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

In 2015 Galp participated in a 75%-25% joint endeavor 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 annually.

It will change waste products, such as utilized cooking oils, into eco-friendly biodiesel and biojet fuel, likewise called sustainable aviation fuel (SAF), using green hydrogen produced by an electrolyser powered by wind or solar energy.

Galp stated in a declaration it got on Wednesday the 3 reactors to process biofuels, which will permit the HVO system to "produce SAF and biodiesel in 2026 ... positioning Galp at the forefront of establishing low-carbon solutions necessary for the energy shift".

Galp is also investing 250 million euros in a 100 (MW) electrolyser unit to produce green hydrogen to power the refinery in Sines. ($1 = 0.9637 euros) (Reporting by Sergio Goncalves