Small scalebiomassgasification– Challengesand …€¢ Biomass gasification ... and micro‐scale...
Transcript of Small scalebiomassgasification– Challengesand …€¢ Biomass gasification ... and micro‐scale...
Kari PieniniemiPhil.Lic. (Chem)
Centria Univeristy of Applied SciencesYlivieska
Small‐scale biomass gasification –Challenges and opportunities?
Content of presentation• Climate Change is a Global Challenge • Renewable Energy is the answer• Biomass gasification
– Small‐scale biomass gasification• Gasification Strengths and Weaknesses
– Technical barriers • Centria Pilot R&D Gasifier21.11.2013 2
Climate Change is a Global Challenge
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CO2 is the primary greenhouse gasHuman activities, such as the burning of fossil fuels release large amounts of carbon to the atmosphere
"20‐20‐20" targets, set three key objectives for 2020:• A 20% reduction in EU greenhouse gas emissions from 1990 levels;
• Raising the share of EU energy consumption produced from renewable resources to 20%;
• A 20% improvement in the EU's energy efficiency.On 27 March 2013, the European Commission adopted a Green Paper on "A 2030 framework for climate and energy policies".http://ec.europa.eu/energy/green_paper_2030_en.htm
Renewable energy (RES) is the answer
Energy Roadmap 2050 to low carbon economy in 2050• RES in energy consumption 75 % in 2050• RES in electricity consumption reaching 97 %higher energy efficiency and shares of renewables are necessary to meet the CO2 targets in 2050
Energy roadmap 2050 (COM(2011) 885 final of 15 December 2011)
IPCC. 2007. IPCC Fourth Assessment Report. Working Group I Report The Physical Science Basis. Summary for Policy Makers, s. 3.
Renewable Energy is the answer
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GAS; 21%
Re‐newables;
13 %
Nuclear; 6%COAL; 25%
OIL; 35%
8%
15%
77 %50 EJ
Renewables
BioenergyHydropowerOther renewables
4%9%
87 % 43 EJ
Bioenergy
Wood BiomassAgricultural Crops & By‐productsMunicipal & Industrial WasteWorld Primary Energy mixture
100 % = 500 EJ (eksajoule = 1018J)
Renewable Energy is the answer
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• R&D to reduce energy unit costs• Realistic perception of resource availability• Sustainable production and closed carbon cycle
• Recognize cost gap between renewable and fossil fuels
• resulting market failure requires policy measures
For the R&D community
20% Renewables means 2/3 Bioenergy
Overall
“The stone age did not end for the lack of stones and the oil age will end long before the world runs out of oil”
Finally..
Sheiikh Zaki Yamani former Saudi Arabia Oil minister
For policy makes
• higher cost cannot be compensated by public subsidies
• In a level playing field industry will take over
Message to consumers
But there are Challenges ….
Renewable Energy is the answer
21.11.2013 6* Hans Sohlström, Vice President UPM‐ Kymmene Corporation, Finland presentation in 18th European Biomass Conference 2010 Lyon France
BIOENERGY AND BIOFUELS are an opportunity for the FinnishForest Industry*
1G FirstGeneration
2G SecondGeneration
HIGHBIO2
www.chydenius.fi/en/natural‐sciences/research/highbio2
Biomass utilization technologiesTechnology/Process State‐of the Art Main Challenges
CombustionCommercial available, low efficiency at small scale
Feedstock variability, feedstock contamination, combustion stability
Gasification Demonstration scale, Earlycommercialisation stage
Cost reduction, gas quality
Anaerobic digestionCommercial status but high costs, low efficiency and low yield
Scale‐up, cost reduction and use of mixed wastes
Processes to bio‐diesel
Proven technology, high cost and low yield
Cost reduction and continuous production
Fermentation to bio‐ethanol
Commercial status, high cost, low yield
Cost reduction, higher yield
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Biomass gasification
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Biomass gasification is a promising, energy‐efficient technology for renewable energy generation
Gasification: Thermal conversion of biomass into a low calorific to medium‐ calorific value combustible gas
Producer gas: The mixture of gases produced by the gasification of biomass at relatively low temperatures (700 to 1000 °C)
