Cesium-Catalyzed Hydrogen Production by the Gasification of Woody Biomass for Forest Decontamination.

The large quantities of contaminated wood produced following the radioactive cesium decontamination of forests after the Fukushima Daiichi Nuclear Power Plant accident in 2011 can be used as a biomass resource for energy production via thermal treatment (e.g., gasification). To store the radioactive Cs ash produced from gasification, the immobilization of Cs in the pollucite structure is possible and requires stable Cs additives. In this study, a Cs additive (Cs2CO3, CsCl, CsNO3, or Cs2SO4) was doped with timber waste sawdust (1-30 wt %). Fixed-bed downdraft-type continuous steam gasification experiments (0.7 g/min) showed that Cs2CO3 enhanced H2 production by 157% at 800 °C. X-ray absorption fine structure analysis and scanning electron microscopy observations revealed that the form of Cs on the surface of the char was Cs2CO3, which provided the active sites for gasification acceleration. Thermogravimetric pyrolysis and CO2 gasification experiments showed that Cs2CO3 lowered the activation energy and frequency factor while also enhancing the reactivity.

Use of thermal treatment with CaCl2 and CaO to remove 137Cs in the soil collected from the area near the Fukushima Daiichi Nuclear Power Plant.

A massive amount of soils and inflammable materials of plants etc. contaminated by radiocesium are generated from decontamination work in the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident affected area. In present study, the removal experiments of 137Cs in a soil collected from the FDNPP accident affected area were carried out in a lab-scale electrical heating horizontal furnace through thermal treatment with CaCl2 addition over a temperature of 900 - 1300 °C. The results indicated that the average radioactive concentration of 137Cs in the soil was 52.8 Bq/g. The removal ratio of 137Cs in the soil treated at 1300 °C was 96.3 % when 20 % CaCl2 was added. The addition of CaCl2 and CaO mixture exhibited a synergistic effect on the removal of 137Cs, relative to the addition of CaCl2 alone. Accordingly, the addition of CaCl2 or its mixture with CaO during thermal treatment is suggested to remove 137Cs in the soil collected from the FDNPP accident affected area. Additionally, segregation of the soil sample to fine and coarse fraction and then treated individually are also recommended.

Pressurised gasification of wet ethanol fermentation residue for synthesis gas production.

Pressurised steam gasification of wet biomass in a fixed-bed downdraft gasifier was implemented to identify reaction conditions yielding the highest synthesis gas concentration and efficiency, and to examine the generation of sulphur compounds. The gasification of lignin-rich fermentation residue derived from a bench-plant for bioethanol production from woody biomass was investigated at p=0.99MPa and T=750-900°C for steam to biomass ratios (S/B) of 3.4-17 and equivalence ratios (φ) of 3.3-∞. The results showed that the highest concentration of around 70mol% was obtained at T⩾850°C, φ=13 and S/B=3.4, the highest efficiency of 0.26 was obtained at T=900°C, φ=3.3 and S/B=3.4, and sulphur compounds were H2S and COS. For the production of BTL synthesis gas, pressurised gasification has the potential to convert the wet residue below 77.3wt.% moisture contents.