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Bamboo-based Co-generation System Built in Kumamoto

2019/09/07 23:06
Sousuke Kudou, technical writer
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The biomass combustion furnace (source: Bamboo Energy, NEDO)
The ORC co-generation facilities

Bamboo Energy Co Ltd (Nankan-machi, Kumamoto Prefecture) announced Aug 29, 2019, that it has built a co-generation system using bamboo on land owned by the Bamboo group in Nankan-machi, Kumamoto Prefecture, Japan.

Bamboo Energy will carry out a trial operation, planning to start the verification of the operation of the system in earnest in October 2019. For the system, the company employed the "ORC (Organic Rankine Cycle)" using bamboo for the first time in Japan.

New Energy and Industrial Technology Development Organization (NEDO) is promoting projects for introducing biomass that coexists with local communities, and Bamboo Energy's project is one of them. In the project, the company was examining the possibility of realizing a local stand-alone system using the cascading of a biomass-based co-generation system set up at a bamboo processing plant.

As raw materials, the new system will use (1) bamboo, whose decay and preservation are becoming issues in various regions of Japan, and (2) bark, whose effective use is becoming an issue. The system will generate heat and electricity with a biomass combustion furnace and ORC co-generation facilities and make full use of them at an adjacent plant that processes products using bamboo.

The new system will use about 8,750t of bamboo per year, and its electric output and thermal output are 995kW and 6,795kW (heat-transfer oil supplied to the bamboo processing plant: 2,800kW, hot water supply: 3,995kW), respectively.

In general, when bamboo is being combusted, its ash is melted at low temperatures and forms clinker, potentially damaging the combustion furnace. The new system combusts bamboo and bark at the same time at ratios of 30% and 70%, respectively, and optimizes combustion temperature and operation mode in the aim of preventing the generation of clinker, which is the largest issue of the combustion of bamboo.

Also, by employing the ORC co-generation method, Bamboo Energy reduced facility cost by about ¥200 million (approx US$1.87 million), compared with a co-generation method using a normal steam turbine.