• can be burned in a boiler for heat production, or• in an internal combustion (IC) gas engine for combined heat and electricity (CHP)
Synthesis gas (Syngas): • Mainly carbon monoxide (CO) and hydrogen (H2)• Can be transferred to synthetic natural gas (SNG) orsynthetic diesel (Fischer‐Tropsch synthesis) or use as a feedstock in production of green chemicals
• Gasification in higher temperatures• Cleaning of the producer gas
Gasification stage gas composition: Carbon monoxide (CO), hydrogen (H2), methane (CH4) light hydrocarbons , water vapour (H2O), carbon dioxide (CO2), nitrogen (N2), tar vapor, and ash particles
Biomass gasification
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Gasification is one stage in the thermal biomassconversion process*
*H.A.M. Knoef (Ed,.) (2005) Handbook Biomass Gasification, . ISBN 90‐810068‐1‐9, p. 13
Tar content • 100 g/Nm3 in an updraft gasifier, • 10 g/Nm3 in a fluidized bed gasifier and • 1g/Nm3 in a downdraft gasifier. (Neeft, 1999)
Small‐scale biomass gasification• Small‐scale CHP (combined heat and power) units for heat and electricity production
• Production of biofuels and chemicals
Downdraft gasification is ideal for small scale CHP production up to about 1 MWth
There are about 50 commercial gasification plant manufacturers in Europe, USA and in Canada from which • 75% were fixed‐bed downdraft type, • 20% fluidized‐bed systems, • 2.5% fixed bed updraft type, and • 2.5% were of various other designs
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Product gas or synthesis gas can be used in
Small‐scale* CHP electrical power < 100 kW Micro‐scale CHP electric capacity < 15 kWe
*Dong L., Liu H. and Riffat S. 2009. Development of small‐scale and micro‐scale biomass‐fuelled CHP systems –A literature review. 2009, pp. 2119–2126
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Markets for small scale CHP
Small scale CHP has growing markets in Europe and other OECD countries
Energy‐intensive industries (metals, cement etc.) has a strong needs to diversify fuel consumption and reduce energy costs & CO2 emissions (Climate Change)
1. Biomass CHP Power Plants
2. Carbon‐free Gas for Industry
3. Decentralized Power
Remote areas are affected by high‐increasing prices of fossil fuel for power production based on diesel generators
Small‐scale biomass gasification
Small‐scale biomass gasification
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Small‐Scale Biomass Gasification, XYLOWATT
XYLOWATT (www.xylowatt.com)• Biomass gasification CHP manufacturer and turnkey provider from Belgium
• aims to be a strong international actor in the small‐scale Woodgas CHP (0,1—10 MWe)
• LHV 5,4 MJ/Nm3
• High quality syngas (< 10 mg/Nm3 tar, < 10 °C, water free)
Fully automated plant—High efficiency with syngas use in IC engine (75% total efficiency, 25% net electrical efficiency)
— Flexibility for the operation (100% woodgas or 100% NG)— Fully automatic, instantaneous power regulation, totally remote controlled
1 950 MWh/yr of electricity 3 900 MWh/yr of heat Saves 1644 CO2 Tons/yr Uses 600 odt/yr of wood
*Handbook Biomass Gasification (2012) H.A.M. Knoef (Ed,.), Chapter 2 Success stories on biomass gasification p 20. ISBN 978‐90‐819385‐0‐1
A Success Story*
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Kempele Ecovillage since 2009, Volter Oy
A Success Story
One liter of oil can be replaceby 2 kg of dry wood
Wood gas is fed to IC engineconnected to generator to produce electricity
The electricity and heat for the ten houses in KempeleEcovillage are produced by a CHP‐plant in the village using Volter's wood gasification technology
http://www.volter.fi/etusivu
Gasification and direct combustion have a number of general strengths and weaknessesStrengths Weaknesses
Gasification
Lower NOx, CO, and particulate emissionsPotential for more efficient conversion process when generating powerVirtual elimination of water needs if generating power without a steam turbine
Technology is in the development and demonstration phaseNeed fuel with rather low size distributionand moisture content
Direct Combustion
Proven, simple, lower‐cost technologyEquipment is widely available, complete with warrantiesFuel flexibility in moisture and size People comfortable with technology
