 Pernick and Wilder present examples which show that the " clean tech revolution " is already under way . Very large corporations such as GE , Toyota and Sharp , and investment firms such as Goldman Sachs are making multibillion @-@ dollar investments in clean technology . Emerging clean tech cities are seen to include Copenhagen , where wind power generates 20 percent of Denmark 's electricity , and Chicago , a leader in " green " buildings saving energy , heating and cooling costs . Statistics from the U.S. and from abroad , especially from China , India , Brazil , and Europe are presented . 
 Pernick and Wilder present examples which show that the " clean tech revolution " is already under way . Very large corporations such as GE , Toyota and Sharp , and investment firms such as Goldman Sachs are making multibillion @-@ dollar investments in clean technology . Emerging clean tech cities are seen to include Copenhagen , where wind power <a href='uninflect' title='1'><mark>generates</mark></a> 20 percent of Denmark <a href='null_genetive' title='2'><mark>'s</mark></a>electricity , and Chicago , a leader in " green " buildings saving energy , heating and cooling costs . Statistics from the U.S. and from abroad , especially from China , India , Brazil , and Europe are presented . 
Pernick and Wilder present examples which show dat the " clean tech revolution " is already under way . Very large corporations such as GE , Toyota and Sharp , and investment firms such as Goldman Sachs r wit multibillion @-@ dollar investments in clean technology . Emerging clean tech cities arreen to include Copenhagen , where wind power generate 20 percent of Denmark  electricity , and Chicago , a leader in " green " buildings saving energy , heating and cooling costs . Statistics from the U.S. and from abroad , especially from China , India , Brazil , and Europe are presented .