Are Desalination Plants Sustainable?

The global gap between available water supply and water demand is expected to grow to over 2700 million cubic meters per day by 2030, equivalent to 40% of total water demand. To address this, desalination plants have emerged as a key solution. Currently, there are around 8950 desalination plants worldwide, with a cumulative capacity of about 38.1 million cubic meters per day.

However, the sustainability of desalination plants is a topic of debate. These plants can be expensive, with costs often comparable to tap water in most countries. A significant portion of water consumption is from agriculture and industries, which are often dependent on large quantities of fresh water that is nearly free. For such industries, desalination plants may be cost-prohibitive.

Environmental Impact and Cost

One of the major concerns regarding desalination plants is their environmental impact. They release large amounts of brine, which, if not properly managed, can harm local marine life. This issue is particularly critical during the design phase of the plants. In addition to environmental concerns, desalination plants are energy-intensive. State-of-the-art reverse osmosis (SWRO) plants require approximately 3–5 kWh per cubic meter of water, compared to as much as 10 kWh per cubic meter or more two to three decades ago. Almost all desalination plants are currently powered by fossil fuels, which are not sustainable.

Proposed Solutions

One potential solution to the sustainability issue in desalination is the use of nuclear power. Nuclear power is a zero-emission energy source that could provide a more sustainable solution for powering desalination plants. The concentrated brine waste stream from desalination plants, when simply returned to the sea, can be used as a feedstock to make several useful products. These products are currently made using brine from expensive wells.

Challenges and Myths

Desalination plants are not sustainable in their current form. They are energy guzzlers, requiring high pressures and temperatures, and produce highly salty sludge that needs to be disposed of properly. A common myth is that desalination is a straightforward process that can be easily managed. However, as we've seen, there are significant environmental and economic challenges to overcome.

Conclusion

Desalination is crucial in providing fresh water to millions of people worldwide. However, it is important to ensure that the plants are sustainable and that the environmental impact is minimized. By addressing these challenges and exploring alternative energy sources, we can move towards a more sustainable future for desalination.