High tunnels greenhouses are extensions of the fossil fuel supply line. The plastic covering requires barrels of petroleum and gallons of natural gas both for feed stock and the energy to manufacture. The support structure requires energy for manufacture and energy for mining in the cases of aluminum or steel.
High tunnels are not sustainable, they are not green, they are not environmentally safe.
“Polyethylene covers on high tunnels and greenhouses make a significant contribution to the growing problem of waste plastics. Most of these plastic films are produced from low-density polyethylene (LDPE #4) resins.” www.uvm.edu/sustainableagriculture/.../HighTunnels_SelectingStructure.pdf
For a round style high tunnel – 20-ft. wide x 12-ft. high x 48-ft. long – it takes approximately 50-ft of 40-ft wide of 6 mil, 4-year plastic. From data at Plastics Europe this can be figured to be more than a couple of barrels of crude oil every four years. This is not a large high tunnel either in length or width so the energy requirements and waste problems would be magnified.
It is important to understand that high tunnels do not offer a sustainable alternative in a world where access to oil and natural gas are requiring more and more energy to extract. In a world where obtaining fossil fuels requires more and more environmentally dangerous practices; coal included with the removal of mountain tops. This does not even consider the carbon and other greenhouse gas emission required for the materials, manufacture, transportation and installation of high tunnels.
My point is not to negate the use of high tunnels as much to require honesty in the promotion of them.
High tunnels as industrial gardening is not a sustainable answer to our food needs nor a back to basics. It is a sideways move to business as usual.