First Author:   Akihiro Otsuka Socio-Economic Research Center, Central Research Institute of Electric Power Industry akihiro@criepi.denken.or.jp   2-11-1, Iwado Kita, Komae-shi Tokyo, 201-8511, Japan   +81 3-3480-2111(Phone) +81 3-3480-2111(Fax) http://criepi.denken.or.jp/en/