral interest.

The University is evaluating several pulping and bleaching systems for processing agricultural residues. The most promising technology is called Organosolv, a water ethanol process that yields between 40-50 percent pulp. The fiber produced by this process is short and thin, but quite strong. Although paper made from straw has a low tear strength, researchers expect that paper smoothness with straw pulp will be better than with wood pulp. This will mean that straw-based papers are good for printing and writing grades. Experts predict that straw pulp will always have to be supplemented by longer fibers , but mills can use up to 30 percent straw pulp in a wood fiber mix without seeing significant differences in paper properties. This makes straw an extremely useful and likely substitute for scarce and expensive wood pulp.

In the fall of 1997, the University of Minnesota will begin to research the environmental issues linked to straw pulping. One of the critical questions to be addressed is what will be done with the effluent. Using the Organosolv process, a pulp mill can redistill ethanol out of the effluent, leaving mainly carbohydrates and lignin. This byproduct can be burned or used as fertilizer. Another question is how to bleach the pulp. University researchers want to look at O2 and H202 (hydrogen peroxide) bleaching in order to avoid producing AOX. Studies show that straw pulp actually responds very well to milder environmentally friendly bleaching chemicals. Using pulping and bleaching processes with recyclable chemical inputs will hopefully mean that the University can design a closed loop, TCF mill that releases no effluent.

The University of Minnesota will also investigate the feasibility of building such a mill in Minnesota. At this point, research suggests that the Red River Valley is the ideal site for agricultural residue pulp mills. Armed with this assumption, researchers will test the philosophy that it will be less expensive to build 2-3 small mills, each of which could produce 100-200 tons/day of pulp than to build a standard "wood pulp" type of mill which can produce 1,000 tons/day. The feasibility study will evaluate the price of water, electricity and other utilities relative to assumed mill needs to gauge the affordability of a mill in Minnesota. The study will also attempt to answer important questions on commercial and economic viability such as marketability, pricing, and return on investment.

B. Construction Materials

1. Agriboard Industries

Agriboard Industries is a manufacturer of construction materials currently operating one plant in Electra, TX. The Electra plant produces a structural insulated panel from wheat or rice straw extruded under heat and pressure. The core material, made entirely of straw, measures 3 inches thick and 40 inches wide. The only adhesive in the finished product is used to attach heavy liner board to the core on all four sides. The liner board is a kraft 69 lb. paper, but the company is exploring the possibility of making that paper out of straw as well.

Agriboard can use any cereal fiber cut for feed rather than seed (wheat, barley, rice, hops, etc.), however for logistical reasons the company is restricted to using residues from a 50 mile radius. In Electra, this means that the plant must use local wheat straw. Advances in collection technology may make it more feasible to expand the radius; the large Heston baler makes 4x4x8 ft. "Texas" bales which leads to more convenient handling, fewer transportation problems, and improved inventory control since straw in this form can be stacked on property 4-5 bales high.

The Electra plant buys its agricultural residue through a wheat producer, who has connections with wheat farmers in the area. The tonnage price is negotiated on annual basis, but on average Agriboard is paying approximately $45/ton of delivered straw. The area around Electra sees wheat straw yields of anywhere between to 2 tons per acre (irrigated wheat is higher yielding, but the farmers Agriboard purchases from grow dry land wheat.). This year, the yield has been about 1 ton per acre due to a late freeze that has affected production. The factory's order for straw this year is 12,000 tons, which means that the residue from about 12,000 acres has been put to efficient use rather than burned or otherwise disposed of. It also means that local farmers received $540,000 for selling their agricultural residues.

Local farmers are extremely enthusiastic about the new market for straw. In 1997, farmers expect to make more from sale of the byproduct than from the crop itself. New laws in many states mandate that farmers have to pay to dispose of crop residues that cannot be burnt. Agriboard offers an alternative by creating markets for agricultural residues.

