A CASE STUDY IN PLANNING A RENEWABLE ENERGY SUPPLY CHAIN

Transcription

1 A CASE STUDY IN PLANNING A RENEWABLE ENERGY SUPPLY CHAIN Part II: Using Life Cycle Environmental Metrics To Select A Biomass Feedstock Pictures morris campus and farming ASEM 2014 INTERNATIONAL ANNUAL CONFERENCE OCTOBER TH VIRGINIA BEACH VIRGINIA JOEL TALLAKSEN, West Central Research & Outreach Center, University Of Minnesota TRICIA SIMO KUSH, PEM, IT Consultant, Minneapolis, Minnesota

2 Typical Supply Chain Management Decisions on technology purchased or built Capital expenses Understanding of points of failure Operational requirements Production Packaging Transportation Technology Staffing Technology Packaging Equipment Fuel Decisions on personnel and training Evaluation of potential outsource of activities All of these are converted to a standard, easy to measure unit: DOLLAR$ End Use Equipment Disposal Staffing

3 Metrics for Managing Environmental Issues Many potential environmental impacts, common areas: Air Ground Water Also need to consider: Impacts on the built environment (i.e. acid rain on stone buildings) Social impacts (i.e., communities and culture) Environmental impacts most frequently studied Fossil energy use Global warming potential A number of approaches for analyzing these impacts

4 Implementing Environmental Metrics More difficult to summarize than economic metrics Many environmental impact concerns (air, water, soil, resources) Often several options for mitigate impacts Options often involve tradeoff Part of the Triple Bottom Line in project design Environmental management has more audiences to please Most environmental management decisions are based on the unique conditions of each project The following case study is used to illustrate one approach

5 Need to Diversify Energy Supply Chains Transitioning from fossil fuels is difficult Costs of new infrastructure Easy use of fossil energy Existing infrastructure Energy dense fuel, simple logistics Current costs are cheap Pictures Natural Gas Prices? Natural Gas Cost Issues Availability & Shortages Environmental Issues

6 Morris Heating Facility as a Case Study Constructed a biomass energy facility in 2011 Key decision was which biomass fuel to use Corn most available biomass Corn Stover (leaves, stalks, and cobs) higher volume, less dense Corn Cobs Lower amount, but better handling and cleaner fuel Examined environmental metrics of these supply chains: Fossil Energy Footprint (MJ per MMBTU) Greenhouse Gas (GHG) Equivalents (kg CO 2 ) Insert pictur e of facility Goal: Determine which biomass energy feedstock (corn stover or cobs) had the smallest impacts on the two environmental metrics selected

7 Setting up the Environmental Metric Assessment Limited life cycle assessment chosen The information was not for regulatory, policy, or certification Farmer field to facility (cradle to gate) Used current technology Infrastructure not included Nor background systems (i.e., energy to get diesel to Minnesota) Does not include factors related to soil carbon and CO 2 release Assumed harvesting was done sustainably

8 Methodology and Data analysis Developed process flow Identified areas of energy use Modelled process energy flow Spreadsheet based modeling Quantified energy use Almost all is diesel fuel Some natural gas Calculated fossil energy footprint Used fossil fuel emission factors for greenhouse gas data

9 Process examined in Biomass Supply Chain A) Corn Stover Cultivation Collection Transport Processing Storage Fertilizer added Stalks Chopped Residues Raked Baled Bales Loaded Moved Via Flatbed Truck Ground Organized Stacks of B) Corn Cobs Cultivation Collection Transport Processing Storage Fertilizer added Cobs Sorted On-site Transport On-site Storage Bulk Loading Moved Via Self Unloading Bulk s Truck No Processing Bulk Piles Additional Fertilizer is needed when biomass is removed

10 Process examined in Biomass Supply Chain A) Corn Stover Cultivation Collection Transport Processing Storage Fertilizer added Stalks Chopped Residues Raked Baled Bales Loaded Moved Via Flatbed Truck Ground Organized Stacks of B) Corn Cobs Cultivation Collection Transport Processing Storage Fertilizer added Cobs Sorted On-site Transport On-site Storage Bulk Loading Moved Via Self Unloading Bulk s Truck No Processing Bulk Piles Stover Harvest Uses Current Equipment Cobs Require Specialized Harvest Equipment

11 Process examined in Biomass Supply Chain A) Corn Stover Cultivation Collection Transport Processing Storage Fertilizer added Stalks Chopped Residues Raked Baled Bales Loaded Moved Via Flatbed Truck Ground Organized Stacks of B) Corn Cobs Cultivation Collection Transport Processing Storage Fertilizer added Cobs Sorted On-site Transport On-site Storage Bulk Loading Moved Via Self Unloading Bulk s Truck No Processing Bulk Piles Stover Transport Uses Commonly Available Flatbed Trailers Cobs Can Be Moved Using Existing Grain Trailers

