The U.S. forest products industry is already the nation’s largest producer of renewable energy and the southern region is no exception. For many decades, the forest products industry has been utilizing, harvesting and manufacturing residues in boilers and kilns for on-site energy usage as well as selling excess energy into the grid. This trend is increasing in light of the recent and expected future volatility in other energy sources such as coal and natural gas.
Against this backdrop are a number of published studies on logging residuals available for bioenergy. What is increasingly obvious is that the amount of truly available logging residues will be nowhere near enough to supply the current and announced bioenergy processors in the Southern U.S. This indicates that appropriate technology for short-rotation bioenergy plantations must be rapidly developed to fill this growing need.
Article Continues After Advertisement
Forest Plantation Concept—Tried and Tested
Forest plantations have been sustainably grown in many parts of the world. While exact records do not exist, it is commonly understood that the Japanese have been planting forests since the 10th century. Forest yields continue to increase on these sustainably managed acres.
In the Southern U.S., the history of forest products and forest plantations is long and successful. It is projected that more than one-half of the wood harvested for processing will be obtained from planted forests in this region. This could not have been possible without the utilization of outreach, education and research from land grant universities, the U.S.
Forest Service, state forestry services, private and state forestry associations and the participation of literally millions of private landowners as well as large timber land companies.
The typical forest plantation today in the Southern U.S. is planted to loblolly pine (Pinus taeda L.) on average at 600 seedlings per acre, on a 25-year rotation with a thinning at the age of 15 years. The thinning typically removes trees for pulpwood while the final harvest is for saw timber and pulpwood. This management scheme has been derived to fill the wood needs of current processors in pulp and lumber. In addition, plantation acres have been established for other conifer or hardwood species in the Southern U.S.
This work is supported by highly trained forestry and logging professionals and land grant universities, amongst others, that yearly yield more than 100 masters and doctoral students.
Novel Idea, But Not New
Bioenergy forest plantations have been practiced in the Southern U.S. since the oil embargoes in the 1970s. In countries such as Brazil and South Africa, eucalyptus plantations have been managed for bioenergy production for decades. What makes the current Southern U.S. situation novel is the short timetable given to develop existing genetic improvement programs and their required silvicultural systems for widespread early adaptation. A forest bioenergy plantation can take 18 months to eight years to reach financial maturity, and the sooner it is planted the sooner it will be ready for commercial harvest.
The tried and tested forest plantation concept in the Southern U.S. produces conifer wood because it is the backbone of the forest products industry for both pulp and lumber. The bioenergy plantation, however, will be more complex and many questions need to be addressed. Does the bioenergy stream allow bark, branches, leaves and wood or is only wood preferred? Does the bioenergy stream need higher lignin content typical for certain species and tree ages? What will be the usage of the ash in co-generation or single-source biomass combustion? How will the development of enzymes change the tree species or rotation age? What are the logistics of harvesting and transporting feedstock cost effectively?
At this time, a number of landowners, research institutions and government entities are researching forest bioenergy plantation management schemes. Early phase testing is also underway on feedstock suitability for wood pellets, cellulosic ethanol and combustion. These research efforts are rapidly expanding due to both research funding and private company research interests.
The forest bioenergy plantation will have more trees per acre, possibly 1,000 to 2,000, and shorter rotations. In fact, for hardwood species that re-sprout (coppice) after harvest, the rotation lengths can be 18 to 36 months. New harvesting systems are being developed for this smaller material and most of these have an on-site chipping or grinding capacity so that the delivered feedstock is ready to be processed directly into bioenergy.
| 1 2 | Next Page --> | |
| View Entire Article | ||