The ex-president was a pioneer on renewable energy and land conservation but his 1980 defeat was a ‘fork in the road’

When a group of dignitaries and journalists made a rare foray to the roof of the White House, Jimmy Carter had something to show them: 32 solar water-heating panels.

“A generation from now,” the US president declared, “this solar heater can either be a curiosity, a museum piece, an example of a road not taken, or it can be just a small part of one of the greatest and most exciting adventures ever undertaken by the American people.”