LISBON, Dec 19 (Reuters) - Portugal's Galp Energia expects to begin producing biodiesel and biojet fuel from waste in an industrial-scale system it is constructing at its Sines refinery in 2026, the business, which is primarily an oil producer and refiner, said 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 loads each year.

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

Galp stated in a declaration it got on Wednesday the three reactors to process biofuels, which will allow the HVO unit to "produce SAF and biodiesel in 2026 ... positioning Galp at the forefront of developing low-carbon solutions 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;-RRB-