Worldwide energy crisis directed the attention to the alternative sources of energy instead of underground fossil fuel (Al Imam, Khan, Sarkar & Ali, 2013). Global energy demand is increase at every single moment and to cope up with this daily need. The role of renewable energy is becoming more important in the development as well as the development of countries to meet partially the need of global energy (Islam, Banerjee & Ali, 2014). The growth of this global in energy demand has induced an active search for alternative energy source (Al Imam, Khan, Sarkar & Ali, 2013). The more efficient of deployment of renewable energy sources will facilitate a reduction in greenhouse gas emissions and air pollution.
Therefore, Malaysia is faced with challenges with respect to the solid waste management sector because of the increase of population, economic growth for sustainable development and inadequate waste legislation enforcement (Nadi, Ahmad, Pirasteh & Shamshiry, 2011). The number of solid waste generated was recorded of 2,000 tons per day. Accordingly, the solid waste generation average for any person is 1.2 kilograms a day (Budhiarta, Siwar & Basri, 2012). Hence, anaerobic digestion can be used to degrade food waste and recover energy. The energy carrier in focus is biogas which is among alternatives to fossil fuels. The biomass used to produce biogas is food wastes. By anaerobic digestion, the wastes could be treated to minimize the environmental impact and at the same time converted into methane gas.
Food waste is food material that is unused, discarded and not safe to be consumed by human for avoidable reasons at production line (Carol & Peissner, 2013). Food waste is edible meats and plants that are harvested to be consumed but not evenly consumed by human because it is spoilt and discarded. Food waste is food appropriate for human consumption that have been discarded whether it is kept before expire date or left to spoil (Carol & Peissner, 2013). Food waste can be due to oversupply to markets, individual shopping habits or eating habits.
The examples of food wastes are fruits and vegetables. Food wastes from households and business normally are sent to landfill for disposal. Rotten food can breakdown to produce methane gas and is harmful to human if not handle properly (Carol & Peissner, 2013).
Methane is potent greenhouse gas that contributes to greenhouse effect and global warming. Methane gas is 25 times more potent than carbon dioxide in causing greenhouse effect (Borrows, 2009). Food waste can cause the emissions of greenhouse gas that increase the surrounding temperature during its production and disposal. Food wastes that dispose in landfills can decompose and produce offensive smell that can harmful to human and environment. Therefore, food waste can be reduced by converting into useful form organic fertilizers to reduce health problem caused by food wastes disposal (Carol & Peissner, 2013). Food wastes can be decomposed in anaerobic digestion by microorganisms to break down food waste into smaller materials and make useful products (Malakahmad, Ezlin, Basri & Md Zain, 2014). This process is carried out inside an enclosed system in the absence of oxygen. Methane gas that produced can be collected and converted into biogas.
Biogas is a mixture of different gases produce by the breakdown of organic matter in absence of oxygen. Biogas was a renewable energy source that can be produced from the raw materials such as food waste, green waste, municipal waste, agricultural waste or manure. Biogas production is a sustainable solution to treat waste and the cost of the waste treatment is low (Verstraete, Morgan-Sagastume, Aiyuk, Waweru, Rabaey & Lissens G, 2005). There is limited competition with food by using kitchen waste and residues to produce biogas (Wellinger, 2009). The effluent from the biogas process supplies essential nutrients which can also be utilized as fertilizer (Vasudeo, 2005). Biogas also can be substituted with other costly energies and needed for developmental activities. Therefore, biogas energy can reduce cost and also can generate power.
Around 1.3 billion tonnes of food is wasted every year in the world (Carol & Peissner, 2013). Fruits and vegetables that include tubers and roots showed the highest amount of wastage of any food. The number of solid waste generated was recorded of 2,000 tons per day in Malaysia. Accordingly, the solid waste generation average for any person is 1.2 kilograms a day. This issues will cause a high cost for solid waste management. Besides, most of the food wastes are disposed at disposal site and causes the lack of food waste recovery in Malaysia. Food wastes are normally sent to the landfill for disposal but it may break down and produce large amount of methane gas. This can become a problem because methane gas is 25 times more potent than carbon dioxide in causing greenhouse effect and global warming (Carol & Peissner, 2013). This issues also can cause the lack of solid waste disposal site in Malaysia as the disposal site become a limited space because of too many food waste is dumped. Lastly, most of people are lack of study in biogas production from the solid waste. Transforming food waste into useful product of natural gas is required to decrease the amount of food waste.