Grantee Research Project Results

2013 Progress Report: Renewable Energy-Powered Bulk Milk Cooling for Smallholder Dairy Farmers

EPA Grant Number: SU836006
Title: Renewable Energy-Powered Bulk Milk Cooling for Smallholder Dairy Farmers
Investigators: Kisaalita, William S.
Current Investigators: Kisaalita, William S. , Rush, Bryan , Ndyabawe, Kenneth , Ssonko, Richard
Institution: University of Georgia
EPA Project Officer: Page, Angela
Phase: II
Project Period: August 15, 2011 through August 14, 2012 (Extended to August 14, 2014)
Project Period Covered by this Report: August 15, 2012 through August 14,2013
Project Amount: $75,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2011) Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Awards , P3 Challenge Area - Air Quality , P3 Challenge Area - Sustainable and Healthy Communities , Sustainable and Healthy Communities

Objective:

• Objective 1: Construct and start-up a cow-dung anaerobic digester to produce biogas and demonstrate that the regeneration of zeolite can be accomplished under this field condition.
• Objective 2: Install a second generation renewable-energy (biogas) powered milk cooler on a small-scale dairy farm and show that the cooling achieved in the laboratory (to 4 ^oC within 4 hours) can be replicated under field conditions and establish the cooling cost per liter of milk.
• Objective 3: Establish the greenhouse gas (methane) production from smallholder farm cow dung open pits. This will enable a more accurate estimate of difference in greenhouse gas-methane - emission due to wide spread cooler use.

Progress Summary:

Objective 1: Construct and start-up a cow-dung anaerobic digester to produce biogas and demonstrate that the regeneration of zeolite can be accomplished under this field condition.

As we indicated in the previous report, we had anticipated the prototype being ready to test in Uganda by December, 2012. We were unable to achieve this goal as it has taken longer to design and test the second component of the system, the zeolite generator. Experiments to determine the optimal temperature for zeolite regeneration of 200^oC were determined with a high temperature oven, acquired during Phase I. We are glad to report that we now have a design of the regenerator (Figure 1, page 2) that can achieve easily the 200^oC, as shown in Figure 2 (page 2). Because, we do not have biogas in our laboratory at the University of Georgia, we have used propane to test the regenerator. We know that propane has a higher energy density than biogas. To ascertain that biogas will work well, we have conducted experiments where we lower the rate of energy input. In all scenarios, we reach the target temperature; it just takes longer as the rate of energy input decreases. Key features of the design include the unique hot gas flow we have used, excellent insulation and use of a “chimney”.

We pointed out in the previous report that instead of constructing a 24 m³ digester (CAMARTC design); we decided to repurpose 10 m³ polyethylene water tanks that are readily available in Uganda.  The second modification that required innovation was sealing the top of the water tank to achieve anaerobic conditions. Because of the high pressures that are generated, we went through two seal designs that all failed in the field. We have now solved the problem by using two polyethylene water tanks; one 10 m³ in the ground and one 8 m³ inverted face down into the larger tank (Figure 3, page 3). As biogas is produced, the small tank rises and the gas is withdrawn via a valve operated tap on top. As shown in Figure 3. This design is being successfully operated at Smallholder Fortunes facility. The gas is currently used for cooking; as we get ready to test the whole system at the facility.

These unanticipated problems have required more resources and time. As such, we have devoted less time on Objective 3. But we have requested for a no-cost extension that was granted. This will give us the time needed to complete the project as proposed. We are also pleased to announce that we have won a $1,000,000 grant from USAID to test the cooler among 50 smallholder farmers in Wakiso district and to transition the project to a business in the last year of the grant, by locally manufacturing the units and scaling to other districts.

Figure 1. Zoelite plates regenerator. Left: showing hot gas inlet from the sides; the bottom inlet is not show. Middle: showing the zeolite plates’ placement. Right: showing the “chimney and powering from propane. In the field, propane will be replaced by biogas, although some of the customers we are talking to are attracted to the idea of using propane.

Figure 2. Typical temperature profiles at three locations: bottom (blue, 10 cm from bottom of chamber), middle (red, 21.25 cm from bottom of the chamber), and top (green, 31.5 cm from bottom of the chamber). Left: 100,000 Btu burner; a fast temperature rise was obtained and after one hour, the propane input was reduced drastically and it was interesting that a small amount of propane was needed to maintain the temperature. After turning off the propane, it took over one-and-a-half hours to cool down, suggesting excellent insulation. Right: 75,000 Btu burner. Detailed experiments are ongoing to establish total energy requirements and operation procedure to minimize energy requirement.

 

Figure 3. The current two polyethylene water tanks digester. On the left, under the canopy, the larger tank is in the ground; its top was cut of and the small tanks’ top was cut as shown on the right and lowered into the larger tank upside down. Under the canopy, the small tank is raised by the pressure of biogas being produced. The flexible tubing that is connected on a valve through which biogas is piped to a burner in the nearby demonstration building is visible. The original inlet and outlet brick structures are still being used for the same purpose.

Objective 2: Install a second generation renewable-energy (biogas) powered milk cooler on a small-scale dairy farm and show that the cooling achieved in the laboratory (to 4 ^oC within 4 hours) can be replicated under field conditions and establish the cooling cost per liter of milk.

As explained above, due to delays in perfecting the regenerator, this study component has been delayed. It will be completed in the third year (a no-cost extension has been granted).

Objective 3: Establish the greenhouse gas (methane) production from smallholder farm cow dung open pits. This will enable a more accurate estimate of difference in greenhouse gas-methane - emission due to wide spread cooler use.

As indicated in the previous report, the original experimental design that called for work on many smallholder farms was too ambitious for the budget level. The work under this objective was restricted to piloting procedures and generating preliminary data that will be used in support of a larger proposal for a wider study. This work has been limited to two Smallholder Fortunes cow dung pits. Using the set-up described in the previous report, gas samples were collected. But unfortunately, the samples were not analyzed. The portable device procured in the USA could not be transported to Uganda, because the calibration gases are considered hazardous and can tot flown to Uganda. A source for the gases was indentified from South Africa and the gases will be available this January, so this work can commence.

Journal Articles:

No journal articles submitted with this report: View all 5 publications for this project

Supplemental Keywords:

Well water, drinking water, effluent-irrigation, biosolid

Progress and Final Reports:

Original Abstract

2012 Progress Report

Final Report

P3 Phase I:

Renewable Energy-Powered Bulk Milk Cooling for Smallholder Dairy Farmers  | Final Report