Renewable energy is gaining popularity in Malaysia because of the country’s new environmental policy, and a greater understanding of the possibilities of green energy (Tock et al. 2009). Because Malaysia has many natural resources in agriculture and forestry, it has several sources for new carbon neutral biofuel feedstocks, such as banana biomass. Currently, research has calculated the theoretical potential power generation to reach more than half of the renewable energy requirement in the new national policy, making banana biomass a feasible source of renewable energy in Malaysia as well as in similar tropical countries in the world.—Elena Davert
Tock, J.A., Lai, C.L., Lee, K.T., Tan, K.T., Bhatia, S., 2009. Banana biomass as potential renewable enrgy resource: A Malaysian case study. Renewable and Sustainable Energy Reviews 14, 798–805.
The nature of a banana plant’s cultivation and structure make it an excellent candidate for a source of green energy. Because it can only produces fruit once during its lifetime, it loses its agricultural value after one season and leaves farmers with large quantities of biomass waste. Banana biomass is also ideal because of its widespread availability and high growth rates. Not only does its rapid growth and harvest rate of 10–12 months allow for a relatively constant supply of energy feedstock, but its sturdy, fibrous stalk structure— it’s pseudostem—and dense planting allow for a high yield of biomass per plant as well as per hectare. Currently, small percentages of banana pseudostems are either used as organic fertilizer, animal feed, or temporary plates and food storage because current methods of extracting banana fiber for textiles are far from economical. In addition to the banana pseudostems, rejected fruits make up about 30% of the total derived feedstock and are easy to both handle and store. The fruit’s peels are also a feedstock consideration in countries in which bananas are a major food crop. When disposed of indiscriminately, rejected fruits and peels produce noxious gasses such as hydrogen sulphide and ammonia as they decompose, both of which are environmental hazards.
Currently there are two feasible methods for conversion of banana biomass into energy: thermal conversion (gasification), and biological converstion (anaerobic digestion). Gasification, or supercritical water gasification (SCWG), utilizes water that supercedes its critical temperature (647 K) and pressure (22.1 Mpa), exhibiting density and viscosity charictaristics between water and steam, in order to create rapid reactions of organic compounds that are mixed within the water. Although SCWG avoids high processing costs associated with drying processes by using wet biomass, it is still a relatively expensive technology. Instead, anaerobic digestion is preferrable because it can also directly process wet biomass, but at much lower temperatures and costs. This is accomplished by the fermentation of chopped and ground banana residue and waste that yields CO2 (that has been fixed during the plant’s lifetime), and methane levels that are higher and more efficient than the fermentation of other fruits. Using these technologies, Malaysia has been able to produce 4.6% its total energy needs, just short of it’s 5% goal.
Because bananas produce a very clean form of biogas, and because the waste is normally dumped in landfills or nearby bodies of water, companies have access to virtually free feedstock for energy production. As the current technologies become more widespread for commercial use, they should be able to meet the growing demand of energy from Malaysia as well as other developing tropical nations. —Elena Davert