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 mostly an oil manufacturer and refiner, stated on Thursday.

Last year 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 capability of 270,000 metric tons each year.

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

Galp said in a statement it on Wednesday the three reactors to process biofuels, which will enable the HVO unit to "produce SAF and biodiesel in 2026 ... putting Galp at the forefront of developing low-carbon solutions vital for the energy transition".

Galp is also 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-