Turning waste into a resource

With landfill sites under strain, can Australia’s capital cities benefit from waste to energy processing? Pablo Perez-Reigosa* from Coffey Environments explains how the technology works and its successful implementation in Europe.

There’s no doubt the total amount of waste going to landfill in Australia’s capital cities is continuing to increase.

State and federal governments recognise the strain our landfill sites are under. The most recent initiative in the federal government’s National Waste Policy was the passing of the Product Stewardship legislation by parliament.

This legislation addresses issues such as:

• How to avoid waste generation
• The concept of waste as a ‘resource’
• How to increase waste re-use and recycling

Bills such as this and their associated regulations also open the door to assess what we can recover by processing waste - the concept of energy recovery from waste or waste to energy (WTE).

WTE is a process that converts waste into energy in the form of heat and electricity. The process can be of a thermal or a non-thermal nature.

All waste in its solid and liquid states has energy in it and waste that cannot be re-used or recycled in an environmentally and economically responsible way can be processed. This process recovers the energy from the waste before it is disposed into landfill, reducing the overall amount of waste going to landfill.

In thermal processes, the waste is mostly converted into gas through combustion with hot air. The gas is used in heat exchangers to make high-pressure steam that drives turbines coupled to electricity generators in a similar way to electricity power stations. Any waste not converted into gas is converted into ashes - solid matter that is 95 to 98% inert.

A number of European countries are already benefiting from the successful integration of thermal WTE plants, reporting a sharp drop in the amount of waste being deposited in landfill.

The European Bureau of Statistics reports that countries such as Germany, the Netherlands, Sweden, Belgium and Denmark dispose of just 2 to 4% of their total waste into landfill. And most of this is made up of the ashes from thermal WTE plants.

In these countries, the amount of waste fed into thermal WTE plants ranges from 35 to 50% of the total waste generated. They also enjoy a very high level of recycling and composting.

In Australia, most of the focus on WTE processing until now has been on non-thermal processes such as capturing the methane gas produced as organic waste disposed into landfill breaks down. Electricity is not currently being generated from thermal WTE plants.

The thermal WTE technology being used overseas can certainly be used in Australia. Estimates presented at a recent waste conference in Australia show that if we want to have the same amount of waste going to landfill in 2020 as we had in 2010, we will need between 35 and 50 thermal WTE plants as well other plants to recycle and compost waste.

The potential introduction of a carbon tax and recent legislation passed by the federal government clearly indicate a level of focus on alternative energy sources. However, looking towards the future there are still uncertainties that will impact the speed of adoption of WTE in Australia or even its consideration as a viable and common energy source.

The impact of impending statutory regulations, taxes, etc will influence the confidence of potential investors into WTE technology. The more confidence investors have in the stability of the statutory and regulatory environment, the more confident they will be in making that investment.

*Pablo Perez-Reigosa is the Principal Engineer Water & Waste Management at Coffey Environments, delivering solutions for waste production, treatment and disposal. He has more than 20 years’ experience in the development and project management of unique engineering solutions to the environmental industry and has worked with a range of private sector industries and public sector departments and agencies.