Power Generation from Renewable Energy Sources

The New South Wales Sugar Milling Co-operative and Delta Electricity have formed a joint partnership named “Sunshine Electricity” to construct two 30-megawatt cogeneration power plants at Broadwater and Condong. Construction of the power plants commenced in late 2005.

The project is one of the largest renewable electricity generation projects currently underway in Australia and from mid-2007 at Condong and late 2007 at Broadwater, these two generators will supply the total electricity needs of the towns of Lismore, Casino, Ballina, Byron Bay and Murwillumbah - all from accredited renewable fuel sources.

The scope of operations at each site includes the provision of a single 150 t/h boiler, a single steam driven 30MW turbo alternator and auxiliary plant systems such as water treatment, ash and fuel handling facilities and on-line storage to support the main plant operation. The power stations will provide steam, extracted from the turbine to the mill for heating and power. Primary condensate will be returned to the cogeneration plant. Plant cooling at Condong is through evaporative cooling towers using water (tertiary treated effluent) from the Tweed Shire Council sewerage treatment plant.

The Federal government’s renewable energy targets place a legal liability on wholesale purchasers of electricity to contribute to an additional 9500 GWh from renewable sources by 2010. Renewable Energy Certificates (REC’s) are created on the basis of accredited renewable energy generation using eligible fuels.

Renewable Fuel Sources

Bagasse
The sugar mills are already self sufficient in their energy needs, producing power by running existing boilers on bagasse, which is the remains of the cane stalk after all the sugar has been extracted during the milling process. The new plants will continue to use the bagasse along with other renewable sources, namely cane leaf and wood waste.

Cane Leaf
Once the sugar cane is ready for harvest, the traditional technique has been to set fire to the cane to burn away the dead leaf, which comprise approximately 25% by weight of the whole crop. Any residual cane leaf is then separated from the cane during the harvesting operation.

However, after the new cogeneration plants are in operation, cane fires will be phased out in the Broadwater and Condong milling areas. Instead, the cane will usually be harvested green and the entire crop transported to the mills, where the leaf and other organic matter will be separated from the cane and used to fuel the boilers. Green harvesting will also reduce other negative aspects of cane fires, including the impact of smoke and ash on the surrounding areas from uncontrolled burns.

The bagasse and leaf from the cane is expected to supply 75% of the fuel needs at Condong and up to 100% of the fuel needs at Broadwater.

Chipped Wood From Renewable Sources
The remaining material is to be sourced from Camphor Laurel, a noxious woody weed rampant in the Northern Rivers of New South Wales, and from sawdust from local millers.

Camphor Laurel was introduced to the area in the 19th century and has spread throughout the entire region. Camphor Laurel is responsible for choking waterways and displacing native flora which inturn reduces the local wildlife populations creating imbalance within local ecosystems. It can grow above 20 metres and is a long living species. An eradication program sponsored by local councils is already underway in the region and the cogeneration projects will assist in their removal and disposition.

Another potential source of fuel may be sawmill residue from local milling operations. Certificates verifying that the source of sawdust residue is from plantation timber would accompany the supply and government agencies will verify the chain of supply.

The Benefits
The key environmental benefit of this project is that bagasse, cane trash (previously burnt in the field) and other renewable fuels will be combusted in a highly efficient cogeneration plant to produce steam and electricity. The electricity produced from these plants will displace electricity produced from non-renewable fuels, primarily coal. It should be noted that because there is a balanced CO2 cycle in growing and processing sugar cane with the cogeneration plants, these projects will yield significant reductions in CO2 emissions by replacing coal fired thermal power with electricity generated from biomass fuels.

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