It may help in contemplating the options to consider the economics of greenhouse production as compared to in-the-ground and outside production. The latter is comparatively pretty efficient, given a congenial growing environment, and that is the biggest constraint. It accounts for California's dominance of the fresh produce business in the cheap energy era. Lots of sunlight, moderate temperatures for a large part of the year, and subsidized water provided a compelling advantage when shipping costs were low. We can compete "in season", but that seasonality led to market dominance by the California (and Mexico and Florida) growers. Greenhouse production to extend the season has always been a part of the equation, but generally for high-value crops. Even then, we were always being undercut by greenhouse operations farther south where less heat and supplemental light are needed. Greenhouses, generally plastic, are often used to extend the season at both ends here, since the heating and lighting needs are lower to do that than for winter production.
What would change this? Improvements in lighting efficiency would help, but since heat is generally needed as well, reduced energy requirements for light would translate into higher need for heating energy. I think the biggest opportunity for expanding production lies in tapping "waste" heat (really it is wasted heat). That occurs in electricity generation. AES Cayuga is one large generator of wasted heat that could support a greenhouse complex producing winter vegetables. Waste heat is also a byproduct of the oxidation of organic matter at the sewage treatment plant, where the methane produced can also be tapped. Ditto for dairy operations, if they were they linked to adjacent greenhouses. I remember reading of the lengths that some northern European countries have gone to to capture and use heat routinely wasted in our cheap energy economy. We can and should to do the same, but agricultural use will have to compete with alternative uses for the same energy. Market forces will distribute the energy to the highest bidder -- and food purchases tend to be made from the lowest cost producers. Without tapping and using currently wasted energy, the best available technology struggles to compete. Rising energy costs will favor outdoor and seasonal production increasingly. I expect the cost of out-of-season foodstuffs to rise more and faster than the basic storable stuff. Maybe there will be a place for growing tomatoes under lights in highly insulated buildings, but they won't be cheap (or very natural, for those of us who care about that). Joel At 11:50 AM 10/2/08 -0400, you wrote: >Hello everybody. > >I ran into this neat but frankly Utopian plan of Dickson Despommier to do >high rise farming in cities...it was written up in >http://www.sciencenews.org/view/feature/id/36823/title/Let%E2%80%99s_Get_Vertical > >but the reality is it will take money and it will take space. We recently >kicked around the >question of what fate the looming resource crunches would deal to suburban >living and sometimes tangle over the sustainability of cities but the hybrid >farm/city envisioned in the article is a slightly different beast. > >Where better than S/T to ask how one dopes out the feasibility of such >schemes. >In particular: >what is the cost/kg of delivered food if you throw in all long and short >term liabilities and subtract subsidies? ...that is the number that has to >beat farming efficiency [including the trucking and refrigeration costs] out >in the farming districts by enough to warrant the regulation and the taking >of city real estate for green houses. > >-George >-- >freedom is not more important than fairness and much easier to fake. >_______________________________________________ >For more information about sustainability in the Tompkins County area, >please visit: http://www.sustainabletompkins.org/ > >RSS, archives, subscription & listserv information for: >[email protected] >http://lists.mutualaid.org/mailman/listinfo/sustainabletompkins >free hosting by http://www.mutualaid.org _______________________________________________ For more information about sustainability in the Tompkins County area, please visit: http://www.sustainabletompkins.org/ RSS, archives, subscription & listserv information for: [email protected] http://lists.mutualaid.org/mailman/listinfo/sustainabletompkins free hosting by http://www.mutualaid.org
