July 31, Mr. Timothy Edman Manager, Regulatory Administration Xcel Energy, Inc. 414 Nicollet Mall Minneapolis, MN Dear Mr.

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1 Energy & Environmental Research Center UNIVERSITY OF NORTH DAKOTA 15 North 23rd Street -- Stop 9018 / Grand Forks, N D / Phone: (701) Fax: Web Site: www,undeerc.org July 31, 2009 Mr. Timothy Edman Manager, Regulatory Administration Xcel Energy, Inc. 414 Nicollet Mall Minneapolis, MN Dear Mr. Edman: Subject: Quarterly Progress Report Entitled "Integrated Gas Turbine-Gasifier Pilot-Scale Power Plant"; Contract No. RD3-71; EERC Fund No Enclosed please find the subject report. If you have any questions, please contact me by phone at (701) or by at phutton@undeerc.org. PNH/hmv Enclosure Phillip N. Hutton Manager Printed on Recycled Paper

2 ,EERC Energy & Environmental Research Center University of North Dakota 15 North 23rd Street, Stop 9018 Grand Forks, ND Project Title: Integrated Gas Turbine-Gasifier Pilot-Scale Power Plant Contract Number: RD3-71 Principal Investigator: Phillip Hutton Phone: (701) Congressional District: (Corporate office) Congressional District: (Project location) Milestone Number: 2 Contract Contact: Not Applicable Not Applicable MILESTONE REPORT Report Date: July 31, 2009 Corey Irion Phone (701) Executive Summary: During this milestone period, the EERC completed bench-scale testing of coal, biomass, and coal-biomass blended fuels on the advanced bench-scale gasifier. The benchscale gasification tests provide the operating conditions and gas characteristics for the design of the integrated system. A total of eight gasification tests were completed; three tests on 100% biomass; one test on 100% coal; one test on 25% biomass and 75% coal; one test on 50% biomass and 50% coal; and one test on 75% biomass and 25% coal. The producer gas composition was consistent throughout all runs, with the energy content of the producer gas varying from 180 Btu/scf to 210 Btu/scf. In addition to gas composition, benzene, toluene, xylene (BTX), ammonia, hydrogen sulfide, and hydrochloric acid levels were measured in the producer gas. Construction of the biomass feed system was completed, and initial cold-flow solids testing commenced using the plexiglass mock-up in place of the gasifier. Prior experience with moving packed-bed gasifiers has shown that approximately two-thirds of the problems with the gasifier are because of solids flow. Cold-flow solids testing will hopefully identify flow issues before the hot gasifier is designed. Initial cold-flow testing cracked the feed auger. The auger is being repaired with thicker flighting for subsequent testing. Requests for quotations for high-temperature heat exchangers were submitted to several heat exchanger manufacturers. In addition, an in-house design of a high-temperature heat exchanger was started, and hightemperature materials were priced. Once quotations, designs, and delivery times are received for the heat exchangers, a decision will be made to either purchase the heat exchanger or construct it in-house. The process flow design for the system was started this quarter, with mass and energy balances and component specifications. Overall, the project is on or slightly ahead of schedule. Milestone 2 was completed as per the Milestone and Payment Schedule. Work is ongoing on Milestones 3, 4, 5, and 8. Project funding is provided by customers of Xcel Energy through a grant from the Renewable Development Fund (RDF). Technical Progress: Both local wood and antelope coal were tested in the advanced benchscale gasifier developed during the first Xcel RDF funding round. The test matrix consisted of 100% wood, 100% coal, 25%/75% wood/coal, 50%/50% wood/coal, and 75%/25% wood/coal. Table 1 provides the proximate/ultimate analysis of both the wood and antelope coal.

