This research conducted the life cycle inventory analyses of biofuels in Taiwan. The biofuels considered include bioethanol production from sugarcane as well as biodiesel production from soybean and rapeseed. Energy inputs and pollutant emission (including carbon dioxide) are the input/output items analyzed. Results obtained from the inventory analyses can be summarized as follows. Bioethanol production from per hectare sugarcane cropland is 5160 L (liters), meanwhile, 476 and 1012 L biodiesel can be produced from 1 ha of soybean and rapeseed, respectively. The energy input to produce a liter ethanol, a liter biodiesel produced from soybean and rapeseed are 1256, 9602 and 5191 kcal, respectively. Those energy inputs are still less than the energy content of ethanol or biodiesel. It can be concluded that there is a positive energy benefit in producing biofuels based on a comparison with the previous work. In addition, through their life cycle, 1478.4 kg CO2 emission is generated from one hectare of soybean land and 2954.1 kg is generated from rapeseed land. Life cycle carbon dioxide emissions released from burning ethanol is 0.08 kg/LOE in contrast to 2.6 kg/LOE released from burning fossil gasoline.
With recent increase in crude oil prices and uncertainty concerning petroleum reserve, there is an emerging interest in the development of biofuels. The scarcity of fossil energy makes renewable energy resources further attractive. Nowadays, numerous countries are devoted to seeking clean and renewable energy. Biofuels are regarded as a new measure for solving energy and environmental problems effectively. They have advantages over conventional fossil fuels including reduced emissions, renewability and cleaning properties (Demirbas, 2006). In general, renewable energy includes biomass, hydropower, wind power, ocean energy, solar energy and geothermal energy. The so-called biomass energy or bioenergy includes solid biomass (i.e., forest product wastes, agricultural residues and wastes, and energy crops), biogas, liquid biofuels and the organic component of industrial waste and municipal solid waste.
Taiwan is a densely populated island with only limited natural resources. According to the statistics released by the Bureau of Energy, Ministry of Economic Affairs (BOE, 2008), Taiwan's total energy consumption has grown greatly over the past two decades, going from 40.68 million kiloliter of oil equivalent (MKLOE) in 1987 to 114.66 million kiloliter in 2007 (the average annual growth rate of 5.32%). In 2007, Taiwan's dependence on imported energy was 98.36% (BOE, 2008). As industry and commerce progress rapidly, increasingly more people are moving to cities for convenience. This leads to greater demand for vehicles, which negatively impact health and environmental quality because of emissions of air pollutants. One of the key solutions to reduce the impacts is the effective use of biofuels.
Taiwan's energy policy hopes to decrease the dependence on imported energy and mitigate greenhouse gas emissions by increasing the supply of renewable energy. In order to encourage the production and use of biofuels, the Ministry of Economic Affairs promulgated the “Measures for Subsidizing Energy Crop” to harvest soybean and rapeseed. This research, thus, conducts a life cycle inventory (LCI) analysis to identify and discuss the inputs and outputs from the bioenergy production and utilization process. This paper is divided into three major parts. The development status of biofuel is introduced first, followed by the LCI analysis of biofuel production in Taiwan. The last part summarizes an analysis from the related findings. The results can thus be used to assess the feasibility of bioenergy development.
