Abstract
Rapid economic expansion, urbanization, and population growth have increased the use of (materially intensive) resources and, as a result, the amount of trash released into the environment. Globally speaking, there is a lack of a comprehensive strategy for waste and resource management that addresses the entire value chain of product design, raw material extraction, manufacture, consumption, recycling, and trash treatment.
Also, hundreds of millions of tonnes of municipal solid waste still wind up in landfills, despite the recent growth of the world’s waste-to-energy (WTE) industry. At least 1.3 tonnes more carbon dioxide are released into the atmosphere for every tonne of waste that is landfilled. This article gives a general overview of the WTE sector and examines current developments in the US that have reduced mercury and dioxin emissions. In order to advance WTE technology, the recently founded Waste-to-Energy Research and Technology Council seeks to bring together international academic and industrial expertise
Introduction
Over 600 waste-to-energy (WTE) facilities burn roughly 130 million tonnes of municipal solid waste (MSW) yearly. The MSW produced by the world’s WTE industry has increased by more than 16 million tonnes since 1995. There are WTE facilities in 35 countries, including big ones like China and tiny ones like Bermuda.
Combustible material landfilling must be phased out within a decade, per a European Union directive[1]. It is unclear, nevertheless, whether all the member nations will contribute the necessary money. Some, like Greece, have no WTE capacity at all, while others, like Singapore, have very little. Table 2.[2] displays the installed capacity and per-person use of WTE for disposing of municipal solid waste in the EU as of the present. For instance, the quantity of WTE used per capita in Japan is 314 kg, in Singapore, it is 252 kg, and in the US, it is 105 kg. China is one of the more recent entrants to WTE, with seven units currently in operation and a potential annual capacity of 1.6 million metric tonnes.
The present condition of the world WTE market
The European waste-to-energy (WTE) industry produced over 40 million tonnes of energy per year in 2002. The Brescia WTE facility in Italy is a good example of cogeneration of thermal and electric energies. It provides at least as much energy as is needed for district heating during the cold winter months.[3]
WTE capacity from the US accounts for around 23% of the global total, and 66% of it is concentrated in seven states along the East Coast.[4] (See Table 1).
Table 1: Major users of WTE in the US
| State | Number of Plants | Capacity (short US tons/day) |
| Connecticut | 6 | 6,500 |
| New York | 10 | 11,100 |
| New Jersey | 5 | 6,200 |
| Pennsylvania | 6 | 8,400 |
| Virginia | 6 | 8,300 |
| Florida | 13 | 19,300 |
| Total | 53 | 69,600 |
Table 2. Reported WTE capacity in Europe[5]
| Country | Tonnes/year (in 1999) | Kilograms/capita | Thermal energy (gigajoules) | Electric energy (gigajoules) |
| Austria | 450,000 | 56 | 3,053,000 | 131,000 |
| Denmark | 2,562,000 | 477 | 10,543,000 | 3,472,000 |
| France | 10,984,000 | 180 | 32,303,000 | 2,164,000 |
| Germany | 12,853,000 | 157 | 27,190,000 | 12,042,000 |
| Hungary | 352,000 | 6 | 2,000 | 399,000 |
| Italy | 2,169,000 | 137 | 3,354,000 | 2,338,000 |
| Netherlands | 4,818,000 | 482 | n.d. | 9,130,000 |
| Norway | 220,000 | 49 | 1,409,000 | 27,000 |
| Portugal | 322,000 | 32 | 1,000 | 558,000 |
| Spain | 1,039,000 | 26 | n.d. | 1,934,000 |
| Sweden | 2,005,000 | 225 | 22,996,000 | 4,360,000 |
| Switzerland | 1,636,000 | 164 | 8,698,000 | 2,311,000 |
| UK | 1,074,000 | 18 | 1,000 | 1,895,000 |
| Total reported | 40,484,000 | 154.5 (average) | 109,550,000 | 40,761,000 |
The Present Condition of WTE Technology
Mass burning is the most popular WTE method since it is straightforward and has a minimum initial investment.
The annual installed capacity of the most popular grate technology, created by Martin GmbH (Munich, Germany), is around 59 million metric tonnes. One of the newest WTE facilities in Europe is the Martin grate at the Brescia (Italy) facility. A schematic representation of its mass-burn combustion chamber is shown in Figure 1. 32 million tonnes are burned as part of the Von Roll mass-burning operation in Zurich, Switzerland. The combined estimated capacity of all other mass-burning and refuse-derived fuel (RDF) processes is more than 40 million tonnes.
Source: https://www.yokogawa.com/fr/industries/renewable-energy/waste-to-energy/
The Advantages of WTE for the Environment
- Landfill Gaseous Emissions:
Some environmental groups in the US still oppose new WTE facilities on principle. Landfills, the only other option for disposing of MSW, have much worse environmental effects. At least 1.3 tonnes more carbon dioxide are released for every tonne of waste that is landfilled. Biogas from landfills typically comprises 46% carbon dioxide and 54% methane.[6] A tonne of landfilled MSW has a maximum methane production potential of 62 standard m3 of CH4.[7] 8 billion Nm3 of landfill gas were captured annually in the US in 2012.
