LISBON, Dec 19 (Reuters) - Portugal's Galp Energia expects to begin producing biodiesel and biojet fuel from waste in an industrial-scale unit it is constructing at its Sines refinery in 2026, the company, which is primarily an oil producer and refiner, stated 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 Grease (HVO) plant, which will have a production capacity of 270,000 metric heaps annually.

It will transform waste products, such as utilized 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 got on Wednesday the three reactors to process biofuels, which will permit the HVO system to "produce SAF and biodiesel in 2026 ... positioning Galp at the leading edge of establishing low-carbon solutions vital 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 in Sines. ($1 = 0.9637 euros) (Reporting by Sergio Goncalves