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

1. Experience with IR 70kW installations on LFG, will current emissionperformance 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 • 2 - 800 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 • CO2 and N2 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 GT2003-38112

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 ppm @15% O2 • California ARB-released source testing results: California ARB, DG Technical Review, 2005-01-03

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: 3.1413 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?