The EU has been very aggressive in preventing global warming. It has set its own goal above and beyond the agreement according to COP3, and is promoting the use of renewable energies including biomass. The preceding article reports on the European marketplace, its background, current situation, scope, future prospects and tasks.
It seems that European society looks back with certain amount of self-recrimination into the history of materialistic prosperity it created, and is considering improving its legacy of the global environment onto the next generation.
We have developed a gasification system for the purpose of achieving high efficiency energy conversion of biomass energy. This system is compatible with various fuels, and is equipped with a circulating fluidized bed that excels in mixing and temperature control. Gasification is accomplished at 800~900°C by air. It is characterized by its ability to produce gas that is free of ash and tar by means of high-temperature filtration using ceramic filter and tar-disintegration by catalyst. In order to evaluate its gasification performance, tar characteristics and system dependability, a pilot plant with the thermal input of 100kWth was built, and the gasification test of wood chips has been conducted in it.
The test results have shown the carbon conversion rate of roughly 95%, the cold gas efficiency of approximately 65% and the gas heating value of 3.5~4.5MJ/m3N, while confirming its capability of stable operation.
Since August 2003, a demonstration test called "Kyoto Model" has been conducted in Kyoto in which biodegradable fish trays are recycled. It aims to establish a system in which fish trays made of polylactide-based plastics are collected after being used in the Kyoto Central Wholesale Market, and converted into biogas together with vegetable scraps, producing biomass-based carbon-neutral energy.
First, we confirmed through a lab test that foamed polylactide-based plastics could be degraded into biogas by the thermophilic methane fermentation process in 30~40 days. In a demonstration test at a pilot plant that followed, it has been proven that the fish trays made of this material can be recycled as energy together with the garbage (vegetable scraps) through this process, with little plastics material remaining in the residue. Except shredding, the fish tray requires no special pretreatment such as solubilization.
In 1999, the Law on Appropriate Treatment and Optimization of Livestock Manure was enacted, setting standards for the facilities and methods of treating livestock manure. Furthermore, the utilization of waste biomass such as livestock waste and food waste has been promoted by the "Biomass Nippon Strategy" established in 2002. With this background, the methane fermentation that can make energy from livestock manure is attracting interest. In the preceding article, we report on a low-cost model plant of the methane fermentation system installed in 2002 at a pig farm for the treatment of the pig manure, using the process developed by the Institute of Environmental Technology for the Livestock Industry.
While a water reclamation facility is indispensable for improving people's lifestyle and maintaining the public water body, proper treatment of the odor it emits during the processes must be assured.
The preceding article reports on the characteristics of the plasma deodorizing system developed jointly by the Sewerage Bureau of the Tokyo Metropolitan Government and ourselves specifically for deodorizing sewage treatment facilities, along with the operational results of a working unit installed in one of the water reclamation centers of the aforementioned Sewerage Bureau, located at Sunamachi.
For the purpose of detoxifying and bulk-reducing combustion residues, we first developed, designed and built surface melting furnaces, followed later by the same steps taken with the plasma melting furnaces. As of this writing, there are three plasma-melting furnaces in operation that we have built, while two more units are at the testing stages, and one more is at the design stage.
The preceding article reports on the operating conditions and the continuous operation results of the three operating plants that have been running for more than two years, including the reuse situation of the molten slag and molten metals.
The report covers the typical problems we have encountered since the start of the commercial operations, and the examples of the solutions, while listing the tasks we must perform in order to improve the plasma melting system.