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Northeast Woody/Warm-season Biomass Consortium

System Performance and Sustainability Metrics

The Sustainability thrust will assess the overall system performance and sustainability of biomass to biofuel systems through a combination of detailed measurements at willow and perennial grass experimental sites, regional simulations using benchmark scenarios, and integration of the techno-economic analysis from task 3.4.  These activities provide information to assess sustainability following the criteria proposed by the Global Bioenergy Partnership:95

  1. Fuels life-cycle GHG emissions;
  2. Changes in soil quality;
  3. Emissions of non-GHG air pollutants;
  4. Impacts on water quality;
  5. Impacts on landscape biodiversity;
  6. Land use and land-use change related to energy feedstock productionl and
  7. Rural and social development.

These metrics provide a comprehensive set of indicators of the systems’ sustainability, and help quantify non-market services that perennial systems may provide.8-9, 96 We will investigate key knowledge gaps leveraging the regions’ extensive research networks for willow (32 experiments established since 1990) and warm-season grasses (30 experiments established since 2007), define these metrics for benchmark scenarios, and analyze the energy efficiency and emissions during biomass production, logistics, and commercial processing into biofuels.

Task 4.1. Site- and crop-specific knowledge gaps (Kemanian, Volk, Hall, Bonos, Smart)

Task 4.1.1. Biomass production

Research in the last decade has provided substantial information on productivity and environmental benefits and impacts of willow85 and warm-season grasses.14,70 Uncertainty remains about the yield progression over time of different willow cultivars and cultivar mixtures and of switchgrass and Miscanthus cultivars growing in NE climates.  We will characterize the production of 10–20 genotypes/cultivars (depending on the trial) in 10 established trials of different age in NJ, NY, PA, and WV, and systematically collect data from ongoing and past research in these and other states in the region to inform the modeling and LCA efforts in Tasks 4.2, 4.3, and 4.4 described below. Plant samples from trials will be analyzed to determine nutrient extraction rates across a range of production conditions in both willow and warm-season grasses to address soil quality concerns and to direct and constrain the process-based simulation models used in the benchmark scenario and regional assessments.  

Task 4.1.2. Nitrogen demand and alternative supply

Recent experimental data97-98 indicates that willow creates a productive canopy with an exceptionally low N requirement (~80 kg N ha-1 compared with >120 kg N ha-1 for annual crops), with much of this N internally recycled year after year.  These data strongly suggest that when coppiced once every three years willow requires between negligible amounts and 1/3 of the N inputs of annual crops while producing >10 Mg ha yr-1. Similar claims of high N acquisition and use efficiency have been reported for Miscanthus.99

Commercial N fertilizer inputs are a major driver of the crop GHG balance.100 Quantifying potential benefits requires a full understanding of the N cycle.  The use of organic amendments also has the potential to reduce GHG balances and further improve the energy balance of these systems. We will install experiments with different N sources (manure, a cover crop legume, and a mixed stand of black locust and willow).  This experiment will be replicated in State College, PA and Geneva, NY, complementing the mineland experiments described in Task 2.3.  Separate micro-plots treated with 15N labeled fertilizer (10% 15N atom enriched KNO3) will be used to track the N retention over several years.  Similar experiments are proposed for miscanthus (manured vs unmanured) to explore alternative fertilizers and N cycling for this crop.  Several studies in the region are already addressing the N budget in switchgrass.

Task 4.1.3. Nitrous oxide emissions

The low N inputs in these systems reduce the risk of large N2O fluxes due to denitrification. We will monitor NO3 in 6 experiments in willow (NY, PA, WV) twice per year throughout the project, targeting a diverse array of soils and plantation age to assess the risk of emissions. No new N2O flux measurement is proposed, as extensive research on N2O emissions and C storage in warm-season grasses is ongoing in experiments involving project PIs, and that data will be available for assessing emissions of these systems.

