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 producer and refiner, stated 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 capability of 270,000 metric lots each year.

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

Galp stated in a declaration it on Wednesday the 3 reactors to process biofuels, which will enable the HVO system to "produce SAF and biodiesel in 2026 ... putting Galp at the forefront of developing low-carbon options 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