Both groups hope to get around these complications, but in different ways.
The researchers at Berkeley, led by Omar Yaghi, announced their results last year.
They propose to replace the zirconium-based metal-organic framework with one based on aluminium.
Not only is aluminium cheaper than zirconium, it is better at binding to and then releasing water, making the trap's operation smoother.
On top of this, Dr Yaghi has found that by mixing graphite into the powder from which the framework is compounded,
in order to make it black, and therefore heat-absorbing, he can eliminate the need for copper foam.
In Connecticut, meanwhile, Steven Suib and his colleagues,
who have just reported their result in Environmental Science and Technology Letters, propose getting rid of both framework and foam,
在《Environmental Science and Technology Letters》中發表了自己的結果，他們建議拋棄框架和泡沫，
and replacing them with birnessite, a type of manganese dioxide. Birnessite is abundant in nature.
It is also easy to make artificially. It is therefore cheap.
Like metal-organic frameworks, birnessite is riddled with tiny holes that allow air to move around inside it, to maximise adsorption.
And it, too, is black and therefore heat-absorbing.
Both proposals work. Tested in desertlike conditions in a laboratory—and in Dr Yaghi's case in an actual desert, too—
they absorb and regurgitate reasonable fractions of their weight of water every day. They are nothing like as productive as desalination plants,
and so would have to be built at large scale to generate water in commercially useful quantities.
But one thing deserts do have is lots of cheap land. If either or both of these inventions can be manufactured at scale,
then the deserts may bloom—if not with plants, at least with water-collection farms.