Summer 2009

Volume 18 No. 2

Editorial Note: Part I in this series, “Wood as a Fuel Source,” was published in the preceding issue of the Woodland Steward. It reviewed the BTU value of wood and how that compares to selected fossil fuels.

The closing of the International Paper Mill at Terre Haute, Indiana, and one hundred other pulp and paper facilities throughout the United States in the last five years provided us with a reason to look at how the closure affected the remaining wood products industry within a sixty mile radius of Terre Haute and what the energy potential of the resource used by the Terre Haute mill might be (Hardwood Review Weekly, 2006; Meadows, 2008). Paper mills provide typically both a demand for pulp chips for paper making and boiler fuel. This demand was important to the local forest products industry that supported the International Paper Mill.

In the process of converting logs into lumber, three potential energy products are produced. These are bark, sawdust, and chips from slabs, edgings, and end trimmings. In addition, most of the tops and other logging slash produced from commercial harvesting is left in the woods to rot. In the area surrounding Terre Haute, there is also a surplus growth of standing timber. All of these components have energy value in spite of their relatively high moisture content. In addition, the secondary manufacturing industry such as furniture and cabinet plants can also produce substantial quantities of dry wood residues. From an industry wide perspective, most of this material is already being used as fuel or animal bedding. Unlike north central and southern Indiana, there are not a significant number of secondary manufacturers in the Terre Haute area, and we did not investigate this resource.

The Terre Haute mill was built in 1917 and by today’s standards, is relatively small. It produced about 200,000 tons of corrugated medium per year. Medium is the inner ply between the outside plys in cardboard. This medium was made using recycled cardboard fibers and wood pulp chips. The mill’s annual consumption of pulpwood was 150 to 170,000 green tons per year. Historic consumption peaked at 200,000 green tons annually. In recent years, nearly 75% of this material came from saw mill residues and whole tree chipping operations within a 60 mile radius of the mill.

This amount of wood could supply a 15 MW power plant. This size plant is considered small in comparison to standard coal fired generating facilities. Nationally, most biomass fired plants are in the 5 to 30 MW range size. This 15 MW size would be equivalent to about 35% of the coal fueled generating plant capacity at Purdue University.

Disposal of sawmill wood chips by producing mills is mandatory. With a typical mill producing a semi load every day, the chips have to go someplace. Research showed that 38 percent of the sawmills in the study area were redirecting their chips to another pulp mill in Hawesville, Kentucky. The average haul distance increased from about 60 miles to 200 miles. Most mill owners indicated wood chip net revenue declined or was nearly consumed by the additional freight costs. Another 32% percent of the sawmills indicated moving their wood chips to a landscape market use. The remaining respondents were already supplying the Hawesville mill, before closure of the mill in Terre Haute.

Sawdust from the Terre Haute area presents another problem since it is mostly used as boiler fuel. Most of it is also hauled to Hawesville as boiler fuel with very little return to the mills. Demand for bedding by local live stock producers has continued, therefore, there is less impact to saw mills than for chip residue.

Bark is not used for pulp and paper production but at times it can be used for boiler fuel at paper mills. Generally, most bark is used for landscape purposes and to a lesser degree in bedding applications. Disposal of bark was not found to be an issue for the producers.

Whole tree chipping operations who supplied the Terre Haute mill are idle, as the Hawesville mill cannot accept chips with bark as produced by these operations. At the time of the study, some operators were considering adding bark removal equipment. Distance to the Kentucky mill is a disadvantage.

Additional Sources of Wood Fuel

In addition to the wood chips previously being used by the Terre Haute mill, there are other large sources of wood suitable for energy production. These include tops left from saw log and veneer log harvesting, thinning, and yes, surplus growth.

If just 50 percent of the tops left from saw log and veneer log harvest are utilized in the study region, another 148,000 dry tons of wood and bark become available. This is nearly equal to the consumption of saw log and whole tree chips previously used by the Terre Haute mill.

