Transcript Woody Biomass Cropping systems for the Southeast

Woody Bioenergy Crops for the Southeastern United States
Mark
1
Coleman
and Keith
2
Kline
1USDA-Forest
Service, 241 Gateway Drive, Aiken, SC 29803; [email protected]
2Oak Ridge National Lab, Oak Ridge, TN 37831-6038; [email protected]
Introduction
Short-Rotation Woody Crops Production Systems
Biomass is an important alternative energy resource that can offset
greenhouse gas emissions from fossil fuels, provide crop options for
marginal farmlands and improve rural economies. Forests cover nearly
60% of the southeastern US. Woody energy crops include fast growing
native species that have shown large productivity gains from improved
genetic resources and cultural practices. Woody feedstocks offer many
advantages compared to other types of biomass and options for
conversion to various types of energy (liquid fuels, electric power, and
other bio-products) are possible. Here we summarize accumulated
learning from southeastern practitioners’ experiences with woody
cropping systems and discuss examples of many of the most promising
woody energy crop species.
• Southern Pines
• Hardwoods
• Coppice
Pine
Process Benefits
• Adaptability of species
to regional areas
• Lower ash content
• Year-round availability
• Stable, consistent
feedstock supply
• High density products
• Easy to store
• Easy to handle
• Mix with the other
woody feedstocks
Sampling
soil sweetgum
Hardwood
Enhanced Pine Production Potential
• Poplar, Eucalyptus,
Sycamore, Sweetgum
• Large growth potential
• Forest operations
equipment
• Genomic resources
• Relatively low input crops
• Genomic Resources
• Multiple market options
Environmental
Benefits
• Protect soil, water and air
•
•
•
•
•
quality
Sustainable production
systems
Sequester carbon
Create wildlife habitat
Increase diversity
landscape
biological
soil microbial and
mesofauna
Improve productivity of
marginal farmland
Energy Conversion of Woody Biomass
• Combustion boilers
• Gasification
 Synthesis gas: 20% H2, 20% C0, 5%
CH3
• Pyrolysis: Bio-oil & Char
 Bio-Oil is a crude containing high value
chemicals
• Biofuels
• Biochemical processes requiring:
 Cellulosic enzymes
 Distillation energy
• Thermochemical process
 Catalytic conversion of synthesis gas
 Alcohols and diesel
Cuttings
for planting
• Elite genetic selections
• Adapted to wide range
of sites
• Variety of selective
herbicides
• Developed operations
Advantages of Using Woody Crops for Bioenergy
• Provide diversity of feedstocks
• Location and geographic distributive
advantages
Coppice
After cut
Willow
• Vegetative propagation
• High density planting
(6000 trees/acre)
• Cut every 3 to 4 years
• Replanting required after 25 years
• Efficient harvesting equipment
• Experience to date has been
with northern temperate culture
• Willow native to southern US,
merits research
• Sycamore coppice yields twice
that of seedlings
Late in year 2
Year 3
Harvester
Eucalyptus
Range
Positive Response to culture treatments
Herbicides
Orlando, FL
• 2 ½-year-old Eucalyptus
Grandis
• Growth Rates of 2 to 3”
diameter/year
• 7.2 dry tons/acre/year
Bainbridge, GA
• 4.5-year-old
• survived > 150 freezing
nights
• 1.7 – 2.7 diameter per year
• 7 dry tons/acre/year
Fertilization
Practitioners Survey
Eucalyptus
E. amplifolia
E. viminalis
E. nova-anglica
E. macarthurii
E. camphora
• Numerous forestry practitioners were interviewed about the potential for
woody energy crops in the southeastern US.
• In total, over 250 person-years of southeastern forestry research experience.
• Each was asked to name potential crop species, management requirements,
expected productivity rates and factors impacting yields.
• The table summarizes results.
Table 1. Summary of practitioner
survey of potential for
woody energy crop species
for southeastern US.
Woody Plantation
Crop
Expected Production
(dry Mg/hectare-yr)
Low Avg. High
Production
Costs
($dry/Mg)
Cottonwood and
Hybrid Poplars
Sycamore
6
9
12
15-95
• Broad genetic resources
7
9
11
15-95
• Rapid early growth
Sweetgum
4
6
8
15-65
Eucalyptus
18
22
25
15-65
Hybrid Aspen
9
10
12
no data
• Broad site requirement
• Disease resistance
• Broad site requirement
• High growth
• Broad site requirement
Loblolly Pine
8
9
10
10-40
Advantages
• Operational infrastructure
• Broad genetic resources
Sycamore
Disadvantages
• Narrow site requirements
• Disease susceptible
• Narrow site requirements
• Disease susceptible
• Relatively slow growth
• Restricted by frost
• Undeveloped genetic material
Pine & Sweetgum
trials - year 12
Conclusions
• Several woody crops offer high growth potential in the southeastern US under
proper silviculture but costs for hardwood plantations may be prohibitive.
• Loblolly pine has the most developed infrastructure. It can be grown at lower
cost and at higher rates on the largest variety of sites.
• Bottomland hardwoods such as cottonwood and sycamore are limited by site
and soil requirements and disease.
• Eucalyptus out performs other species in biomass output/year but is limited
by frost to Florida and a narrow band along the gulf coast.
• Coppice crops offer potential to rapidly expand production but require
research to identify the best species and cultivars for a given locale and to
develop appropriate cultural practices and operational equipment.
• Extensive natural hardwood and mixed forest resources in the southeast also
merit further study for potential contributions to bioenergy.