The plant in Electra has drawn a lot of attention from states that are attempting to phase out in-field burning. For example, the State of California recently approached Agriboard about building a facility in intensive grain growing regions. The California Trade and Commerce Commission is currently considering approval of a plant in California. Agriboard sources hope that the plant, slated to be built in the Sacramento Valley, will be ready next year. The company is also working on starting mills in Ohio, South Dakota, and overseas. Furthermore, Agriboard has a contract with Raytheon Construction for 10 plants over the next five years. The main criteria for a new plant are that there be abundant agricultural residues within a 50 mile radius of the plant, and that there be a strong construction market within a 500 mile radius of the plant. In its existing mill in Electra, Agriboard plans to add an additional line to increase production and eventually gear up to three around-the-clock production lines.

Demand is extremely high for Agriboard products, and the company has had to turn down business. Agriboard is entertaining approximately $40 M in contracts right now (the company is currently producing panels to meet $5.5 million in signed contracts) The new interest in green buildings has created a huge demand, resulting in the company's reception of over 4,600 inquiries for information about their product from homebuyers and the commercial industry via internet, telephone, and trade shows.

Despite the obvious and overwhelming demand for the product, Agriboard Industries has encountered some barriers to conducting business. In state of Iowa, where Agriboard first attempted to build a plant, bankers do not loan money for start-up companies. As a result, the plant was developed in TX, where resources were available. As a startup company, resources are limited. However, Agriboard is affiliated with AARC and has gotten equity investment grants and loans from them. Regardless of obstacles, Agriboard has high hopes for success, both economic and environmental. The company aims to have a profound effect on the building industry. And since Agriboard's product can reduce the use of framing lumber by up to 90 percent in a structure, this product will have a profound affect on the conservation of our natural resources.

2. PrimeBoard, Inc.

WheatBoard(TM) is an engineered composite panel-particleboard alternative made from wheat straw. The producers of WheatBoard, PrimeBoard, Inc. collect the wheat straw from farms within a 60-mile radius of Wahpeton, ND. Currently, the company buys 50,000 tons of straw per year at a price of $30/ton (delivered). This represents an additional $1.5 M source of income for local wheat farmers. In addition to providing an economic benefit to farmers, the harvesting of wheat straw facilitates the planting of sugar beets, which are often the following crop in local farmers' rotations.

WheatBoard is produced as follows: first, straw is refined to bring it to the proper particle size; then MDI (formaldehyde-free) resin is added; finally the straw mixture is put into a press, sanded, cut to size, and packaged. In addition to the finished product, the process also creates wheat dust, which can either be used as energy to heat the plant or as an additive in cattle feed supplements.

WheatBoard is used in applications in furniture, windows, doors, mill work, counter tops, and cabinets. It competes with particleboard/fiberboard or Medium Density Fiberboard (MDF), but it tests in the particleboard category. The plant in Wahpeton has 30 million square feet of production capacity of WheatBoard annually, but demand remains higher than production. To remedy this situation, the manufacturer plans to double capacity by adding another line of production. Although WheatBoard is currently more expensive than particleboard, it stands up better to moisture than wood products, offers excellent machining qualities, and is lighter in weight (up to 20 percent). Furthermore, market projections indicate that as this portion of the industry continues to grow, WheatBoard will become increasingly more price-competitive.

3. Pierce International/Stramit Industries

Stramit Industries has been operating in Europe for years, producing a product made of straw that replaces drywall and 2x4s. Only in 1983 did Stramit Industries begin to export its product to the United States, and now it appears that the first Stramit Industries plants will go on-line in the United States in 1998. Pierce International/Stramit Industries has been conducting research in the United States for the last four years to determine ideal sites for mills based on product marketability, raw material availability, and other factors. The first plants will be built in Idaho, Washington State, and Virginia, followed by plants in Ohio, Kansas and Utah in 1999. When those plants have been built, they will source their wheat straw from within a maximum 50-mile radius of the plant.

A spokesperson for Pierce International says that each new plant will contain the same basic equipment but will be managed by the owners and operators of the plant. For example, although the majority of the owners of plants will be farmers, some have chosen to run plants as cooperatives, while others have chosen to run plants as corporations.

