Waste-to-energy Plants Research Articles

Alternative strategies for energy recovery from municipal solid waste: Part A: Mass and energy balances

This two-part paper assesses four strategies for energy recovery from municipal solid waste (MSW) by dedicated waste-to-energy (WTE) plants generating electricity through a steam cycle. The feedstock is the residue after materials recovery (MR), assumed to be 35% by weight of the collected MSW. In strategy 1, the MR residue is fed directly to a grate combustor. In strategy 2, the MR residue is first subjected to light mechanical treatment. In strategies 3 and 4, the MR residue is converted into RDF, which is combusted in a fluidized bed combustor. To examine the relevance of scale, we considered a small waste management system (WMS) serving 200,000 people and a large WMS serving 1,200,000 people. A variation of strategy 1 shows the potential of cogeneration with district heating. The assessment is carried out by a Life Cycle Analysis where the electricity generated by the WTE plant displaces electricity generated by fossil fuel-fired steam plants. Part A focuses on mass and energy balances, while Part B focuses on emissions and costs. Results show that treating the MR residue ahead of the WTE plant reduces energy recovery. The largest energy savings are achieved by combusting the MR residue “as is” in large scale plants; with cogeneration, primary energy savings can reach 2.5% of total societal energy use.

Burn or Bury? A Social Cost Comparison of Final Waste Disposal Methods

This paper uses private and environmental cost data for the Netherlands to evaluate the social cost of two final waste disposal methods, landfilling versus incineration using waste-to-energy (WTE) plants. The data only provide some support for the widespread policy preference for incineration over landfilling if the analysis is restricted to environmental costs alone. Private costs, however, are so much higher for incineration, that landfilling is the social cost minimizing option at the margin even in a densely populated country such as the Netherlands. Implications for waste policy are discussed as well. Proper treatment of and energy recovery from landfills seem to be the most important targets for waste policy. WTE plants are a very expensive way to save on climate change emissions.

Waste not, want not: the private and social costs of waste-to-energy production

Communities, and whole countries, are considering implementing the quickly-evolving technologies of waste-to-energy (WTE) production. Unlike other energy sources, waste-to-energy plants have two objectives. In addition to generating useful energy, these plants are designed to ensure the safe and effective disposal of municipal solid waste (MSW). Energy production and solid waste management both involve complicated and large-scale production processes which generate substantial environmental impacts. Traditional analysis of the desirability of adopting WTE technology has compared its costs and benefits either to other forms of energy production or to other forms of solid waste management. Traditional analysis also tends to focus on private production costs with limited consideration of broader social environmental impacts. Using data from Germany, Sweden, the UK and the US, this paper bundles together the energy generation and waste disposal services offered by WTE and estimates the associated private production and social environmental costs. In so doing, this economic study provides insight into whether WTE plants can compete on the energy production side with fossil-fuel-fired plants and on the waste management side with landfill disposal.

The role of chlorine in high temperature corrosion in waste-to-energy plants

High temperature corrosion has been a serious problem in municipal solid waste (MSW) incinerators since the emergence of waste-to-energy (WTE) plants in the 1960s. Early researchers conjectured that corrosion was caused by sulfur compounds, but it soon became evident that the dominant corrosive species are chlorides, typically in combination with alkali metals (Na, K) and heavy metals (Pb, Zn). Yet, many uncertainties remain with respect to the complex interactions between metallic materials of construction and their corrosion products with aggressive species in the combustion atmosphere and in fireside deposits. Following a review of historical background, MSW incineration technology and refuse boiler materials/corrosion, this paper will examine the causes and mechanisms of high temperature corrosion in WTE plants, as well as the environmental and alloy-related factors affecting metal wastage. Attention will be called to remaining uncertainties regarding corrosion mechanisms, and to apparent incongruities and conflicting data on materials performance to help identify areas for further R&D.

Recycling Energy Values of Municipal Solid Waste

The equivalent fuel value methodology was used to compare recycling to recover material values with recycling to recover energy values at a mass burn waste to energy (WTE) plant and a refuse derived fuel (RDF) WTE plant, both generating electrical power. It was determined that the equivalent fuel value, under conditions that existed in Pinellas County Florida during the Middle East crises, reached $57.41 per ton of as‐received municipal solid waste. There is a saving of from 1.15 to 1.35 barrels of No. 2 fuel oil per ton of municipal solid waste (MSW) when the waste is used to generate electrical power. Some of the other waste component equivalent fuel values determined were 2.4 barrels of No. 2 fuel oil per ton of newsprint, 5.63 barrels of No. 2 fuel oil per ton of polyethylene, and 0.81 barrels of No. 2 fuel oil per ton of lawn grass with 65% moisture. Various environmental impacts that can result from collection, shipping, and the lost energy opportunity values appeared to exceed the environmental ben...

Avoided-cost pricing of electricity from waste-to-energy plants The regulatory economics of a negative cost fuel

This paper examines the role of the 1978 federal Public Utilities Regulatory Policies Act (PURPA) in shaping the economic feasibility and regional distribution of waste-to-energy plants (WEPs) in the USA. PURPA marked a watershed in US energy policy by mandating private utilities to purchase electricity produced by small generators. This mandate, together with wide-spread exhaustion of municipal solid waste landfills, enhances the attractiveness of WEPs as both an energy source and a waste management option. PURPA rules and rates vary widely both across and within states according to the allowance of generating capacity credits, as well as a utility's fuel mix, excess capacity, and load growth. In general, environmental imperatives and high avoided-costs of alternative power production options have led developers principally to Northeast and Southern locations. In the next decade, county and municipal governments pressed by landfill exhaustion will likely be forced to settle for high disposal, or tipping, fees to offset stable or declining fuel and capacity credits. Developers, in turn, will be drawn to areas where PURPA rules and rates will most insulate WEPs from conventional fuel price swings that have undermined the revenue projections of many recent projects.

The external aspects of the sun—its photosphere and spots—its chromosphere and corona

In this work, the performance of an amine-based post-combustion carbon capture system using MEA (monoethanolamine) integrated to a Waste-to-Energy (WtE) plant is studied. WtE plants are affected by fluctuations at different time-scales, due to changes in waste properties as well as variations in district heat demand. A dynamic model of the combined plant is used to study the effect of flue gas fluctuations on capture plant operation, and the effect of integrating the capture plant into the WtE plant.When the two plants are considered separately, the heat requirement of the capture plant corresponds to 27% of the nominal thermal capacity of the WtE plant. When integrating the two plants, steam extraction from the boiler drum to provide the heat necessary to the capture plant reduces the power and district heat production of the WtE plant by 30% and 6% respectively, while extraction from the turbine causes a reduction of 8% and 12%. By modifying the condensers’ temperature, it is possible to maintain 96% of the original district heat production. By performing carbon capture only when excess heat is available, it is possible to capture 47% of the CO2 emitted by the WtE plant, while reducing the power production by only 5%.