There is a plant on the east coast of China that, in the general silence, is showing what the future of water and energy could look like. No bombastic announcements, no slogans: just numbers that speak clearly. From sea water it is able to obtain drinkable water at a very low cost and, at the same time, green hydrogen, exploiting what would normally be wasted.
It happens in Rizhao, a coastal city whose name means “sunlight” and which has been seriously investing in renewables for years. Here domestic hot water is already produced with solar power and the UN, not surprisingly, has included it among the most livable cities in the world. Today, however, it is this new desalination plant that is making headlines.
In the first days of activity it demonstrated that it is possible to do what until now seemed too expensive or too energy-intensive: transform salt water into an accessible resource, without leaving a trail of environmental problems in its wake.
How it works
Operation is less complicated than it seems. For every large amount of seawater treated, the plant produces ready-to-use fresh water, a significant amount of green hydrogen and a mineral-rich brine that is not discharged into the sea, but sold to the chemical industry. In practice, nothing is thrown away. And this is precisely one of the most interesting aspects.
Hydrogen is obtained through electrolysis, the process of separating hydrogen and oxygen using electricity. The difference here lies in the energy source: the plant uses waste heat from a nearby steel mill, i.e. energy that would otherwise be lost. The result is truly green hydrogen, because it requires no additional fossil fuels. A solution that fits perfectly into the Chinese industrial context, where steelworks and production plants along the coast are certainly not lacking.
The hydrogen produced is enough to power dozens of city buses, reducing emissions and offering a concrete alternative to traditional fuels. But it is the data on water that is most striking. The final cost is approximately 28 US cents per cubic meter, a surprising figure when compared with other large plants in the world. In Saudi Arabia, where some of the world’s largest desalination facilities are located, the price is about double. In California, in Carlsbad, it costs over two dollars for the same amount of water.
The historical critical issues of desalination and the sustainable management of brine
Desalination, after all, has always been an ambivalent technology. On the one hand it represents a concrete response to water scarcity, on the other it consumes a lot of energy and produces waste that is difficult to manage. The membranes used in traditional processes require aggressive chemicals and the residual brine, if discharged into the sea, can seriously damage ecosystems.
In Rizhao the problem is tackled at its root. Brine is not considered a waste, but a resource. It is recovered and reused, reducing environmental impact and lowering overall costs. It is a change of perspective that makes the difference, especially in a historical moment in which fresh water is becoming increasingly precious.
In recent years, research has already proposed interesting solutions, such as solar systems capable of accelerating the evaporation of sea water without large energy consumption. This Chinese plant, however, shows something more: the real integration between industry, renewable energy and intelligent resource management.
This does not mean that this model can be replicated everywhere, but it clearly indicates a direction. In a world facing the climate crisis, water scarcity and the need to reduce emissions, examples like this demonstrate that solutions exist. Sometimes they don’t make any noise, but they work.
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