BioGTL® advanced biofuel project

The BioGTL advanced biofuel project is a development programme which links a series of proven conversion technologies, designed specifically for the processing of biomass-to-liquids in integrated second-generation bio-refineries.

The core element of this production process, whereby biogenic syngas (rather than being used as an FT-feed) is catalytically converted to mixed alcohols, which are subsequently oligomerised, hydrogenated and fractionated into pure bio-hydrocarbon distillate fuels, Diesel and Jet.

The ATD process is based on a mixed alcohol platform allowing relatively low engineering costs, high thermal efficiencies and smaller scale production most suited to the dispersed nature of biomass and SMW feedstocks, thus optimising transport logistics.

Although the ATD process can be used to convert any carbonaceous feed using thermochemical gasification technologies it is optimised to unlock the bioenergy stored in lignin, cellulose and hemi-cellulose which is bound up in plant waste, agricultural and forestry residues, non-food energy crops and urban waste materials.

These mixed alcohol feeds are then converted in an oligomerisation reactor using a zeolite catalytic conversion to produce exceptionally pure iso-paraffinic hydrocarbon fuels and specialty chemicals.

ATD – FT COMPARISON

1) An analysis which compares ATD and FT technologies for converting Biomass to liquid using syngas as the starting point

	FT Fischer Tropsch	ATD Catalytic Conversion of Alcohols to Distillates
Syngas production	FT requires high purity syngas with an optimum ratio H/CO 2:1. The gasification of biomass results in lower H ratio 1.5:1 or less. Using 100% biomass derived syngas results in a H deficiency for FT. Requires more expensive catalyst. Less flexible because syngas must be produced at site of FT reactor.	Catalytic conversion of syngas to mixed alcohols requires a lower quality syngas which is less pure saving costs on gas cleanup. Lower H:CO ratio required. More robust less expensive catalyst required. Dispersed small scale gasifiers able to produce mixed alcohols which can be easily transported as intermediary product to centralised ATD reactor
Basic reactions	Fischer Tropsch reaction can be depicted as follows: nCO + (2n+1)H₂ --> C_nH_(2n+2)+nH₂0 Syngas (CO +H2) is catalytically converted into paraffins (CnH(2n+2)), emitting water in the process.	Chemically, the ATD-process can be described as follows: nCO + 2nH₂ ----> C_nH_(2n+1)OH + (n-1)H₂0 xC_nH_(2n+1)OH+H₂ ---->C_xnH_(2xn+2)+xH₂0 Syngas (CO + H2) is first converted into mixed alcohols (CnH(2n+1)OH), which are subsequently catalytically dehydrated and oligomerised to hydrocarbon range products in one single processing step.
Fuel quality comparison	Due to predominantly n-paraffin content, FT-products often do not meet the required product specifications for jet fuels (especially those concerning density and cold flow properties), thus necessitating further isomerisation, using hydro-/iso-crackers.	ATD is capable of producing in-spec biojet fuels and Arctic diesel that meet the required energy content and key performance specifications, whilst meeting good fuel density and cold-flow properties. Depending on the reactor configuration production flexibility mitigates economic risk.
Conversion Cost / Hydrogen Consumption	The FT-process uses hydrogen (H2) to reduce the O from the syngas (CO + H2). As a result the consumption of hydrogen in the FT-process is much higher than that of the ATD-process.	ATD-process reduces the O from the alcohols (CnH(2n+1)OH) through thermocatalytic conversion.
Energy Consumption	The FT-reaction is exothermic, producing emissions of heat (and water), thus requiring energy-intensive cooling-systems to keep the reactor under control.	The reactions during the ATD-process are exothermic and respectively endothermic, meaning that the heat emitted during oligomerisation can be used to power the simultaneous dehydration-process requiring energy input resulting in a much more efficient energy-consumption.
Economies of scale	FT-installations require a certain magnitude to benefit from economies-of-scale and be economically viable.	The ATD process can be economical on a smaller scale, as well as overcoming transportation problems caused by bulk biomass transportation by prior conversion to alcohol feedstock which is easier and cheaper to transport.