Land application of biochar (or charcoal) has increasingly been recognized due to its favorable effect as soil amendments. However, depending upon the nature of biomass and pyrolysis condition, biochar may be rich in hazardous inorganic elements. Giant Miscanthus showed its potential as a promising source for biochar manufacture but, the risk of heavy metal leaching from Giant Miscanthus-derived biochar (GMB) has not investigated. The objective of this study was to investigate the heavy metal leachability of GMB manufactured from 3 different temperatures (400, 500, and 700oC). Elemental composition of C, N, H, S, O and 18 metals were analyzed. Leaching concentration of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn was analyzed using 4 different methods (0.1 N HCl, 1 N NH4OAc, toxicity characteristic leaching procedure, and synthetic precipitation leaching procedure). For comparison, same analysis were performed for two char materials, municipal solid waste char (MWC) and sewage sludge char (SSC), manufactured from pilot-scale muncipal waste gasification plant. Elemental composition of GMB complied with the fertilizer guideline whereas the several heavy metal content (Cd, Ni, Pb, and Zn for MWC, Cr, Cu, Ni, and Zn for SSC) was beyond the criteria. From leaching test, concentration of heavy metals from GMB was positively increased with pyrolysis temperature and the acidity of extractant solution. Leaching concentration of plant nutrients (Ca, K, and Mg) was the highest by 1N NH4OAc. Meanwhile, leaching concentration of Cu from MWC and Pb from SSC exceeded the regulatory standard of Korea and US EPA, respectively. In conclusion, with respect to the risk of heavy metals, Giant Miscanthus-derived biochar will be suitable for land application as a soil amendment, while care should be taken for using municipal waste-derived char materials.

Korea has adopted a federal renewable electricity standard that begins at 2% in 2012 and requires companies to source 10% of their electricity from renewables by 2022. Therefore the interest in the use of biomass as a renewable energy resource is growing. By importing biomass, the Korea, which produces too little biomass of its own, can meet the needs of the renewable energy sectors. In the case of import biomass, it will cost a great deal on the transportation and logistics of biomass materials. Therefore new research and development on the biomass fuel with high energy density is needed to reduce logistics cost on transportation of the biomass fuel. Torrefaction is a thermochemical treatment process of biomass at temperatures ranging between 200 and 300oC. Typically, 70% of the mass is retained as a char product, containing 90% of the initial energy content. Torrefaction experiments on samples of EFB were performed in a fixed bed reactor to determine the effect of operation variables such as reaction temperature (205-310oC), reaction time (20-40 min) and air ratio (0-0.18) on char yield and characteristics. Increase of the torrefaction temperature led to a decrease of the yield of the char. The heating value of char increased with the increase of the reaction temperature, because the carbon content increased and hydrogen and oxygen content decreased. The yield of char decreased with increasing air ratio. This suggested that oxidation of EFB occurred during torrefaction in the presence of oxygen.

In this study, a cold model of a circulating fluidized bed is developed and tested for designing a char combustor. This study has been carried out to investigate effects of the solid circulation rate and superficial gas velocity on the hydrodynamic characteristics in a circulating fluidized bed. Solid holdup and pressure drop in the riser increases with the increase of solid circulation rate, but decreases with increasing superficial gas velocity. The solid holdup in the dense region increases with increasing solid circulation rate at lower gas velocities, whereas it is independent of solids circulation rate at higher gas velocities.

바이오매스에서 얻어지는 바이오차는 토질 개량제와 탄소 격리제로 제한적인 분야에서 성공적으로 사용되고 있다. 현재 산업전반에서 CO2 에 의한 환경에 부정적인 영향을 완화시키고 지속가능성을 증진시키기 위한 연구가 활발히 진행되고 있다. 이에 본 연구에서는 고탄소 바이오차를 탄소 격리제 또는 시멘트의 혼화재로써 활용 가능성을 평가하고자 하였다. 견목재에서 얻어진 바이오차를 혼화재로 사용하여 시멘트 배합조건을 달리하면서 모타르의 압축강도, 마이크로구조, 압축강도, 유동성, 중량감소와 같은 화학적, 물리적 재료성질을 평가하였다. 또한 플리이애쉬를 사용한 모르타르의 역학적 특성과 비교 평가하였다.