The United Arab Emirates’ first nuclear power plant began commercial operations on Tuesday, the Gulf Arab state’s leaders said on Twitter.

The Barakah nuclear power plant in the Abu Dhabi emirate is the first nuclear power station in the Arab world and part of the oil producing state’s efforts to diversify its energy mix.

Vice President Sheikh Mohammed bin Rashid al-Maktoum wrote on Twitter that “the first megawatt from the first Arab nuclear plant has entered the national power grid.”

De facto ruler Abu Dhabi Crown Prince Mohammed bin Zayed al-Nahyan said it was a historic milestone for the country, which this year celebrates 50 years since its formation.

The construction of Barakah nuclear power plant has faced delays as the United Arab Emirates builds a nuclear industry from scratch.

Unit 1 received its operating licence from the nuclear regulator in 2020, 3 years after its expected planned start up in 2017.

Last August, Unit 1 was connected to the national power grid and in December reached 100% of reactor power capacity during testing.

Unit 2 was issued an operating licence in March this year.

When completed Barakah, which is being built by Korea Electric Power Corp (KEPCO), will have 4 reactors with 5,600 megawatts (MW) of total capacity – equivalent to nearly 25% of the UAE’s peak demand.