Grantee Research Project Results
Final Report: Development of a Robust Anaerobic Biogas System for Use in Developing Countries
EPA Grant Number: SU834724Title: Development of a Robust Anaerobic Biogas System for Use in Developing Countries
Investigators: Skerlos, Steven J. , Cook, Sherri , Dorer, Heather , Hwang, Jinhyung , Li, Zijia , Collins, Michael , Schulman, Bryan , Frederick, Tiffany , Nagal, Adam , Kaniz, Nasrin , Twill, Kevin , Coir, Elizabeth , Bandari, Aditiya , Sung, Catherine , Gupta, Anisha , McCleary, Emmie
Institution: University of Michigan
EPA Project Officer: Page, Angela
Phase: I
Project Period: August 15, 2010 through August 14, 2011
Project Amount: $9,888
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2010) RFA Text | Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Air Quality , P3 Awards , Sustainable and Healthy Communities
Objective:
The University of Michigan Biogas Team, working alongside the nonprofit organizations Green Empowerment and the Phoenix Association, visited rural communities in Nicaragua during the summer of 2009 in order to learn about the success and failures of different renewable energy projects, in particular anaerobic digesters. After visiting several sites and helping to construct two anaerobic digesters, the team noticed many challenges faced by these communities. One challenge is the lack of available energy, as the villages we visited were only recently connected to the nation’s power grid and most homes can only afford one light bulb. The villagers were also dependent on wood for cooking and heating (Figure 1). Obtaining wood is labor intensive and is becoming increasingly difficult as deforestation worsens the areas’ environmental situation. Health problems due to cooking with wood is another issue for these communities; females cooking all day are constantly exposed to smoke and particulate matter from wood burning and are at risk for respiratory and eye irritation problems. However, since the head of the household does not usually know conditions in the kitchen and health services are rare, these health problems are usually not addressed.
Figure 1. Traditional wood stove used for cooking; pictured in Nicaragua.
The team believes that the severity of these problems can be reduced by the implementation of anaerobic digester systems for families in these rural communities. Anaerobic digestion converts organic waste materials into several byproducts, such as methane gas and nutrient-rich effluent. Several different designs exist for anaerobic digester in Nicaragua, some with and without cement bases (one example in Figure 2). Economically, the digesters provide energy for cooking and heating and reduce the use of other fuels such as petroleum products or wood, which reduces current, periodic expenses for fuel. The nutrient-rich fertilizer from the effluent can increase crop yields if used as a fertilizer; extra crop yields or the selling of this fertilizer to others can provide a source of income. Socially, burning the methane in the biogas offsets wood burning and will improve indoor air quality; this improvement of the females’ main environment can reduce health problems and increase quality of life. Digesters can also reduce labor required from collecting wood, and allow families to become more independent by supplying a sustainable energy source. Environmentally, by offsetting wood burning, deforestation and erosion can be reduced. By using biogas, emissions from petroleum products and animal wastes that are left on the field will also be reduced.
Figure 2. Half-bag digester with a cement base with a plastic top; pictured in Nicaragua.
Summary/Accomplishments (Outputs/Outcomes):
At the start of the Project Phase I, the student team was divided into four sub-teams that focus on different aspects of anaerobic digestion system: environmental and health assessment sub-team, the experimentation sub-team, design sub-team and social venture sub-team. Each of these teams contributed their efforts to Phase I in different ways.
The environmental and health assessment sub-team compiled and thoroughly analyzed the material and energy inputs of traditional wood stoves, the currently implemented digesters and the team’s improved digester design. Using this data, the sub-team performed a life cycle assessment (LCA) using life cycle inventory databases found in SimaPro and the EPA’s TRACI impact assessment method. This sub-team discovered that compared to the traditional wood stove, anaerobic digesters are overall worse for global warming and ozone depletion. However, they also found that anaerobic digesters substantially improve the global environmental conditions by reducing several emissions, such as those in the acidification and carcinogens categories (Figure 3). Local environmental impacts were improved by decreasing deforestation and reducing particulates emitted from burning wood in the kitchen.
Figure 3. Relative magnitude of emissions for respiratory effects, acidification, and ecotoxicity potentials for three scenarios (emissions relative to the Wood scenario).
The experimentation sub-team performed laboratory experiments to confirm their expectations that dry digestion is practical and also to investigate the effects of mixing on biogas production. The sub-team designed experiments to mimic local waste types using batch reactors (Figure 4).
Figure 4: Setup of the bench-scale dry digestion and the lab-scale mixing experiments.
The sub-team discovered that biogas production in dry conditions is definitely possible and had inconclusive results for the impact of mixing on biogas output due to technical complications.
The design sub-team built and tested a cost effective mixer (Figure 5) and a water recycling device (Figure 6). The mixing apparatus can serve as a retrofit to the currently failed anaerobic digesters; it can also be an added feature for newer digesters that use less water and could benefit from more mixing. Recycling water from the effluent to the influent can reduce water requirements to operate the digester, and the device is made with locally available materials. This sub-team focused on making the system robust and reducing potential failures of the biological process while trying to reduce resources needed to maintain the system.
Figure 5. Digester Mixer made out of PVC components and Cement
Figure 6. Water Recycling System made of polyester
The social venture sub-team investigated the potential for a business to start from the team’s improved digester product. They performed a customer discovery in which interviews with world-wide NGOs, corporations and health professionals helped them form a customer profile to market the digester to and comprehend how businesses are both started and run. A business model that tries to sustainable implement anaerobic digesters in developing countries is being developed.
Conclusions:
The University of Michigan Biogas team has developed an improved anaerobic digester to replace the common firewood stove as an environmental, health and social benefits to its users. The team’s work and results has made it clear that the improved digesters hold the potential to succeed sustainably in Nicaragua. The team has proven it has the resources and knowledge to go forward and implement its improved anaerobic digester design into the field.
Supplemental Keywords:
alternative energy, animal waste to energy, developing nation sustainable energyThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.