Biofuels and bioenergy industry has evolved significantly in recent years. Commercial scale operating data are increasingly available, and technology development is becoming more holistic and data driven. This creates great opportunities to integrate LCA in process designs and planning scenarios to inform business decisions and policies to drive better outcome (the “triple bottom line”).

In this session, you will hear various case studies where LCA is used to enhance decision quality through (1) assessing environmental impact holistically across various categories for new technologies, (2) re-evaluating decision framework (system boundary and base case scenarios) to better understand trade-offs between alternatives and identify risk early, and (3) demonstrating benefits of including end-of-life issues in early decision making through quantitative analysis.

Key Discussion Points:

  1. Alternative fuels and energy derived from biomass serve as a critical solution to climate change and greenhouse gas emission reduction, primarily due to its large volume potential, capability to utilize existing infrastructure, and flexibility in technologies that can convert waste materials into reusable forms of energy. Could you share your perspective on this through your experience with biofuels and bioenergy industry?
  2. What are some of the advantages and limitations of using LCA to evaluate products from biofuels and bioenergy systems and for informing decisions?
  3. What are some of the lessons learned?
  4. What are your recommendations/plans to further improve LCA applications in this industry?
CHAIR: Hong Jin
15:30 Joel Tallaksen and Michael Reese

Life Cycle Impacts of Using Renewable Produced Nitrogen Fertilizer for Corn Production

ABSTRACT. Fossil energy use in food, feed, and biofuel production systems currently links our agricultural production systems to fossil fuel availability, pricing and environmental impacts. Nitrogen fertilizers comprise a significant portion of this fossil dependency. A recently completed pilot-scale, wind-powered nitrogen fertilizer production facility has begun the manufacture of renewable anhydrous ammonia fertilizers. Previous life cycle assessment work [1] examined the global warming potential (GWP) and fossil energy intensity of fertilizer produced at a scaled-up version of this system. The system relies on energy exchanges with the electric grid during periods with little wind and therefore, does still have some reliance on fossil energy in grid electricity production. This study uses life cycle assessment to conduct a preliminary examination of the GWP and fossil energy intensity of corn production using renewably produced nitrogen fertilizer. In the cradle-to-gate assessment, the renewable ammonia fertilizer was used as a drop-in replacement of commonly used anhydrous ammonia. The grain production system was examined over a range of scenarios covering different ratios of wind and grid electricity in fertilizer manufacture. Results indicate that GWP and energy intensity impacts were dependent on the degree to which the renewable fertilizer production system used the grid backup. In scenarios where little grid power was needed for fertilizer manufacture, crops were less dependent on fossil fuels and emitted less CO2 equivalents. In scenarios with more linkage to the electrical grid, fossil use and CO2 emissions were greater than conventional fossil production of ammonia fertilizer. These results suggest that renewable nitrogen fertilizer can reduce fossil energy and related emissions in agricultural systems. However, care must be taken to examine the renewable fertilizer production system and its inputs. Based on these findings, more work should be conducted to look at reducing the need for grid backup electricity in wind-based fertilizer system.

Reference: [1] Tallaksen, J., F. Bauer, C. Hulteberg, M. Reese, S. Ahlgren, Nitrogen fertilizers manufactured using wind power: Greenhouse gas and energy balance of community-scale ammonia production. (in Press)

15:45 Michela ZanettiFrancesca PierobonAndrea SgarbossaStefano Grigolato and Raffaele Cavalli

Environmental impact assessment of wood products for bioenergy in Europe

ABSTRACT. In the last years the world energy demand has rapidly increased as a consequence of the worldwide economic growth and development and it is expected to increase faster in the next decades. Therefore the replacement of fossil fuels with renewable resources is considered to be crucial. Among different ways of producing renewable energy, biomass represents one of the most promising energy source. In this context, this work aims to compare the environmental impacts of different biomass supply chains, as firewood and pellet produced in Europe. The differences between the biomass supply chains are assessed through a “gate to grave”. Life Cycle Assessment for the impact categories: Global Warming Potential (GWP) and Ozone Depletion Potential (ODP); Photochemical Ozone Creation Potential (POCP) and Human Toxicity Potential (HTP). The boundary of LCA takes into account the forest operations and does not consider tree seedling, site preparation, fertilizer and herbicide treatments because of the naturalistic silvicultural practice used in Italy. The environmental impacts were calculated based on the method CML 2001 – Apr. 2013 from the Leiden University. The functional unit is 1 MJ of energy for domestic heating. The majority of the emissions are constituted of biogenic carbon dioxide produced by the biomass combustion. In the case of firewood supply chain, the study has outlined that for the short supply chain the critical phase of the life cycle in terms of GWP, POCP and HTP is combustion. Moving to the long supply chain, the on-road transport is the most critical phase: the contribution to GWP becomes more than double than the short supply chain and five times higher to ODP. Concerning the pellet supply chain, it was found that some specific processes (burning, drying, pelletizing) are the biggest contributors for all the four impact categories. Comparing the two biomass production, firewood shows the lowest impacts because of the less energy intensive production processes. Although most of the chemicals emitted in the life cycle of biomass cannot be offset, a sustainable naturalistic forest management, common practice in Italy, can completely offset the fossil CO2 emissions, the largest emissive component of greenhouse gases.

16:00 Christina CanterJennifer Dunn and Michael Wang

Key Assumptions in Life Cycle Analysis of Woody Bioenergy Feedstocks

ABSTRACT. Concerns have been raised that using woody feedstocks for bioenergy (power and liquid fuels) incurs a carbon debt that takes a potentially unacceptably long time to repay. Analysis of woody feedstock-derived bioenergy relies on several key assumptions that influence the GHG emissions of this form of energy versus conventional, fossil energy for power plants and vehicles. In this presentation, we will examine two of these issues. The first is the fraction of harvested wood that is used to produce harvested wood products (HWP), which varies regionally and by tree type. The second is the type of counterfactual scenario that is used as the baseline. Both of these factors influence the carbon dynamics of forest systems in the context of bioenergy and the life-cycle GHG emissions of woody-derived bioenergy. When conducting an LCA of woody-derived bioenergy, an analyst must assume what fraction of harvested wood is used to produce bioenergy and what fraction is used to make different HWPs (e.g. construction lumber, paper). The range of expected lifetimes for various types of HWPs are found in literature, along with their landfill decomposition times. We will present different HWP splits for bioenergy-relevant forestry systems (e.g., loblolly pine in the Southeastern US) and illustrate the sensitivity of woody bioenergy life-cycle GHG emissions to these parameters. Secondly, woody bioenergy life-cycle greenhouse gas emissions are generally compared against an alternative, counterfactual scenario. Typically, this scenario considers a forestry system that produces primarily HWPs, while only precommercial thinnings and forest residues are used for energy generation. Many other features characterize counterfactual scenarios and their design can have a significant influence on woody bioenergy analysis results. For example, counterfactual scenarios can feature different rotation lengths, timing of thinning events, or even alternative fates of forested lands (e.g., no harvest scenarios). We will discuss selection and design of counterfactual scenarios to permit relevant comparisons to woody bioenergy scenarios. Furthermore, we will illustrate how choice of counterfactual scenario affects the comparison of a scenarios in which forest-derived feedstocks are and are not used for bioenergy