Due to the population explosion and the industrial revolution, our need for the electricity is drastically increasing. The fossil fuel we are using, however, is running short. Even though the supply is not a problem now, it will become sooner or later. Also, the deterioration rate of the Earth environment is alarming. The remediation must be taken immediately. For this, using more renewable energy is an ideal method to tackle the problems, reduce the global warming effect and provide a better living standard. The nation all over the world has investigated the method to less rely on the fossil fuel. Hong Kong, being a part of the world, should also take the responsibility to do so. Many may wonder is Hong Kong potential enough to use more renewable energy? The answer is simple-why isn’t it? Renewable Energy in Hong Kong
There are many types of renewable energy, hydropower, wind powers, solar energy, etc. However, developing renewable energy in Hong Kong always faces lots of problems and limitations. The factors such as capital, pollutants or technology required are the consideration in the process of developing the renewable energy. For example, as a small place with no indigenous resources such as land resources and geological location, Hong Kong cannot mainly rely on the large construction of plants. Upon reflection, developing Energy-from-Waste (EFW) would be a possible method to promote environmental friendly and highly adaptable in Hong Kong.
One of the method of energy-from-waste is converting the internal energy of municipal solid waste (MSW) into thermal energy and then electricity is generated. By way of municipal solid waste combustion, flue gases are produced with high temperature and the thermal energy can be used to raise steam to drive a turbo-generator to generate electricity. Municipal solid waste combustion is not only a method of treatment and disposal of wastes but also can be used to recover a substantial proportion of the energy from waste. Municipal solid waste combustion systems can be divided into two main types: Mass Burning Type and Refuse-Derived-Fuel (RDF) Burning Type, depending on the way that the refuse is combusted and the fuel preparations steps. -Mass Burning Type (1)
Mass Burn energy-from-waste technology is the most commonly used technology for treating MSW while generating energy.
Mass Burning is a method which the refuse combusted in a hearth or stoker are directly collected from the sources. Stokers are designed to include drying, burning and ash burnout sections with each of these sections requiring different combustion air quantities. Burning untreated refuse can avoid the substantial cost and commitment of land area for different process for example, refuse shredding, screening etc. and produce a minimum total residual quantity. The cost for taking this approach is that the furnace combustion environment must be designed and operated to fully respond to any adverse process consequences arising from the heterogeneity of the waste. This technical challenge has been fully overcome by several firms throughout the world -Refuse-Derived-Fuel Burning Type (1)
Refuse-Derived-Fuel (RDF) Burning is where the refuse is first processed to generate a more homogeneous “fuel” i.e., RDF. RDF processes separate out the non-combustibles from the MSW. This would benefit the combustion as higher heat release intensity and smaller flue gas quantities. With more uniform fuel, one expects to operate with lower excess air and, therefore, less air pollution.
-Successful example (2)
In Western Europe, combustion is the second most common form of waste disposal. Denmark combust 65% of MSW, Sweden combusts 55% of MSW, France combusts 42% (including 100% for Paris), the Netherlands 40% and Germany 30% of MSW. In Singapore, MSW is collected daily, with 85% combusted (with energy recovery) in three modern combustors equipped with gas cleaning equipment. In...