Waste to energy is increasingly becoming an attractive option, with local suppliers such as Skala Australasia recently entering the market.
Converting organics into energy carries with it numerous benefits, from reducing waste to landfill to lowering a business’ overheads.
It’s a process being investigated and implemented by numerous local governments across Australia. As one example, Byron Shire Council, based in the Northern Rivers region of NSW, has been investigating bioenergy processes since 2016, which has potential to offset retail energy prices.
Simon Toal, Director of equipment and systems supplier Skala, says waste to energy (WtE) is fast becoming more economically feasible in Australia.
“Many councils will have some form of green waste processing, so this replaces some of their existing operating costs,” Simon says.
With strong potential for WtE systems in Australia, Skala is now working to launch a turnkey solution to the Australian market. Skala offers this through the BEKON system – an international WtE technology provider based in Germany. Simon says the BEKON Mini provides an optimal solution for the local market, due to its low capital and operational expenditure and input quantities. He anticipates this would be appealing to municipal councils running small-scale operations.
He says he’s received extensive interest from the local government and waste management sector over the past six to eight months.
Simon says BEKON Mini uses dry fermentation, which involves the breakdown of materials via anaerobic digestion, to convert organics into biogas. He says it is superior to other methods due to its simple and robust operation. Organic waste does not need any pre-treatment before the anaerobic digestion process, so this saves businesses operational costs. Biomass also does not need to be pumped through pipes as liquid fermentation does, therefore reducing risk of blockages.
Thomas Ganzhorn, Sales Manager, BEKON, says dry fermentation offers an economical and efficient way of converting WtE. He says a plant based in Enger, roughly an hour south of Hanover in Germany, offers a suitable case study for Australians. He says it could be an excellent starting point for any municipality that has a minimum of 4000 tonnes of solid organic waste per year. With the plants being modular, further expansion is always possible.
Thomas says BEKON’s systems are used in more than 50 plants worldwide, including the US, Italy, Switzerland and Mexico. “There are two main factors which determine whether a plan can be run economically and that’s the gate fee and the value of the biogas. You will get a certain amount of money per kilowatt for electricity ejected into the grid,” Thomas says.
Thomas says the BEKON Mini was designed to minimise costs. BEKON Mini is the standardised solution for a capacity from 4000–10,000 tonnes per year and is suitable for processing garden waste/grass cuttings, organic agricultural waste, renewable raw materials, animal faeces, organic fraction municipal waste and biowaste. The result means the material can be converted into products ranging from nutrient-rich fertiliser to biogas-fired heat and energy.
The system has the capacity to generate up to 300 kilowatts of electricity and thermal while also treating fermentation residue, such as biological drying into high-nutrient fertiliser. BEKON systems deal with all types of solid organic waste, Thomas says, with the only conditions being that the waste should be a minimum of 30 per cent dry matter and less than 70 per cent moisture.
The process begins with the fresh waste material being placed into a fermenter with a wheel loader together with digestate that has already run through the process. The materials are then placed into a dry fermenter, which helps inoculate the fresh material and blend the necessary bacteria into the mixture. Once this is done, the fermenter door is closed and a gas purging process removes all the oxygen within the fermenter to allow for anaerobic digestion. The liquid draining from the waste material is brought to the percolate fermenter which is at the back of the fermenter. During the anaerobic digestion process, the percolate is regularly sprayed back on the material to keep a stable biology.
“We also heat the walls and the floor of the fermenter to get the optimal process temperature as soon as possible,” Thomas says.
The material then stays inside the fermenter for four weeks allowing for biogas production. The biogas is then brought into a gas holder, which is transferred to the combined heat and power system. Before it enters the engine the biogas is cooled and compressed and runs through an active carbon filter to remove hydrogen sulphide. Electricity produced can be injected into the grid.
Overall, Thomas is buoyed by the potential of the technology to advance in Australia.