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

Last year 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 heaps per year.

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

Galp said in a declaration 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 forefront of establishing low-carbon solutions vital for the energy shift".

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;-RRB-