Reread the article. They are using a refrigerant to produce gasses to drive the turbine - not steam. This should remove problems of stuff rusting out. They do use groundwater as a coolant though - but you could always use a closed system with something other than water.
Did you notice that they said 15 square meters? That's almost 160 square feet to get 1 Kw of electric. Due to the space requirements, this isn't going to be very practical for urban environments.
They said this cost a couple thousand dollars - about half of what 1 Kw of solar panels would cost.
I think they would be further ahead to use the parabolic mirror solar collector focused on a solar panel, than trying to generate electric via steam turbine.
As a side note, it might be worthwhile to study this for an application for a refrigerator or freezer in remote locations. This absords the heat from the sun - with a refrigerator, we want it to remove the heat from the inside of the fridge/freezer. The liquification and gasification processes of the refrigerant would be the same in both applications.