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 mainly an oil manufacturer and refiner, said on Thursday.

Last year Galp got in into 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 capability of 270,000 metric heaps each year.

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

Galp stated in a declaration it received on Wednesday the 3 reactors to biofuels, which will enable the HVO system to "produce SAF and biodiesel in 2026 ... placing Galp at the forefront of developing low-carbon options essential for the energy transition".

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-