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[1] Dissolved methane (DM) concentrations were measured in 17 lakes as part of the operations of the 45th Japanese Antarctic Research Expedition in ice-free rocky areas along the eastern coast of Lutzow-Holm Bay (Syowa Oasis) in East Antarctica in the summer of 2003–2004. DM at the surfaces of 14 lakes ranged from the atmospheric equilibrium concentration (about 4 nmol L−1 for freshwater) to 385 nmol L−1. Relatively low DM of less than 50 nmol L−1 were observed in about 60% of the lakes. Many of the lakes (area fraction of 85%) were supersaturated and are thus sources of methane to the atmosphere. The exchange coefficient was calculated using wind speed data at Syowa Station. Area fraction frequency distributions with four surface DM ranges were applied to all lakes at Syowa Oasis (110 lakes, total lake area of 9 km2). Extrapolation to the whole Syowa Oasis gives an estimate of total emission of about 1 t CH4 yr−1. This is the first estimation of methane flux from the surfaces of thawed lakes to the atmosphere in Antarctica. Since a methane efflux of about 2 t CH4 yr−1 was estimated in our previous study from frozen bubbles in lake ice, a total amount of 3 t CH4 yr−1 would be released to the atmosphere from the lakes during the ice melting season (December–January) at Syowa Oasis.

An actual renewable energy house, equipped with a geothermal heat pump (GHP)-powered floor heating system was investigated and analyzed. Daily annual monitoring between February 2005 ~ February 2006 and real-time continuous system monitoring within selected periods during the winter season between November 2006 ~ January 2007, were carried out in order to establish the actual performance of the system. It emerged that the GHP-powered floor heating system is sufficient for space heating, with the maintenance of near-uniform room temperatures even during the coldest days in a very cold region like Hokkaido, Japan. About 37% average of the floor heat losses are recoverable and more than 50% of the ventilation heat losses are recovered due to various innovative energy-saving techniques built into the system. Annual heat loss from the house estimated by the numerical simulation showed good agreement with the measured annual thermal demand for room heating. The simulation also estimated that annual running costs and Green House Gas (GHG) emissions reductions of 47% and 49% respectively, can be realized with this system compared to an equivalent conventional system. A detailed cost analysis for the GHP-only system revealed that if the cost of fuel oil increases by about 50% from the current value of \80/L, then the payback period for a GHP-powered renewable energy system is about 14 years. This payback period reduces to about 10 years if 30% of the initial cost of the GHP-powered system is externally funded., application/pdf

A simplified double grade meteorological data model for the simulation of the annual performance of a domestic-size renewable energy system is proposed. With the model, only two representative days (clearest and cloudiest) during each season of the year are necessary to estimate annual energy balances, carbon emissions and the running costs. The model was chosen in preference to other simplified models based on the error distributions from the results of the continuous simulations in a test period. Detailed numerical simulation studies show that the carbon emissions from the renewable energy system are about 16% of a comparable conventional system. The thermal energy produced by a solar collector during the winter season, however, is insufficient to meet all the loads so that frequent heat pump operations and the auxiliary boiler are necessary in cold climate regions., application/pdf

Five different kinds of domestic-size renewable energy system configurations for very cold climate regions were investigated. From detailed numerical modeling and system simulations, it was found that the consumption of fuel oil for the auxiliary boiler in residential-type households can almost be eliminated with a renewable energy system that incorporates photovoltaic panel arrays for electricity generation and two storage tanks: a well-insulated electric water storage tank that services the hot water loads, and a compact boiler/geothermal heat pump tank for room heating during very cold seasons. A reduction of Greenhouse Gas Emissions (GHG) of about 28% was achieved for this system compared to an equivalent conventional system. The near elimination of the use of fuel oil in this system makes it very promising for very cold climate regions in terms of energy savings because the running cost is not so dependent on the unstable nature of global oil prices., application/pdf

We report measurements of the spectral transmittance and calculations of the total transmittance of magnesium chloride-water solution to be used as the working fluid for a solar pond. The spectral transmittance of MgCl2-water solution in the visible, infrared and nearby regions decreases with increasing salt concentration. The total transmittance of MgCl2-water solution can be calculated using an exact integration method and a simple 5-band partition method over a 3 m depth of pond water. The simple method is useful in practice to calculate the total transmittance for a conventional solar pond, because the rate of difference between the results calculated by the two methods is less than 10% at shallow depths and then it decreases rapidly being followed by 0% at a depth of 3 m. Furthermore, the absorption coefficient calculated from the spectral transmittance of the present work is compared with that from Usmanov's data as shown in references (6) and (7).

We describe the measurements of spectral transmittance and the calculations of the total transmittance for sodium chloride and potassium chloride water solutions. The spectral transmittance of NaCl and KCl water solutions over the infrared and nearby regions increases with increasing salinity. In the visible region, the spectral transmittance of NaCl w-s increases slightly, while that of KCl w-s decreases with increasing salinity. The total transmittance of the two salt water solutions can also be calculated by means of an integral method and a simple 5-partition method over 0∼3 m water depth. The simple method is of practical use to calculate the total transmittance for a conventional solar pond, because the rate of error between the two methods is about 10% at shallow depth and 0% at 3 m depth.

The transmission properties of water and sodium chloride water solutions with various salt concentrations were investigated. This paper concerns the measurement of the spectral transmittance and the calculation of the total transmittance for water and NaCl water solutions. The spectral transmittance of the NaCl water solutions over the infrared and nearby regions increased with increasing salt concentration for constant specimen thickness and air mass. The spectral transmittance was found to be useful for precisely calculating the thermal performance of a solar pond, and by using an effective absorption coefficient, a five-partition method dividing the wavelengths into five bands by which the total transmittance up to a water depth of 3 m could be calculated, was found to be important as a practical method of solar pond technology. © 1997 Scripta Technica, Inc. Heat Trans Jpn Res, 26(1): 1–15, 1997

The transmission property of water and sodium chloride-water solutions with various salinity concentrations was clarified using spectra. This paper deals with the measurement of the spectral transmittance and the calculation of the total transmittance for water and NaCl-water solutions. The spectral transmittance of the NaCl-water solution over the infrared and nearby regions increased with increasing salinity concentration for constant specimen thickness and air mass. It was found that the spectral transmittance was useful for precisely calculating of the thermal performance of a solar pond, and by using an effective absorption coefficient, a 5-partition method dividing wavelength into five bands by which the total transmittance up to a water depth of 3m could be calculated, was found to be important practical example of solar pond technology.

Dissolved methane concentrations (DM) at twelve major lakes in Hokkaido, the northernmost island in Japan were observed in the open water season during 2006 ~ 2009 to estimate diffusive flux from lake surfaces to the atmosphere. An inverse relationship between lake size and DM was obtained in lakes in Hokkaido as was found for the European boreal lakes. All lake images larger than 0.001 km2 were obtained by image processing of map data and area and number distributions were analyzed in order to calculate mass fluxes of diffusive methane. Total area of all (1,269) lakes in Hokkaido is 809 km2. Regional diffusive flux of methane from lakes to the atmosphere in Hokkaido was estimated to be 0.581 Gg CH4 yr–1. Average diffusive flux density (per lake area) was about 0.718 g CH4 m–2 yr–1. This is a similar value to that in European boreal lakes on no-permafrost inland areas. Extremely high flux was found in Lake Abashiri-ko, one of highly eutrophic, meromictic lakes.