Once a plant is in operation, it will require 15,000 tons of agricultural residue per machine operation per year. Because climates and growing patterns and practices change by region, it is difficult to predict the average acreage needed to produce this amount of agricultural residue. However, Pierce International expects that the owners of the processing plants will pay between $25 and $40 per ton of delivered straw. This means that each group of participating local farmers will receive between $375,000 and $600,000 additional income per year.

As seems to be the trend in other agricultural residues ventures, some of the farmers who will supply agricultural residues to the local plants will take stock options in lieu of cash payments for straw, or in combination with cash payments. According to Pierce International, most farmers are just happy to know there is a place to take their residues, and would rather reserve an investment position for later than take the cash for straw.

In the Stramit Industries process, wheat straw is heated, compressed, and turned into a building panel, all without the addition of glue. As mentioned before, the panels replace drywall and 2x4s, but they can also be used as office partitions (with high sound reduction), doors, and storage sheds. Although dry wall is undeniably cheaper than the Stramit Industries panels, one SI panel effectively replaces two panels of dry wall and four 2x4s. Additionally, SI panels can be reused again and again, and the panels provide noticeable sound reduction and a noticeable difference in insulating. Finally, after factoring in labor (framing costs), the rule of thumb savings will be approximately 18-20 percent for standard home using Stramit Industries panels.

Demand is high for Stramit Industries panels. The United States group has been taking orders for the past year and expects that demand will outpace supply. Although the panels have been imported since 1983, the imports are expensive, and will clearly be cheaper when they are produced domestically. As the demand for U.S.-produced panels rises, the domestic arm will be able to add on more production lines to existing plants.

In recent years builders and contractors have expressed frustration about the low-quality lumber that has flooded the market. Stramit Industries panels may provide some hope for builders looking for reliable materials, and the Pierce International spokesperson notes that the company receives daily requests for information from architects, the construction industry, and schools of architecture.

Conclusion


Agricultural residues are a promising alternative to virgin wood fiber as an industrial feedstock. Residues are abundant, cheap, and their use will yield economic as well as environmental dividends. To utilize this resource fully, however, we must answer some pressing questions and take direct steps towards promoting agricultural wastes as a viable fiber source.

One of the big gaps in the data is how much straw is available each year in the United States. Related to this issue are the following questions: where is the straw grown? what is the right amount to leave on fields? does this number change according to the region? Without answers to these questions, the demand reduction community is left with little information about how large or small a role agricultural residues can play as a substitute for virgin wood fibers. Once these data are collected we will be able to make reasonable, verifiable predictions about agricultural residues' efficacy as alternative fiber.

Information about individual types of fibers is also critical. There are differences between all of the types of agricultural residues discussed in this paper. Some of these differences will become apparent in the strength of the products for which they are used as feedstocks. More data about strength and other properties of different fibers will help producers make decisions about which is most appropriately used for their product. Other remaining questions include how to reduce the cost and energy use of transportation of agricultural residues and how to cost-effectively bring together urban recycled fibers with rural agricultural residues.

To find solutions to these problems, farmers, producers, entrepreneurs and environmentalists will require funding for research and marketing. Most of the projects currently testing or actively using agricultural residues are local in scope. Private, state and federal funding are needed for projects that will make information about these projects available on the national level. This type of information dissemination will save time, money and resources and will allow local groups to avoid duplication of effort. In addition, producers of paper and construction materials who use agricultural residues will need funds for product development, testing and marketing. Finally, grassroots and national environmental, consumer, and rural development advocates will need to launch campaigns to alert the public to the many benefits of using agricultural residues as an industrial feedstock and an alternative to virgin wood fiber.

