The facility will recover approximately 7.9 megawatts (MW) of baseload electricity. This source of energy is considered a partially renewable energy, capturing the embedded energy within the otherwise landfilled waste.
Utilising this valuable resource through recovery of the energy offers a sustainable improvement to waste management services currently being provided in Melbourne, while reducing the overall greenhouse gas emissions and the potential environmental impacts associated with landfilling.
Before selecting the technology for the facility, GSWT undertook extensive worldwide research of available WtE technologies. GSWT has entered into an engineering agreement with Energos for the design and supply of the gasification technology to be used at the facility. A key factor in GSWT’s selection of Energos technology is its successful operational record in Scandinavia and proven ability to meet stringent European Union (EU) Industrial Emissions Directive (2010/75/EU) performance criteria. Energos gasification plants have completed over a million operational hours of reliable performance.
Modular means versatile
The facility will receive waste seven days per week, receiving approximately 100,000 tonnes per year, however is modular and can be scaled as required, without any loss of performance. The facility will be situated within an enclosed purpose built building, with all operations, including waste unloading, within the building.
How the Energos WtE technology works
This image shows the Energos gasification combustion process (source: Energos)
Click image to enlarge
Energos technology used for the facility is a two-stage thermal process that includes drying, pyrolysis, gasification and oxidation. The gasifier unit is divided into a primary chamber where drying and gasification of the solid waste takes place, and a secondary chamber where the oxidation of primary gases is completed. The following image shows a perspective view of the proposed plant, noting that this is for a single-line plant, whereas the proposed facility is dual-line.
The gasification process consists of two thermal conversion stages:
Partial oxidation and gasification of the waste to a synthetic gas (syngas) takes place in the primary chamber on a fixed grate. The waste is fed into the primary chamber at a controlled rate where it is directed onto agrate. Drying, pyrolysis and gasification of the waste occurs in the primary chamber, where the syngas is produced. The last section of the grate secures burnout before the decarbonised waste falls into a waterbath / air lock where it is removed and transported as bottom ash.
Temperatures are maintained at a minimum of 850 degrees Celsius in the primary chamber.
The second thermal conversion stage is combustion. The syngas generated in the primary chamber flows through to the secondary chamber, where oxygen and recirculated flue gas is introduced, and the syngas is fully combusted. The temperature in the secondary chamber maintains a minimum 850 degrees Celsius for a minimum of two seconds. The heat of the combustion gases from the second thermal conversion stage is then transferred to a boiler system where high-pressure steam is produced for powering a turbine for the production of electricity.
Fuel preparation is critical in ensuring the performance and emissions profile are consistent. A key aspect of Energos technology that ensures high thermal efficiency and low emissions is the pre-treatment of waste to ensure a sufficiently high surface-to-volume ratio and a low content of metals. The facility will pre-treat the waste using a shredder and ferrous metal separation to achieve this.
GSWT has built a strong relationship with leading waste to energy supplier, Energos, since 2011 and are pleased the Norwegian-based company has awarded us exclusive rights to its best practice WtE technology in Australia.
Energos is a leading supplier of small-scale energy from waste plants and technology. Energos technology provides a robust, local solution for the treatment of municipal, commercial and industrial waste, by converting it into renewable energy. This energy can then be used to provide local communities with heat and power.
Energos technology has been utilised in eleven plants with total 18 gasifier lines across Europe, with several more under development… Each is designed to process different amounts of waste and produce different volumes of energy.
The first Energos was commissioned in 1997 and today the company’s combined operating experience exceeds 800,000 operating hours at 8 plants across Europe.