Alternative strategies for energy recovery from municipal solid waste
Part B: Emission and cost estimates
, M. Giugliano
, M. Grosso
Department of Energy Engineering, Politecnico di Milano, P.zza Leonardo da Vinci, 32 20133 Milano, Italy
DIIAR – Environmental Section, Politecnico di Milano, P.zza Leonardo da Vinci, 32, 20133 Milano, Italy
Accepted 14 September 2004
This two-part paper assesses four strategies for energy recovery from Municipal Solid Waste (MSW) by dedicated Waste-To-
Energy (WTE) plants. In strategy 1, the residue of Material Recovery (MR) is fed directly to a grate combustor, while in strategy
2 the grate combustor comes downstream of light mechanical treatment. In strategies 3 and 4, the MR residue is converted into
Refuse Derived Fuel (RDF), in a ﬂuidized cumbuster bed.
The results of Part A, devoted to mass and energy balances, clearly show that pre-treating the MR residue in order to increase the
heating value of the feedstock fed to the WTE plant has marginal eﬀects on the energy eﬃciency of the WTE plant. When consid-
ering the eﬃciency of the whole strategy of waste management, the energy balances show that the more thorough the pre-treatment,
the smaller the amount of energy recovered per unit of MR residue.
Starting from the heat/mass balances illustrated in Part A, Part B examines the environmental impacts and economics of the var-
ious strategies by means of a Life Cycle Assessment (LCA). Results show that treating the MR residues ahead of the WTE plant
does not provide environmental or economic beneﬁts. RDF production worsens almost all impact indicators because it reduces net
electricity production and thus the displacement of power plant emissions; it also increases costs, because the beneﬁts of improving
the quality of the material fed to the WTE plant do not compensate the cost of such improvement.
Ó 2004 Elsevier Ltd. All rights reserved.
1. Background and scope
This two-part paper reports the main outcome of re-
search aimed at comparing four alternative strategies for
energy recovery from MSW downstream of Material
Recovery (MR). The four strategies, extensively de-
scribed in Part A, correspond to the options now being
considered by several Italian municipalities to recover
energy from MSW within the framework of so-called
‘‘Integrated’’ Waste Management Systems (WMS)
1. combust the MR residue ‘‘as is’’ in a grate
2. remove the organic, ‘‘wet’’ fraction by sifting the MR
residue ahead of combusting it in a grate combustor;
the wet fraction is bio-stabilized and then landﬁlled;
3. produce RDF with aerobic bio-stabilization of the
whole MR residue ahead of sifting, and then feed
RDF to a dedicated ﬂuidized bed combustor;
4. produce RDF by ﬁrst removing the organic fraction
by sifting and then feed RDF to a dedicated ﬂuidized
bed combustor; the organic fraction is bio-stabilized
and then landﬁlled.
The basic goal of the research was to understand
whether manipulating waste ahead of combustion can
either increase the eﬃciency or reduce the environmental
0956-053X/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved.
Corresponding author. Tel.: +39 02 23996430; fax: +39 02
E-mail address: email@example.com (M. Grosso).
An Integrated Waste Management System consists of a number of
coordinated actions to recover material and energy and to minimize
Waste Management 25 (2005) 137–148