Biomass as a source of energy and chemicals: the Biorefinery Concept

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Biomass as a source of energy and chemicals
the Biorefinery Concept

• Michele Aresta

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Outline

• The need to decouple
• biomass production and land utilization
• food and energy use of raw materials
• The aquatic biomass utilization option
• Microalgae and macroalgae
• Coupling biomass growth and water treatment
• Applying the Biorefinery concept
• Total utilization of the biomass production of
  chemicals, fuels, hydrogen
• The application of the LCA methodology for the
  evaluation of the economic, energetic and
  environmental benefits
• Concluding remarks

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The need to reduce the CO2 immission into the
atmosphere

• The world energy demand is increasing at a rate
  never experienced before during the next 30
  years an increase of 20-66 PWh is foreseen from
  the actual 16 PWh.
• Emerging economies will use over 60 of the total
  energy with respect to actual less than 40
• Fossil C-based fuels provide over 80 of the
  used energy
• The accumulation of CO2 into the atmosphere is
  causing serious worries for its potential effect
  on climate change

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The CO2 control technologies

• Efficiency technologies
• Production of electric energy
• Use of energy
• Fuel shift
• Gas lt oil lt coal
• Innovative technologies for electric energy
  production
• IGCC
• Non carbon-based fuels
• Nuclear
• Perennial
• Solar, wind, hydro, geothermal
• Renewables
• Biomass
• CCS
• CO2 capture and disposal
• Utilisation
• Chemical, Technological, Biological (enhanced CO2
  fixation)

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Strategic value of the utilization of
bio-feedstocks
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Biomass exploitation

• Several international programmes aim at the
  expansion of the use of terrestrial biomass
• Residual biomass
• Wood industry, agro-food industry, sludge, others
• Energy grown biomass
• Seed plants ? Bio-oil, bio-diesel
• Cereals ? Bio-ethanol
• Cellulosic materials ? Bio-ethanol, Bio-Syngas
• Lignine ? Bio-Syngas
• Growing terrestrial biomass rises the problem of
  land utilization-availability

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Bio-feedstock utilization

• Several feedstocks (cereals, oils) may be used as
  food or energy source.
• This may rise social problems and cause
  destabilization of the food market (this issue is
  already under serious debate).
• It is, thus, compulsory to decouple the food and
  energy use of land and biomass.
• Although marginal areas could be used, it is not
  so simple to find a convenient solution that must
  be economic

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The aquatic biomass option

• A way to reduce the land utilization is the use
  of water environments
• Natural or artificial basins can be considered
  for exploitation or resources recovery
• Cultivation on coastal areas or off-shore
• Lagooning waste water for treatment
• Fisheries are interesting candidates for
• coupling water treatment and aquatic biomass
  growing
• Municipal and process waters can be used, with
  the additional benefit of water treatment and
  better resource utilization

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Terrestrial vs Aquatic

• Light efficiency 6-8
• (or higher when irradiated bioreactors are
  used)
• May not require land for cultivation (coastal,
  offshore)
• Low lignocellulose content
• Richer in water
• Lipid/protein/polysaccharide content can be
  adjusted
• Easy to grow in bioreactors (light-temperature
  adjustment) decoupling from climatic conditions.

• Light efficiency 1.5-2.2
• Requires land and water
• Productivity depends on soil quality (for a
  given plant)
• Soil additives may be required
• (environmental and economic costs)
• Biomass is generally rich in ligno-cellulosic
  components
• Seed plants are most used
• Open area more than greenhouse cultivation

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Comparison of different sources for the
production of the biodiesel needed in the
transport sector in the USA
Y. Chisti / Biotechnology Advances 25 (2007)
294306
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Algae farm
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Photobioreactor
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A 1000 L helical tubular photobioreactor at
MurdochUniversity, Australia.
Y. Chisti / Biotechnology Advances 25 (2007)
294306
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Microalgae - Chlorella and Spirulina
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Chaetomorpha linum (O.F. Muller) Kutzing
(Cladophorales, Chlorophyta)
C. linum is present in the unattached form in
both estuarine systems and coastal lagoons
subject to eutrophication. Several
eco-physiological studies have demonstrated the
ability of C. linum for short term adjustment of
internal allocation of both nutrients and carbon.
This makes C. linum greatly competitive for
living in environments characterized by either
light or nutrient supply variability. Therefore,
C. linum can live throughout the year and can
reach high biomass values, estimated at 5 kgfwt
m-2 in the Venice lagoon and 3.5 kgfwt m-2 in the
Mar Piccolo of Taranto.
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Surroundings
Discovered in 1993, is 150.000 years old. He has
Neanderthal morphology
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Products from microalgae
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Classes of compounds extracted from macroalgae
and their uses
 
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High Product Distribution Entropy!

• Entropy control
• Physical manipulation
• Growing conditions
• Genetic manipulation
• Implementation of the Biorefinery concept
• Cascade of technologies
• Non destructive-Semi destructive-Destructive
• The cultivation of algae for energy purposes may
  not be sustainable coupling the production of
  fuels to that of chemicals may the winning
  strategy. The Biorefinery concept at work!

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Oil content of some microalgae
Y. Chisti / Biotechnology Advances 25 (2007)
294306
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Lipid content in some marine macroalgae
12 - 20
The free acid content can be as high as 7-10
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Composition of the fatty acid fraction extracted
from some seaweeds
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FAMEs present in thalli of Chaetomorpha l.
cultured at 10 CO2 concentration
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Macroalgae vs Microalgae
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Technologies available for the treatment of the
biomass

• Extraction (pressure, solvent)
• Thermal (pysolysis, liquefaction, gasification)
• Treatment with SCF
• Extraction with sc-CO2, also in presence of
  co-solvents
• sc-H2O gasification (Syngas, H2-CO)
• Fermentation (alcoholic, anaerobic) (ethanol,
  bio-gas, bio-hydrogen)

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Conversion of glycerol use of biosystems

• Bacterial strains have been identified that are
  able to convert aqueous glycerol either into
  1,3-propanediol or into hydrogen and acids.
• The acids can be converted by another bacterial
  strain into CO2 and hydrogen.
• Pure hydrogen can be collected at 0.6 MPa ready
  for distribution.
• Hydrogen is CO-free and only contains traces of
  CO2.

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H2 production using strain ADK1
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Substrate addition
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Produced gas (mmmol)
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No buffer (20 g/L)
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Buffer (20 g/L)
Buffer with H2 removal (40 g/L)
Buffer with H2 removal (65 g/L)
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0
0
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100
150
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Time (h)
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Chemical vs biological conversion of glycerol
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Adapt the technology to the biomass

• Macroalgae
• Low lipid content ? Biogas Sludge
• High lipid content ? Lipid extraction ?
  Biodiesel, H2
• Residual biomass ? Syngas ? Chemicals, H2
• Microalgae
• High lipid content ? Lipids ? Biodiesel
• Residual biomass ? Syngas ? Chemicals, H2
• Bioglycerol
• Conversion into Chemicals, H2