LISBON, Dec 19 (Reuters) - Portugal's Galp Energia expects 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 manufacturer and refiner, said on Thursday.

Last year Galp entered 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 capability of 270,000 metric lots per year.

It will transform waste materials, such as used cooking oils, into eco-friendly biodiesel and biojet fuel, likewise called sustainable air travel fuel (SAF), utilizing green hydrogen produced by an electrolyser powered by wind or solar power.

Galp said in a statement it received on Wednesday the three reactors to process biofuels, which will enable the HVO system to "produce SAF and biodiesel in 2026 ... placing Galp at the forefront of establishing low-carbon services important for the energy shift".

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