Putting Waste to Work in Our Cities

In Australia, we are one of the highest waste producers in the world and almost half of our household waste goes directly from kerbsides to landfill. Per year, that’s over 21 million tonnes of waste rotting in landfills which generates greenhouse gases like methane and can leach toxins into the surrounding land and waterways. 

Today’s problem will become a larger and uglier one in the future, as our waste production increases and finding suitable landfill sites becomes more difficult. Meanwhile our cities are missing out on an opportunity to generate reliable power using this waste, which includes a large component of renewable energy as a significant proportion can be used as fuel is from biomass (such as wood or food scraps).

Based on population growth forecasts from the Australian Bureau of Statistics, we could produce up to 74 million tonnes of waste every year by 2060 unless current behaviour and waste management policy changes significantly.

Wasted Opportunity

Waste-to-energy plants use household waste, known as municipal solid waste or MSW, as fuel to create electricity and/or heat. Council collection trucks drive waste to a plant where the operator is paid to receive it and then uses the waste as fuel. This is contrary to the current Australian waste arrangements where councils – and taxpayers – pay landfill operators levies to dispose of waste in the ground.

The technology for waste-to-energy has been around for decades and has been thoroughly road-tested in thousands of plants around the world. Europe and Asia, currently have approximately 450 and over 1500 waste-to-energy plants respectively.

Most plants process the waste in a furnace, creating steam that drives a steam turbine to generate electricity (see Figure 1). In cold climates, the residual heat in the steam exhausted from the turbine can be used for district heating schemes.

Given the unpredictable composition of waste, regulators around the globe require strict control of the quality of the flue gas (combustion products) released to the atmosphere. The emissions limits specified by the European Union’s Waste Incineration Directive are the most commonly referenced benchmark. 

To meet these limits, a range of treatment processes are implemented including urea injection for NOx gas reduction, caustic scrubbing to remove acid gases, activated carbon injection to adsorb volatile metals and organic compounds, particulate matter collection using bag filters, and control of flue gas temperature to limit the formation of dioxins.

So where are the large-scale MSW energy-to-waste facilities in Australia today? Most experts attribute this to an historical abundance of landfill sites with very low or non-existent state-based landfill levies and the public perception that incineration is a harmful process. This is not surprising since air pollution concerns ultimately led to the banning of the iconic Aussie backyard incinerator.

Today, with rising population density in our major cities, the reduction in suitable landfill sites and significant improvements in combustion processes and environmental control technologies, the balance is strongly swinging in favour of a change to our past practises – and the advantages of converting waste to energy are increasingly outweighing the disadvantages (see Table 1).

Construction is set to begin in early 2017 on Phoenix Energy Australia’s AUD400m Kwinana Waste to Energy project, the first of its kind in Australia (see Figure 3). The project will integrate the disposal of waste with the generation of energy, providing a practical solution to two community challenges: waste disposal and renewable energy supply. 

The WSP team has provided engineering support for this project to date, working for the preferred EPC provider BGC Contracting. WSP has extensive global expertise in the waste to energy field and has been a technical advisor to governments and project developers throughout Europe and the Asia-Pacific for many years.

The new project is proposed for the Kwinana Industrial Area, south of Perth and is expected to reach financial close during the 2016/2017 Financial Year. Phoenix Energy has signed 20-year waste supply agreements with the Rivers Regional Council, which represents six local government authorities and the City of Kwinana.

Instead of driving waste to landfill, trucks will soon deliver the waste directly to the Kwinana Waste-to-Energy complex. The project will divert up to 400,000 tonnes per annum of waste from landfill and will produce approximately 32 megawatts of electricity – enough to power up to 50,000 WA households.

International companies, Mitsubishi Heavy Industries Environmental and Chemical Co, will provide the core combustion and heat recovery technology at the heart of the plant. Meanwhile, WSP will provide power specialists with extensive detailed design, construction and commissioning experience throughout Australia and New Zealand, as well as specialist waste-to-energy experts in the United Kingdom.

Designing for the World Stage

In some communities, waste-to-energy plants are still a contentious issue. While incineration has suffered from a poor public image in the past, a mixture of legislative drivers and technical innovation has led to vast improvements in energy efficiency and environmental outcomes. This is why project developers in other countries, particularly across Europe, have gone to great lengths to make such plants welcome in any city.

For example, in Copenhagen, Denmark a new state-of-the-art plant is being constructed. The Copenhill / Amager Bakke project is setting new standards for environmental performance, energy production and waste treatment with innovative technology.

The developers have paid particular attention to the architecture, visual rendition and local acceptance, such as including a roof-wide artificial ski slope open to the public. It also includes a steam ring or ‘donut’ that regularly rises from the facility to symbolise the CO2 emissions avoided due to the plant’s operation, with one steam donut representing one tonne of CO2 emissions avoided. The aim is to create a multi-purpose facility that incorporates a waste treatment plant and energy producer, an architectural landmark and a leisure facility (see Figure 4).

The plant will have double the electrical efficiency of the 45-year old plant it replaces. Owned by five Danish municipalities, it will be equipped with two furnace lines and a joint turbine and generator system. By 2017, the energy plant will treat around 400,000 tonnes of waste annually and supply a minimum of 50,000 households with electricity and 120,000 households with district heating.

Meanwhile, Danish firms Schmidt Hammer Lassen Architects and Gottlieb Paludan Architects are designing the world’s largest waste-to-energy power plant in China. From 2020, the Shenzhen East Waste-to-Energy Plant is set to convert 5,000 tonnes of waste to energy per day and will help the city manage its growing waste. This will be achieved by using one third of the rubbish generated by the city’s 20 million inhabitants each year.

With a 66,000 square metre roof, two thirds of which is covered in solar panels, the building will also generate its own photovoltaic renewable energy – and it will welcome visitors for a behind-the-scenes tour of the plant’s operations and a panoramic view of the rooftop and surrounding landscape.

Recovering Valuable Resources

Waste-to-energy is not just an alternative to landfill waste disposal. It has the potential to recover valuable resources such as metals. In some countries, the recyclables separation process is already sophisticated, with various elements of the recovered materials being re-used. For example, some of the ash generated is used in building and industry materials such as road surfaces, roof tiles, bricks and concrete production.

Waste-to-energy is an opportunity for our cities to limit the waste going to landfill, thereby reducing their environmental impact and contributing to meeting their own energy needs. 
It is time for Australian cities to become more resilient by putting their waste to work.