Lecture 10
Biomass • Basics of biomass production • Biomass and bioenergy potential • Solid biomass • Extra: Land-use changes (LUC and ILUC see supplementary material)
C6370 Peter Lund 2014
Bioenergy in short • What is biomass and bioenergy ? – All forms of organic material (forests, plants, crops, algae, forestry and municipal waste, garbage, manure, etc.) is biomass; terrestrial (3/4) and ocean biomasses – Often biomass and waste Alows are handled separately (e.g. in bioenergy statistics) – Biomass is converted into bioenergy: • Thermal, chemical and biochemical conversion processes • Solid, liquid and gaseous bioenergy/fuels • Bioenergy from biomass waste streams or from virgin biomass
• Role of bioenergy in energy production – Finland >20%, world 6% (14%), EU 4% of all energy (10% of all fuels in 2020)
• Future of bioenergy – Key issue is production of sustainable biomass resources – Different advanced conversion paths: bio CHP, anaerobic fermentation, gasiAication, waste, biofuels, energy crops, lignocellulosic biofuels C6370 Peter Lund 2014
Relative share of bioenergy forms in EU presently
Evolution and nature’s energy systems Energy process Energy cocktail!
DNA cell/bacteria (fermentation)
plants/animals
mammals
Carbon stores
CO2
anaerobic assimilation / cyanobact. aerobic assimilation
Waste
Oxygen in atmosphere
O2 ↓
CO2
Ilmakehän happipitoisuus
Life form
korkeat elämän muodot
0.01
yhteyttäminen
0.001 0.0001
3
2
1
aika, mrd vuotta, nykyhetki=0
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0.1
kasvit/hengitys
4
human
1
nykytaso, 21% happea
0
Natural production of biomass light
– Photosynthesis 6 CO2+6H20 → C6H12O6+6O2; glucose as end product – Light absorbs in chlorophyll which is located in chloroplast (cell) – Conversion efAiciency of photosynthesis process from light to energy η(max) • • • •
Wavelength response (400-700 nm) ReAlection losses (20%) Quantum efAiciency (8 photons/Aixation) Plants own use (metabolisim)
50% 80% 28% 60%
Total (max) 6.7% – C4-plants (4-C sugar as Airst product; sugars and starch, corn), theoretical η= 6.7% – C3-plants (trees, wheat) η=3.3% (light saturation, only 30% of light utilized) ; 95% of all plant biomass – Practical efAiciency of C4 plants is 2-3%
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C3 and C4 processes to fix carbon dioxide and produce biomass • The C3 pathway requires 18 ATP for the synthesis of one molecule of glucose while the C4 pathway requires 30 ATP • C4 has four carbon atoms in the intermediate compound and is more advanced than C3 (Calvin cycle, picture below)
C6370 Peter Lund 2014
Biomass productivity of different ecosystems Producer
Biomass productivity (gC/m²/yr)
SWAMPS AND MARSHES
2,500
CORAL REEFS TROPICAL RAIN FORESTS ALGAL BEDS RIVER ESTUARIES
2,000
8
16
2,000
0.28
0.56
TEMPERATE FORESTS
1,250
19
24
650 140 125 3
17
11
311 50
39 0.15
CULTIVATED LANDS TUNDRAS OPEN OCEAN DESERTS
Total production (billion tonnes C/ yr)
2,000 1,800
Peter Lund 2013 Source Wikipedia
Total area (million km²)
Amount of biomass produced through photosynthesis • World-wide biomass production is around 220 billion tons, or ten-fold world’s energy demand; 20% of this is used as food for land (animals) – Total photosynthetic productivity of Earth is much higher or 1500-2250 TW – Amount of biomass of bacteria ~ Amount of biomass of plants – Biomass is an important carbon binder (110 billion tons of C/yr), it’s use inAluences climate-change
• Energy value of biomass: in average 17-18 GJ/ton (dry mass; water content of fresh biomass may be quite high, 40-90%); woody biomass 20 GJ/ton • Yields (incl water) : C4-plants 150 ton/yr per ha, C3-plants 70 ton/yr, but sensitive to temperature and amount of light, much lower values in north – Mid-west USA 208 ton/yr per ha (C4)
– Utilization: ½ of the biomass can be utilized (exl. roots, stump, branches → max 30-35 ton/year per ha C6370 Peter Lund 2014
Sunshine, water and heat = biomass • Optimal temperature for biomass growth is 20-30 oC, if < 0-5 oC no production • Water demand is 300-1000 ton H2O/1ton dry mass (C4 more effective) • Solar radiation in tropics 5-6 GJ/ m2 yr, in north less than ½; biomass production is ca 1,5 g drymass per 1 MJ of solar radiation • CO2 increases growth (in particular C3) C6370 Peter Lund 2014
Effect of solar radiation on growth (C3) • Saturation may occur already at 100 W/m2 (max solar is 1000 W/m2)
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Net dry matter production
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Biomass productivity of different ecosystems Producer
Biomass productivity (gC/m²/yr)
Total area (million km²)
