Sustainable Waste Management for the 21 st Century

Transcription

1 Il Recupero Energetico del Rifuiti: Esperienze internazionali a confrontofirenze,, February 20, 2007 Sustainable Waste Management for the 21 st Century By Prof. Nickolas J. Themelis, Columbia University

2 To approach sustainable development humans need to control emissions to water, air, and land The developed nations are doing a fairly good job with regard to water and air, except for greenhouse gases (GHG) But.

3 When it comes to controlling emissions to land, the U.S. is much behind Japan, Denmark, Switzerland, the Netherlands, Germany, Sweden, Singapore and several other nations. What is less understood is the adverse impact of landfilling municipal solid wastes (MSW) on the land and also on GHG emissions.

4 Hierarchy of Waste Management Recycling/composting is the first priority for managing solid wastes but. in many cases, recycling is practically impossible for certain materials (e.g., 80% of U.S. plastics are still landfilled). Therefore, in advanced nations, the next priority, after recycling, is waste-to-energy (WTE), i.e. the recovery of energy and metals by controlled combustion. Legislation and regulations encourage WTE and discourage its only alternative, landfilling.

5 THE GLOBAL LANDFILLING PICTURE (N.J. Themelis and P. Ulloa, Capture and Utilization of Landfill Gas, in Renewable Energy 2005) MSW to global landfills: 1.25 billion tonnes/y * * Landfill Gas (LFG) generation: 70 billion Nm 3 CH 4 Mass of LFG: 50 million tonnes CH 4 LFG collected: 5 million tonnes CH 4 LFG emitted globally: 45 million tonnes CH 4 * *

6 THE GLOBAL WTE PICTURE Nation Million tonnes to WTE EU Japan 40.0 USA 26.3 Taiwan 7.0 Singapore 4.0 China 3.0 Switzerland and Norway 3.8 South Korea 1.0 All other 9 Total 143

7 State of the Garbage in America (Earth Engineering Center Survey of 2004 data (BioCycle, April 2006)

8 Simulation of landfilling reactions in the laboratory (Prof. Barlaz,, NCSU; speaker at 2006 WTERT Meeting) Most of the methane was generated in less than one year 1.4 cubic meters of methane per ton MSW per day two tests Day

9 Effects of landfilling on GHG Corresponding CO2 emissions to atmosphere: > 1 billion tons of CO2 (about 4% of carbon emissions; the low-hanging fruit on the GHG control tree ). The U.S. is the world s largest landfiller: 226 million tonnes of MSW annually, I.e., one fifth of the global total.

10 Effects of landfilling on land: At the present rate of landfiling in the U.S., thousands of acres are lost annually to landfills. E.g., metropolitan Los Angeles is served by about 20 landfills of average life of 10 years. The new sanitary landfills have a lifetime of about 20 years. The 2,500-acre Fresh Kills landfill of New York City was filled in about fifty years. Landfilling is not sustainable management of solid wastes.

11 Modern sanitary landfills are much better than the old ones because they control liquid emissions and 50-60% of gas emissions.but they also create new mountains Los Puentes Landfill, LA, CA

12 Comparison with WTE: Rochester, MA The SEMASS WTE occupies 25 acres, closed over 40 landfills, and for fifteen years has served one million people in 100-km radius: SE Mass, Cape Cod, Martha s Vineyard, Nantucket Cape Cod

13 WTE can be a major source of Renewable Energy (U.S. DOE 2002) Energy source Billion kwh % of total renewable generated energy Geothermal % WTE (from 7.4% of % the MSW) Landfill gas (from % 64.1% of the MSW) Wood/other biomass % Solar thermal % Solar photovoltaic % Wind % Total % 1 ton of MSW=550 kwh==1 barrel of oil

14 Another important contribution of WTE to Sustainable Development: Recovery of metals At present, 700,000 tons of ferrous scrap are recovered at U.S. WTEs If the MSW that are now landfilled were combusted in WTEs, an additional 7 million tons of ferrous metals would be recovered. Saving metals also entails saving of energy

15 The Air Pollution Control system of a modern WTE accounts for 50% of the capital and operating cost ( cleanest high temperature stack gas ) Maximum Achievable Control Technology (EPA s MACT): Dry scrubber, ammonia injection, activated carbon injection, fabric filter baghouse, continuous monitoring

16 MACT result: Change in dioxin emissions from U.S. WTEs between 1987 (10,000 g TEQ) and 2002 (<10g TEQ) BBB WTE

17 In contrast: In addition to methane emissions, the U.S. landfills generate annually: 39,329 tons ammonia 39,213 tons sulfides/mercaptans 742 tons toluene 503 tons dichloromethane 201 tons tetrachloroethylene 112 tons vinyl acetate 92 tons acetone 64 tons dichloroethane 65 tons xylenes 63 tons trichloroethylene 51 tons vinyl chloride 36 tons styrenes Smaller tonnages of another ten VOC compounds Computed from: Landfill gas constituents as per Tchobanoglous Handbook x (106 million tons of MSW x 62 Nm 3 LFG/ton - collected landfill gas as per Berenyi Landfill Yearbook)

18 Interstate Transport of Municipal Solid Wastes (Congressional Research Service) Questions under debate on the Hill (from CRS web): Should Congress Grant States the Authority to Limit Out-of-State Waste? Should States and Localities Be Allowed to Control the Flow of Privately Collected Waste?

19 Getting more energy from MSW: Use of waste steam for district heating in Europe Analysis of 97 plants by Confederation of European WTE Plants Courtesy of Ms. Ella Stengler, CEWEP Executive Director (speaker at 2006 WTERT Meeting, October 19-20, Columbia University) MSW processed, million tons 24.1 Thermal energy in MSW, kwh/tonne 2850 Net electricity to grid, kwh/tonne 302 Net thermal energy to district heating, kwh/tonne 878 Avoided fossil fuel use at assumed 35% conversion efficiency of heat to electricity, kwh: 302/ = = 1741 Overall thermal efficiency of the 97 EU plants 61%

20 In closing: WTERT 2006 Awards for Outstanding Contributions to WTE and Integrated Waste Management globally: 2006 Industry Award: To one of thecbest WTE facilities in the world: ASM Brescia Education Award: To person who has advanced Integrated Waste Management: Prof. Paul H. Brunner, of Technical University of Vienna

21 Co-generation Power plant WTE co-generation at Brescia, Italy City of Brescia Waste-to-Energy Plant (1998) District Heating plant

22 A future must for WTEs: Co-generation of electricity and district heating or cooling Brescia hot water pipeline Building substation (30 flats) Brescia

23 WTERT invites WEB Links to WTE and Integrated Waste Management. Please links to

24 With thanks to Ferambiente for their invitation to participate in this convegno