Seawater Electrolysers and Fuel Cells: A Possible Approach to Desalination?

Could seawater electrolysers followed by fuel cells become a significant contributor to desalination? This concept, while intriguing, appears to be less efficient than directly using wind and solar electricity in membrane desalinization plants. Let's explore this idea further and understand why it might not be as viable as one might initially think.

Utility Scale Wind and Solar Now Cheaper Than Fossil and Nuclear

The transition to renewable energy has been significant. In 2017, utility-scale wind and solar became the cheapest sources of electricity in most parts of the world, surpassing both fossil fuel and nuclear generation. This revolution in energy production has far-reaching implications for various industries, including desalination.

Electrolysis and Hydrogen Production

Electrolyzing water to separate hydrogen is just one method. There are at least a few other processes that can separate hydrogen from oxygen, with efficiencies ranging from 70% to 90%. However, the exact cost-effectiveness of these more efficient processes is unknown. The market will inevitably move towards the most cost-effective option, much like how commercial solar panels operate at around 22-24% efficiency compared to laboratory models that can achieve up to 40% efficiency.

Adding Another Layer of Reduction in Efficiency

Using hydrogen in fuel cells to produce electricity introduces another layer of inefficiency. While burning hydrogen directly or using it in a fuel cell has its advantages, it's often less efficient than directly using the electricity generated from hydrolysis. This extra step might add unnecessary costs and reduce the overall efficiency of the desalination process.

Renewable Energy and Excess Capacity

The real change on the horizon is the abundant and cheap electricity that will come with a large-scale renewable energy infrastructure. Currently, there are occasional hours when wind and solar power produce more electricity than the grid needs. However, with enough installed capacity, we will have excess energy for many hours per year, which can be stored or used directly in high-demand applications like water desalination.

Hydrolysis, being a technology that requires significant and immediate electricity, will greatly benefit from this excess capacity. This will make hydrogen, and by extension, desalination through electrolysis, more cost-effective than it is today.

Conclusion and Future Considerations

While the idea of using seawater electrolysers followed by fuel cells for desalination is an interesting one, it is likely to face challenges due to its inefficiency compared to direct use of wind and solar electricity. Nevertheless, it is an area that might be explored further with well-designed systems that could produce water and power competitively.

The real focus should remain on making renewable energy more accessible and cheaper. The promotion of clean energy is crucial in addressing the urgent need for clean water. With a significant number of researchers working on clean water technologies and systems, the intersection between clean energy and water desalination could still yield innovative solutions.

There is a lot of work to be done, and the future is promising, especially when the reliable and abundant electricity from renewable sources becomes more prevalent. Let's continue to support and invest in clean energy initiatives to ensure a sustainable future for all.