Progress 09/01/11 to 08/31/14
Outputs
Target Audience: The target audience of this project are rural agricultural communities throughout Hawaii and the American Pacific Region, who have a keen interest in sustainable development. Whereby they would greatly benefit through the introduction of anaerobic digestion (AD) technology and the appropriate stewardship of our island resources. Throughout this project, we have worked closely with the University of Hawaii at Manoa (UHM) - College of Tropical Agriculture and Human Resources (CTAHR), along with the Molecular Biosciences & Bioengineering (MBBE) Department and the Hawaii BioEnergy Producers (HBP) Cooperative; to include working in the rural community of Waianae moku, on the island of Oahu, in the City & County of Honolulu, Hawaii - Congressional District 2. Waianae is a rural community in a district that is predominately populated with underserved Native Hawaiian Homesteaders and local minorities, who have a keen interest in supporting community-based economic development projects - promoting economic growth within the local economy, while increasing environmental sustainability throughout. Changes/Problems: In 2008, the production of corn ethanol and biodiesel increased with the implementation of federal mandates and incentives to produce and utilize more biofuels. In Hawaii, the production of biodiesel from oil seed crops, such as Jatropha curcas, a tree crop that grows very well in the islands. However, the production biodiesel, also produces a significant amount of by-product residues, such as Jatropha seedcake, fruit hulls and crude glycerin. In fact, Hawaii presently consumes 270 million gallons of diesel, annually. Therefore, in order to produce several million gallons of Jatropha biodiesel, producers would also have to deal with several thousand tons of Jatropha by-product residues that readily accumulate on the farm - awaiting proper disposal. Observantly, OmniGreen Renewables (OGR) LLC submitted a project proposal to develop a proper treatment application to better manage on-farm biomass accumulation, utilizing anaerobic digestion (AD) technology, in which, microbes break down the organic waste materials, into bio-chemicals that are then converted into biogas (a mixture of 65-75% methane and 25-35% CO2). The biogas is then cleaned and utilized to generate power and heat, to effectively operate a small biodiesel facility and a solar food-drying plant that utilizes the produced heat to assist in dehydrating food products, during cloudy days and over-night hours. Therefore, all of the waste produced from the biodiesel and dehydration production are then processed through the AD system and reduced to a smaller fraction of materials, called digestate (an AD effluent), which as a bio-fertilizer that contains more micronutrients than chemical fertilizers, which replenishes the soil and its moisture retention capacity for long lasting soil fertility. This material is readily used to increase crop production, which actually creates a virtuous cycle that improves biogas output and farm productivity. Through this project, OmniGreen Renewables has effectively accomplished the objectives listed within the project proposal, in which, the project was able to: 1.) Determine the appropriate quantities of Jatropha seedcake, hulls and crude glycerin residues, to be blended with other co-digestion substrates to assess the optimum loading rates, leading to a stable process and adequate retention time, within the digester that proves to be the most efficient in the production of methane gas. 2) Assure long term process stability. 3) Optimize throughput volume and size of the digester capacity that would prove to be the most efficient for the system and to adequately handle the volume of feedstock produced by the biodiesel production on a daily basis. 4) Measure rates of methane production that will sustain a power block's output of thermal and electrical energy to properly meet the demands of the biodiesel operation and the biogas-solar dehydration system. 5) Estimate whether or not the system can provide sufficient biogas output to become profitable in its surplus energy sold to the utility grid. 6) Optimize the quantity and quality of thermal energy available to the integrated dehydrator. Given the maximum availability and collection of feedstock, at an approximate average of 2.3 tons/day, the stated feedstock blend (shown below) reports the digester's loading capacity to be at 1.25 tons/day of co-digestion feedstock fed into the AD system. Therefore, feedstock blend consisted of approximately 0.20 tons of Jatropha Seedcake; 0.15 tons of Moringa Leaf; 0.08 tons of Glycerin/FOG; 0.37 tons of Food Processing Residues; and 0.45 tons of Commercial Food Waste. Note: Utilization of this feedstock blend also demonstrates our ability to process all types of feedstock (including commercial food waste) to maximize the use of feedstock with the highest biogas potential, such as the Jatropha, Moringa and Glycerin/FOG. This blend was subject to changes, upon further trials and discussions conducted throughout the project. Any change in the blend would result in a slight change of output in terms of gas and power generation. Feedstock Blend Summary: Co-digestion Feedstock Daily