Endnotes


i. Based on Agri-Pulp case study, section VI.A.1

ii. International Institute for Environment and Development, "Towards a Sustainable Paper Cycle," p. 32: 1996

iii. See Thomas Michael Power, "The Wealth of Nature," Issues in Science and Technology, Spring 1996, pp. 48-54

iv. Alex Wilson, "Straw: The Next Great Building Material" in Environmental Building News vol.4, no. 3 (May/June 1995)

v. Al Wong, "The Agri-pulp Newsprint Alternative." Presented at the Newspaper Association of America Super Conference, Miami, FL. March 6, 1996

vi. Stephan Albrecht, et al. "Is Burning an Effective Management Practice for the Pacific Northwest Cereal Region?" Agricultural Research Service report number: 0000061281. See also Paul Rasmussen, et al. "Effect of Annual Burn No-Till Wheat on Soil Organic Matter Content and Bulk Density." Agricultural Research Service report number: 0000078618.

vii. Personal communication with Al Wong, 9/29/97. Personal communication with Chuck Henry, 10/15/97. See also David Morris "The Coming Fiber Revolution," speech given at the Future Fibers Conference, Monterey, CA. June 2, 1997

viii. Al Wong, "Agricultural Fibre Supply for Pulp Production." Presented at the Fiber Futures '97 Conference, Monterey, CA. June 2, 1997

ix. Paul Patterson, et al. "The Availability, Alternative Uses and Value of Straw in Idaho." College of Agriculture, University of Idaho. September 18, 1995

x. Institute for Local Self-Reliance, The Carbohydrate Economy, volume no.1, issue no.1, fall 1997, p. 14

xi. Alex Wilson, "Straw: The Next Great Building Material" in Environmental Building News vol.4, no. 3 (May/June 1995)

xii. Jon Matthews, "Rice fields may burn in spring: Bill promises to help farmers, not hurt air," The Sacramento Bee. July 18, 1997

xiii. Al Wong, "The Agri-pulp Newsprint Alternative." Presented at the Newspaper Association of America Super Conference, Miami, FL. March 6, 1996

xiv. Rainforest Action Network/Turner Foundation. Cut Waste, Not Trees. Page 4: 1995. See also World Resources Institute, "The Last Frontier Forests: Ecosystems & Economies on the Edge," page 20: 1997

xv. R. Bruener, "Fiber Supply Crisis in the Pacific Northwest--Options & Solutions," presented at the 47th Annual Seminar of the Pacific Section of Tappi, Seattle, WA, 1994

xvi. 140 million tons estimate: Alex Wilson, "Straw: The Next Great Building Material" in Environmental Building News vol.4, no. 3 (May/June 1995). 260 million tonnes estimate: Al Wong, "Agricultural Fibre Supply for Pulp Production." Presented at the Fiber Futures '97 Conference, Monterey, CA. June 2, 1997

xvii. Institute for Local Self-Reliance, The Carbohydrate Economy, volume no.1, issue no.1, fall 1997, p. 14

xviii. 123 million tons estimate: Economic Research Service, "Straw and Kenaf Make Inroads in Building Materials and Paper," in Industrial Uses of Agricultural Materials: Situation and Outlook Report, page17: 1997. 235 million tons estimate: Al Wong, "Agricultural Fibre Supply for Pulp Production." Presented at the Fiber Futures '97 Conference, Monterey, CA. June 2, 1997

xix. See Paul Patterson, et al. "The Availability, Alternative Uses and Value of Straw in Idaho." College of Agriculture, University of Idaho. September 18, 1995

xx. Jay Jeyasingam, "Problems facing non-wood pulp and paper mills due to the presence of silica: from raw material preparation to the finishing of paper," in Tappi Proceedings: 1985 Pulping Conference (Book 2). Tappi Press: 1985. See also Ashok Kulkarni, et al. "Appropriate Technologies for Pulping and Paper Making of Unconventional Raw Materials in India," in Tappi Proceedings: 1990 Pulping Conference (Book 1). Tappi Press: 1990

xxi. Al Wong, "Agricultural Fibre Supply for Pulp Production." Presented at the Fiber Futures '97 Conference, Monterey, CA. June 2, 1997