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Solar CITIES Biodigester Research Project at Rosebud Continuum Sustainability Education Center with Patel College of Global Sustainability

October 3rd, 2017
By: T. H. Culhane


Hurricane Irma, coming on the heels of Hurricane Harvey, showed the southern US and southern Florida that the era of climate uncertainty and intensified storms has the potential to wreck economies and disrupt lives. In the aftermath of such storms, millions of people are left without power, potable water, and the ability to flush toilets. This creates many health hazards such as overflowing septic systems and the absence of scheduled garbage pickup.

The Patel College of Global Sustainability (PCGS) professor Thomas H. Culhane, however, was one of the few lucky people in the Tampa area for whom a lack of municipal power, water, garbage pickup and sewage system functioning was no problem. In fact, the aftermath of the hurricane was an opportunity to show just how well the Food, Energy, Water and Nexus technologies that he, Professors Joseph Dorsey, Kebreab Ghebremichael and David Randle and their students study actually works.

On the property where Culhane lives in Land O Lakes, PCGS professors and students are helping a local family, the Bishop Family of Bishop Construction Co, create a non-profit field research site. This site is called the Rosebud Continuum Education Center where they have already built three 9-foot-tall and wide cement Chinese biodigesters. They have also installed off-grid solar energy systems and vertical hydroponic growing systems, like the kind seen in Disney's EPCOT, and rain-water capture systems. These systems kept Culhane and his wife going in the absence of municipal power and a shortage of gas and propane – particularly the biodigester systems, which safely turn food and toilet wastes into fuel and fertilizer.

If there was a difficulty in the days leading up to the hurricane and its immediate aftermath, it was getting access to enough food waste to keep producing at peak levels. For days preceding Irma's approach, the Bishops picked up barrels of food scraps from a nearby Beef O'Brady's restaurant, but this one small restaurant does not produce enough waste to keep all three digesters going and people were trying to conserve gasoline, which had run out from the gas stations. When there is enough waste (roughly three 55 gallon barrels a day is the desired amount -- 1 barrel per digester per day) the digesters can produce enough bio-methane to keep a generator running. For this reason, the PCGS Professors and their students are seeking to create partnerships with other institutions – restaurants, supermarkets and school cafeterias in particular, who are interested in providing the organic residuals that are a problem for them but a solution for the research site in sustainable living.

In addition to needing food waste delivered on a regular basis, the initiative needs better waste grinding systems to expedite the process and increase its efficiencies.

Also, to really show how organic refuse can be an asset rather than a liability in South Florida, the Rosebud Continuum site (along with others in Patel's UN Observatory areas in the Tampa St. Petersburg areas) need funding to construct more digesters. This would allow them to get data and do the research to show precisely which wastes produce the best results, in what quantities and with what feeding schedules. This would produce the data that would allow them to customize this solution for different sectors in the region.

While large scale digesters are well known to industry insiders (Disneyworld, for example, has a huge Harvest Power Co. biodigester that produces 5.2 Megawatts of Electricity from the theme park's restaurant wastes) there has been very little research into small community and home scale digesters. This research would be the most useful to disaster impacted communities, particularly when infrastructure, roads and power lines are down. It is Dr. Culhane's hope that, just as the aftermath of this last hurricane was made easy for Culhane by the biodigesters and at Rosebud, future hurricane effects can be easily dealt with through the expansion of our program throughout the region.