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 mainly an oil manufacturer 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 Oil (HVO) plant, which will have a production capacity of 270,000 metric heaps per year.

It will change waste products, such as utilized cooking oils, into eco-friendly biodiesel and biojet fuel, likewise understood as sustainable air travel fuel (SAF), using green hydrogen produced by an electrolyser powered by wind or solar energy.

Galp stated in a declaration it received on Wednesday the three reactors to process biofuels, which will allow the HVO system to "produce SAF and biodiesel in 2026 ... positioning Galp at the leading edge of developing low-carbon solutions necessary 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