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 constructing at its Sines refinery in 2026, the business, which is primarily 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 capacity of 270,000 metric tons annually.

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

Galp stated in a statement it received on Wednesday the 3 reactors to process biofuels, which will allow the HVO unit to "produce SAF and biodiesel in 2026 ... placing Galp at the leading edge of developing low-carbon solutions important for the energy shift".

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-