Total production (billion tonnes C/ yr)
swamps and marshes
2,500
tropical rain forests
2,000
8
16
coral reefs algal beds river estuaries
2,000 2,000 1,800
0.28
0.56
temperate forests
1,250
19
24
650 140 125 3
17
11
311 50
39 0.15
cultivated lands tundras open ocean deserts Source Wikipedia
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Energy yields from crops
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Sources of solid biomass • Waste streams from food production and forestry industries correspond to 20-25% of world energy • All that waste cannot be utilized: – Too dispersed, too low quality – Other economic use – Recycling (fertilizers)
• ½ of all roundwood goes to industrial use, ½ to energy and charcoal – Using natural forests as such for energy may be questionable
• Energy plantations – Short circulation plants – Yearly (grasses) and 3-5 year-periodicaly harvested (trees) plants – Sorgum, perennials, poppel, ruokohelpi
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Sources of biowaste Waste sources (EJ)
14-17 GJ/ton C6370 Peter Lund 2014
Energy balance of biomass plantations
• Net energy is deAined as energy contents of produced biomass divided by energy needed to produce that biomass • Net energy ratio above 10 is possible
C6370 Peter Lund 2014
Potential of solid biomass in world energy production • Overall potential of waste streams is around 10% of world energy • Energy plantations: – assume 15 ton/ha per year – 2050: potential could 60-70% of world energy (260 EJ/yr, corresponds to 10% of useful land)
C6370 Peter Lund 2014
Biomass in Europe • Bioenergy corresponds to 4% of EU’s primary energy, potential of own biomass sources is 15% • Environmental constraints put limitation to use
source: EEA C6370 Peter Lund 2014
Where does biomass come from in EU? • Biomass from waste and agricultural residuals have largest potential
source: EEA C6370 Peter Lund 2014
Summary of differerent biomass potential estimates by 2050 • • • • • • •
Residues from agriculture Organic waste Dung Forestry waste Energy crops Energiaplantations (poor land) Biomaterials
• Total
15-70 EJ 5-50 5-55à0 30-150 à0 0-700 (100-300) 60-150à0 40-150
40-1100 EJ
(250-500 EJ )
• World energy use presently ~ 450 EJ
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Sustainable biomass potential • 30% of present energy use
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Finland’s biomass resource base • Huge biomass resource base: wood 50, agriculture 8, waste 5 Mton/yr, peat reserves total 2060 Mtons • Wood grows 100 Mm3/year, 900 PJ/yr; total energy use 1400 PJ • Energy crop yields would be 4-5 t /ha per year
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Biomass energy use in Finland and potential
• Bioenergy use at present in Finland 310 PJ (22%), peat 100 PJ
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Indirect and direct land-use changes • LUC and ILUC
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Indirect and direct land-use changes • aa
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Your Work # 10 • Home work from Lecture 10 (Biomass) – How much could/should Finland increase its renewable energy use through biomass resources?
• In preparing for Lecture 11 (Bioenergy) – Have a look on the biofuel stuff, just overview)
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Extras
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Photosynthesis on molecular level (basis for 4th generation biofuels)
• Microalgae and cyanobacteria show several energy reaction mechanisms : • Basic photosynthesis reaction: CO2+H20 + light→ CnHmOn+O2 • Anaerobic conditions: 4H20 + hydrogenase entzyme (side product of photosynthesis, sensitive to O2) + light → 2O2 + 4H2; • Cyanobacteria and nitrogenase entzyme: –
N2 +8H++8e-+16ATP → 2NH3+16ADP+16Pi+ H2
• Purple bacteria – From organic material or H2S electrons à proton gradient (H+) à ATP (energy storage that drive charge transfer mechanisms) C6370 Peter Lund 2014
Purple bacteria
Application: Biohydrogen from microbes Thermophylic bacteria that operate at temperatures up to 70°C give higher yields than bacteria that operate at ambient temperatures. A typical chemical reaction is: C6H12O6 + 2H2O = 2CO2 + 2CH3COOH + 4H2 The yields can be increased further by using phototropic bacteria that convert acetic acid to hydrogen, as follows: CH3COOH + 4H2O = 2CO2 + 4H2
C6370 Peter Lund 2014
Photobiochemical efficiency in bioH2 • Bacteria can be used to produce fuel or chemicals (see previous slide) • Yield of biological H2 120 l/ha/day in southern Europe, in north half of this • In future photobioreactors
C6370 Peter Lund 2014