3.            IMPLICATIONS

3.1        Energy Efficiency Implications

The efficiency of incineration correlates with the calorific value of the feedstock, which depends on the starting material and the external conditions like storage and moisture content. The calorific value is in linear relation with the moisture content of the organic matter. The moisture content diminishes the calorific value. The low sulphur content of biofuels is advantageous from an environmental point of view, but disadvantageous as far as the calorific value is concerned. In addition to the calorific value another factor that determines energy efficiency is the energy loss caused by flue gases. Low calorific value increases the amount of flue gas produced, which is a disadvantage as far as efficiency is concerned. In case of perfect combustion this loss is around 15-18%, while imperfect combustion results in 35-40% energy loss.

The key to perfect combustion is control. Effective incineration requires:

·         sufficient temperature,

·         sufficient residence time at that temperature,

·         maximum turbulence and

·         excess oxygen.

The higher the temperature the more effective the incineration and the lower the possibility of any un-burnt waste being released or hazardous by-product being formed. It is necessary to hold the waste at high temperatures for sufficient time to ensure destruction (residence time). The longer the material is held at high temperature the more likely it is to be destroyed. The residence time for gaseous substances is a minimum of 2 seconds. For solids the residence time could be minutes or even hours. Turbulence enables waste and air to be well mixed. Turbulence should be maximized so that contact between the waste and the oxygen in air is as high as possible. Excess oxygen must be present to ensure that the oxidative processes predominate and the pyrolytic processes are minimized. Generally oxygen should be present at 50-100% higher concentration than is theoretically required to oxidise the waste.

3.2        Social Implications

Incinerators can improve the management of both municipal and industrial solid waste; in addition, they are capable of destroying any hazardous components in the waste. Furthermore the heat produced by incineration can be utilised in non-polluting energy generation schemes, preferably using a waste stream from which recyclable items have been extracted. Heat-from-waste schemes may offer the best benefits to regions further away from the main electricity and gas generation/distribution centres.

As waste incineration is deployed to produce heat and/or electricity, the technology is now seen as an integral part of sustainable development, for it contributes to the two key goals of sustainable development:

·         economic development, and

·         protection and enhancement of the environment.

More than half the waste incinerated consists of organic materials, such as wood, paper and carton. Using organic material to generate electricity and/or heat displaces fossil fuels such as natural gas, coal and oil, thus reducing their use and cutting the region’s dependence on imported fuels. Wider deployment would also reduce dependence on land filling thus mitigating methane emission.

3.3        Environmental Implications

In recent years improvements in waste disposal technology have greatly reduced the adverse environmental impacts of incineration. Though modern incinerators are more secure than ever and adverse environmental impacts can be properly addressed, even today there is a great – furthermore increasing - public resistance towards mass burning. This opposition can be traced back to older incinerators with poor pollution control systems, which produced significant air quality problems. Concerns about emissions from combustion have produced strict emission regulations now embodied in EU and national legislation. This has led to the evolution of combustion technology with gas cleaning which can meet these and even more stringent standards. With modern control systems for waste that cannot be avoided or directly recycled incineration is an ecologically viable option. For waste that is not possible to be stored at a landfill site due to legislative requirements, incineration is often the only option. Nonetheless combustion projects often face opposition because of fears about the environmental effects of emissions.

Today energy-from-waste is not only an excellent alternative source of energy. Modern energy-from-waste plants also offer unique environmental benefits. They act positively to decrease CO₂ emissions and act as a dioxin sink, destroying around 80% of dioxins contained in the waste entering the plant. They also act as an important clean-up tool for a wide variety of micro-pollutants, which are ubiquitous in the environment and, this way, treat the waste left over by other waste management techniques without polluting the atmosphere.