LISBON, Dec 19 (Reuters) - Portugal's Galp Energia expects 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 mainly an oil producer and refiner, stated on Thursday.

In 2015 Galp entered into a 75%-25% joint venture with Japan's Mitsui to invest 400 million euros ($415 million) in the Hydrogenated Vegetable Oil (HVO) plant, which will have a production capacity of 270,000 metric heaps annually.

It will change waste materials, such as used cooking oils, into renewable biodiesel and biojet fuel, likewise known as sustainable air (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 process biofuels, which will permit the HVO unit to "produce SAF and biodiesel in 2026 ... putting Galp at the leading edge of establishing low-carbon services vital for the energy transition".

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