SNG: A Renewable, Regional Biofuel. Looking at Possible Markets Thomas Cheney cheney (at) unbc.ca
What is SNG● SNG stands for synthetic natural gas created by anerobic digestion or methanization of gasified wood .● Renewable Power Methane is a related product● Can be used in existing natural gas infrastructure.
Objectives ● Introduce SNG production methods ● SNG uses ● SNGs role as energy currency in renewable energy1 MW SNG production facility at Gussing,Austria system
How SNGis Made fromWoodFeedstock Gasification Gas GasificationPre-treatment Cleaning CO2 Gas Grid Methaniz removal, ation Compression
SNG Markets ● Space and Water Heating ○ Existing gas furnaces ○ Peak load for alternative fuel systems ● Power Generation ○ intermittent ○ peak loadwww.energy.alberta.ca - ● Vehicle Fuels ○ Liquified bionatural gas ○ Compressed bionatural gas
Energy Efficiency ● 60-70+% wood to SNG on LHV basis) ● ~ 90% including cogeneration ( ● 10-15 % higher than biomass to liquids efficiency (GM2012) ● Potential for polygeneration ● Allothermal and autothermalFrom ECN ● Low temperature gasification for efficient ~850 C
Allothermal vs Autothermalgasification heat gasification heatproduced outside of the produced insidegasifier the gasifier Diagrams from Gassner and Marechal (2012)
Two Allothermal DesignphilosophiesSwiss-Austrian Dutch● Steam Assisted ● Uses simple low-steam gasification content, gasification system● reforming tars in gasification ● Needs better tar cleaning system● Biodiesel gas cleaning requires cleaner gas ● 6% higher modeled SNG ○ less efficient process production efficiency. due to steam content http://www.ecn.nl/docs/library/report/2010/m10050.pdf
Allothermal Gasification ● Higher capital costs ○ $927-$1755 /KWth ○ complex system ○ lower pressures to allow for heat transfer by fluidization medium ● Slightly lower efficiency ● Based on avoiding requirement for oxygen generation on site. Photo: www.aer-gas.de/index.php?l=C&m=A
Allothermal Gasification process inGassner and Marechal 2012
Autothermal CFBGasification● Lower capital cost ○ $1240-$521/KWth ○ Simpler system ○ pressurized gasification and higher methanization pressure● Requires oxygen supply● Slightly higher efficiency than allothermal systems
Autothermal GasifierFrom Gassner and Marechal (2012)
SNG Production Prices $/GJ Low Wood Cost High Wood Cost5 MW CFB $26.42 $33.2320 MW CFB $18.76 $25.56100 MW CFB $13.48 $19.625 MW FICFB $32.42 $39.4520 MW FICFB $22.25 $29.28100 MW FICFB $18.08 $24.81Larger and autothermal plants have lowercosts. Based on Gassner and Marechal (2012)and adapted to British Columbian conditions
ButSNG is so expensive! A carbon price of $100 per tonne CO2 increases the cost of natural gas by $5 per GJOnly when the costs of the carbon dioxide climate damage areignored (Ackerman and Stanton, 2004)
Biofuels $/TCO2 Reduction SNG has competitive mitigation S N costs GFrom Fulton et al. (2004) Biofuels for Transportation. http://www.cti2000.it/Bionett/All-2004-004%20IEA%20biofue20report.pdf
GHG Effects of SNG ● Carbo et al (2011) found significant potential to combine CCS with carbon capture and storage ● Net negative CO2 when combined withwww.climate101.org carbon capture and storage
Methane Leakage● Depends on the quality of the grid● Life-cycle analysis of shale gas and natural gas suggests limited impact of methane emissions from transmission.
Natural gas has better thanGHG balance than coal!Biomethane has even lower seeing role ofcombustion GHG
With SNG any natural gasbus can be a biogas bus
Buses ● Natural gas buses are widely used ● 150 units in Canada ● $45,000 Capital premium Source: Marbek (2010)
Truck ● 700- 900 miles range ● $70,000 more expensive capital costs ● Spark ignition and HPDI (natural gas/diesel mixture) ○ spark ignition 10% less fuel economy. ○ or 5% diesel mixture
Marine Traffic LNG MS Stavangerfjord● LNG becoming popular as a marine fuel due to large mobile "point" source of demand.● Ferry in operation in Norway● Considered by BC Ferries (BC ferries uses 118 Million liters of diesel p/.a) and Washington State Ferries
SNG Electricity generation● SNG works in existing natural gas generators and turbines● Can provide flexible low capital cost biomass power● Natural gas turbines cost 1.2 Mil Canadian per MW.http://www.emr.gov.yk.ca/oilandgas/pdf/eagleplain_.pdf
Renewable Power Methanehttp://www.iwes.fraunhofer.de/de/publikationen/uebersicht/2010/towards_100_integrationofresimulationscenariosandstoragebylinkin/_jcr_content/pressrelease/linklistPar/download/file.res/2010-049_Towards-Integration_NREL.pdf
Peak Load Heating ● Technological and Economic barriers ● Biomass boilers high capital costs ○ 5 MWth $ 600 per KWth ○ Nat Gas. $196 per KWthhttps://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcRcml0wFkH4yJA2uYFq0Y546UUP55zcHFktcBeUARpm_v1CQ9uO
Challenges with biomass systems ● Turndown Ratio ○ Max prod: Min Prod ● Typically 3:1 ○ Load variation much greaterhttp://www.riebenbauer.at ○ Long start up time for solid biomass systems makes load following by start up and shutdown unfeasible
Heat Pump System Limits ● High capital cost ● Air source units have much lower heat production at low temperatures ● natural gas backup and peaking ○ SNG can replace fossil natural gas
SNG Heating ● SNG Heating can work where natural gas works, due to quick start-up of boilers and furnaces ● SNG is expensive so other options will likely make sense for baseload!
Flying on Liquified NG?XB-70 Boeing SUGAR Freeze
LNG vs Hydrogen LBM greater energy storage density· Liquid Biomethane 22.2 MJ/L· Liquid Hydrogen 8.5 MJ/L Liquid hydrogen better energy KG/Mass· Liquid Biomethane 53.6 MJ/KG· Liquid Hydrogen 141.6 MJ/KG LBM is a better fuel choice when volume is limited.
The decarbonization Triangle e- Various energy currencies CO2 H2O O2CH4 H2 4H2 + CO2 CH4 + 2H2O Muradov (2013), DOI: 10.1039/c3ee22879g
ConclusionSNG offers● energy efficient biofuel production● Second generation biofuel● Transportation, heating and power generation fuel● Low emissions● Existing infrastructure● Integration with Wind, Water Solar sources through Renewable Power Methane.