Greater NOx, CO, and particulate emissionsInefficient conversion process whengenerating power alone—some advanced designs are improving efficiencyRequires water if generating power with a steam turbine
Gasification Strengths and Weaknesses
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Gasification Strengths and Weaknesses
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Potential Health, Safety and Environmental aspects of gasification plants*
Guideline for Safe and Eco‐friendly BiomassGasification
http://www.gasification‐guide.eu/
Health, safety and environmental (HSE) issues are found an important barrier to the market uptake of biomass gasification technology
Risk assessment in biomass gasification is becoming increasingly important all over the world
*H.A.M. Knoef (Ed.) Handbook Biomass Gasification 2nd Ed. (2012) . ISBN 978‐90‐819385‐0‐1, p. 374 ‐ 432
Gasification Strengths and Weaknesses
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Producer gas properties regarding to HSE aspects
Small‐scale biomass gasifiers operate normally with air as a gasification agent => gas composition differs largely from other gases like biogas or natural gas
• desired products: permanent gas (H2, CO, CH4, CO2, N2) and ashes with low remainingcarbon content
• undesired products: particulate matter, dust, soot, inorganic (alkali metals), H2S, COS, NH3, HCN, HCl and organic pollutants(tars or PAH compounds)
Typical characteristics of producer gas compared to other gases
Parameter Producer gas
Biogas Natural gas
CO (vol %) 12‐20 <1 <0.5H2 (vol %) 15‐35 <1 <0.5CH4 (vol%) 1‐5 50‐75 90‐99CO2 (vol %) 10‐15 20‐50 <1N2 (vol%) 40‐50 <1 <1Heating value MJ/Nm3 4.8‐6.4 18‐26 35Explosion range (vol%) 5‐59 3‐14 4.5‐15Air to gas ratio 1.1‐1.5 5‐7.5 10
Gasification Strengths and Weaknesses
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Explosion levels and combustion pressure
Gas composition 1st stage 2nd stageTar components 0.04 mole/mole 0.02 mole/moleMole weight 24.3 kg/kmol 22.3 kg/kmolStoichiometric combustion air mole air/ mole gas
3.00 mole air/ mole gas
1.59 mole air/ mole gas
LEL 0.104 0.12UEL 0.395 0.62Deflagration pressure at 15°C 6.6 barg 6.1 bargFlame temperature at 15°C 1695 °C 1575 °CDeflagration pressure at 500 °C 3.4 barg 2.5 bargFlame temperature at 500°C 2480 °C 1820 °C
The following analysis comes from a two‐stage gasification plant. The first stage is evaporation and pyrolysis of wood chips by indirect heating. The second stage is pyrolysis of gases by direct heating with combustion products.
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Gasification Strengths and WeaknessesGuideline for Safe and Eco‐friendly Biomass GasificationRiskAnalyzer computer program
The Guideline is intended to be a training tool and a resource for workers and employers to safely design, fabricate, construct, operate and maintain small‐scale biomass gasification facilities (up to about 1 MWe)
http://www.gasification‐guide.eu/
Tars in producer gas is the largest single problem that has to be overcome in order to commercialize gasification processes
Gasification Tehnical Barriers
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In Large Scale: “Two of the most important operational barriers for both the BFBG and CFBG are the risk for defluidisation and the presence of tar in the product gas.”
Most important way to avoiding condensation is to maintain the gas above the tar dew point (~ 400 °C)
Ref: Stefan Heyne, Truls Liliedahl, Magnus Marklund,(2013) Biomass gasification ‐ a synthesis of technical barriers and current research issues for deployment at large scale (f3 2013:5)
requirements on product gas purification are very high to prevent poisoning of the catalysts.
In Production of fuels and chemicals from the syngas As soon as the temperature of the
producer gas drops below the dew point, tars will form aerosols or directly condense on the inner surfaces of the equipment, resulting in plugging and fouling of pipes, tubes, and other componentsdownstream the gasifier.
In Energy Production
Internal combustion (IC) engines and synthesis applications require cooling of the gas before use
Tar free producer gas can be achieved in many ways.
