By Marta Nogueira

RIO DE JANEIRO, July 10 (Reuters) - Acelen Renovaveis, an energy company backed by Abu Dhabi's Mubadala Capital, has signed a five-year agreement with agribusiness giant Bunge BG.N to supply 1.5 million metric tons of certified soy oil for a sustainable aviation fuel (SAF) and renewable diesel (HVO) project in Brazil's Bahia state, executives from both companies told Reuters.

Under the deal, Bunge will supply 300,000 metric tons of soy oil per year starting in 2029, when Acelen's biorefinery is expected to begin operations.

Acelen is investing more than $3 billion in the project, which is expected to produce 1 billion liters of SAF and HVO annually. The agreement is Bunge's largest soy oil supply contract in South America, according to the companies.

Bunge Commercial Director Tito Martinho said the company is Brazil's largest soybean crusher and that the contract volume is equivalent to about 15% of its domestic soy oil production capacity.

The contracted volume will cover about 30% of the feedstock required to start the biorefinery, Acelen Commercial and Trading Vice President Cristiano da Costa said.

Another 60% has already been secured from used cooking oil (UCO), including supplies from commodity trader Trafigura and another undisclosed provider, Costa said. The remaining 10% was intentionally left open to allow the company to develop alternative feedstocks.

The plant was designed to eventually use macauba palm oil, a feedstock Acelen is developing, although Costa said it is expected to be incorporated gradually from 2032.

About 88% of the plant's future output has already been sold under long-term contracts, mainly to customers in Europe and the United States. While exports will be the initial focus, Acelen is also in talks with potential Brazilian buyers as demand for SAF is expected to rise under Brazil's "Fuel of the Future" law.