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 mostly an oil manufacturer and refiner, stated on Thursday.

Last year Galp entered 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 change waste products, such as used cooking oils, into renewable biodiesel and biojet fuel, also referred to as sustainable air travel fuel (SAF), using green hydrogen produced by an electrolyser powered by wind or solar power.

Galp said in a statement it got on Wednesday the three reactors to biofuels, which will enable the HVO unit to "produce SAF and biodiesel in 2026 ... placing Galp at the forefront of developing low-carbon options important for the energy shift".

Galp is likewise 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