CNG, LNG, and Other Fuels from Landfill Gas ---Prospects for Future Development----

Size: px

Start display at page:

Download "CNG, LNG, and Other Fuels from Landfill Gas ---Prospects for Future Development----"

Godfrey Hunt
8 years ago
Views:

1 CNG, LNG, and Other Fuels from Landfill Gas ---Prospects for Future Development---- California Biomass Collaborative 4 th Annual Forum March 28, 2007 Sacramento, California Patrick Sullivan SCS Engineers Sacramento, California

2 Landfill Gas Utilization Electric power generation Medium-Btu gas utilization High-Btu gas production

3 Operating Landfill Gas to Energy Facilities in the United States Electric Power projects Medium-Btu (direct use) projects Pipeline Quality Gas -- 8 projects

Power -- 290 projects Medium-Btu (direct

4 Electric Power Generation Reciprocating engines Combustion turbines Steam cycle power plants Emerging technologies Microturbines Fuel cells Stirling Cycle engines

5 Why are Medium & High-Btu Gas Projects Positioned for Growth? Dramatic increase in natural gas and vehicle fuel prices Well proven technologies are available Conflicts with wellfield operation are resolvable

6 Medium-Btu Gas Utilization Direct pipeline to end user Blend with natural gas or install new burners at end user Light clean-up (refrigeration and filtration) 50 psig to 100 psig $600,000 to $900,000/mmscfd for plant Pipeline = $30 to $50/foot

clean-up (refrigeration and filtration) 50 psig to 100 psig

7 High-Btu Gas Production Pipeline quality gas or vehicle fuel Technologies now in use include: Membrane process Molecular sieve Absorption processes Require zero air infiltration wellfield operation Plant sizes are generally 5 to 10 mmscfd (inlet) $1.25 to $1.5 million per mmscfd installed

Absorption processes Require zero air infiltration wellfield operation

8 CNG and LNG are Viable Alternatives to Diesel/Gasoline Compressed natural gas (CNG) Liquefied natural gas (LNG) Now produced from pipeline gas

9 Natural Gas Prices Have Risen

10 CNG/LNG Versus Diesel/Gasoline CNG/LNG Benefits Reduces air emissions Lower cost than liquid fuel Safer than liquid fuel Lower engine maintenance costs CNG/LNG Disadvantages Engines are more expensive Fewer available fueling stations

liquid fuel Lower engine maintenance costs CNG/LNG

11 CNG Versus LNG LNG has a higher energy density Less expensive to store Less expensive to transport Less onboard storage volume required LNG vehicles are more complex and expensive LNG costs more to produce LNG is convertible to CNG at a fueling station

volume required LNG vehicles are more complex and expensive

12 Landfill Gas Conversion to Vehicle Fuel Landfill gas can be used to produce: Compressed natural gas (CNG) Liquefied natural gas (LNG) CNG or LNG can be used to: Fuel landfill vehicles Refuse trucks (short or long haul) Supply the general clean fuels market

gas (LNG) CNG or LNG can be used to: Fuel landfill vehicles

13 Typical Landfill Gas Characteristics Component Methane Carbon Dioxide Oxygen Nitrogen Carbon Monoxide Hydrogen Sulfide NMOCs Siloxane Range 35% to 55% 20% to 45% 0.5% to 5% 2% to 45% <10 ppmv 20 to 500 ppmv 200 to 2000 ppmv 0.2 to 10 ppmv

Sulfide NMOCs Siloxane Range 35% to 55% 20% to 45% 0.

14 Typical CNG Vehicle Fuel Specification Methane Ethane (C2) C3 and higher C6 and higher Hydrogen Oxygen Carbon Monoxide Inert Gas (CO 2 + N 2 ) Sulfur 88% 6% 3% 0.2% 0.1% 1% 0.1% 4.5% 16 ppmv

15 Conversion of Landfill Gas to CNG Remove carbon dioxide through either: Membrane separation Molecular sieve (pressure swing adsorption) Both have been used to produce pipeline quality gas on a large scale To date only membrane separation has been used for vehicle fuel on a production scale Fuel specification for oxygen and nitrogen limits these parameters in the raw landfill gas to about 0.6 percent and 2.5 percent, respectively

only membrane separation has been used for vehicle fuel on a production scale Fuel specification for oxygen

16 Residual Gas Permeate Gas Feed Gas

19 Puente Hills Landfill CNG Project Los Angeles County Sanitation Districts 250 scfm of 55 percent methane landfill gas converted to 100 scfm of 96 percent methane CNG 1,000 gallons of gasoline equivalent per day 70 percent of raw methane to final product and 30 percent of raw methane to waste Construction cost in 2006 dollars $1.6 million

1,000 gallons of gasoline equivalent per day 70 percent of raw methane to final

20 Puente Hills Landfill CNG Project Landfill gas compression and moisture removal; Activated carbon; Gas heating to 140º F; Membranes for carbon dioxide removal; Compression of the product gas to 3,600 psig; Compressed gas storage facilities; and A fuel dispenser to dispense 3,000 psig CNG.

dioxide removal; Compression of the product gas to 3,600 psig;

24 Sonoma County CNG Project Sonoma County Transit currently fuels its bus fleet with CNG A 100 scfm (inlet) pilot scale project is currently being implemented The full scale project is expected to be 860 scfm (inlet) Project is to be located at the County s s Central Landfill

25 Sonoma County Pilot Scale Project 100 scfm (inlet) and 40 scfm (outlet) Compression to 125 psig, chilling, and activated carbon treatment Membranes for carbon dioxide removal Compression to 3,900 psig Waste gas to engines or flare CNG production cost = $9.30/mmBtu

26 Sonoma Full Scale Project 860 scfm (inlet) and 360 scfm (outlet) Hydrogen sulfide removal, compression to 145 psig, chilling, and activated carbon treatment (TSA) Membranes for carbon dioxide removal Compression to 3,900 psig Waste gas burned in a flare Production cost = $6.60/mmBtu

32 Conversion of Landfill Gas to LNG Purify landfill gas and remove carbon dioxide, and then follow with liquefaction of methane Cryogenic process generally used for this purpose Montauk has recently commenced operation of a project at the Frank R. Bowerman Landfill in Orange County Prometheus Energy is in development of project at Kiefer Landfill for Sacramento County Several stops and starts at Bay and Los Angeles area landfills have occurred

33 Typical LFG/LNG Module 5,000 gal/day of LNG from 900 scfm of landfill gas LNG is 97% methane / 20 psig / -250º F 750 kw of power is required Production cost = $1.00/gallon (?)

34 LFG/LNG Issues Fuel specification for methane percentage at 97 percent limits nitrogen and oxygen in the raw landfill gas to about 1.5 percent combined (unless process employed can also strip nitrogen and oxygen) High oxygen in feed stock may represent an explosion risk Requires ultra-low low carbon dioxide prior to liquefaction Loss of economy of scale at LFG facility sizing

35 Conclusion Experience with landfill gas to vehicle fuel is limited One long-term, successful, small LFG-to to-cng project exists. Another pilot scale project is being implemented One commercial LFG-to to-lng demonstration project has been completed. Conversion of landfill gas to CNG and LNG is technically feasible, and is economically feasible if natural gas cost exceeds $6.00/mmBtu

David Mezzacappa, P.E. SCS Engineers Contractor to U.S. EPA on LMOP

LMOP Workshop: LFG Collection & LFG Energy Technologies David Mezzacappa, P.E. SCS Engineers Contractor to U.S. EPA on LMOP Introduction Goal convert LFG into a useful energy form Technologies include: