Alonso struggled with traffic and the timing of his final lap in the opening stage of qualifying on Saturday in Barcelona, causing him to finish a lowly 17th and drop out in Q1.
Ahead of Sunday’s race, FIA technical delegate Jo Bauer confirmed that Alpine had opted to fit Alonso’s car with a complete new set of power unit elements, taking him over the season limit.
As a result, it triggers a penalty that means he will start the race from the very back of the grid for his home race in Spain on Sunday.
Alonso’s power unit will feature a fourth engine, turbocharger, MGU-H and MGU-K, all going over the season limit of three. A third energy store and control electronics is also over the limit of two parts permitted for the year.
The penalty for Alonso lifts Lance Stroll, Alex Albon and Nicholas Latifi each up one position for the start.
Even before his engine change Alonso believed that only a “mega fantastic safety car” would allow him to make progress after stranding in 17th during a frustrating qualifying session.
“I think there is not much you can do," he said. "This is Barcelona, not much overtaking, a lot of tyre degradation when you run behind cars. So let's see.
“The last couple of races people starting at the back they got very lucky, and they scored points. I'm one of those tomorrow.
“So if I have one of those mega fantastic safety cars in the right moment maybe I get lucky, and I take couple of points, but I doubt it. I think it's going to be a difficult race.”
This weekend has been the latest setback for Alonso through a difficult start to the season that has seen him score just two points in the opening five races.
Alonso has claimed that he is in his most competitive position since 2012 with Alpine, but has been left frustrated by factors out of his control, such as decisions by the FIA stewards who he called out for “incompetence” after a post-race penalty in Miami.
