BenefitsBenefits
Environmental Benefits
Ethtec's ethanol production technology features strong environmental benefits not found in most other transport fuel options.
The key environmental benefits of the Ethtec process and approach are:
- extremely low life-cycle greenhouse gas emissions and high positive energy balance, compared with other transport fuels (including biofuels);
- closed loop recovery and recycling of process liquids and energy, with reduced total water consumption and elimination of wasteful effluent; and
- utilises waste fibre sources from existing, established industries (such as sawmills, sugar mills, etc) without the need to dedicate new food crops to ethanol production, utilise harvest stubbles, or otherwise compete with food crops.
Greenhouse benefits
Figure 1 below demonstrates the comparative greenhouse gas benefits of this ethanol source compared with alternative fuels, on an equivalent energy basis.
Importantly, the processes for producing ethanol from grain starch, sugar juice and lignocellulosic materials evaluated by the US EPA in these studies does not include the additional energy-saving and recycling benefits of the Ethtec process. Therefore Ethtec believes its greenhouse gas performance will be even better than these US EPA data suggest.
Closed loop water, energy and materials recycling
In conventional ethanol production, energy consumption is high due to the need to distil the ethanol from the fermentation broth at the end of the process. This step also produces large amounts of liquid effluent.
The Ethtec process reduces the energy consumption by replacing the conventional distillation step with a low-energy phase separation technology, which also allows for recycling of the water component back to earlier phases - eliminating liquid effluent.
The process uses approximately half the energy per litre of ethanol produced, compared with modern vapour recompression distillation processes (1 MJ/L compared with 2 MJ/L, respectively). There are further energy savings by eliminating the need for liquid effluent treatment, which can amount to between 0.8 and 8.0 MJ per litre, depending on the comparable effluent treatment process.
The Ethtec technology also provides the capability for the plant to be a net exporter of energy by combusting in a cogeneration process the lignin and flocculated solids produced at the end of the process. This would produce "green electricity" as an added bonus. Alternatively, and subject to prevailing markets, the lignin and/or flocculated solids can be utilised as agricultural fertilizer or for the production of other value-added products.
Finally, in Phase 2 of the process, the novel separation of the acid from the sugars allows the acid to be recovered and recycled back to the Phase 1 hydrolysis step, thereby saving transport and other cost inputs associated with acid inputs.
Use of genuine industrial waste fibre, avoiding diversion of soil organic matter or food crops
Some forms of ethanol production have generated adverse sentiment due to their diversion of crop starch and sugars away from food production toward transport fuel.
Further, an emphasis on the use of the "whole crop" for energy production, including stubble and other crop residues can lead to soil degradation and biodiversity reduction due to loss of important organic matter to sustain soil processes.
The Ethtec process avoids both these legitimate concerns by focusing on use of waste products of existing industries which use harvested raw materials under strict management and codes of conduct. These include sawmill residues and bagasse, but could also extend to urban green waste and other materials currently either landfilled or used for lower-value purposes.
Industrial Benefits
The compact nature of the Ethtec process will allow the locating of transportable modular hydrolysis units in close proximity to feedstock sources. Such units would produce intermediate products that could be collected and transported to a large centralised facility for lignin/acid/sugar separation and ethanol production thereby gaining benefits of economy of scale. As well as these production economies, the transport costs of feedstock could be dramatically reduced through this strategy.
The Ethtec proposal meshes well with the existing framework of the sugar, timber and other rural industries to maximise benefits from vertical integration, waste elimination and value-adding. Potential linkages to existing industries are shown in Figure 1.
Leveraging the technological and industrial opportunities
There is an intensive research and development effort underway worldwide to demonstrate economically-feasible and environmentally-sustainable conversion of lignocellulosic materials to ethanol fuel.
If successful, the Ethtec pilot plant project will be the first in the world to achieve this result and the associated intellectual property therefore has considerable potential to be marketed worldwide through licence agreements.
In addition, Phase 4 of the Ethtec process involves new technology that could be retrofitted to existing ethanol manufacturing facilities to improve efficiency, and environmental performance of those plants.
Such opportunities include:
- elimination of energy-costly distillation processes;
- improving liquid effluent management and recycling; and
- energy capture and co-generation systems.