1 Experience with IR 70kW installations on LFG, will current emission performance be enough? January 26, 2005

2 Example Landfill Characteristics Small, closed municipal solid waste landfill Located in Southern California 1.8M tons of waste over 18 years Owned / operated by local county authority No operator on-site

3 Landfill Gas Collection 40 vertical extraction wells 7,000 feet of 4 to 10 inch gas collection piping 3 condensate pumps 2,400 gallon condensate storage tank scfm gas extraction blowers 800 scfm enclosed flare with condensate injection Pierce, Benson, SCS Energy

4 Landfill Gas Condition Methane content typically 33% to 40% Up to 10% swings per day Has been measured as low as 28% On-site fuel conditioning system Removes water and contaminants, compresses landfill gas Siloxane removal for 2 microturbines only

5 Microturbines in Facility 4 – 70kW microturbines Sized to consume 100% of gas Commissioned March 2002 On-site continuous methane analyzer and calibration gases Microturbines start-inhibited under low methane conditions Microturbines operate as a group (sequential startup)

6 Microturbine Power Production 24/7 electricity (baseload) mostly exported to the grid Site equipment only consumes 5% of power $250/kW grant from CEC Five year, fixed price PPA at $0.06/kWh with local utility 64,376 hours through December 2004 About 1,500,000 to 1,750,000 kWh electrical output per year

7 Microturbine Annual Run History

8 Operating Experience Fuel composition has become more stable Low methane start-inhibit improves facility control Siloxane levels appear to be low Enclosure working well, no corrosion, minimal dust Ambient temperatures range from about 100°F midday summer to 30’s in the night Converted MTs from internal fuel gas boosters to high pressure fuel valves to handle wind-driven ambient temperature variations

9 Fuel Analyses of Various LFG Sites Wide variety in constituent volumes CO 2 and N 2 composition affects adiabatic flame temperature Which in turn controls key chemical reactions: NOx formation and CO destruction

10 Fundamental Engine Emission Limits Thermal NOx formation significant above 1850°K CO occurrence increases at lower temperatures –Lower reaction rates –Less oxidation Result is a narrow temperature regime to realize both low NOx and low CO Rokke, Hustad, Rokke, Svendsgaard, ASME GT

11 Microturbine Emissions Using LFG Microturbines represent a clean method of eliminating LFG that generally meets today’s non- attainment area permitting limits for “waste gases” Typical district NOx and CO permitting limits around 9 to 15 O 2 California ARB-released source testing results: California ARB, DG Technical Review,

12 Natural Gas Emissions Limits In California By default, MTs are permitted in California unless they meet certain exceptions –fueled by natural gas and –below a certain size threshold and –not located in a “sensitive” area. If not permitted, must be certified by CARB

13 Future Emissions Limitations Trend in non-attainment regions: –Lower Distributed Generation (DG) emissions to “Central Plant BACT” (CARB 2007) levels NOx at 0.07 lb/MWh CO at 0.10 lb/MWh VOCs at 0.02 lb/MWh –January 1, 2007 (if not earlier) in California –Natural gas-fueled DG Over a longer period (2012 to 2015?), force “waste fuels” emissions to Central Plant BACT levels as well

14 Future Microturbine Emissions Meeting 2007 BACT limits will be a challenge for microturbines In natural gas applications microturbines can claim CHP credits –Example: MMBtu of recovered heat equivalent to 1 MWh of output –Credits act to “lower” criteria emissions results when compared to limits However, no equivalent credit exists for “waste fuels” DG emissions Credit for displaced LFG flare emissions?