I don't think that the energy cost of irrigating in the desert will ever be sustainable. If you have a counter-example, I'm interested. But I do see the possi

I don't think that the energy cost of irrigating in the desert will ever be sustainable. If you have a counter-example, I'm interested. But I do see the possibility of solving the problem by using photovoltaic energy (though maybe not optimally, because not having to move the water would allow to use the electricity for other usages). Bear in mind that the alternative is to grow crops in countries where it is raining most of the time. Plants fare really really well in rainy countries, they don't mind at all that the sun is less present. The only real drawback is the shortened growing period, if the country is too far north or too far south.