Since the earthquake and tsunami on 11 March 2011 and the resulting power shortage due to a number of power plants being offline, prefectures around Tokyo and in the Northeast that were the hardest hit by the disaster, have to deal with imposed power outages. In consequence, industry, commercial sectors, and households need to deal with three hours per day without neither electricity nor, in most cases, hot water.
However, households at least are not entirely cut off from hot water supply. Six major Eco Cute manufacturers (Corona Corporation, Daikin, Toshiba-Carrier, Panasonic, Hitachi, Mitsubishi) have published information on their websites, about which features of their CO2 heat pumps work without electricity.
Whether hot water can be supplied even during the black-out seems rather to depend on the Eco Cute model than on the manufacturer. Most of the Eco Cutes hold the set temperature from before the power outage in their tanks and hot water can be released via manual emergency controls. Additional features such as automatic fill-stop, temperature regulation in the bathtub etc. however do not work.
Access to the hot water in the tank is only possible for domestic heat pumps. Commercial-size Eco Cute in apartment buildings for example cannot supply hot water to the single apartments without electricity.
CO2 heat pump for €7,350
Sales of Toshiba-Carrier's CO2 version of the ESTIA heat pump for the residential market started in Japan at the end of March. The ESTIA “over-slim type” as it is called in Japan (ESTIA HWH-FB371WC) has a 370l tank and is designed for 2-5 people households. The selling price is around ¥895,650 (~ €7,350).
The ESTIA series is a high-pressure hot-water supply system equipped with a silver-ion generation system. Silver ions are eluted when filling the bathtub with hot water, to keep the bathwater clean.
Eco Cute to reduce carbon footprint of households
All-electric houses featuring i.a. Eco Cute are being promoted in Japan for their substantial contribution to reducing the carbon footprint of household. The carbon emission savings can be further optimised by combining the Eco Cute system with solar electricity generation.
The Japanese housing and immobility company Misawa Home says that the number of houses combining Eco Cute, solar power and the home fuel cell Ene Farm that they are planning to sell over the next year will allow to save a total of 1,400t of CO2 emissions.