Ethtec Cellulosic Ethanol Pilot Plant

Summary

Need

According to the Commonwealth Department of Environment and Energy’s 2014 Emission Reduction Fund White Paper, transport emissions increased by 50 per cent between 1990 and 2012, the fastest sectoral growth over that period. Emissions increased because growth in transport activity outpaced improvements in fuel and transport efficiency. The Climate Change Authority’s (CCA) Light Vehicle Emissions Standards Research Report notes, without further policy action, overall transport emissions are projected to increase until 2030 unless significant efficiency gains are realised from the use of mass transport, more efficient vehicles and lower carbon intensity fuels.

The CCA views light vehicle electrification and biofuels for light vehicles as being able to deliver significant emissions reduction over the longer term. For heavier vehicles, biofuels and greater use of natural gas are considered to have the best potential to reduce the emissions intensity of Australia’s heavy vehicle fleet. Assessing the emissions reduction potential of a large range of transport options, the Australian Low Carbon Transport Forum found the top four options for delivering emissions improvements all involved changes to light vehicles: electrification, use of biofuels, fuel efficiency technologies and downsizing.

Action

Ethtec is developing and commercialising new technology for environmentally sustainable production of ethanol biofuel from lignocellulosic materials, i.e., non-food, woody or fibrous biomass such as sugar cane bagasse, crop stubbles and forest material (the Ethtec Process). The Ethtec Process is comprised of four phases:

Phase 1: Lignocellulosic feedstock is fed into a twin screw extruder and impregnated with high concentration sulphuric acid whereupon the cellulose and hemicellulose components of the feedstock are decrystallised and solubilised. The output from the extruder passes to a hydrolysis reactor whereupon the solubilised cellulose and hemicellulose release their component sugars (glucose, xylose, galactose, mannose and arabinose) into solution.

Phase 2: The output from the hydrolysis reactor is filtered to recover the solid lignin component of the feedstock, which is used for energy generation. The filtrate liquid mixture of sugars and acid is separated by chromatography into a sugars stream (hydrolysate) and a diluted acid stream. The acid stream is re-concentrated and recycled to phase 1.

Phase 3: The full range of sugars in the hydrolysate are fermented to ethanol using Ethtec’s yeast platform.

Phase 4: Ethanol is recovered at a concentration suitable for use as a biofuel, simultaneously with treatment of the waste and recycle of the water in a novel non-distillation process.

Phase 1 and Phase 2 have been completed. The project will complete Phase 3 and Phase 4 and demonstrate the integrated Ethtec Process through the construction of a Pilot Plant demonstration facility.

Outcome

The Pilot Plant is expected to have an ethanol production capacity of 270,000 litres per annum. It is intended to be a scalable demonstration facility and centre for research and development to aid in the roll-out of cellulosic ethanol production at commercial scale.

The Ethtec Process is being developed based on detailed economic modelling of the sensitivity of the internal rate of return of an Ethtec Process Plant to a wide range of variable factors including feedstock cost, capex, opex, ethanol selling price and the value of a flexible range of co-products, including electricity.

The project aims to enable the production of ethanol in volumes that are significant in the context of meeting liquid fuel demand, at a price without subsidy that is competitive with the price of petroleum fuels derived from crude oil, after having paid a reasonable price for the lignocellulosic feedstock.

Additional impact

An ethanol fuel industry based on production from lignocellulosic materials is unique in that if successful, it could result in substantial reductions in greenhouse gas emissions in the transport and industrial sectors, while simultaneously providing solutions to rural unemployment and land degradation through enhancing the economics of crop and forest production.