It would be hard to miss the impacts of urbanization, invasive species, environmental shortcomings, and resource scarcity on the cost of agriculture.  One person leading the charge to begin public discourse is Dr. Dickson Despomier, professor at Colombia University.   He advocates for a term that is catching on, “vertical farming”, where high rise buildings in urban settings are used to grow local produce using hydroponics.  Few companies have commercialized hydroponics to address this type of structure, most rely on greenhouse or land based conventional production.  All suffer from climate issues and any user of solar radiation must make accommodations for plant needs as shown in the graph where the blue line is actual level of sunlight (for latitude 42 degrees North) and the red line is what is desired for plant growth.  Of course any modification to meet plant needs costs money, especially in energy to cool, heat, or light.

Clean technology comes into play as soon as you start limiting sunlight in a tall building and deal with too much or too little sun in the 10 months of the year when you have to make modifications.  Using a hydroponic system allows most easily for artificial light application indoors addressing most of the climate related difficulties.  There are three main forms of hydroponic system and each is best suited for what it grows.  A system of shallow ponds with styrofoam floats is best suited for head and more mature plant  production.  Systems that periodically flood roots (NFT) are best suited to taller crops or where picking of the produce is required.  Aeroponic systems which spray the nutrient solution onto the roots is best suited to baby leafy green production.  By adding artificial sources of light, any of these systems could be moved indoors – into the empty buildings in most urban areas and initiate the vertical farming that is predicted to come.