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

Last year Galp participated in a 75%-25% joint endeavor 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 transform waste materials, such as used cooking oils, into sustainable biodiesel and biojet fuel, also referred to as sustainable aviation fuel (SAF), utilizing green hydrogen produced by an electrolyser powered by wind or solar power.

Galp said in a declaration it got on Wednesday the 3 reactors to process biofuels, which will enable the HVO unit to "produce SAF and biodiesel in 2026 ... placing Galp at the forefront of establishing low-carbon options important for the energy shift".

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