LISBON, Dec 19 (Reuters) - Portugal's Galp Energia anticipates to start producing biodiesel and biojet fuel from waste in an industrial-scale system it is constructing at its Sines refinery in 2026, the company, which is primarily an oil manufacturer 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 per year.

It will change waste materials, such as used cooking oils, into sustainable biodiesel and biojet fuel, likewise referred to as sustainable air travel fuel (SAF), using green hydrogen produced by an electrolyser powered by wind or solar energy.

Galp said in a declaration it got on Wednesday the three reactors to process biofuels, which will allow the HVO system to "produce SAF and biodiesel in 2026 ... putting Galp at the leading edge of establishing low-carbon services essential 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;-RRB-