評論
打印
Water supply
供水
A better fog trap
更好的霧網
A clever upgrade of a humble but useful technology
一種不起眼但有用的技術的聰明升級
Every night, air cooled and moistened by the Humboldt current blows over Chile's northern coast and across the Atacama desert. The billowing banks of fog thus created might look insubstantial, but there is water here to be captured—and in this, the driest place on Earth, capture it people do. Fog-harvesting will never be big business, for it needs particular conditions to operate well. But in zones like the Atacama, where moisture-laden breezes bring fog but no rain, the invention in the 1960s of traps which can pluck that moisture from the air has helped sustain settlements otherwise on the brink of drought.
每天晚上，洪堡洋流吹過智利北部海岸和阿塔卡馬沙漠，使空氣變得涼爽、濕潤。由此產生的滾滾大霧可能看起來并不真實，但這里有水可以收集——在這里，在這個地球上最干燥的地方，人們是這樣做的。霧收集永遠不會成為大生意，因為它需要特殊的條件才能運作良好。但在像阿塔卡馬這樣的地區，潮濕的微風帶來霧，但沒有雨，20世紀60年代發明的網可以從空氣中吸收水分，幫助維持住在干旱邊緣的定居點。
Fog traps are polymer-mesh screens mounted in metal frames. As misty zephyrs blow through them, droplets of water adhere to the mesh. These absorb others until the result breaks free and runs down the screen, as a raindrop runs down a window pane, into a collector. A typical trap, with a 40-square-metre collecting area, yields about 200 litres a day. That is enough to supply around 60 people with drinking water. Such a collector costs $1,000 or so, and will last a decade.
霧網是安裝在金屬框架上的聚合物網屏。當霧蒙蒙的和風吹過它們時，水滴就會粘在網孔上。它們吸收其他物質，直到釋放出來并沿屏幕流下，就像雨滴沿窗玻璃流下，進入收集器。一個典型的霧網有40平方米的收集面積，每天可以產出約200升的水，足以為大約60人提供飲用水。這樣的霧網價值約1000美元，可以用10年。
A simple idea, then. But even simple technology can be upgraded. And that is exactly what Urszula Stachewicz of the AGH University of Science and Technology, in Krakow, Poland, proposes to do.
這是一個簡單的想法，但即使是簡單的技術也可以進行升級。而這正是波蘭克拉科夫AGH科技大學的厄休拉·斯塔切薇茲打算做的。
Her upgrade relies on giving the mesh a slight electrical charge. Overall, the molecules in it are electrically neutral. But polymer molecules are large, and their electrons can move about within them. Uneven distribution of these electrons means some parts of a molecule are positive and some negative. That fact might be exploited to give the outside of each thread in a mesh one electrical polarity (either positive or negative) while burying the other polarity in the thread's interior. Just as static electricity will attract a balloon to a wall, a surface charge created in this way will attract water droplets from the air.
她的升級方法是給網眼輕微的電荷。總的來說，它的分子是電中性的。但是聚合物分子很大，它們的電子可以在其中移動。這些電子的不均勻分布意味著分子的某些部分帶正電，某些帶負電。這一事實可能會被利用來給網中的每條線的外部一個電極性(無論是正的或負的)，而把另一個極性埋在線的內部。就像靜電會把氣球吸引到墻上一樣，用這種方法產生的表面電荷也會吸引空氣中的水滴。
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