Waste wood, biomass crops approaching viability as fuels
R.C. Rittenhouse, Managing Editor
Waste wood goes into landfills in many parts of the United States; a loss of a potentially valuable energy source. However, Savannah Electric reports successful completion of basic research into methods for using discarded wood as boiler fuel. Aided by a consulting firm, Fiber Fuel International, Savannah`s staff mixed pulverized wood and coal and fired it in a boiler at the company`s Plant Kraft. An initial three-day test burn, conducted more than a year ago, consumed 5,500 pulverized, nonreusable wood pallets from Savannah, Ga.`s, seaport. The boiler burned 17 ton/hr of wood at one point during the test.
Several advantages exist for burning scrap wood (e.g. tree trimmings, retired utility poles) at coal-fired power plants. On the Savannah system, the benefits range from reducing NOx emissions to allowing peaking plants to operate as base load units. The latter advantage results from savings in fuel transportation costs. The expense of moving coal to these power plants forced their use as standby units and access to ample nearby supplies of waste wood greatly reduces that cost.
Surveys of the area show that almost 1.4 million tons of wood waste is produced each year within 150 miles of Savannah, Ga. Primary sources include pulp and paper industries, and utility companies of the Southern Co. Plans are to take advantage of this available fuel. Site selection is underway for a wood yard to service Plant Kraft, which is earmarked to burn 30,000 tons of dry pulverized wood during the 1996 peak season. The wood yard must eventually process 600,000 tons/year of wood waste when fully operational.
Environmental advantages gained, beyond reduced emissions, have pleased the Georgia Forestry Commission and others. The project can help to eliminate wood from landfills. In addition, landowners who harvest trees could plant new crops sooner, because they will have a source for quick disposal of waste. This also avoids the comparatively high landfill costs.
Woody biomass crops
Landowners eventually could become involved in another endeavor to enhance the environment; growing trees expressly for use as an energy source. Advocates of this well known concept now introduce the hope of developing crops that are cost competitive with other energy sources. According to the Electric Power Research Institute (EPRI), costs of developmental energy crops have dropped to $2 to $3.50 million/Btu. Coal is at $1 million/Btu and natural gas is at $2 million/Btu.
Various sources acknowledge that biomass energy crops could reduce some forms of stack emissions compared to coal. This includes roughly 6,000 ton/yr of SO2 for each megawatt of capacity. Before that can happen, the crops must be made more economically viable as a fuel. Hopes of improving woody crop yields lie in recommendations of a report from EPRI`s Renewable Energy Program. With a title as long as this “Environmentally Speaking” column, the report discusses the benefits to be gained from genetically engineered woody biomass crops. Engineering involving gene transfer can increase growth, improve disease resistance, and enhance drought tolerance of trees.
Research at Washington State University and the University of Washington`s College of Forestry has continued since 1978. The work improved crop yields. Native cottonwood yields were 3 tons/acre, but the growth of selected hybrids reached 8 to 11 dry tons/acre. Those involved in this highly specialized work see genetic engineering as the answer to biomass fuels in many regions of the United States. However, all of those who attended a recent workshop agreed that an “interdisciplinary approach is essential” to founding a new biomass fuels industry.
Much is yet to be learned about gene flow among woody species. Meanwhile, geneticists and agronomists, who have laid the groundwork, feel that ecologists and biologists as well as regulators must become involved in the effort. To this end, recommendations for guiding principles to provide safeguards for large scale biomass testing were written. The authors are Steve Strauss of Oregon State University, Milton Gordon of the University of Washington, Dan Robison of State University of New York, Syracuse, and Don Riemenschneider of the U. S. Forest Service.
Contact the EPRI Distribution Center at (510) 934-4212 for Report TR-104896. Call Michell Wu at (415) 855-2180 for a copy of the principles.
Tropical rain forests
The Smithsonian Tropical Research Institute seeks more precise measures of exactly how much CO2 trees actually absorb and convert to wood fiber. Researchers have known for years that vegetation does this, but they lack specific numbers. Southern Co. wants to know and, for this reason, has contributed $300,000 to Smithsonian for its research of tropical rain forests. If a formula can be developed to show how much CO2 a given number of trees absorbs, then utilities that plant trees can show how much of a contribution to the environment these trees actually make.
The study began in October 1994 and continues through 1997 in Panama, Ecuador, Sri Lanka and other areas. Development of enhanced data may help to improve economic evaluation of tropical forests as critical defenders against global warming and so-called greenhouse gases. Without precise numbers, economic calculations show that a rain forest is more valuable when cleared for agriculture and the wood is sold. That conversion is worth $3,000 a hectare. Sus tainable timber use of the land is worth $2000 and preservation of the forest is worth $1,500, including all aspects of environment, water conservation and tourism. END
Report on mercury
Mercury Atmospheric Processes: A Synthesis Report summarizes the findings of a panel of atmospheric scientists as expressed in a March 1994, workshop. The Florida Electric Power Coordinating Group co-funded the meeting along with EPRI, several state groups and a Canadian organization. State-of-the-science information on mercury emissions and their transport, deposition, patterns and other scientific data are examined in detail. This report, important to those who must anticipate changing regulatory demands, is available from the EPRI Distribution Center, 207 Coggins Drive, P.O. Box 23205, Pleasant Hill, Calif. 94523, or call (510) 934-4212.