Tedcor has a knowledge and innovation partnership with Dutch waste to energy company HVC Groep. HVC is a joint venture of 55 municipalities in the provinces of North Holland, Flevoland, South Holland and Friesland in the Netherlands. Minimising waste and reusing its by-products is part of the sustainability challenge. Un-recyclable waste can also be used to generate renewable energy through different treatment processes. Waste to energy plants can provide innovative and environmentally friendly solutions to the power crisis of the 21st century.
HOW A WASTE TO ENERGY PLANT WORKS
Incineration and energy generation
In a waste to energy plant, waste that is unsuitable for recycling is incinerated. A plant with four incineration lines, for example, could process approximately 660,000 tons of waste a year. The incineration lines operate 24 hours a day, 7 days a week. In the waste bunker the waste is mixed and becomes a homogeneous fuel, after which it is led to the ovens. There it is burnt at temperatures between 850 and 1100 degrees Celsius. The incineration heat that is produced is used to generate electricity and heat. HVC’s plant in Alkmaar, for example, generates 68 mega¬watt of electricity (sufficient for a city of 130,000 residents or more in the case of South Africa) a year.
Use of Residues
Most of the residues left after incineration are reused. Upgraded bottom ash would be used as level up material in road construction and as foundation material. The fly ash that is released during the incineration process is used as filling material for asphalt concrete. Other 'incineration products' such as salts are used as filler in old mines to prevent their collapse. Filter cake is land filled in a controlled way until new means of utilization are found.
Metals that are released during incineration are sold to the steel industry as scrap. Non-ferrous metals (which do not contain iron) are upgraded and sold as semi-finished products. They are used to make pans for example.
Approximately half the energy that is generated is sustainable energy and comes from incinerating biomass. This heat is produced without having to burn natural gas in a central heating system, which would release carbon dioxide (C02). Another major advantage is that the heat is not released into the air or into the surface water. HVC Alkmaar uses 8 megawatt of the generated energy for its own use. The remains of the sustainable energy, 60 megawatt, could be sold to municipalities or the power generation grid on attractive terms.
Heat generated could be supplied to businesses in the in the vicinity of the plant. This means a potential emission reduction of approximately 20 million kilograms of carbon dioxide a year, which is the annual quantity of exhaust fumes from nearly 100 000 motor cars.
Fuelling organic waste
HVC has piloted a fermenting plant through which organic waste can be converted to “green” transport fuel and compost. The plant is capable of producing 3 million cubic meters of bio gas and 12 000 tons of compost each year. The project produces a sustainable life cycle, in that the vehicles used to collect the organic waste run on the bio gas produced by the plant.