Gasification Technical Barriers
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Physical methods used for removing condensed tar aerosols are same used in removing particles; wet scrubbers, electrostatic precipitators, etc.
Thermal and catalytic methods
Tar cleaning
Tar cleaning
OLGA: Oil Scrubber
The occurrence of tars in producer gas is still the single largest problem that has to be overcome beforecommercialize gasification processes for various purposes
There are two main strategies for dealing with the tar once it is present in the producer gas:• removal and use and • in situ conversion
Removal and use, OLGA process
OLGA has been developed by the Energy Research Centre of the Netherlands (ECN)
The washing and absorption media (“oil”) is fatty acid methyl esters (FAME) produced by the transesterificationof triglycerides from plants (bio‐diesel)
OLGA operates in the temperature range wheretars condense, but water doesn’t (above the dew point of water)
Gasification Technical Barriers
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Condensation step: • Inlet temperature of the gas can be up to 350 °C•Gas is cooled down by the recirculating oil, which washes out the condensed heavy tars
• Part of the oil/tar mixture is returned to the gasifier•WESP is used to remove droplets of tars and oil from the gas
Light tar absorber:• Absorber temperature is just above the water dew pointStripper:• Absorbed tars and oil are fed into a stripper where the light tars are stripped off by hot air• Regenerated oil (FAME)is fed back to the absorber
Gasification Technical Barriers
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Removal and use, OLGA process
Tar cleaning
In situ conversion
tars are converted in the producer gas by some kind of thermal or catalytic process
Gasification Technical Barriers
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Catalytic tar crackingBasic catalysts, such as dolomite, magnesite, and olivine, must be calcinated into oxides (activation)• high temperature (>700°C) and low pressure (<10 bars)
• tar‐cracking catalysts convert tars into synthesis gas (i.e., CO, CO2, and H2) but not into the lower hydrocarbons
Catalytic steam reforming
catalyst of metallic nickel (Ni)water is consumed during the reaction
⇌ 3
reforming temperatures of ~850 °C and steam/carbon ratios 3nickel‐based catalyst is very sensitive to contaminants, especially sulphur
Tar cleaning
Producer gas contains dust, ash, tars, and other contaminants and needs to be cleaned before use.
Tar, dust and ash removal
• Cyclones are standard equipment in producer gas treatment.
• Cyclones generally remove particles from 1 mm down to 5 m in size and work with dry particulates
Cyclones
Candle filtersCandle filters consist of a porous metallic or ceramic filter material that allows gases to pass but not the particulates
Candle filters can be operated at temperatures up to 500 °C and can effectively remove particles in the 0.5–100 mm range
Bag filtersBag filters are made of polymeric, ceramic, or natural fibresThey operate like candle filter and are regularly vibrated or back‐flushed to remove the built‐up filter cake. The maximum operation temperature of a bag filter is approximately 350 °C
• Cyclones can operate at actual gas temperatures (up to 900–1000 °C) to avoid cooling the gas
• Cyclones can be used in series as multi‐cyclone
Gasification Technical Barriers
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In an electrostatic precipitator, ash and dust particles receive a negative electric charge when they pass an electrode connected to a high voltage source (10–100 kV DC).
