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 building at its Sines refinery in 2026, the company, which is primarily an oil producer and refiner, said on Thursday.

In 2015 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 annually.

It will transform waste materials, such as used cooking oils, into sustainable biodiesel and biojet fuel, also referred to as sustainable air travel fuel (SAF), utilizing green hydrogen produced by an powered by wind or solar power.

Galp stated in a statement it received on Wednesday the 3 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 shift".

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