If surplus growth is considered, another 366,000 dry tons per year become available. Surplus growth is annual volume growth above current removal (harvest) rate. This estimate assumes that the saw timber volume is harvested and that only one-half of the remaining residue is removed. As conservative managers, not many would support harvesting at this high level. The fact remains, however, that this amount of wood could be removed and the resource would remain sustainable. Indiana has a positive surplus growth, whereas the current cut of southern pine timber is very close to or exceeds growth.

Table 1 is a summary of the sawmill residues, harvest residues and surplus growth available within a 60 mile radius of the Terre Haute mill. The megawatts of electricity that could be produced by direct firing of the material and an estimated value to the producer are also given.

Due to certain reduced regulatory requirements, legislative requirements for green energy, and consumer interest in green energy, a 15 MW power plant is not inconceivable. However, from the example given earlier, wood residues are not competitive with Indiana coal for electrical power generation. Potential legislated demand for “green” energy may change the situation. Forest residues and some portion of surplus growth and sawmill residue volumes, expands the potential supply volume. These volumes could support a significant wood biomass facility. However, commercial and residential applications are now economically viable when compared to natural gas.

Various companies or individuals have expressed public interest in the use of woody biomass as an energy source. Two companies were investigating the use of biomass to produce wood pellets in the Greencastle, IN area. In northeast IN an ethanol plant was looking at considering the core of all types of biomass as boiler fuel. None of these efforts have materialized at this time. However, Liberty Green Renewables LLC announced that it would build a wood biomass fired 28 MW plant near Milltown in Crawford County, IN. Additional information is available at http://www.insideindianabusiness.com/newsitem.asp?id=33235&ts=true and http://www.corydondemocrat.com/Articles-i-2008-12-30-209355.114125_Renewable_energy_company_plans_facility_near_Milltown.html#mail.

The conversion of woody biomass to liquid fuels is not a current reality, but research continues and hopefully, progress is being made.

Other Considerations

Until recently grain, land and food prices have all escalated. As the economy recovers and/or oil prices increase, the escalation of land and food prices will resume. The large growth of corn ethanol production has increased the demand for corn grain, raising corn prices and concerns with respect to food price increases. Substantial research is directed at developing and producing other crops such as switch grass, and hybrid poplar as energy feedstock for liquid fuel production. Existing and future agriculture crops all compete for a relatively fixed amount of available agricultural land. The use of wood residues for energy production, especially those left from current harvesting operations and surplus growth, will not compete for available agricultural land. This resource is available now; generally it is available 24/7 and 365 days a year. The technology to harvest, transport and burn wood as fuel, is well known. Just-in-time harvest for consumption at a bio-refinery would eliminate storage cost and management that is quite expensive for lignocellulosic biomass. Its use would generate employment, mostly in rural areas were few other opportunities exist. Given the current cost structure and regulatory environment, it will not compete with coal. However, if some mix of “green” energy is required, especially if Indiana establishes a renewable electricity standard (RES), it has potential for use as a power plant fuel co-fired with coal in existing boilers. Because of its physical properties and higher density, it can be fed into coal fired boilers using existing coal feeding equipment. Research found that paper mill closure is a bio-energy opportunity.

From a negative standpoint, we do not fully understand the impact of forest residue removal on future site productivity, wildlife habitat, forest flora and other potential ecological impacts. Utilization of the resource ultimately depends on economics, legislation requiring “green” energy, and government subsidies. With the growing interest in renewable energy and the vast experience gained in using wood as a fuel, woody biomass can provide a low cost barrier entry feedstock for power generation in existing systems.

References

FIA Data and Tools, Forest Inventory Data Online. USDA Forest Service, Forest Inventory and Analysis. Accessed March 2008 from http://www.fia.fs.fed.us/tools-data.

Hardwood Review Weekly. 2006. The Future of North American Pulp and Paper Production. 20 (49): pp 1, 21, 23.

Meadows, Edwin Lee. 2008. Central States mill closure and opportunity for bio-energy. M.S. thesis, Purdue University, West Lafayette, IN. 85pp.

 Home