The capital cost of equipment to generate electricity from waste is generally much higher than for conventional power generation equipment to burn fossil fuel. Plant design is specialized and must include refinements for emission control that are not necessary in a fossil fuel plant. Grate design is unique too.

Against this must be offset the revenue of the plant, not only from the electricity generated but also from the fuel itself, the waste. Industry and municipalities expect to pay to dispose of their waste. Consequently, the economics of a project should be designed so that the revenue from the waste disposal con- tracts are adequate to enable the power from the plant to be sold competitively. It should be remembered, however, that a waste to energy plant has as its pri- mary purpose the treatment and elimination of MSW. Electricity is a useful by- product of this process but generation is not the main function of the plant.

A study carried out for the Mayor of London and published in 2008 looked at the cost of the principle waste combustion technologies. The main findings are shown in Table 16.2. The study concluded that a conventional incineration facility would cost around £45 m for a plant with the capacity to treat 100,000 tonne/y of MSW while for a 200,000 tonne/y plant the cost would

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be £76 m. With the maximum power output from the smaller plant put at 6 MW, this equates to £7500/kW while the larger plant has a maximum output of 12 MW, equating to 6300/kW.

Advanced thermal treatment plants such as gasifiers and pyrolysis plants have slightly higher costs, as shown in the table. Their potential power outputs are also slightly lower. As a consequence the unit cost of a 100,000 tonne/y advanced plant is £9100/kW while for the 200,000 tonne/y plant the unit cost is £7700/kW. Operating costs for the plants are broadly similar at between £40/ tonne and £70/tonne depending upon plant size.

U.K. costs are similar to estimates for plants in the United States where the cost of a typical municipal waste combustion plant was put at $5,000–10,000/ kW during the middle of the first decade of the 21st century. Again smaller plants are relatively more expensive than larger plants.

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