A Cleaner Future
Reducing Climate Pollution

Greenhouse gas emissions are nearly eliminated from SHARE farms through the use of solar thermal heating and wind energy.  During certain periods though wind speeds are too low and the turbine will have no generation capacity, requiring that electricity be taken from the grid.  Throughout the year, however, the turbine produces significant amounts of excess electricity, offsetting that which is occasionally supplied by the grid. 

According to the American Wind Energy Association (AWEA), a single 20 kW wind turbine annually displaces the CO2 produced by five average sized automobiles.   Over its life, the same wind turbine can offset approximately 1.2 tons of air pollutants and 200 tons of greenhouse gas pollutants. On a larger scale, if wind energy were to provide 20% of the nation’s electricity needs, more than a third of the emissions from coal-fired power plants could be displaced.

In a typical year, the solar thermal system should provide all the necessary auxiliary heating for the high tunnel.  Back up propane heaters, however, are an option in case a prolonged stretch of cloudy weather prevents the system from delivering enough heat.  In most cases, though, these fail safe heaters should not be required. 

A full length high tunnel requires approximately 500 gallons of propane fuel in the Upper Midwest.  A single gallon of propane generates 11 pounds of CO2.  So this translates into 5,500 pounds per year for a single high tunnel or 770,000 pounds emitted over a ten year period by 14 high tunnels (one acre).

SHARE farms further reduce greenhouse gas emissions because they are far more efficient at carbon sequestration than field grown produce. According to the Intergovernmental Panel on Climate Change (IPCC), roughly 100 billion metric tons of carbon could be sequestered in the world’s soils during the next 50 years, offsetting 10–20 percent of carbon emissions from fossil fuels. Carbon storage is also good for soils. It increases organic matter, improving soil structure and water infiltration, which can improve yields. At Pennsylvania’s Rodale Institute, the long-running Farming Systems Trial showed that after 23 years, organic systems each stored about 1,000 pounds of carbon per acre per year due to cover crops and crop rotations. The conventionally fertilized system did not accumulate significant amounts of carbon.