Task 4.1.4. Carbon storage

The C and water flux of willow and switchgrass will be measured using eddy covariance in adjacent willow and switchgrass plantations (>30 ac each) to be established in State College in 2012, providing the first side-by-side comparison of these crops and a detailed picture of the C balance during establishment years.  The trial in which NO3 will be monitored will be sampled for soil C balance at the project’s beginning and end, continuing ongoing, long-term monitoring particularly in the NY trials.  The short-term C balance will be assessed using a variety of techniques, including a newly acquired portable stable C isotope analyzer (Picarro Inc.) that allows estimates of humification, soil organic matter turnover, and partitioning root and microbial fractions of total soil respiration.  Data limited to one clone in one site suggests that belowground C storage in willow makes the system a GHG sink.101 Additional data will be collected across a chronosequence and for high biomass producing clones at different sites.

Task 4.2. Benchmark scenarios (Kemanian, Woodbury, Hall, Volk)

These point-based scenarios provide modular information to enable regional assessments of biofuel production for a combination of areas dedicated to willow and warm-season grasses in the NE, using a process-based modeling platform.  They will provide estimates of biomass production, C balance, N requirements and associated N emissions, and effects on water quality across representative soils, climates, and management strategy of a given region.  The benchmark scenarios will be defined following the outcome of a recent USDA-AFRI workshop on this specific subject.68 The modeling platform will test the system response to climate and market scenarios in terms of GHG balance and soil erosion using models with a biophysical102-104 (or a hybrid biophysical and statistical) structure, and estimate impacts on biodiversity and wildlife using empirical models.

Task 4.3. Regional feedstock supply and environmental assessment (Woodbury, Yanosky, Kemanian, Boyer)

We will scale-up outcomes from point-based scenarios to the regional scale.105 The allocation of land uses will consider the actual and planned siting of the industrial plants.  We will assimilate the process based-modeling and experimental data from Task 4.2 into a geospatial framework.  We will estimate yield output and variability along with nutrient losses, water quality impacts, and GHG balance for each county supplying biomass or siting a biorefinery in the NE.

Baselines for these variables (except biomass) will be based on the region’s 2007 land use and NASS reporting district data (business as usual). Alternative scenarios will incorporate a growing allocation of willow and warm-season grasses to current herbaceous cover, abandoned land, and mine land, such that current food production levels are not affected by the millions of hectares that can be allocated to bioenergy crops in the NE: detailed analysis is available for NY.106 Air quality impacts will be assessed by compiling existing emissions-testing information with respect to know pollutants from gasification (N oxides, CO, and particulate matter <2.5 µm), and inputting this information in a Gaussian dispersion model.  Model outputs will help describe air quality impacts downwind from a full-scale plant to determine at which distance the plant’s emissions negligibly impact air quality, and therefore the optimal sitting of the plant. Scaled-up assessment and raw information from the simulations and field data databases will be publicly available on the NEWBio geoportal, allowing project members or other parties interested in tailoring analyses to particular needs. 

Task 4.4. Biomass to Biofuel LCA and multi-criteria sustainability assessments (Spatari, McAloon, Mortensen, Woodbury, Volk, Kemanian)

We will develop a full LCA assessment of baseline and alternative scenarios for each commercial demonstration, including feedstock production (farm gate assessment), supply chain logistics, biomass pre-processing and industrial conversion to fuel.  A systems level accounting of market and non-market ecosystem services will be performed to guide adjustments in biomass production systems that optimize production and that are neutral to or enhance important non-market services. Here NASS reporting district data on land use will inform a ‘current’ land use state, then scenarios that represent scaled up biomass production practices will be modeled to estimate the impact on landscape scale biodiversity of select indicator species. Supplemental qualitative analysis will focus on complex externalities like biodiversity19,107-108 as framed by the Global Bioenergy Project.95

Expected outcomes

Expected outcomes include:

NEWBio (consortium members below) is supported by Agriculture and Food Research Initiative Competitive Grant no. 2012-68005-19703 
from the USDA National Institute of Food and Agriculture.
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