SNG: A Renewable, Regional Biofuel

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Describes markets and production for biomass based synthetic natural gas.

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SNG: A Renewable, Regional Biofuel.

Looking at Possible Markets

Thomas Cheneycheney (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 energy system1 MW SNG production facility at Gussing,

Austria

How SNGis Made from WoodFeedstock Pre-treatment

Gasification GasCleaning

Gasification

Methanization

CO2 removal, Compression

Gas Grid

SNG Markets● Space and Water

Heating○ Existing gas furnaces ○ Peak load for alternative

fuel systems● Power Generation

○ intermittent ○ peak load

● Vehicle Fuels○ Liquified bionatural gas○ Compressed bionatural gas

www.energy.alberta.ca -

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 autothermal

● Low temperature gasification for efficient

~850 C

From ECN

Allothermal vs Autothermal

gasification heat produced outside of the gasifier

gasification heat produced inside the gasifier

Diagrams from Gassner and Marechal (2012)

Two Allothermal Design philosophiesSwiss-Austrian

● Steam Assisted gasification

● reforming tars in gasification

● Biodiesel gas cleaning requires cleaner gas ○ less efficient process

due to steam content

Dutch

● Uses simple low-steam content, gasification system

● Needs better tar cleaning system

● 6% higher modeled SNG production efficiency.

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 in Gassner and Marechal 2012

Autothermal CFB Gasification

● Lower capital cost○ $1240-$521/KWth○ Simpler system○ pressurized gasification and higher methanization

pressure● Requires oxygen supply● Slightly higher efficiency than allothermal

systems

Autothermal Gasifier

From Gassner and Marechal (2012)

SNG Production Prices $/GJ

Larger and autothermal plants have lower costs. Based on Gassner and Marechal (2012) and adapted to British Columbian conditions

Low Wood Cost High Wood Cost

5 MW CFB $26.42 $33.23

20 MW CFB $18.76 $25.56

100 MW CFB $13.48 $19.62

5 MW FICFB $32.42 $39.45

20 MW FICFB $22.25 $29.28

100 MW FICFB $18.08 $24.81

ButSNG is so expensive!

Only when the costs of the carbon dioxide climate damage are ignored (Ackerman and Stanton, 2004)

A carbon price of $100 per tonne CO2 increases the cost of natural gas by $5 per GJ

SNG With Carbon Tax$ emissions mitigations cost

low wood cost High wood costs

5 MW CFB $388.49 $524.54

20 MW CFB $235.12 $371.16

100 MW CFB $129.51 $252.39

5 MW FICFB $508.36 $648.95

20 MW FICFB $305.09 $445.69

100 MW FICFB $221.64 $356.11

Biofuels $/TCO2 Reduction

SNG has competitive mitigation costs

SNG

From Fulton et al. (2004) Biofuels for Transportation. http://www.cti2000.it/Bionett/All-2004-004%20IEA%20biofuels%20report.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 with carbon capture and storage

www.climate101.org

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 than GHG balance than coal!

Biomethane has even lower seeing role of combustion GHG

SNG USES

© Lasse Hejdenberg/Hejdlösabilder

With SNG any natural gas bus can be a biogas bus

Buses● Natural gas buses are

widely used● 150 units in Canada● $45,000 Capital

premium

Source: Marbek (2010)

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

Norwegian LNG Ferry

http://baltictransportjournal.com/poland/last-of-four-lng-ferries-for-torghattan-nord,23.html

Rail LNG LOCOS

CN Rail exploring LNG propulsion

Biogas Train in Sweden

fr.wikipedia.org

Retrofit cost of 1 Million Euro 1.3 Million $ Canadian

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

Peak Load Heating● Technological and Economic

barriers● Biomass boilers high capital

costs ○ 5 MWth $ 600 per KWth○ Nat Gas. $196 per KWth

https://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

greater○ Long start up time for

solid biomass systems makes load following by start up and shutdown unfeasible

http://www.riebenbauer.at

Food vs Fuel?

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 HydrogenLBM 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

H2

e-

Muradov (2013), DOI: 10.1039/c3ee22879g

CH4

CO2

H2OO2

Various energy currencies

4H2 + CO2 CH4 + 2H2O

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.

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