- Mercury Emissions from landfills:
The majority of the mercury in MSW is in metallic form (fluorescent lamps, thermometers, etc.). At landfill temperatures (40°C), its vapour pressure is 0.007 mm Hg as opposed to 5.67mm Hg for water. A mercury droplet of the same size will evaporate in four weeks if an exposed water droplet evaporates in an hour.
The Next Generation of WTE Processes
A Waste-to-Energy (WTE) facility has three times the capital and operating expenses of a coal-fired power station that produces the same amount of electricity. Oxygen enrichment, used in the metallurgical industry, and flue gas recirculation are two ways to increase the turbulence and transport rates in the WTE chamber. The Brescia WTE facility has already used the latter to great success. Martin GmbH[8] is now constructing two “next generation” plants in Arnoldstein, Austria, and Sendai, Japan. Syncom-Plus uses an infrared camera to monitor the temperature of the bed on the grate. It has a complex control system to assure complete combustion and create bottom ash that is nearly fused.
The WTE Research and Technology Council (WTERT)
Waste-to-energy (WTE) is increasingly important to the US economy. There are currently no industrial or governmental research centres dedicated to advancing WTE technology. The WTE Research and Technology Council’s purpose is to promote waste-to-energy technologies’ economic and environmental performance. Creating connections between academic teams working on various WTE technology issues is one of the goals. The Council was formed with the assistance of Columbia University’s Earth Institute (WTERT). The image below is a view of the WTE plant in Brescia, Lombardy – Italy[9]
WTERT is currently supported by its founders, the US EPA, the Municipal Waste Management Association of the US Conference of Mayors, the Solid Wastes Processing Division of ASME International, and other groups. The interactive database “SOFOS,” which offers information on technical papers and studies linked to the integrated management of solid wastes, is one of the services offered by WTERT.
The Earth Engineering Centre, Department of Earth and Environmental Engineering, and Department of Civil Engineering from Columbia University, USA; the Department of Civil and Environmental Engineering at Temple University in the United States; the Marine Sciences Research Centre at the State University of New York at Stony Brook in the United States; Department of Applied Earth Sciences at the Delft University of Technology in the Netherlands; The United Kingdom’s Sheffield University Waste Incineration Centre (SUWIC), are now taking part in the WTERT University Consortium. WTERT invites additional universities that share the Council’s objectives to join this alliance.
Conclusion
Waste-to-Energy (WTE) facilities burn about 130 million tonnes of municipal trash annually. 47 new WTE plants have begun construction since 2001 or are currently under construction. WTE expansion in the US has been hampered by environmental opposition that ignores the significant decrease in gas emissions made by the US WTE industry because of the adoption of the US EPA regulations for Maximum Available Control Technology and by the fact that current legislation does not acknowledge the significant environmental benefits of WTE, in terms of energy generation, environmental quality, and reduction of greenhouse gases. Significant improvements in WTE technology have been made in recent years, including the utilization of flue gas recirculation and the construction of new plants that will utilise oxygen enrichment of the main air. This group brings together universities that are interested in waste management. The Council was established because of the significance of WTE in the international drive for sustainable development. The Council began its operations by compiling a list of the available research resources as well as the global WTE market. Enhancing the economic and environmental performance of technologies that can be utilized to recover materials and energy from solid wastes is the Council’s overarching objective.
[1] European Union, Council Directive 1999/31/EC of 26 April 1999 on Council Directive 1999/31/EC of 26 April 1999 on the landfill of waste, the landfill of waste,
Official Journal of the European Official Journal of the European Communities Communities, pp. L182/1-19 (July 1999).
[2] International Solid Wastes Association, Energy from Waste, State-of-the Art Report, www.wte.org
[3] Bonomo, A., WTE Advances: “The Experience of Brescia WTE Advances: The Experience of Brescia” (April 2003), Keynote presentation at the 11th North American Waste-to-Energy Conference, Tampa FL.
[4] Nickolas J. Themelis in Waste Management World (www.iswa.org), 2003-2004. Review Issue, July-August 2003, p. 40-47
[5] International Solid Wastes Association, Energy from Waste, State-of-the-Art Report, www.wte.org.
[6] Themelis, N.J. and H.Y. Kim, “Material and Energy Balances in a Large-scale Aerobic Bioconversion
Cell”, Waste Management and Research, 2002, 20:234-242.
[7] Franklin Associates, “The role of recycling in integrated waste: The role of recycling in integrated waste management in the US”, Rep. management in the US, Rep. EPA/530-R-96-001 EPA/530-R-96-001, USEPA, Munic. Industrial Waste Division, Washington, DC. 1995.
[8] Martin GmbH, www.martingmbh.de.
[9] Waste to energy plant in Brescia, Lombardy – Italy Stock Photo – Alamy