The three-dimensional (3-D) Cauchy condition surface (CCS) method code, 'CCS3D', is now under development to reconstruct the 3-D magnetic field profile outside a non-axisymmetric fusion plasma using only magnetic sensor signals. A new "twisted CCS" has been introduced, whose elliptic cross section rotates with the variation in plasma geometry in the toroidal direction of a helical type device. Independent of the toroidal angle, this CCS can be placed at a certain distance from the last closed magnetic surface (LCMS). With this new CCS, it is found through test calculations for the Large Helical Device that the numerical accuracy in the reconstructed field has been improved. Further, the magnetic field line tracing indicates the LCMS more precisely than with the use of the axisymmetric CCS. A new idea to determine the LCMS numerically has also been proposed.

A combined heat and power (CHP), sometimes called as cogeneration, is generally independently installed into buildings without networked to the power grid, but unbalanced heat/electricity ratio of the CHP output and the demand significantly limits CHP's performance. This study investigates the effect of the networked CHP system to the power grid on CO2 reduction and cost. The networking concept of CHPs is that CHPs are installed to buildings with large heat demand, and excessive electricity is consumed in buildings in the network via power grid. The analysis was applied for a model area in Sapporo, which is an urban residential area covered by electric feeders from a distributing power substation. The results show that the networked CHP system can reduce CO2 significantly compared to the non-networked system with the same cost. This is due to the fact that CHPs can be operated for the heat demand without limited by the electricity demand of the building by the networking, and their capacities of the system can be utilized effectively. Therefore, the maximum CO2 reduction extent is also increased. These results indicate the significance of the networking concept. Sensitivity analysis of the results for the unit costs and CO2 emission factors of the grid power was also made, and the networking effect was confirmed for various conditions. The paper also investigates the suitable type of CHPs installed to households, showing that fuel cell can reduce larger amount of CO2 than gas engine with the networking condition.

A combined heat and power (CHP), sometimes called cogeneration, is one of the effective technologies for reducing CO2 emission. In the previous research, the authors proposed a concept of "Networked CHP system", which allows surplus electricity of CHP to be reversed to the power grid and to consume it effectively in the network. Result of the analysis clarified significant CO2 reduction with minimum social cost compared to the non-networked system. The social cost is the amount supplying energy to the area, and it is different from the benefit of individual customer. Customers select the capacity and operation of CHP to have the minimum cost for them, and it is mostly different from the social optimum. This paper analyzes the conditions of energy prices to direct customer selection to the social optimum for cost and CO2 reduction. The results of the analysis show that the electricity/gas price ratio normalized by CO2 emission factor should be unity, and the sell/buy ratio of electricity between the grid for the customer should be larger than 0.6. As an example of measures to keep the profit of electric company for increasing CHP, FIT price of about 1% is enough to be added on the electricity and gas prices. To make customers to select the optimum capacity of the CHP, clear guideline of the optimum kW for unit floor area should be indicated and the CHP price should be in the acceptable range for customers; this is due to the fact that effective subsidy for CHP selection is hardly determined, as the minimum cost for customers does not vary much for the capacity of the CHP.

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In the previous research, the authors proposed a concept of "Networked CHP system", which allows surplus electricity of CHP to be reversed to the power grid and to consume it effectively in the network. Result of the analysis clarified significant CO2 reduction with minimum social cost compared to the non-networked system. This paper analyzes the conditions of energy prices to match customer selection to the social optimum. The results show that the electricity and gas prices normalized by CO2 emission factor should be identical, and the (reverse power)/electricity price ratio should be larger than 0.6. To keep the profit of electric company same as the conventional level before CHP introduction, it is enough to support electric company by FIT with adding very small amount of price on the electricity and gas.