Waste-to-Energy (WtE) is a form of energy reclamation. It is a process whereby energy, in the form of heat or electricity, is generated by burning waste (see Appendix 2, Figure 1). This process reduces or even eliminates waste substances which would otherwise find their way into landfill sites where their decomposition results in the emission of greenhouse gases. There are various possible WtE process flows. Most WtE applications produce electricity by incinerating waste, or produce combustible (raw) materials such as methane, methanol, ethanol, or synthetic fuels. Biogas, for example, can be produced by means of a WtE application and subsequently upgraded to natural gas quality. More information about this process can be found under the ‘Green gas in the region’ concept.
The traditional waste management approach (removal, landfill) can now be replaced by a more comprehensive concept which involves the 'up-cycling' into energy. It closes the cycle of waste materials just as in the ‘Cradle-to-Cradle’ concept. Waste to-Energy will have a positive effect in terms of the energy autonomy of airports, production facilities, islands, local communities, and other locations at which waste production and energy consumption coincide.
The Greenzone concept
This Waste-to-Energy concept involves two distinct technologies:
1. Waste to liquid 'fuel’ by means of pyrolysis (EOS)
2. Production of electricity, heat and clean CO2 using innovative Dutch gas turbine technology
Most waste consists of oil derivatives. The Greenzone concept involves a technology for processing waste whereby it is heated to induce pyrolysis (the chemical decomposition of condensed substances that occurs spontaneously at high enough temperatures). The product is a liquid fuel and gas with a high energy yield (although the exact figure will depend on the quality of the waste). Of this fuel, part of the gas is reused to provide heat for the process itself. The remainder is channelled into a Heron gas turbine (see Appendix 2, Figure 2) with a capacity of 1.7 MW: enough to meet the total electricity requirement of Schiphol Amsterdam Airport. Electricity generated in this way could also be fed to the charging stations for electric vehicles. The residual heat produced by the process is transported to glasshouses, offices, and other buildings, while the clean CO2 is used in the horticultural industry.
Afval Energie Bedrijf Amsterdam (AEB)
Afval Energie Bedrijf (Waste and Energy Company) of Amsterdam generates electricity using steam turbines. The heat released from the combustion of waste is used to heat the water in the boiler compartments, whereupon it vaporizes into steam. This steam is then ‘super-heated’ using heat from the same process, creating enormous pressure to drive the turbines which generate electricity. The heat which remains following the production of steam can be used in district heating systems.
Unique Selling Points
• The energy yield of a waste mixture combusted to produce high-pressure steam is around 80%.
• The use of heat generated from waste offers the best opportunities (in both economic and environmental terms) to achieve the current energy reduction targets, i.e. the ‘energy performance norms’ for new-build residential properties.
• The concept eliminates the need to deposit waste in landfill sites (which take up valuable space).
• The Greenzone concept also represents a major reduction in transport costs (500,000 km per annum per plant), since the waste is produced, collected and processed within a closed circuit (Schiphol Airport). It is therefore no longer necessary to transport waste into other regions.
The WtE concept reduces or eliminates waste materials which would otherwise be deposited in landfill sites, resulting in the emission of greenhouse gases. Moreover, the WtE concept reduces the demand for energy on the existing local transport grids and/or can supply locally generated energy to the national grid, which will reduce CO2 emissions from the large power stations.
Climate impact of AEB
AEB’s net output is over 545,000 MWh per annum, representing a CO2 reduction of approximately 350,000 tons. The ‘green’ electricity produced is enough to meet the demand of approximately 161,000 Amsterdam households. Output is to be further increased in the near future. The supply of heat via district heating systems is also taking off in Amsterdam. Some 5,000 household equivalents are being connected to such systems each year (3,500 actual homes and 1,500 home equivalents in the form of large-scale users). In the Westelijke Tuinsteden district, no fewer than 2,200 homes were connected in 2009 alone. Growth of 5,000 household equivalents per annum is expected over the next few years.
Market parties and research institutes
AEH Power, Afval Energie Bedrijf (AEB), Cirmac International, Gasunie, Global Green International*, KEMA, MSwitch*, Optimum Environmental & Energy Technologies, Prologa, Raedthuys Group, Wilaard Holding, WWE Sustainable Solutions, A. de Jong Group (NB This list is not comprehensive)
Best practice reference projects in the Netherlands
• Greenzone, Schiphol
• Landfill site, Neunen
• Afval Energie Bedrijf, Amsterdam
• AVR waste incinerator, Rotterdam
• HVC, Alkmaar
Possible obstacles to international business
• In some regions, the process of acquiring the necessary environmental and planning permits can be extremely lengthy.