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Solar Thermal Can Reduce Propane Costs

November 20, 2014

Propane consumers are being hit with a “one-two” punch: a propane supply shortage from a flow reversal of the Cochin Pipeline, and what is shaping up to be a long, cold winter. Further, propane consumers do not benefit from utility efficiency programs and rebates because those programs focus on natural gas utilities, not unregulated propane suppliers. The rising cost of propane is hitting Midwesterners especially hard, where propane plays a much larger role in agricultural production. With this in mind, policy-makers have turned their attention to solar thermal technologies that will help mitigate against propane price spikes.

Generally, solar thermal devices harness solar energy into thermal energy by collecting solar radiance in a medium – air under a glazed panel, or a liquid glycol solution – and transferring that heat into an existing hydronic or HVAC system. There are several types of solar thermal collectors, including: solar hot water, solar hot air (a/k/a solar furnace), and solar transpired air.

(air heat diagram-

Solar furnace and solar transpired air collectors are normally mounted on south-facing walls to maximize solar radiance capture, but may also be engineered to rest on rooftops (hyperlink with example). Hot air is then transferred indoors through conventional ducting. While solar air heating is suitable for all sorts of programs (commercial, industrial, multi-residential, institutional, etc.), it is particularly appropriate for rural applications, especially when you consider the skyrocketing cost of propane. These applications include poultry and livestock ventilation and most importantly crop drying and processing (the most energy intensive operation of grain farming). Furthermore, solar air heating is capable of generating 7.3 million BTUs of thermal heat annually, the equivalent of 80 gallons of propane, significantly diminishing heating expenses.

(transpired air on a turkey barn –

If you’re seriously considering the technology, I encourage you to visit the Rural Renewable Energy Alliance site. They both manufacture and install solar furnaces, with the possibility of financial assistance. I also encourage you to look into the Minnesota Department of Commerce’s Made in Minnesota Solar Thermal Incentive Program. For solar furnaces manufactured in Minnesota, individuals (or companies) can receive a rebate equal to 25% of the system installed cost up to a maximum of $2,500 for residential, $5,000 for multi-family and $25,000 for commercial systems. And finally, the Toronto-based engineering firm, Conserval Engineering Inc. is well known for their Solar Wall solar air heating product. I urge you to check out their chicken farm and swine farm case studies!  Good luck and capture those savings!

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