Grantee Research Project Results
Final Report: Wind-Actuated Vibrating Electrochem (WAVE) Digester
EPA Grant Number: SU836778Title: Wind-Actuated Vibrating Electrochem (WAVE) Digester
Investigators: Pisciotta, John M
Institution: West Chester University of Pennsylvania
EPA Project Officer: Callan, Richard
Phase: I
Project Period: October 1, 2016 through September 30, 2017 (Extended to September 30, 2018)
Project Amount: $14,490
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2016) RFA Text | Recipients Lists
Research Category: Sustainable and Healthy Communities , P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources
Objective:
This project seeks to address Public Health and business needs in the water energy nexus. Many rural agricultural areas around the world lack access to an electric power grid or clean water supply. Bloomberg New Energy Finance estimates that the roughly 1.2 billion people in want of grid access spend an estimated $27 billion per year on electricity; often in the form of batteries which may end up in landfills. Since energy is used to treat wastewater, clean water is a related resource that is not always available in developing nations. Waterborne pathogens including bacteria, viruses and various parasites cause 2.2 million deaths per year with most occurring in the developing world (Ramirez-Castillo 2015).
Although renewable energy, like solar, is abundant and freely available to developing nations, it is not available on demand, for instance at night. Storage of renewable energy in batteries is costly and disposal of old batteries can result in toxic heavy metal contamination. Pumped hydro storage is the leading large-scale energy storage method but is not cost effective at the household to village level. Water electrolysis provides yet another possible means of storing renewable energy as hydrogen. Water electrolysis requires expensive precious metal catalysts (ex. platinum) for high efficiency and therefore is not a viable option for much of the impoverished world lacking access to the electric grid. Here we propose a wind actuated electrochemical digester that treats wastewater while reducing CO2 to methane for renewable energy storage and delivery. The name of this device is the WAVE digester to illustrate that it is an efficiently wind-mixed device.
Summary/Accomplishments (Outputs/Outcomes):
Phase I testing identified vertical-axis Savonious type turbines equipped with rotating electrical contactors (i.e. slip rings) as the optimal configuration for the construction of Wind Actuated Vibrating Electrochemical (WAVE) digesters. Savonious turbines feature scoop type blades that can be started at low wind speed. The WAVE digester concept was validated during Phase I testing as methane gas was formed inside 100 ml digesters, as determined by GC headspace gas analysis. Organic carbon was simultaneously consumed, as determined by spectrophotometric COD analysis, while bioelectrochemically-generated electrical current was detected by potentiostat. The presence of exo-electrogenic bacteria in WAVE digesters was confirmed by 16s rDNA gene sequence analysis. Metagenomic denatured gel gradient electrophoresis (DGGE) analysis indicated distinct microbial communities were selected for inside of electrically-connected digesters compared to conventional anaerobic digester. Quantitative analysis of methane production did not indicate a significant difference in methane production in stationary, electrically-connected controls versus WAVE digesters although both produced greater amounts of methane versus conventional anaerobic digesters.
Phase I testing thus identified certain limitations to our initially preferred bioelectrochemically operated embodiment of the WAVE Digester. These limitations included low biogas production, lack of immediate start up of gas formation and possible difficulty maintaining strictly anaerobic conditions inside actively rotated digesters. In response, the WCU team devised and tested an improved electrochemical system for storing greater amounts of renewable energy as hydrogen gas while quickly disinfecting water. Unlike CH4, release of energy stored as H2 does not produce CO2 and it can be converted directly to electric current. The new purely electrochemical design provides unskilled workers with an easy to implement solution to the problem of how to store intermittent renewable energy, like solar. The electrochemical embodiment is ideally suited for developing nations and developed countries alike because it can be constructed largely from society's waste materials, such as scrap metals and bottles. The electrochemical version, unlike the bio-electrochemical digester, does not require strictly anaerobic conditions. Therefore, it is less prone to failure and can be operated in a "plug and play" manner. The system effectively eliminated 99% of fecal coliforms in 10 min at 15 V as it stored energy as hydrogen gas and formed valuable Cu2(OH)3Cl (TBCC) mineral product, as determined by X-ray diffraction analysis.
Three advantages should propel adoption and use of our new "CrystalLogic" WAVE Digester embodiment. The first advantage is instant startup of hydrogen gas production. The second is effective disinfection of waterborne T4 virus and bacteria (99+% reduction in 10 min). The third benefit of this system is that it produces useful, valuable mineral products (ex. atacamite or TBCC, Fig. 1) as a crystalline coproduct that is already widely used in agriculture and in animal feed.
Fig. 1 Crystal structure of Cu2(OH)3Cl (TBCC) showing coordinate bonding (Scanning electron microscope image from Liu et al., 2017).
Conclusions:
In conclusion, the electrochemical device embodiment can serve developing as well as developed markets in multiple ways. The long-term goal is to literally empower socioeconomically disadvantaged people while promoting public health. TBCC as a locally sourced mineral coproduct, can be used as a fungicide or as an alternative to antibiotics in animal feed (Aquilina et al., 2011). However, to generate early revenue and demonstrate profitability, for our initial customer base we plan to target US schools and continuing educational facilities, like those dedicated to the training of solar and other green collar workers. Even today US jobs in the solar field number around 300,000; significantly greater than jobs in the coal industry. It will be important to recruit this portion of the work force as customers and advocates. For the younger demographic, we plan to sell educational kits and packaged lessons and labs that use the"CrystalLogic" system to teach and demonstrate concepts in sustainability. These include clean energy capture, energy storage and manufacturing through green chemistry. Drs. Pisciotta and Mbuy are well suited for this as they are professional educators with experience in Public Health, lesson design and educational outreach (Reyher, 2012). The competitive advantage of this apparatus relies on the value proposition that it stores renewable energy, generates useful chemical products and concurrently disinfects waterborne pathogens.
References:
Aquilina G., et al. 2011. Scientific Opinion on safety and efficacy of di copper chloride trihydroxide (tribasic copper chloride, TBCC) as feed additive for all species. European Food Safety Authority. EFSA Journal. 9(9):2355
Liu X., et al. 2017. Paratacamite phase stability and improved optical properties of Cu2(OH)3Cl crystal via Ni-doping. Materials & Design. 121(5)194-201.
Ramirez-Castillo FY., et al. 2015. Pathogens. 21;4(2):307-34.
Reyher, CM. 2012. Waterborne pathogens: detection methods and challenges.
Journal Articles:
No journal articles submitted with this report: View all 5 publications for this projectSupplemental Keywords:
Water Disinfection, Energy Storage, Fungicide, NanomaterialRelevant Websites:
Progress and Final Reports:
Original AbstractThe 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.