Waste to Energy
Despite our green image in Aotearoa New Zealand, our municipal waste to landfill has increased by 48% in the last decade. Reduction of waste to landfill should be central to our sustainability journey with Municipal Solid Waste (MSW) being seen as a resource rather than something requiring disposal.
The New Zealand Waste Minimisation Act 2008 encourages the reduction of waste generated and disposed of in landfills. It does this through education, recycling, and a Levy placed on all waste to landfills. Despite this Landfills remain a problematic waste disposal solution with negative impacts on ground water, surrounding soil and climate impact issues. According to NZ Ministry for the Environment, Municipal Solid Waste (MSW) landfills are the second largest source of methane emissions in New Zealand.
Due to the high level of biogenic materials in municipal waste streams, a large portion of the energy that can be produced by MSW can be considered renewable. Typically, a tonne of MSW has about one-third of the calorific value of coal (8-12 MJ/kg as received for MSW and 25-30 MJ/kg for coal) and can give rise to about 600 kWh of electricity.
Modern Waste to Energy (WTE) plants are nothing like the old trash incinerators of old. In Western Europe, Japan and elsewhere, waste to energy is an important waste management method. In New Zealand, however, there are no waste to energy plants. Two small trials were conducted in 2015 (Waste to Energy) and, more recently, a private equity company is proposing to build a WTE plant in the South Island (Project Kea).
Life Cycle CO2 emissions – grams per kWh of electricity Ref: IEA Bioenergy - Municipal Solid Waste and its Role in Sustainability
The soon to be completed East Rockingham Waste to Energy plant near Perth, Australia, will combust 300,000 tonnes per year of post-recycling residual municipal waste and export 28.9 MW of electricity to the Australian grid. Due to the composition of the waste, more than 50% of the power generated will be deemed to be renewable.
The key to understanding the benefits of WTE in New Zealand is viewing it as a multi-pronged solution, i.e. metals and minerals recovery, emergency management for disposal of large amounts of sometimes hazardous storm and flood debris, and baseload power supply. WTE plants operate better as base load power supply rather than intermittent renewable energy sources such as wind and solar, having availability factors of 85% or greater, which is sharp contrast with other renewable energy sources. What’s more, WTE plants are typically sited close to urban areas that produce the MSW, providing good voltage stabilization and a reliable and dependable energy source.
Given that the amount of waste and the demand for energy will only increase in the coming decades, WTE facilities have the potential of providing a low carbon source of power generation and an environmentally sustainable management of municipal waste.
Reducing waste and improving quality are the corner stones of sustainability. Siecap (NZ) is a project management advisory working with both councils and industry and are well placed to provide advisory services regarding waste reduction and sustainability.
Further reading - Waste to energy guide for New Zealand
For more information around WTE, Siecap’s capability or if you require support, contact Kevin Pickworth at siecap@siecap.co.nz