Numerical Simulation Analysis of Wind Conditions over a Rectangular Prism-Shaped Building for Mounting Small Wind Turbines.

Dr. Takaaki Kono (Japan)

Assistant Professor, Kanazawa University

IEC 61400-2 Ed.2 (2006) is an international standard regarding design requirements for small wind turbines (SWTs) that have a rotor-swept area smaller than 200 m² and generate at a voltage below 1000 V A/C or 1500V D/C. However, the wind conditions used in IEC 61400-2 Ed.2 do not cover complex turbulent flow fields such as those over buildings, which are usually accompanied by separation and reattachment of wind flows. Currently, the SWT market is growing rapidly and the number of installations of SWTs on the roofs of buildings is also increasing. Therefore, the formulation of standards or guidelines for installing wind turbines on the roofs of buildings is desired. However, the information on the wind condition a short distance from buildings’ roofs is highly limited; most research studies regarding the wind near buildings have focused on the pressure on the walls or the wind environment near the ground surface.

  This study investigated the wind conditions over a building from the viewpoint of mounting SWTs. Large-eddy simulations (LES) of the wind flow around a rectangular prism-shaped building, whose ratio of breadth, length, and height is 1:1:2, was performed. The LES results confirmed that above the vicinity of the building’s leading edge, wind power density is relatively large and velocity standard deviation is relatively small. It was also confirmed that the regions with higher values of standard deviation of the stream-wise wind velocity component that exceeds the value given by IEC61400-2 for the normal turbulence model are large.

Environmental constrains for sustainable development in the Beijing Metropolitan Area

Dr.Ying LONG*(China), Zhenjiang SHEN

*Beijing Institute of City Planning

The Beijing Metropolitan Area (BMA) with an area of 16,410 km² has witnessed significant urban expansion for decades. There are many environmental constraints (ECs) in the BMA, and they are geographically interacted with urban expansion. ECs can be classified into two clusters: natural resource protection (like the wetland, water resource protection, bio-diversity space protection) and disaster prevention (like flood control, geological disaster prevention, seismic prevention). Inappropriate urban expansion (e.g., urban sprawl) without considering ECs may create various negative impacts such as over-consumption of land resources, encroachment of eco spaces as well as potential hazard for neighborhood. On the contrary, appropriate urban form can provide a precondition for a sustainable city. Therefore, these ECs should be addressed in spatial plan for promoting sustainable development in Beijing. In this lecture, I would introduce how to conduct the urban containment planning of Beijing to combining all 60 ECs for containing future urban expansion in predefined spaces. Each EC has control indicators for land use type control, urban activity control, building height control, as well as underground development control. A planning support system was established for automatically compiling the Beijing urban containment plan considering all ECs with various control indicators. The compiled plan was also applied for reviewing urban master and district detail plans in Beijing.

Sewage Sludge Treatment in Kanazawa City

Shinichi Miyamoto(Japan)

Director, Manufacturing Indudtry Support Section,

Kanazawa City

Kanazawa city had drawn up a sewerage master plan in 1961, and started the sewerage service from 1962. Coverage area and population are 8,103 ha and 425,499, respectively, and sewered population ratio is 95.6% in 2010, which is relatively high ratio compared with the local city with a similar population. According to increase in the coverage ratio, sewerage sludge generation also increased. In fiscal 2010, the amount of produced dewatered sludge was 29,551 tons with 70,781,601 m³ of sewerage treatment.

To decrease sludge disposal and CO₂ emission, we started the several trails in the sewerage plants. In Seibu WWTP, which is located near a solid waste incineration plant, dewatered sludge is mixed with city waste and incinerated in the stoker furnaces with power generation (170t/day×2). In the other 3 main WWTPs (Saigawa-sagan, Johoku and Rinkai), in which 72% of sewered area are covered, methane gas is recovered by anaerobic digestion. Recovered gases are used for power generation in Sagawa-sagan WWTP, for sludge incineration in Johoku WWTP, and for city gas in Rinkai WWTP. In fiscal 2010, provided digestive gas to the city gas plant in Rinkai WWTP was covered with about 1% of total city gas, which is equivalent amount of gas usage in 1,840 households. The sale income of the gas in a year was about 23 million yen, and reduction of CO₂ emission was evaluated as 852t-CO₂/year. Dewatered digestive sludge produced in Saigawa-sagan and Rinkai WWTPs are transported to Johoku WWTP and incinerated. Flied ash was recycled as asphalt filler after pretreating by calcium and EDTA. Recycling ratio of sludge was about 3%.