水时代——人类美好未来

技术专家倾向于关注最珍贵或技术上最有用的自然资源和商品，例如黄金、稀土或锂。然而，每天需要大量简单得多的资源来维持我们的文明：淡水。

Investors and technologists tend to focus on the most precious or technically useful natural resources and commodities, such as gold, rare earth, or lithium. However, a much simpler resource is needed in massive amounts daily to sustain our civilization: fresh water.

投资者和技术专家倾向于关注最珍贵或技术上最有用的自然资源和商品，例如黄金、稀土或锂。然而，每天需要大量简单得多的资源来维持我们的文明：淡水。

While it literally falls from the sky in most of the world, its availability is still under severe pressure in modern civilization, as we consume much of it for industry, agriculture, and human needs.

虽然它在世界大部分地区实际上是从天上掉下来的，但在现代文明中，它的可用性仍然面临着巨大的压力，因为我们将其大部分用于工业、农业和人类需求。

Only 3% of the world’s water is usable fresh water, with 97% being saline (saline groundwater and seawater). Of this freshwater, 69% is held in glacier and polar ice caps, 30% is groundwater, and only 1% is surface water.

世界上只有 3% 的水是可用的淡水，97% 是咸水（含盐地下水和海水）。其中 69% 的淡水存在于冰川和极地冰盖中，30% 是地下水，只有 1% 是地表水。

Source: USGS

资料来源：美国地质调查局

As a result, in many places, the only available water source is saline. Desalination is possible but requires a tremendous amount of energy. Until now, it has often been done with fossil fuels, as most desalination techniques are energy-intensive and require constant and stable energy inputs.

因此，在许多地方，唯一可用的水源是盐水。海水淡化是可能的，但需要大量的能源。到目前为止，海水淡化通常使用化石燃料来完成，因为大多数海水淡化技术都是能源密集型的，需要持续稳定的能源输入。

This could change, thanks to a new method developed by MIT engineers and published in Nature Water under the title “Direct-drive photovoltaic electrodialysis via flow-commanded current control.”

这种情况可能会改变，这要归功于麻省理工学院工程师开发的一种新方法，并以“通过流量命令电流控制进行直接驱动光伏电渗析”为题发表在《自然水》上。

Solar Desalination

太阳能海水淡化

At first glance, solar power seems to be the most logical energy source for powering desalination operations. Not only is it provided for free by the Sun, but it is also generally abundant in dry regions like deserts, which often need desalination the most.

乍一看，太阳能似乎是为海水淡化作业提供动力的最合理的能源。它不仅由太阳免费提供，而且在沙漠等干燥地区通常也很丰富，这些地区通常最需要海水淡化。

With solar power becoming cheaper by the day, it will likely continue to grow as an energy source, as we covered in our article “The Solar Age—A Bright Future To Mankind.”

随着太阳能变得越来越便宜，它作为一种能源可能会继续增长，正如我们在《太阳能时代——人类光明的未来》一文中所讨论的那样。

There is still one problem – solar energy is only produced when the sun shines. This means that to operate efficiently, most solar-power-only desalination operations would need to be coupled to a battery system, increasing costs.

还有一个问题——太阳能只有在阳光照射时才会产生。这意味着为了高效运行，大多数仅使用太阳能的海水淡化作业需要与电池系统相结合，从而增加了成本。

This is especially problematic for current desalination techniques, like reverse osmosis, which needs stable conditions and a stable energy supply to be efficient. This is because it requires constant pressure on the osmosis membranes.

这对于当前的海水淡化技术（例如反渗透）来说尤其成问题，因为该技术需要稳定的条件和稳定的能源供应才能有效。这是因为它需要渗透膜上有恒定的压力。

This precludes any small-scale desalination and any low-cost methods, at least as long as energy storage is still expensive. This might change, as we discussed in “The Future Of Energy Storage—Utility-Scale Batteries Tech”; still, it could be better to also adapt to the natural fluctuation of solar power, including very short-term ones like clouds passing by.