12 Process examined in Biomass Supply Chain A) Corn Stover Cultivation Collection Transport Processing Storage Fertilizer added Stalks Chopped Residues Raked Baled Bales Loaded Moved Via Flatbed Truck Ground Organized Stacks of B) Corn Cobs Cultivation Collection Transport Processing Storage Fertilizer added Cobs Sorted On-site Transport On-site Storage Bulk Loading Moved Via Self Unloading Bulk s Truck No Processing Bulk Piles Processing is Needed Only For Stover

13 Process examined in Biomass Supply Chain A) Corn Stover Cultivation Collection Transport Processing Storage Fertilizer added Stalks Chopped Residues Raked Baled Bales Loaded Moved Via Flatbed Truck Ground Organized Stacks of B) Corn Cobs Cultivation Collection Transport Processing Storage Fertilizer added Cobs Sorted On-site Transport On-site Storage Bulk Loading Moved Via Self Unloading Bulk s Truck No Processing Bulk Piles Outdoor Storage For both Debatable whether investing in protected storage has a payback

14 Fossil Energy Use Measured in MegaJoules of fossil energy per MMBTU MMBTU is a standard unit for natural gas (NG) in the U.S. Equals a decatherm which is a 1000 cubic feet of NG Morris campus heating needs peak at 19 MMBTU/Hour Cultivation energy (fertilizers) were higher for stover Harvest energy was greater for cobs Stover Cobs Natural Gas Cultivation Harvesting Transportation On site energy Processing The processing energy was very significant for stover Total Fossil Energy ,054 Fossil energy for both biomass sources were considerably lower than natural gas

15 Global Warming Potential Measured in carbon dioxide equivalents All other compounds are tied to CO 2 For example: 1 kg NO 2 is equivalent to 22 kg CO 2 Trends followed fossil fuel pattern Stover Cobs Natural Gas Cultivation Harvesting Transportation on site energy Processing 1.76 Total CO 2 Equiv

16 Sensitivity Analysis Examination of which model variables had large effects on the results. Based on results from a 35% increase and decrease in certain variables Grain yield (which translates to biomass yield) was very critical for cobs Cob harvest equipment uses significantly more fuel to collect the needed biomass Total Energy (MJ) CO 2 Equivalents Change in Factor Increase 35% Decrease 35% Increase 35% Decrease 35% Factors stover cobs stover cobs stover cobs stover cobs Processing Energy 12% 16% 12% 0% 12% 16% 12% 0% Yield 3% 15% 5% 30% 3% 15% 5% 30% Percentage of Farmers 0.1% 0.2% 0.2% 0.4% 0.1% 0.2% 0.2% 0.4%

17 Overall Findings Cobs had less of an environmental footprint Roughly 2/3 the GHG and Fossil Fuel Use Stover processing largest difference in metrics used Both Cobs and Stover had very significant reductions in environmental impacts than traditional fossil energy. When put in context of the existing fossil system, the relative difference in environmental metrics indicated that either cobs and stover would meet project goals.

18 Recommendation For Project Corn cobs should be used. Implementation steps to pursue: (Partially based on the need to add the processing of stover) Contract suppliers who are willing to purchase/lease harvest equipment Establish storage sites that will accommodate cobs Areas of Concern: From sensitivity analysis: low yields could increase GHG and Fossil Use Major changes (increases) in biomass demand may increase GHG and Fossil Use Larger supply radius for cobs

19 Evaluating Case Study Methodology Level of analysis supported goal of identifying supply chain impacts A low resolution assessment met the needs of this project Data was needed for an internal decision on the choices between supply chains. Need to balance the environmental choice with social and economic options The next questions need to be: Is the option with the least environmental impacts cost competitive? Will the other actors in the supply chain (farmers, truckers, processors) be willing to support the proposed supply chain?

20 Acknowledgment University of Minnesota Morris Lowell Rasmussen, Vice Chancellor University of Minnesota, WCROC Mike Reese, Project Director Data and scenarios provided by projects previously funded by the Minnesota Corn Research and Promotion Council, the USDA SunGrant, and the University of Minnesota, Initiative for Renewable Energy and the Environment (awarded to staff at the U of MN) Image Credits Wikipedia, Tractors.wikia.com (Stream Tractor), National park service (Triple Bottom Line), John Deere (Green Tractor), AgCo (Grey Tractor)