Ten avoid execution – but only for now

better production than noble metals,’’ he said. ‘‘It is 20 to 30 times cheaper, too. We’re talking about an improvement of 20-30,000 times.’’

He anticipates that the research, also reported in Science, can be used in conjunction with conventional power plants to make a fuel ‘‘loop’’.

‘‘I envisage having a small solar farm next to a chemical and power plant, taking carbon dioxide out of the stream, injecting it into the leaf and producing fuels. If you make a loop of this, it could be very efficient’’.

Nocera said that whichever technique proved best, the research was now at a level that no serious technical impediments remained, and all that was needed was the investment to scale it up into a usable product. Human rights groups are calling on Indonesia to halt further executions immediately, after four people faced the firing squad overnight and another 10 were granted a last-minute reprieve.

‘‘The injustice already done cannot be reversed, but there is still hope that it won’t be compounded,’’ Rafendi Djamin, Amnesty International’s director for South East Asia and the Pacific, said.

Amid heavy rain, Indonesian man Freddy Budiman, and Nigerians Seck Osmane, Michael Titus Igweh and Humphrey Jefferson Ejike Eleweke were shot by a firing squad at the notorious Nusakambangan island prison.

Another 10, including Indonesian woman Merry Utami, who were also listed to face the death penalty, were not executed for reasons yet unknown.

But Noor Rachmad from the Attorney General Office said they would face the death penalty at a later date.

The prison island in Central Java known as the Alcatraz of Indonesia is the same place where Australians Andrew Chan and Myuran Sukumaran were executed, along with six others, in April last year.

Had all 14 people been executed overnight, the former lawyer for the Australian men and anti-death penalty advocate Dr Todung Mulya Lubis said it would have been the largest mass execution in Indonesian history.

Australian barrister Julian McMahon, who also represented Chan and Sukumaran, tweeted: ‘‘After 15 months of govt hype, today 4 out of 14 were shot in Indonesia. 10 were very suddenly ‘not shot’. The whole sad circus is shameful.’’

Australian artist Ben Quilty, a friend of the two dead Australians, lashed out at Indonesian President Joko Widodo, tweeting: ‘‘There is a swathe of violence across the planet. You jokowi are driving indonesia backwards.’’

Community legal aid organisation LBH Masyarakat also took to the social media platform, expressing its deep sadness.

‘‘We lost another client, another friend: Humphrey Jefferson. Another dark day for us . . . very dark.’’