LISBON, Dec 19 (Reuters) - Portugal's Galp Energia anticipates to begin producing biodiesel and from waste in an industrial-scale unit it is constructing at its Sines refinery in 2026, the company, which is mainly an oil producer and refiner, said on Thursday.

In 2015 Galp participated in 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 capability of 270,000 metric loads per year.

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

Galp stated in a statement it received on Wednesday the three reactors to process biofuels, which will enable the HVO system to "produce SAF and biodiesel in 2026 ... placing Galp at the forefront of developing low-carbon options 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