Electrostatic precipitator (ESP)
Electrostatic precipitators can be operated at temperatures up to approximately 400 °C. Collected dust must regularly be removed by vibration
Wet electrostatic precipitators (WESP)WESP are also used to remove oil droplets (FAME) released by oil scrubbers used for tar removal
Gasification Technical Barriers
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In a small scale biomass gasification power plant for IC engine tar and ash particles are filtered from the gas stream using
Small- scale biomass CHP
o Cyclone to remove coarse particles o Scrubber for removal of tar, some dust particles and gas cooling
o Catalytic tar cracking unitso Course filters made of packed beds of porous materials o Fine filters made from fabric material for removal of very fine particles
Typically producer gas is cooled to about 35 °Co increases density => increase in the engine power output
o lowers thermal efficiency o increases need for waste water treatment (harmful e.g. phenols )
Tar, dust and ash removal
Centria Pilot R&D Gasifier
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Fuels used in the gasification Solid, air dried wood chips is normally used as a fuel in the gasification process
• size of the chips 0 to 100 mm and• moisture content can be up to 40 vol‐%
• CENTRIA Gasifier is based on patented EK gasifier (GasEK)o Downdraft gasifiero IC engine CHPo Stirling engine CHP
• Used in HighBio2 research project
Centria Pilot R&D Gasifier
Power Tar concentration of the product gas (dry, STP: 0°C, 1 atm)
9 kWe 24 ± 5 mg/Nm3Low tar content
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Centria Pilot R&D Gasifier
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1. Wood chip storage2. Wood chip screw conveyor3. Gasifier4. Raw gas pipe 5. Scrubbers6. Water tank7. Ash barrel8. Engine 8.4 liter9. Generator 50 kW10. Startup pipe11. Exhaust pipe12. Heat exchanger for exhaust
gas13. Cooler14. Heat exchanger
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Centria Pilot Gasifier is a Small Scale CHP based on wood gasification
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Stirling engine CHP
Solo Stirling‐engine electric power 9 kWe . thermal power 26 kWth ´From left Yrjö Muilu and students Kauko Jarva and Mauri Niskanen
Centria Pilot R&D GasifierGas engine CHP
• Downdraft gasifier and • 8 cylinder 5,4 L gas engine• Electric power 20 kWe• Thermal power 50 kWth
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Centria Pilot R&D Gasifier
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Measured flue gas component
Measured flue gas composition
Concentration (dry, STP 0°C, 1 atm) mg/Nm3
O2 0.4 vol% ‐
CO2 17 vol% ‐
CO 568 ppm 170
SO2 8 ppm 25
NOx 162 ppm 332
Emissions of the IC engine* Emissions of the Stigling engine**
*MuiluY.,Pieniniemi K.,Granö U.‐P.&LassiU(2010) ANovelApproachtoBiomassGasificationinaDowndraftGasifier.In:Proceedingsofthe18thEuropeanBiomassConferenceandExhibition,2010inLyon,ISBN‐10:8889407565,ISBN‐13:978‐8889407561pp.688‐692.
**Pieniniemi K.,MuiluY.andUllaLassi(2013)Micro‐CHPBasedonBiomassGasificationinaDowndraftGasifier andStirlingEngine. In:Proceedingsofthe21stEuropeanBiomassConferenceandExhibition,2013inCopenhagen,ISBN:978‐88‐89407‐53‐0,DOI10.5071/21stEUBCE2013‐2CV.3.21.pp.814– 819
Measuredflue gascomponent
Measuredflue gascomposition
Concentration(dry, 6% O2, STP 0°C, 1 atm) mg/Nm3
O2 4,10 vol% ‐
CO2 16,6 vol% ‐
CO 9 ppm 10
SO2 0,2 ppm 0,4
NOx 22,5 ppm 41
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Main task of the CENTRIA R&D in HIGHBIO2 research project is to support the local, decentralized small‐scale heat and power production by research and development work in co‐operation with the partner universities Focus of the research in CENTRIA R&D is
o on improving controllability of the gasification process and o on online analysis of the produced syngas and flue gases
Partners and Funding:
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Video
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VTT ‐ Biomass and Waste Gasification, from R&D to industrial success (20.9.2013) (YouTube)
VTT‐ Gasification of Waste technologies (15.05.2013) (YouTube)
Wood biomass remains the main energy source for widespread biomass powered CHP systems at small and micro‐scale
Gasification of biomass using a gas engine (or gas turbine) presents interest possibility for small to medium scale co-generation
The Stirling Engine coupled with a gasifier is an interesting option for distributed CHP and should be available very soon
Conclusion - Future for Small-Scale Biomass Cogeneration
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Tars are still the single largest problem that has to be overcome before commercialize gasification processes
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Advantages and disadvantages of decentralised electricity production
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Advantages Disadvantages
Reduced emissions from fossil fuels Increased complexity for connectivity
Reduced transmission losses Lower output efficiency
Reduced transmission infrastructure Higher capital and generation costs
Increased reliability of power supply Need for regulation of power quality
Creation of employment Labour intensive
Encourages CHP generation Possible high reliance upon natural gas
Usage of a broader range of (renewable) fuels Higher maintenance costs
Enhanced fault tolerance
Greater research and innovation opportunities