Costilla County BioDiesel
Costilla County is a sparsely populated, agricultural county in southern Colorado that has built a very unique facility: a biodiesel plant that makes biodiesel from locally grown canola. The biodiesel is used to power the county's fleet of vehicles: road graders, dump trucks, tractors, etc. The plant's bi-product, a canola cake that remains after the oil has been pressed from the seed, is sold back to local farmers as animal feed. Neither the major inputs nor the outputs of the plant are trucked long distances-- it is a truly local product.

This solar thermal system was installed at a local County-owned biodiesel plant for the purpose of heating raw oil feedstock (canola oil) before being transferred to a chemical reactor to be made into biodiesel. The County had previously heated the oil with electricity, and was looking for a way to utilize renewable energy in their production process.

Nine Sun Earth EC-32 collectors are roof-mounted on the metal building that houses the plant. Cold oil is pumped from a storage tank into the solar tank, and is heated by means of internal copper heat exchanger coils. Hot oil is drawn off the top half of the tank in 100 gallon batches and pumped to the reactor vessel where it is combined with several chemicals and processed into biodiesel at a target temperature of 180 F. The system was designed to heat 200 gallons of oil per day, and is expected to save the county a significant amount of electricity that would have otherwise been used to heat the oil. In addition, the system will improve production by decreasing the amount of time that it takes to get the oil up to temperature. A Modine hydronic fan coil, sized for the heat output of the collectors, is installed as a backup heat dissipator to prevent overheating of the collector loop during holidays and vacations when the plant is inactive.