Reuse of heat energy in wastewater: implementation examples in Japan

N. Funamizu; M. Iida; Y. Sakakura; T. Takakuwa

doi:10.2166/wst.2001.0640

Reuse of heat energy in wastewater: implementation examples in Japan

Water Science & Technology ◽

10.2166/wst.2001.0640 ◽

2001 ◽

Vol 43 (10) ◽

pp. 277-285 ◽

Cited By ~ 57

Author(s):

N. Funamizu ◽

M. Iida ◽

Y. Sakakura ◽

T. Takakuwa

Keyword(s):

Wastewater Reuse ◽

Heat Pumps ◽

Heat Energy ◽

Sewerage System ◽

Melting Snow ◽

Heat Transfer Efficiency ◽

Technical Developments ◽

Heating And Cooling ◽

Key Factor ◽

Large Heat

Sewage and treated water can be a heat source in urban area due to large heat capacity, thus recovery and reuse of its energy is one of the most desirable plans for the sewerage system. In this paper, characteristics of heat energy in wastewater, reuse plans, and some experiences in Japan are presented. Full-scale reuse projects for heating and cooling in the Tokyo Metropolitan Districts and project for melting snow in Sapporo City are discussed. The key factors found in experience of Tokyo were setting the heat pumps near the demand points and the technical developments of equipment to prevent system from clogging, corrosion, and decrease in the heat transfer efficiency. It was also found through the project for melting snow in Sapporo that the key factor in public acceptance was the multi-purpose use of the sewerage system both for melting snow in winter and retaining rain water in summer.

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Energy Recovery from Wastewater: A Study on Heating and Cooling of a Multipurpose Building with Sewage-Reclaimed Heat Energy

Sustainability ◽

10.3390/su12010116 ◽

2019 ◽

Vol 12 (1) ◽

pp. 116 ◽

Cited By ~ 3

Author(s):

Daniele Cecconet ◽

Jakub Raček ◽

Arianna Callegari ◽

Petr Hlavínek

Keyword(s):

Heat Exchangers ◽

Urban Areas ◽

Energy Recovery ◽

Heat Recovery ◽

Energy Requirement ◽

Heat Pumps ◽

Heat Energy ◽

Heating And Cooling ◽

Conventional Solution ◽

The Impact

To achieve technically-feasible and socially-desirable sustainable management of urban areas, new paradigms have been developed to enhance the sustainability of water and its resources in modern cities. Wastewater is no longer seen as a wasted resource, but rather, as a mining ground from which to obtain valuable chemicals and energy; for example, heat energy, which is often neglected, can be recovered from wastewater for different purposes. In this work, we analyze the design and application of energy recovery from wastewater for heating and cooling a building in Brno (Czech Republic) by means of heat exchangers and pumps. The temperature and the flow rate of the wastewater flowing in a sewer located in the proximity of the building were monitored for a one-year period, and the energy requirement for the building was calculated as 957 MWh per year. Two options were evaluated: heating and cooling using a conventional system (connected to the local grid), and heat recovery from wastewater using heat exchangers and coupled heat pumps. The analysis of the scenarios suggested that the solution based on heat recovery from wastewater was more feasible, showing a 59% decrease in energy consumption compared to the conventional solution (respectively, 259,151 kWh and 620,475 kWh per year). The impact of heat recovery from wastewater on the kinetics of the wastewater resource recovery facility was evaluated, showing a negligible impact in both summer (increase of 0.045 °C) and winter conditions (decrease of 0.056 °C).

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Utilizing Asphalt Heat Energy in Finnish Climate Conditions

Energies ◽

10.3390/en12112101 ◽

2019 ◽

Vol 12 (11) ◽

pp. 2101 ◽

Cited By ~ 1

Author(s):

Anne Mäkiranta ◽

Erkki Hiltunen

Keyword(s):

Renewable Energy ◽

Temperature Difference ◽

Heat Pumps ◽

Heat Energy ◽

Distributed Temperature Sensing ◽

Frozen Ground ◽

Climate Conditions ◽

Difference Curve ◽

Heating And Cooling ◽

The Difference

Geothermal energy is a form of renewable energy, which offers carbon-free solutions for heating and cooling spaces. This study evaluates the use of renewable asphalt heat energy in frozen ground conditions. Asphalt heat energy can be harnessed using a low-energy network, heat collection pipes and heat pumps. This study measured temperatures under the asphalt layer during a three-year period between 2014 and 2017. Measurements were made using a distributed temperature sensing method based on light scattering. Temperatures taken at four different depths under the asphalt (0.5 m, 1.0 m, 3.0 m and 10 m) are presented here. These temperatures are compared with that detected at the depth at which the temperature remains constant all year round. The temperature difference curve between 0.5 m depth and the constant soil temperature depth indicates that from April to October the soil at 0.5 m depth is warming and the temperature difference is positive, even as much as 18 °C. Instead, at the 3.0 m depth, the difference curve is smoother and it varies only from −5 to +5 °C. It is positive from June to November. The surface layer (0 m–1.0 m) is suitable for harvesting heat that can be stored in a deeper (1.5 m–3.0 m) purpose-built storage or in a bedrock heat battery. The calculated heat capacities indicate that asphalt energy, because of high temperatures, is a noteworthy renewable energy source.

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