By using municipal solid waste (MSW) as feedstock for a waste-to-energy (WTE) process, the waste stream can be reduced in volume and the waste disposed. The thermal energy that is released during combustion can be used as direct heat or converted to electricity using a steam turbine. Only the fraction derived from biogenic materials can be considered renewable. Important issue remains to reduce, recycle and re-use waste material streams as much as possible, and to prevent the emission of polluting substances. An alternative route for MSW is to dispose of it in a landfill site. Anaerobic digestion occurs naturally over time to produce methane biogas that can be used for energy purposes, usually for power generation, so landfill gas is not considered here.
 |
 |
Table A7 • Cost parameters for a modern waste-to-energy facility for incineration of municipal solid waste in 2005 (excluding VAT) with projections out to 2030*
The current situation for waste disposal differs from country to country. Where landfills are common practice, a new reference situation could be to construct an advanced WTE installation. Where
incineration is used for volume reduction without energy recovery, the additional investments needed to give WTE indicate the cost of heat and/or power generated. In a situation in which electricity is already generated, additional investments for heat generation are relatively small but must also account for the losses from the resulting reduced electricity generated[39].
The economics of a WTE process (Table A7) are primarily based on the income from waste treatment, with a tariff that should cover the operational costs of the plant. In other words, the cost of the heat and electricity generated strongly depends on other revenue generated from waste disposal as well as the additional cost for disposal of residue streams such as ash. In some situations the cost of producing the heat leaving the plant could be practically zero.
The often high capital costs for the heat distribution system were not included in the methodology (Figure A1). The price for heat at the end-user level is generally similar to that supplied from other technologies. So in practice the economics of heat utilisation are basically determined by selling the heat to pay back the initial investment of the heat distribution system (Koppejan 2007).
In this current analysis, the reference situation chosen was construction of a new, technically advanced WTE plant, with an electrical efficiency of 15% to 30% and a thermal efficiency of 20% to 40%. Note, that a heat-only MSW incinerator (as used in Denmark and Sweden) could have a thermal efficiency of 70% to 80% but was not considered here. The investment costs of a MSW installation are mainly determined by the flue gas cleaning costs that can be allocated to the core process of waste treatment rather than to the heat production process. Data used were based on Tilburg (2006) and Gerlagh (2007).
In the resulting cost analysis, fuel costs have been set at zero so that the dominant cost factors are for capital investment and O&M. The overall average cost of heat could reduce from €5.0 /GJ in 2005 to €4.6 /GJ in 2030 (with ranges remaining similar at €2 to 12 /GJ). It should be noted that a WTE plant continuously offers heat supply so that where the heat demand fluctuates, this can influence the cost of delivered heat, but since it is very site-specific, was not considered here.
