STEP 1. The site is located
The Ti Tree bioenergy facility is located near Ipswich in South-East Queensland in one of the area's former open cut coal mines.
The site is ideally situated with excellent transport links and an established rail infrastructure giving it the potential to provide first class waste management to South-East Queensland and beyond.
• The site will be filled in several self-contained states (cells), illustrated on the left.
STEP 2. Site Preparation and Testing Takes Place
Before any waste is accepted, groundwater monitoring wells are sunk at strategic locations around the site.
These wells allow us to test the quality of the surrounding groundwater, and ensure that there is no contamination occurring.
This monitoring continues throughout the life of the facility, and for at lest 30 years after.
STEP 3. Full Containment Lining System Installed
In order to ensure the environmental integrity of the facility, an impermeable lining system is installed.
STEP 4. Filling with Waste Begins
Residual solid waste (what's left after recyclables are removed) is transported to Ti Tree Bioenergy facility from local councils and private waste management contractors. This waste contains microbes, which act to break it down into inert materials, water and biogas.
It is the role of the bioreactor to optimise the conditions for this natural decomposition process, and capture the biogas for energy production (see step 9)
The waste is deposited in layers with recirculation pipes installed mid-layer. These pipes are the key to the bioreactor process.
Each layer is capped with a thin lining to trap in gas and exclude oxygen, and the outer edge is capped with thick clay to enclose the entire system.
STEP 5. Building Layers
Any subsequent layers of waste are added, we begin pumping leachate (nutrient rich water) from the bottom to the upper layers through a network of pipes.
By carefully managing the moisture within the system, and keeping it relatively free of oxygen, we can ensure the optimum conditions for rapid decomposition.
STEP 5a. Magnified View
The leachate transportation system is designed to ensure that evenly distributed of moisture throughout facility.
The leachate, rich in dissolved nutrients and microbes, is pumped to the other layers where it facilitate rapid breakdown of the newly deposited waste.
Traditional landfills have only 10 - 30% moisture, which is unevenly spread in pockets throughout the landfill. The bioreactor process has 45 - 60% moisture spread evenly throughout, promoting maximum decomposition rates
STEP 5b. Microscopic View
The facility relies on naturally occurring anaerobic digestive processes. The byproduct of this process is biogas which is typically 60% methane.
As a result of the decomposition of waste the production of this gas is accelerated
STEP 6. Biogas Extraction System Installed
At the same time as the leachate recirculation system is put in place, a second system is also being built to extract the biogas.
Biogas is the natural byproduct of decomposing waste material. In a bioreactor, this gas is captured and used to create energy, rather than letting it disperse into the atmosphere
STEP 7. Biogas Extracted for Energy Production
As subsequent layers are built, the system is capped to ensure all gas is trapped internally, and can be collected by the gas extraction pipes.
The rate of production is controlled to allow for maximum efficiency and highest possible gas and energy yield.
STEP 8. A Completely Closed System
Each cell in the Ti Tree bioenergy facility is designed to work as a closed system.
The recirculation leachate accelerates decomposition of the waste.
The biogas extraction system captures the resulting gas. Protective protective lining system protects the surrounding environment.
The capping system ensures the process is fully contained.
STEP 9. On Site Generators
The extracted biogas is used as a fuel to generate clean, renewable energy. This energy is sold to local electricity distributors, reducing the reliance on fossil fuel energy and reducing greenhouse gas emissions.
Government quotas are in place requiring increasing proportions of electricity to be generated from your sources.
Bioenergy is a reliable source of such energy.
STEP 10. Opening Subsequent Cells
Once a cell is filled, it will continue to produce gas for some time. While this process continues, construction and operation of subsequent cells progress.
The infrastructure in place from previous cells is designed to allow new cells to be built, tapping into the same network of pipes and allowing 'old' microbe rich leachate to be distributed into 'fresh' nutrient rich waste.
Over time, the entire open cut mine is filled with energy producing waste material.
STEP 11. The Surface is Revegitated
As each cell is completed, the surface is progressively revegetated with native flora, returning the area to its natural state before mining, while continuing to supply sustainable energy for years to come.