ABSTRACT
Under the Saudi Green Initiative, a hydrogen production of 2.9 million tons per year is targeted for 2030 and 4.0 million tons per year by 2035 (Argus Media 2021).
Those production rates will comprise blue hydrogen and green hydrogen production. Only the green hydrogen produced by electrolysis will require a water supply. For the purpose to estimate the amount of desalinated water required for the green hydrogen production, it has been assumed that about 50% of the planned total hydrogen production or about 2.0 million tons per year would be green hydrogen. As the water demand for the electrolysis process may be in the range of about 10–15 m3 of desalinated water per ton of hydrogen, this would correspond to a required desalination plant capacity in the range of 60,000–90,000 m3/day. In comparison to a total water consumption in Saudi Arabia of about 8.0 million m3/day in 2019 and a projected consumption of 12.3 million m3/day in 2040 (US–Saudi Business Council, 2021), the desalinated water demand for the green hydrogen production would be in the range of 0.50%–0.75 % of the total water demand. Assuming further that in 2019 about 60% of the total water demand or about 6.4 million m3/day has been produced by desalination plants and this rate may increase with the increase of the total water demand, the percentage of desalination water capacity for the green hydrogen production would be in the range of about 0.7%–1.1% of Saudi Arabia’s future total desalination plant capacities. The question here is, how green may desalinated water be in the future and would it be suitable for the production of green hydrogen, or should green hydrogen plants be designed with their own desalination systems driven by renewable energy only
Goal: In regards to reduction of the environmental impact of seawater desalination plants, critical items are the reduction of allocated CO2 emission and minimization of the use of chemicals discharged with concentrated brine back to the sea or disposed with sludge or solid waste from zero liquid discharge desalination systems.
