With the increasing demand of low carbon emission reduction, green hydrogen production technology has received more and more attention. Hydrogen production by electrolysis of water using renewable energy is a process with low carbon emissions among many hydrogen source schemes. Hydrogen energy is of great strategic significance in the transformation of a clean, low-carbon, safe and efficient modern energy system. Among them, electrolysis of water hydrogen production technology is considered as a potential hydrogen production technology in the future.

So how much water does this technology require? Will it limit future large-scale production of hydrogen? Experts in the field of hydrogen and power-to-X (clean energy based energy conversion) at the International Renewable Energy Agency have studied the issue in depth.

Even under a very conservative scenario, the cost of water (treatment and transportation) would be less than 2% of the total cost of hydrogen production if desalination is used, and the energy used for desalination is only about 1% of the total energy required to produce hydrogen. These numbers suggest that water consumption should not be a major obstacle to expanding the use of green hydrogen.

1. Water consumption of green hydrogen: Limiting factors for expanding application scale?

Water consumption mainly comes from hydrogen production and upstream energy carrier production.

Step 1: Hydrogen production

In terms of hydrogen production, the limit low consumption of hydrogen production by electrolysis of water is about 9 kgho/ KGH. Considering the desalination process of water, the ratio is about 18 to 24 kGho/ KGH.

Step 2: upstream energy carrier production

In terms of upstream energy carrier production, the water consumption of photovoltaic power generation varies from 2.4 to 19 kgho/ KGH (50 to 400 L/ MWH), and that of wind power generation varies from 0.2 to 2.1 kgho/ KGH (5 to 45 L/ MWH).

Generally speaking, the total water consumption of hydrogen produced by photovoltaic and wind power generation is 32kgHO/kgH and 22kgHO/kgH on average.

2. Total water footprint: Lower when using renewable energy.

The low water footprint of hydrolytic hydrogen production is achieved by using renewable energy sources. If fossil fuels are used, the amount of water used for the whole process suddenly increases.

3.2050: Global use of green hydrogen exceeds 70EJ, how much water is needed?

Despite the increasing demand for energy conversion and hydrogen energy, the amount of water used to produce hydrogen through electrolysis will increase dramatically. But from a macro point of view, the water consumption of electrolysis for hydrogen production will still be much lower than other fields.

In recent years, the rapid development of clean energy has created good opportunities for hydrogen production from electrolytic water. On the one hand, hydrogen production from renewable energy power generation can achieve full cycle and zero carbon emissions, and achieve real green hydrogen production; On the other hand, the cost of hydrogen production will continue to fall as the cost of wind power, photovoltaics and cheap Internet access comes down