成果報告書詳細
管理番号20160000000431
タイトル*平成27年度中間年報 地熱発電技術研究開発 地熱発電の導入拡大に資する革新的技術開発 地熱発電適用地域拡大のためのハイブリッド熱源高効率発電技術の開発
公開日2016/7/13
報告書年度2015 - 2015
委託先名一般財団法人電力中央研究所 国立大学法人富山大学
プロジェクト番号P13009
部署名新エネルギー部
和文要約
英文要約Title: Research and Development of Geothermal Power Generation Technology, Innovative Technology Development for Promotion of Introduction of Geothermal Power Plant, Development of Hybrid Geothermal Power Plant Combined with other thermal energy sources (FY2013-FY2017) FY2015 Annual Report

-Feasibility estimate of hybrid geothermal power plant (hybrid GPP)
We have developed highly efficient hybrid GPP combined with other thermal energy sources, which are biomass, solar thermal energy, or exhaust heat from fuel cells, and so on. It is expected that the thermal efficiencies of these systems are improved by superheating the main steam through the use of the other energy sources. We have looked into the system feasibility of these hybrid GPPs in the light of the engineering, economic performance, environmental laws and regulations. Our results are followings.
-- Hybrid GPP achieves a high thermal efficiency of more than 20% HHV as geothermal power generation system.
-- Hybrid GPP combined with biomass has greater feasibility than other external energy sources.
-- Hybrid GPP is suitable for the small and medium size scale facilities. In a case of three megawatts GPP, it is expected a 25% increase in power output.
-- Net thermal efficiency of biomass in hybrid GPP is improved to 22% HHV by our estimate. It is greater than that of biomass power generation system which is the same as one megawatt of power generation capacity.
-- Depending on the type of biomass, such as wood pellets, wood chips and thinning residues, the COEs (Cost of electricity) are estimated to 24 yen/kWh, 20.5 yen/kWh and 39.7 yen/kWh, respectively.
-- A steam super-heater of hybrid GPP with biomass doesn't have critical technical problem.

-Development of a fiber optic sensor for scale formation
Field tests of the effect of precipitated carbonate and silica scales on the transmittance response of fiber optic sensors (scale sensor) were performed at Matsushiro, Nagano and Sumikawa, Akita, respectively.
At Sumikawa, the silica precipitation can be continuously monitored within 1 day by using the scale sensors with a sensing region of 8 to 24 cm. The drastic change of the transmittance was observed within 6 hours due to the silica scale precipitation on the fiber surface from geothermal brine. This indicates that the fiber optic sensor is applicable for monitoring silica scale formation. Also, some scale inhibitors had been tested to prohibit silica scaling from geothermal brines. From the obtained results, it was clarified that the proposed sensor can be successfully used to evaluate one of the inhibitors which reduce the precipitation rate. This new scale monitoring system enables the selection of a suitable inhibitor for silica scaling.
At Matsushiro, carbonate scaling rate was measured with scale sensors. The results showed that the fiber transmittance decreased exponentially within 2 days. The carbonate precipitation rates were measured to be ca. 10^(-9) mol/cm2/sec as similar to the reported values.
In laboratory, the change of transmittance responses of four fiber optic sensors were simultaneously monitored for 120 minutes in individual carbonate solutions. This results show that the scale sensors can be applied multiply to monitor of scale precipitation rates.
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