3 Table 1. Proximate/Ultimate Analysis of Biomass and Coal, as received Wood Antelope Coal Proximate Analysis, % Moisture Volatile Matter Fixed Carbon Ash Ultimate Analysis, % Hydrogen Carbon Nitrogen Sulfur Oxygen Ash Heating Value (Btu/lb) Calc. Calorific Value The proximate/ultimate analysis shows higher volatile matter in the biomass than the coal and higher ash content in the coal. The sulfur content was low in both the wood and coal. The heating value was slightly higher in the coal then the wood. In situ dry gas composition was monitored with a Sick Maihak $715 gas analyzer. Throughout the test runs, BTX, ammonia, H2S, and HC1 were sampled using Draeger calorimetric tubes. Table 2 provides a summary of the gas compositions and contaminant levels for various wood-coal blends. The dry gas composition was found to be relatively stable throughout the test runs regardless of the wood/coal composition. The energy density of the dry gas varied from Btu/scf. Examination of BTX levels found that the tar composition was composed primarily of heavier aromatic hydrocarbons (xylene). This may indicate a tar condensation temperature of approximately 150 C. Hydrogen sulfide levels varied from ppm. Ammonia levels were typically greater than 30 ppm, and HC1 levels were typically very low, at less than 4 ppm. Table 2. Gas Composition and Contaminant Levels for Gasified Wood-Coal Blended Fuels Wood-Coal Blend 100/0 75/25 50/50 25/75 0/100 Dry Gas Composition, % CO CO H CH Nz Balance Balance Balance Balance Balance Btu/scf Contaminant Levels, PPM Benzene Toluene Xylene Ammonia H~S HC Construction of the feed system was completed and an initial cold-flow solids test conducted with dry corn. The feed system consists of a primary hopper feeding a rotary isolation valve that then augers the biomass/coal to the gasifier. The isolation valve prevents backflow of

4 combustible/hazardous gases from the gasifier to the hopper. The initial cold-flow solids test demonstrated satisfactory operation of all feed components except the feed auger to the gasifier. The tip of the auger cracked and bent, as shown in Figure 1. A heavier, one-quarter inch thick, flighting has been ordered for the auger. The auger repair is expected to be completed in early August and cold-flow testing recommenced at that time. Depending on the results of the cold flow tests, additional modifications of the feed systems may be incorporated to minimize solids flow issues. EERC PH CDR Figure 1. Damaged auger after initial cold-flow solids testing. Balance of plant component specifications were calculated, and the process flow diagram with heat and mass balances commenced. A specification for a high-temperature heat exchanger was submitted to four manufacturing plants. In addition, an in-house design was begun. Depending on the cost, design, and delivery times for the heat exchangers, a decision will be made to purchase a heat exchanger or construct one in-house. Overall, the project is proceeding on schedule, with the second milestone completed per the Milestone and Payment Schedule. Work is ongoing for Milestones 3, 4, 5, and 8. Additional Milestones: Work has commenced on Milestones 3, 5, and 8. Completion of Milestone 3, Process Flow Diagram with Mass and Energy Balances, is on schedule to be completed in the next milestone reporting period as per the Milestone and Payment Schedule. Work has commenced early on Milestones 4 (Gasifier Design), 5 (Equipment Procurement), and 8 (Power System Construction). Milestone 7 (Microturbine Modification and Testing) has been put on hold until final decisions have been made on the heat exchanger and piping dimensions. Project Status: The project is slightly ahead of schedule and on budget.

5 LEGAL NOTICE THIS REPORT WAS PREPARED AS A RESULT OF WORK SPONSORED BY NSP. IT DOES NOT NECESSARILY REPRESENT THE VIEWS OF NSP, ITS EMPLOYEES, OR THE RENEWABLE DEVELOPMENT FUND BOARD. NSP, ITS EMPLOYEES, CONTRACTORS, AND SUBCONTRACTORS MAKE NO WARRANTY, EXPRESS OR IMPLIED, AND ASSUME NO LEGAL LIABILITY FOR THE INFORMATION IN THIS REPORT; NOR DOES ANY PARTY REPRESENT THAT THE USE OF THIS INFORMATION WILL NOT INFRINGE UPON PRIVATELY OWNED RIGHTS. THIS REPORT HAS NOT BEEN APPROVED OR DISAPPROVED BY NSP NOR HAS NSP PASSED UPON THE ACCURACY OF ADEQUACY OF THE INFORMATION IN THIS REPORT.