1. The future for biofuels
BioenNW, Brussels, 24 September 2015
Tony Bridgwater
Bioenergy Research Group
European Bioenergy Research Institute
Aston University, Birmingham B4 7ET, UK

2. Thermal conversion for hydrocarbons
Primary conversion
Fast pyrolysis to bio-oil
Gasification to syngas
Hydrothermal processing to bio-crude
Secondary conversion
Fermentation of syngas to ethanol
Synthesis of alcohols (MeOH, EtOH etc) from syngas
Catalytic cracking bio-oil for deoxygenation
Hydrodeoxygenation bio-oil or HTU product
Synthesis of hydrocarbons e.g. Fischer Tropsch et al.
Tertiary conversion
Alcohol dehydration and oligomerisation
Refining
Refining to specified fuel standards

3. Routes to biofuels Gasification routes Pyrolysis routes HTP routes
Biomass
Fast pyrolysis
Hydro-
thermal
processing
Bio-oil
Gasification
Zeolite
cracking
Syngas
Ferment
Synthesise
Hydro-
treating
Hydro-
treating
-OH dehydration
Refining
Hydrocarbons

4. Fast pyrolysis Fast pyrolysis requires:
High heating rates: Small particle sizes needed
Dry biomass: <10wt.% water:
Carefully controlled temperature: ~500C
Rapid and effective char removal: Char is catalytic
Short hot vapour residence time: to avoid product loss reduces liquid yield
Atmospheric pressure to minimise char formation
The liquid product bio-oil is obtained in yields of up to 75wt.% on dry feed. It has high oxygen, around 25wt.% water and is not miscible with hydrocarbons. Charcoal is consumed in the process..

5. Decentralised fast pyrolysis
Bulk density
Biomass density can be as low as 100 kg/m3
Bio-oil density is kg/m3
Bio-oil liquid storage, handling and transport
Tanks and pumps are used
No windblown refuse, vermin, or mechanical handling
Provides optimum use of loading weight restrictions
Central processor e.g. for biofuel 5

6. Hydrothermal processing
Otherwise known as liquefaction, biomass is heated under pressure in a liquid environment at moderate temperatures up to 350C
The technology was demonstrated at Albany, Oregon around 1980 with wood in a 1 tph plant. The liquid phase was either water or recycled product oil.
Shell subsequently developed their own process - HTU
Others have also investigated the technology.
The product has much lower oxygen than fast pyrolysis (~15% vs 40%), has high viscosity, and phase separates from the aqueous phase. It is particularly suitable for wet feedstocks.

7. Bio-oil for biofuels Indirect production Direct production
Gasification of bio-oil followed by hydrocarbon or alcohol synthesis. There are many technical and economic advantages of gasification of liquid bio-oil rather than solid biomass; but higher costs for bio-oil
Direct production
Via catalytic upgrading of liquid or vapour
Catalyst can be added to biomass; incorporated into the fluid bed material; use of a close coupled reactor; use of a remote reactor
Ex-situ or secondary reaction offers independent control over process conditions;
Direct feeding bio-oil into a suitable refinery operation 7

8. Bio-oil and HTP oil upgrading
Zeolite cracking rejects oxygen as CO2
Vapour processing in a close coupled process
No hydrogen requirement, no pressure
Extensive coking requires burn-off as in FCC
Hydro-deoxygenation rejects oxygen as H2O
Liquid processing with hydrogen and high pressure
Extent of deoxygenation depends on severity of upgrading conditions – pressure, temperature, catalyst and residence time
Complex from hydrogen recycling and multiple steps
Completion of partial upgrading in conventional refineries is an attractive opportunity for access to economy of scale and expertise.

9. Gasification methods
Gasification is the conversion of organic material into a mixture of CO, H2, CO2, CH4 and impurities of which tar is critical.
Type
Gas HV %
Comments
Oxidative Air
Oxygen
~5 MJ/Nm3
~12 MJ/Nm3 Hi
Mod
Simple but N2 precludes biofuels
High cost and high energy use
Indirect
~17 MJ/Nm3 Lo
More complex. Gas needs compression for biofuels
Pressure Air
~10 MJ/Nm3
Higher cost, but higher efficiency
O2 for biofuels 9

10. System requirements - large scale
Minimum FT size considered to be viable is bb/day = 1 mt/y product requiring 5 mt/y biomass
Mini-systems under development e.g. Velocys
Entrained flow gasifier requires small feed size or liquids. Pretreatment is necessary
Grinding biomass has high economic and energy cost
Torrefaction gives a brittle feed = higher costs
Fast pyrolysis gives a liquid = higher preparation costs
Pressure = higher cost; but higher efficiency;
Oxygen for nitrogen free gas = high cost + high energy
Indirect gasifiers give nitrogen free gas but are not large scale and cannot be pressurised
Large scale gives higher efficiency 10

11. Criteria for evaluation
The key criteria for technology and process evaluation are:
Development costs including demonstration
Biomass availability, cost, logistics, characteristics
Product selection
Scale of operation
Process route complexity and maturity
Efficiency of process of biomass to biofuels
Capital cost
Biofuel production cost
Integration into established infrastructure
Scaleability
Technology risks and uncertainties
Current status

12. BTL energy self sufficiency
Energy conversion
Mass conversion
Self sufficient in heat and power. This costs about 4% in mass yield and 10% in energy yield
Process

13. Capital cost

14. Capital costs Capital cost, million € 2008
Pyrolysis + large FT
Small gasification + small FT
Biomass input million dry t/y
Capital cost, million € 2008
Large gasification + FT
Small FT unproven
Small pyrolysis & large FT proven
Large gasification unproven

15. Costs of bio-hydrocarbons
Yield, wt%
€/t product
HHV, GJ/t
€/GJ product
€/toe
Wood feed (daf)
100 67 20 3
145
Pyrolysis oil output 70
147 19 8
331
Diesel (EXCL H2) & 23
592 44 13
578
Diesel (INCL H2 from biomass) &
880
860
Gasoline & 22
453 10
443
FT diesel #
1060 42 25
1030
MTG gasoline # 26
1320 43 31
Crude oil at $100/bbl -
560 15
& Basis: t/d daf wood feed at 67 €/dry t, 2006
# Basis: 1 mt/y product derived by gasification (DENA report ) 2006

16. Unit processes and scale
Max size
TRL
Risks
Primary conversion
Fast pyrolysis to bio-oil
125 t/d 7
Scale up
Gasification to syngas
50 t/d
Size; gas cleaning
Hydrothermal
25 t/d 3
Pressure, Feeding
Secondary conversion
Fermentation of syngas
1000 t/d
Contamination
Cat cracking bio-oil
50 kg/d 5
Unproven
HDO bio-oil and HTU oil 2
Hydrogen; Unproven
Alcohol synthesis
1000 t/d 8
Minimal
Hydrocarbon synthesis
200 kbbl/d 9
Tertiary conversion
Alcohol dehydration
kg/d
Refining
Refining to standards
100kbbl/d

17. Conclusions Fast pyrolysis provides a liquid as an energy carrier
Gasification has many variants but oxygen and pressure needed for biofuels. Gas clean up is critical.
HTU has been demonstrated a long time ago. Increased interest for wet feedstocks. Liquid has higher HV than bio- oil but lower yield. Less developed, more costly.
Hydrocarbons via ethanol dehydration offers potentially high yields and a “controlled” product.
Process optimisation is essential with integration into established infrastructure
Downscaling potential for dispersed biomass but capex increases
No current “best” method but criteria are well understood 17

18. Thank you