2021-05-04 石炭で脱炭素 www.google.com www3.nhk.or.jp www.google.com https://scholar.google.co.jp/scholar?q=%E7%9F%B3%E7%82%AD%E3%81%A7%E8%84%B1%E7%82%AD%E7%B4%A0&hl=ja&as_sdt=0&as_vis=1&oi=scholart