Integrating Energy Recovery into Solid Waste Management Systems

Rationale – Significant Amount of Biomass Material in Waste

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:composition_of_wasteFigure 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.

EU_Framework_Directive_Hier

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.

Table 1: Energy from waste in different regions

 

EU

North America

ROW

Dominant
waste management system

Mixture:
across EU treatment varies substantially between Member States. Landfill
accounts for 40% of waste treated in EU in 2010. Highest incineration rates
are in north and west EU countries and are related to waste policies, use of
energy and lack of landfill void space.

In 2010 11.7% US
MSW went to EfW.
Many States define EfW as renewable. Some
areas, e.g. New England send much higher quantities to EfW.

3% Canadian waste
goes to EfW.

LF
dominates (e.g. Australia, Malaysia, Thailand, Philippines and Indonesia)
with exceptions such as Japan, Taiwan and Singapore (where incineration
dominates).  The dominance of LF is due
to waste composition and cost.

Main
policy driver(s)

Waste
Framework and Landfill Directives. These include: diversion of organic matter
from landfill; adhesion to Waste hierarchy; recycling targets; recovery of
energy from waste related to efficiency of plants.

Cost
effective waste disposal. In USA the use of lignocellulosic
waste for biofuels is important for the future, with some advanced conversion
demonstrations coming on line over 2013-14. In parts of N America where LF
space is restricted recycling and EfW is playing a
greater role.

Japan:
conversion of incinerators to efficient EfW.

 

Elsewhere:
cost effective waste disposal. Recycling policy increasingly important in
some countries (e.g. Australia).

 

In
Indonesia incineration has been banned. In other countries (e.g. Thailand and
Australia) there is public opposition to incineration.

 

ASEAN,
India and Africa: many of these countries have low budgets for waste
management, but growing waste production, particularly in urban areas.

Level
of recycling

EU
target: 50% recycling by 2020 for MSW. Some countries achieving higher.

 

Production
of solid recovered fuel and refuse derived fuel from residual waste.

Increasing
interest in recycling. 34% recycling in USA (2010). Some Canadian provinces
and cities achieve high recycling

Increasing
importance, particularly in Australia, New Zealand and some regions in SE
Asia.  Some regions are setting high
recycling or zero waste targets. Plastic waste is an increasing issue in
ASEAN countries.

Key
issues

Development
of EfW technologies that are integrated with
recycling.  End of waste protocols
associated with recycling targets.

Canada:
improved recycling; cost effective small scale systems for rural areas.

 

N
America: public opposition to EfW; increasing cost
of LF.

Cost
effective systems needed for developing countries and emerging nations. Cost
effective small-scale plants needed for regions with lower population
density.

 

Increasing
pressures from increased population, urbanisation
and emerging economies.

Development
of EfW

Major
drivers to improve efficiency of EfW plants.  Waste hierarchy may be overturned for waste
where environmental impacts can be demonstrated to be lower, particularly GHG
emissions.

 

Majority
of EfW are combustion systems. Some interest in
development of gasification.

 

Trans-border
shipments of recovered fuels.

USA:
move towards integration with biofuels production; Increased interest in EfW in some States where landfill costs are
increasing.  Some provinces in Canada
are developing EfW due to lack of landfill void space.

Most
EfW are combustion plants; there is development of
gasification for biofuels.

Developed
countries: integration with recycling. Recovery of heat as well as power.

 

Most
plants are combustion, except for Japan where there is a significant use of
gasification.

Emerging
economies: EfW for high organic, high moisture, low
CV waste.

Challenges for market deployment

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:

  • Current and future options for energy recovery and how they compare (e.g. in terms of efficiency of energy recovery, cost effectiveness, mass balance and environmental impacts).  How can we improve the potential for the use of heat from energy recovery?
  • How energy recovery options integrate with the other requirements of waste management.
  • The implications of waste management policies for recovery of energy from waste: for example do they result in changes in the composition of waste going to combustion, and if so, how does this impact combustion, emissions, ash production and other combustion characteristics of the waste?
  • How we can best communicate the need for/role of energy recovery with the wider public.
  • What are the impacts from commercial and industrial wastes ?
  • What is the impact of the development of recovered fuels (solid recovered fuel or refuse derived fuel) from waste and the potential to co-combust these fuels with fossil, biomass and other waste fuels.
  • When or whether it is possible to declare that a waste is no longer a waste, but a fuel product. This is a uniquely EU problem at present, but one likely to spread as re-processors seek to prove that they have developed products that are no longer waste and to transport such ‘fuels’ across borders.