Extensive research carried out during the 1980's identified ETHANOL (ethyl alcohol) as being the most practical of the environmentally acceptable alternative liquid fuels proposed for the use in motor vehicles. It is possible to use straight ethanol in specially designed engines, but more importantly, 10-20% ethanol can be simply blended with petrol (to form GASAHOL) and used in conventional petrol engines. This can be done without the need for any modifications to the vehicle or any loss of performance and yet gives dramatic reductions in the levels of exhaust gas pollutants.

Many countries believed that their major source of smog was the exhaust from heavy trucks and the huge fleets of diesel buses used in densely populated cities. To replace these with new, purpose built vehicles running on ethanol fuel was too expensive to contemplate. However, an Australian invention which allows 10-15% ethanol to be emulsified with diesel (to form DIESAHOL) suitable for use in unmodified diesel engines has provided an immediate solution to the problem.

The use of 15% DIESOHOL virtually eliminates visible smoke and gives dramatic reductions in the emissions of carbon dioxide, carbon monoxide and the nitrous oxide gases. Some countries have now legislated to make the addition of ethanol to motor fuel compulsory in congested cities during the winter months.

The use of GASOHOL and DIESOHOL has resulted in a huge increase in world demand for fuel grade ethanol. Accordingly there has been a rapid increase in the volume of ethanol produced overseas for use as a motor fuel additive or substitute.

Being an alcohol, ethanol is produced by the fermentation of sugars in the presence of yeast. The sugars used come from various sources but mostly corn starch or wheat starch. Because of the high cost of the material used and the need to treat the huge amounts of process waste generated, the ethanol produced in this way is quite expensive and has to be subsidised in order to be cost comparable with oil based liquid fuels. Many Governments do offer such financial subsidies to the ethanol producers in order to reduce the environmental problems associated with motor vehicle emissions.

It is possible to avoid the high cost associated with the use of food grade starch materials by producing mixed sugars from the chemical hydrolysis of cellulose. Cellulose forms the fibrous component of almost all vegetation and is readily available in huge quantities often as a waste stream from other agricultural activities such as waste from timber mills, stubble from cereal grain crops, trash from cotton gins or even as woody weeds and garden prunings.

Waste cellulose may offer cheap raw material but the various processes currently used to convert cellulose to ethanol are chemically complex and expensive to operate.

Current processes all suffer some or all of the following difficulties:

1. Inefficient acid hydrolysis causing low yield of sugars and high acid consumption.
   
2. Inability to separate sugars from acid, requiring another step to neutralise the acid. This involves the cost of chemicals consumed, cost of waste disposal and high cost of acid replacement.
   
3. Inefficient fermentation of mixed sugars causing low yield and a slow process.
   
4. Costs of separation of alcohol from aqueous fermentation liquor brought about by the high-energy consumption in the distillation process, the need to dispose of large quantities of high nutrient waste water and the need to replace the large amount of water consumed in the process.

1. A multi-stage double screw reactor that ensures good mixing and efficient hydrolysis of cellulosic material to sugars.
2. An ion exchange process to separate the sugars from the acid which is then recycled back to the hydrolysis reactor.
3. Fermentation of the mixed sugars is carried out in the presence of bacteria, which are far more efficient than simple yeast.
4. A unique phase separation process is then used to separate the ethanol from the aqueous phase without the need for distillation. The waste products all form as flocculated solids in the water phase. These are filtered out and disposed of as boiler fuel and the clean water is recycled back to the fermentation stage.

The closed loop type process ensures that virtually no material goes to waste, thereby avoiding both the environmental and financial costs of waste disposal. The burning of the solid wastes produces more energy than that consumed by the other process steps. A pilot plant is to be built at Nowra to demonstrate the viability of this patented new technology and to produce operating data for the design of full-scale commercial facilities.

Cost effective manufacture of fuel ethanol from cellulose will require ready access to an ongoing supply of waste cellulose at low transport cost. Waste timber from the hardwood plantation, forestry and timber processing industries on the North Coast appears to offer the most attractive concentrated source of low cost cellulose for this purpose. Plantation thinnings and the wasted heads and branches from forestry operations can be chipped on site and transported in bulk to a central ethanol processing facility. Timber mills produce sawdust and odd shaped offcuts after having transported the round logs out of the forest. The timber mill has already met the major freight component of this material.

The Northern Rivers Regional Development Board has undertaken a study to identify the quantity, location and probable species mix of the timber wastes likely to be generated in the region in the foreseeable future with a view to selecting localities with adequate raw material supplies to support a commercial ethanol plant. Trials will then be conducted in the Pilot Plant using the actual species mixes available at that location.

Infrastructure and planning approval requirements will be identified and relevant regulatory and community organisations will be involved in the selection of suitable sites so that by the time the technical trials have been completed at the pilot plant, all relevant information will be available for a full commercial feasibility evaluation to be made.

Further information on the ethanol project can be obtained by contacting the Northern Rivers Regional Development Board on telephone
(02) 6686 3008

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