这排除了任何小规模海水淡化和任何低成本方法，至少在能源存储仍然昂贵的情况下是如此。正如我们在“储能的未来——公用事业规模电池技术”中讨论的那样，这种情况可能会改变；尽管如此，最好也能适应太阳能的自然​​波动，包括​​非常短期的波动，例如云层经过。

Flexible Batch Electrodialysis

灵活的间歇式电渗析

The MIT researchers favored this approach. They studied electrodialysis, an alternative method to reverse osmosis for desalination. Electrodialysis uses an electric field to draw out salt ions as water is pumped through a stack of ion-exchange membranes.

麻省理工学院的研究人员赞成这种方法。他们研究了电渗析，这是一种反渗透海水淡化的替代方法。当水被泵送通过一堆离子交换膜时，电渗析利用电场提取盐离子。

Source: Nature Water

来源：自然水

For their new design, they created a model-based control system connected to sensors in all parts of the system. It predicted the optimal rate at which to pump water and the voltage that should be applied to maximize the amount of salt drawn out of the water.

对于他们的新设计，他们创建了一个基于模型的控制系统，连接到系统所有部分的传感器。它预测了抽水的最佳速率以及为最大限度地从水中提取盐量而应施加的电压。

By doing so, the desalination operation could fluctuate according to the solar power produced in real-time.

通过这样做，海水淡化操作可以根据实时产生的太阳能而波动。

Source: Nature Water

来源：自然水

On average, the system directly used 77 percent of the available electrical energy produced by the solar panels, which the team estimated was 91 percent more than traditionally designed solar-powered electrodialysis systems.

平均而言，该系统直接使用了太阳能电池板产生的 77% 的可用电能，该团队估计这比传统设计的太阳能电渗析系统多出 91%。

Further Improvement

进一步改进

The almost doubled rate of solar power utilization compared to previous electrodialysis systems could still be improved with more regular optimization & automation:

与以前的电渗析系统相比，太阳能利用率几乎翻了一番，但仍然可以通过更定期的优化和自动化来提高：

We could only calculate every three minutes, and in that time, a cloud could literally come by and block the sun.

我们只能每三分钟计算一次，在那段时间里，一朵云实际上可以遮住太阳。

The system could be saying, ‘I need to run at this high power.’ But some of that power has suddenly dropped because there’s now less sunlight. So, we had to make up that power with extra batteries.”

系统可能会说：“我需要以如此高的功率运行。”但由于现在阳光减少，部分电力突然下降。因此，我们必须用额外的电池来补充电力。”

Amos Winter – Director of the K. Lisa Yang Global Engineering and Research (GEAR) Center at MIT

Amos Winter – 麻省理工学院 K. Lisa Yang 全球工程与研究 (GEAR) 中心主任

This was a proof-of-concept work and will be turned into a commercial design soon, as the team will be launching a company based on their technology in the coming months.

这是一项概念验证工作，很快就会转变为商业设计，因为该团队将在未来几个月内基于他们的技术推出一家公司。

This research project was also supported in-kind (provided material for free) by Veolia Water Technologies and Solutions (VIE.PA) and Xylem Goulds (XYL -1.17%).

该研究项目还得到了威立雅水务技术与解决方案公司 (VIE.PA) 和 Xylem Goulds (XYL -1.17%) 的实物支持（免费提供材料）。

Not Just Seawater

不仅仅是海水

The research team focused on the desalination of brackish groundwater found underground in New Mexico. As many dry area population centers are far from the sea, this can be an important water source currently unavailable due to its salt content.

研究小组专注于新墨西哥州地下发现的咸水地下水的淡化。由于许多干旱地区的人口中心远离大海，由于其含盐量，这可能是目前无法获得的重要水源。

“The majority of the population actually lives far enough from the coast, that seawater desalination could never reach them. They consequently rely heavily on groundwater, especially in remote, low-income regions. And unfortunately, this groundwater is becoming more and more saline due to climate change.”

“大多数人口实际上生活在距离海岸足够远的地方，海水淡化永远无法到达他们的身边。因此，他们严重依赖地下水，特别是在偏远、低收入地区。不幸的是，由于气候变化，地下水的含盐量越来越高。”

Jonathan Bessette – MIT PhD student in mechanical engineering

Jonathan Bessette – 麻省理工学院机械工程博士生

The research model was already able to provide enough fresh water

研究模型已经能够提供足够的淡水