LISBON, Dec 19 (Reuters) - Portugal's Galp Energia expects to start producing biodiesel and biojet fuel from waste in an industrial-scale unit it is developing 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 endeavor 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 transform waste products, such as utilized cooking oils, into sustainable biodiesel and biojet fuel, also referred to as sustainable aviation fuel (SAF), using green hydrogen produced by an electrolyser powered by wind or solar power.

Galp stated in a statement it got on Wednesday the 3 reactors to process biofuels, which will permit the HVO system to "produce SAF and biodiesel in 2026 ... placing Galp at the leading edge of establishing low-carbon options essential for the energy transition".

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