All countries produce waste, although the composition differs, depending on local factors. However, most country statistics show that a significant proportion of their household, commercial and industrial waste is of biomass origin.
For many IEA Bioenergy Agreement countries this is important, as the biogenic fraction of waste is regarded as renewable and included in their renewable energy targets. For example, the EU National Renewable Energy Action Plans show that the EU Member States assume the biomass content of their municipal waste to be between 35 and 60%; and it is estimated that European waste (municipal, commercial and industrial) contains 118-138Mt biomass.
The biomass content of waste is high outside the EU as well. The figure below shows results from an IEA Bioenergy Task 36 review of waste:Figure 1: Composition of residential waste in selected cities from Europe, North America, East Asia, and Africa (source: Vehlow 2009).
This means the amount of biomass material in waste is significant and it is an important bioenergy resource in IEA Bioenergy Agreement countries.
In selecting methodologies to treat waste decision makers have a number of needs: they want to achieve efficient use of resources (including waste reduction, re-use and recycling) and they want to ensure appropriate treatment of the residues. They also want to do this cost effectively, without adding to environmental impacts and with carbon emissions in mind. Additionally many countries require decision makers to observe a waste hierarchy in which actions to reduce, re-use and recycle waste take priority over recovery and stabilisation, with disposal only for those fractions left after treatment.
An example of this is the waste hierarchy set out in the revised EU Waste Framework Directive, which provides five steps for managing waste in order of priority (see Figure 2). The waste hierarchy accepts the integration of recovery of energy into waste management. In Europe, the Waste Framework Directive adds consideration of environmental factors (such as carbon emissions) into the hierarchy, so that if it can be shown to be of carbon benefit to recover energy from specific waste streams energy recovery may be a preferable option.
Options for energy recovery include combustion, gasification, pyrolysis and anaerobic digestion. Currently, only the first and last of these are well-developed, although there has been increasing investment in gasification of waste, particularly processed wastes and waste wood and there are a number of plants operating in Japan and Europe.
Figure 2: EU Waste Framework Directive waste Hierarchy
Although waste hierarchies are being adopted increasingly around the world, locally there may be different approaches and different issues. For example, in Europe there are trends towards banning some fractions of waste (e.g. biodegradable or combustible fractions) from landfill and increasing trans-boundary shipment of waste for use in energy plants. Elsewhere the pressures for zero waste to landfill is important; and in some regions the development of energy from waste may be hampered by public concerns (see Table 1).
IEA Bioenergy Agreement Task 36 aims to enable discussion of these topical and important issues. Energy from waste plants are expensive and may be in use for 20 years or more. It is very useful to pool experience to ensure that policy and decision makers can benefit from knowledge from elsewhere. Task 36 has provided case studies on plants, including gasification plants; supported events on key issues (such as a recent workshop on solid recovered fuel); and in 2010 it published a guide to energy from waste aimed at decision makers. This proposal details plans for the prolongation of the work of Task 36 to continue to exchange information that underpins decisions in this constantly evolving area.
|
EU |
North America |
ROW |
Dominant |
Mixture: |
In 2010 11.7% US 3% Canadian waste |
LF |
Main |
Waste |
Cost |
Japan:
Elsewhere:
In
ASEAN, |
Level |
EU
Production |
Increasing |
Increasing |
Key |
Development |
Canada:
N |
Cost
Increasing |
Development |
Major
Majority
Trans-border |
USA: Most |
Developed
Most Emerging |
Waste policies have changed significantly over the past decade in response to improved understanding of the environmental and health impacts of traditional waste management. As indicated above policy makers currently prioritise reduction of waste, followed by recycling as much as possible of what is left. Although there are a range of options to achieve this, it has not proved possible to find markets for all waste and 100% recycling remains elusive. Consequently there is a residual left after recycling, which needs to be treated or stabilised prior to disposal.
There are two main options for treatment/stabilisation of the residual waste: biological treatment and combustion. Both of these options include the opportunity to integrate energy into solid waste management. Task 36 considers the issues associated with combustion options for recovery of energy, but it also includes work on the consequences of biological treatment on energy recovery.
Currently the major challenges relating to the integration of energy recovery into waste management are: