A STUDY ON THE AMOUNT OF RENEWABLE ENERGY SUPPLIED BY HEAT PUMP

A rough estimate of the amount of renewable energy from air-source heat based on the EU guideline

Abstract

 In 2009, the natural heat such as air-source heat was defined as renewable energy. However, there exists no quantitative method for evaluating the amount of renewable energy supplied by heat pumps from heat collected from the air, and the actual performance of heat pumps are therefore unknown. In the present study, we investigated a method to estimate the renewable-energy-based heat from air supplied by a heat pump in Japan. This method is based on the quantitative evaluation method by the EU. And we estimated it roughly.

 

 With the aim of introducing aerothermal, hydrothermal, and geothermal energies as renewable resources, the EU defines the Guideline for the calculation method of the amount of renewable energy supplied by a heat pump. It represents renewable aerothermal, hydrothermal and geothermal energies captured by the heat pump, which is the amount of heat supplied by the heat pump minus the input energy of the heat pump.

 

 Although the EU defines the statistics of the heat pump output and default SPF values, this is not the case in Japan. Therefore, in the present study, these values were estimated using statistical data from the government and various organizations. The analytical targets considered in the civil sector (such as offices, hotels, commercial buildings, and hospitals) were air-source heat pumps for central air-conditioning, electric heat pumps for individual air-conditioning, and heat pump water heaters. The analytical targets considered in the civil sector (residential buildings) were room air-conditioners and heat pump water heaters. In the industrial sector, the targets considered were air-source heat pumps for factory heating. The target considered in the agricultural sector was heating for greenhouses (housing 10 varieties of vegetables, 16 varieties of fruits, and five varieties of ornamental plants).

 

 We investigated the method used to estimate the amount of renewable energy supplied by air-source heat pumps based on the quantitative evaluation method of the EU. Upon making estimates based on data from 2013, we obtained the following findings:

 1) Although the EU has statistics and default values prepared for quantitative evaluation, Japan does not have such information. Thus, we proposed a macro-level estimation method that uses the statistical data from the government and various organizations. Specifically, we calculated the SPF and Q_usable values for each department, each building application, and each heat use application according to the approximate procedure shown in the flow charts (Fig. 2-8). Then we arranged each value as shown in Table 18-(a), (b). And by using these SPF and Q_usable, we estimated the amount of renewable energy supplied by the heat pump.

 2) The renewable energy supplied by air-source heat pumps was 75.5 PJ/year for non-residential buildings in the civil sector, 328.1 PJ/year for residential buildings in the civil sector, 35.7 PJ/year in the industrial sector, and 0.09 PJ/year in the agricultural sector, resulting in a total of 439.4 PJ/year. The renewable energy supplied by the air-source heat pumps was equivalent to approximately 36.1% of the renewable energy with an existing track record, such as solar power (1,216 PJ/year).