The Sustainability Analysis team will evaluate the economic feasibility, along with the social and environmental impacts, of the three proposed in-woods biomass conversion technologies being studied in Conversion Technologies. Incorporated into these evaluations will be integrated analyses of the sorting, collection and comminution operations being studied in Feedstock Development. A life cycle analysis will be performed to identify tradeoffs between uses from both an economic and environmental perspective. A community outreach program will help to identify local concerns as well as establish effective communications between the project team and the local community(ies) and promote the adoption of the conversion technologies.
The short-term economic viability of the proposed technologies requires that the revenue stream generated from each conversion technology exceeds the capital and operating costs associated with that particular technology. An understanding of the potential demand for bioenergy products within domestic and international markets is important in developing business strategies for bringing these products to market. Finally, the long-term economic success and sustainability of the proposed conversion technologies requires assessing the social, environmental, and economic viability (micro- and macro-level) of each technology.
The avoided cost aspect of producing bioenergy products from forest residues must be considered when estimating the total economic costs and benefits of these products. The literature identifies the avoided costs due to reduced greenhouse gas emissions from bioenergy products (where they directly replace fossil fuels) as an important environmental and economic aspect. Potential benefits of producing bioenergy products from forest residues and thinnings include: avoided costs associated with the disposal of forest residue (from thinning or harvesting operations), avoided costs of uncontrolled catastrophic fires by thinning overstocked forests, and avoided costs associated with forest diseases like infestation of pine beetle. Other benefits include avoided costs associated with transportation disruptions and displacement of sensitive industries (e.g., tourism) due to poor air quality. Finally, some bioenergy products (e.g., biochar), when applied to the surface in land restoration projects, can help reduce eutrophication of lakes, impoundments, and slow moving bodies of water by fixing phosphorous and nitrogen from fertilizers in the soil and preventing their rapid runoff during periods of heavy rains. These avoided costs and environmental benefits are important factors to consider when measuring the true socioeconomic benefits and long-term profitability of the bioenergy products being proposed in this project.
Biomass harvesting affects complex ecological processes that determine forest development and productivity. Historical and recent studies show that, in some cases, forest biomass removal has negative impacts on soil productivity due to the loss of surface organic matter. However, biomass removal can also enhance seedling growth and have minimal impacts on soil nutrient pools. Much less is known about the effect of removal of small diameter woody biomass on soil and site quality. Removing excess woody biomass (live trees, dead trees, or both) from forests can decrease wildfire hazard if the treatments address surface, ladder, and crown fuels and increase disease resilience if resistant species are promoted.
Production of briquettes and torrefied pellets will result in removal of some biomass, although biochar can be returned to the forest as a soil amendment. Impacts on the soils in particular need to be evaluated if biochar is to be used on a large scale as a forest soil amendment. An important environmental and economic aspect of bioenergy products is the potential carbon sequestration benefits. For example, Woolf indicated that global implementation of bioenergy-based carbon sequestration could offset as much as 12% of current anthropogenic carbon emissions equivalent. Other recent studies have estimated that by using appropriate strategies, the global technical potential for carbon mitigation in agriculture could be 4,500–6,000 Mt CO2 equivalent per year by 2030 and bioenergy products could play a significant role in this effort. For example, recent research has highlighted the effectiveness of biochar as a soil amendment in helping to achieve higher levels of carbon sequestration in agriculture and forestry.
Research is needed to better understand the impacts of biochar as an amendment to forest soils. While some work has been done, especially on agricultural soils, far less research has been done with interactions of biochar and forest soils. Because biochar changes a soil’s cation retention characteristics, elemental analysis for beneficial nutrient levels is necessary as well as analysis of possible contaminants such as mercury, cadmium, and arsenic that could be deposited by prevailing winds. In addition, biochar can alter soil waterholding capacity, particularly in low fertility, coarse-textured soils. Given that forests are important regulators of water quality and flow, an understanding of the positive, as well as possible negative, interactions of forest soils and biochar is especially important.
To achieve some of the project’s Sustainability Analysis objectives will require innovative approaches in economic feasibility, ecological, and life cycle analyses. The economic analysis will be novel in that it will be using the breakeven costs generated by one processing operation as input costs for the next operational stage. Because it is possible that different components of the system may be owned by different contractors, flexible models are needed that incorporate costs of capital and financing into the breakeven costs that will be used as transfer prices within the system. By calculating these costs, a final breakeven cost for each product can be determined that will be compared with estimated product prices (as determined by market surveys). This will also show areas within the product systems where the greatest opportunities for cost savings can be achieved.
Some aspects of the ecological analysis of biochar and forest soils will also require innovative approaches. The research into the possible interaction between biochar and contaminants such as heavy metals is itself a new area of study. For this reason, SEMEDXA surface analyses will be performed for a semi-quantitative carbon:oxygen ratio for additional biochar characterization. If successful, this analytical approach, not previously applied in this area of study, will provide complementary results to the elemental analysis. In addition, it will provide an estimation of energy values for the biochar.
Life cycle comparisons will require a new approach of comparing the relative carbon consequences of producing biochar from forest waste streams generated from forest restoration efforts on federal lands, and commercial operations on private lands, over alternatives that are likely to occur in the absence of restoration efforts and forest operations. These alternatives include insect and disease proliferation and direct and indirect impacts of catastrophic wildfire including reduced air quality. The normal sequence of a life cycle impact assessment (LCIA) is to conduct the life cycle inventories (LCI) followed by the life cycle assessment (LCA) within defined boundary conditions. Cooper has found that for biological systems it is necessary to model fate and transport separately from the LCI to avoid double counting. Using Cooper’s approach the team will produce the biochar LCI, feed the relevant parameters into an intermediate model such as DAYCENT to determine fate and transport of emissions that fall outside the LCI boundary, categorize those emissions separately from those inside the boundary, and combine emissions (biological and nonbiological) together for inclusion in a final comprehensive LCA. This approach will provide strategic guidance on treating forests to produce bioenergy and bio-based products relative to the consequential impacts of forest fire proliferation across western landscapes.
Learn more about the subtasks in this technical area:
- Construct a suite of economic models to evaluate the equipment being studied in the Feedstock Development and Conversion Technologoy technical areas
- Develop a tool to evaluate the value of biochar as a soil amendment for carbon sequestration
- Identify an input/output modeling protocol to assess economic impacts of biomass conversion technologies on local communities
- Develop air quality indicators
- Conduct a workshop to explore stakeholder perceptions
- Evaluate impacts on forest soils
- Conduct life cycle analyses
- Evaluate impacts on fire reduction and forest productivity gains
- Conduct outreach