Fernando Alonso says Renault has "everything they need" to succeed in the future.

After a two-year sabbatical, the double world champion is returning to Formula 1 next year as Renault becomes Alpine. He got down to work at Renault's Enstone (UK) and Viry (France) factories last week.

"These were days that were full of emotions," Alonso, 39, is quoted by Corriere dello Sport.

"Many things have changed. The simulator is new, the wind tunnel has been updated, but certain things have remained the same - the offices, the gym.

"It was a bit like the first day of school, with so many things to learn and information to digest, but it was extremely productive," the Spaniard added.

"I followed a program in the simulator, got a little bit used to the car, tested the systems. The last time I was here the simulator didn't exist yet.

"I then fitted the seat before meetings with the key people to understand next year's program."

It is expected that Alonso will get some actual running in the coming weeks, including with Renault's two-year-old car and perhaps in the post-Abu Dhabi test.

He says he is upbeat about Alpine's chances for 2021 and beyond.

"I believe the team has everything they need for the future. The last few races have been encouraging for everyone, including me. Seeing Renault competitive again is good for the sport and I am happy to see this progress," said Alonso.

"The road is still long and the middle of the standings is extremely tight, but I think they have done an incredible job on the track.

"Now I will do everything the team expects of me - days in the simulator, give my help on certain weekends and be available for whatever the team needs," he added.