LISBON, Dec 19 (Reuters) - Portugal's Galp Energia anticipates to start producing biodiesel and biojet fuel from waste in an industrial-scale unit it is building at its Sines refinery in 2026, the company, which is primarily an oil producer and refiner, said on Thursday.

In 2015 Galp got in into a 75%-25% joint venture with Japan's Mitsui to invest 400 million euros ($415 million) in the Hydrogenated Grease (HVO) plant, which will have a production capacity of 270,000 metric tons annually.

It will change waste materials, such as utilized cooking oils, into sustainable biodiesel and biojet fuel, also called sustainable aviation fuel (SAF), using green hydrogen produced by an electrolyser powered by wind or solar energy.

Galp said in a declaration it received on Wednesday the 3 reactors to process biofuels, which will allow the HVO system to "produce SAF and biodiesel in 2026 ... positioning Galp at the forefront of developing low-carbon options important for the energy transition".

Galp is also investing 250 million euros in a 100 megawatt (MW) electrolyser system to produce green hydrogen to power the refinery in Sines. ($1 = 0.9637 euros) (Reporting by Sergio Goncalves;-RRB-