Utilization of Driftwood as an Energy Source and Its Environmental and Economic Benefit Analysis in Taiwan

Using standard methods for the determination of approximate analysis, ultimate analysis, and calorific value, the thermochemical properties of driftwood have been analyzed in the present study. The preliminary results showed that woody waste obviously comprised a large percentage of volatile matter at 72.56 ± 4.58 wt%. The molar ratio of hydrogen to carbon (H/C) was about 1.1, which was lower than those of cellulose (H/C = 1.67) and hemicellulose (H/C = 1.6), and seemed to be in accordance with its higher heating value (18.7 MJ/kg). However, the content of nitrogen was slightly higher, suggesting that the emissions of nitrogen oxide gases from biomass-to-heat facilities will arouse concern. Under the carbonization temperature of around 500 C, the calorific value (25.5 MJ/kg) of the resulting biochar from driftwood was relatively enhanced. Based on the 1,000,000 tons driftwood in Taiwan and the Tier 1 method recommended by the Intergovernmental Panel on Climate Change (IPCC), the environmental benefit of mitigating greenhouse gas emissions and the economic benefit of selling electricity were preliminarily calculated to be around 1.5 × 10 6 tons and US$ 7.0 × 10 , respectively.