Availability (Year) Tons Feedstock Blend (Daily) Tons Jatropha Seedcake SFeedstock Seedcake Seedcake 0.20 0.20 Moringa Leaf 0.15 0.15 Glycerin/FOG 0.25 0.08 Food Processing Residues 0.78 0.37 Commercial Food Waste 1.12 0.45 Total 2.30 1.25 DIGESTER PERFORMANCE Methane Yield/Production Loading 1.25 tons of co-digestion blend each day, the system has consistently produced approximately 212.8 m3of biogas, capable of generating an average of 19 kW of electricity per day. Total Biogas production is 212.8 m3per day Total MMBtu production is 4.52/day, 135.6/month and 1,649.8/year. Total electricity production is 447 kWh/day, 13,406/month and 163,155/year. Impact: The amount of energy produced is sufficient to power approximately 14 U.S. homes with electricity, or 16 U.S. homes with natural gas. Methane Yield 1.25 TONS PER DAY Feedstock Availability (Daily) Use (Daily) Biogas output, m3/ton Methane Concentration Biogas output, m3/day Glycerin/FOG 0.25 0.08 731 65% 58.4 Moringa Leaf 0.15 0.15 104 63% 15.6 Jatropha Seedcake 0.20 0.20 468 62% 93.6 Food Processing Residues 0.78 0.37 37 58% 13.7 Commercial Food Waste 1.12 0.45 70 62% 31.5 Total 1.25 212.8 Note: Output results are always subject to change, depending on various factors, such as feedstock blend, auxiliary gas consumption and generator efficiency. In conducting the project, utilizing a modular AD system, operating in a modified plug flow configuration (single-stage/batch process), with a loading capacity of 1.25 ton/day - proved to be inefficient, cumbersome and inflexible throughout the production of a higher quality methane gas to be produced. Thus, through the project's research and feedstock trial accomplishments, many of the common AD issues were flushed-out and proved to be consistently inefficient and time consuming, using this particular operational system. At the completion of the project, an assessment of the information obtained help to identify and confirm the need for a more productive AD system design, which would improve production efficiency and flexibility, while increasing the digester's loading capacity - through a more proficient process - utilizing a continuous mix configuration, operating as a more flexible: high solids multi-stage AD system. The project's new system design stands to enhance AD production, by upgrading the system's configuration, from a plug flow single-stage process, to a more proficient continuous mix configuration that is designed to operate as a high solids multi-stage AD system. This design is a far more efficient, sustainable and productive biogas process, surpassing the single-stage process, used throughout the project. This innovative AD design features a modular system that is compact, scalable and containerized in 5 forty-foot shipping containers, which facilitates shipping logistics and the on-site delivery and final assembly of this 2.5 ton/day digester capacity AD facility to remote locations throughout the American Pacific Region. From the very onset of the project, we have been involved with the University of Hawaii - College of Tropical Agriculture and Human Resources (CTAHR) and the Molecular Bioscience & Bioengineering (MBBE) to assist in the project objectives and lab research work. In addition, we have been working closely with community-based organizations, like the Hawaii BioEnergy Producers (HBP) Cooperative, providing project development updates and the disseminating project information (Farm Production Plans) and rural development projects. What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest? Through the completion of this project, we were able to better assess the common issues and limiting parameters, presented in the treatment of on-farm biomass waste streams: utilizing anaerobic digestion (AD) technology to off-set, reduce and dispose of on-farm generated wastes. Thus, effectively defining the parameters involved with detailing the design, construction and operations of a multi-stage AD system that is modular, compact, cost effective, scalable and easily delivered to rural island communities in Hawaii and the American Pacific. The availability of such green technology, in rural island communities, will help to enhance the local community's capacity to properly manage, reduce and dispose of organic waste streams, by converting this biomass accumulation, into a bioenergy resources that proactively off-sets the farmers' costs for electricity, heat and fertilizer products and effectively reduces their dependency upon imported fossil fuels and chemical fertilizers. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
The goal of the project is to definitively determine the design, construction and operation of a high-solids modular anaerobic digestion (AD) facility, or biogas plant that is capable of utilizing Jatropha biodiesel residues consisting of Jatropha seedcake, crude glycerin and fruit hulls; that are mixed with other co-digestion substrates, such as Moringa oleifera, farm crop residues, processed food wastes, MSW (municipal solid wastes) organic residuals and commercial food waste products. This AD system is able to convert low-value residues into a valued renewable energy resource - in the form of biogas (a mixture of methane and CO2 gas), utilized to generate electricity and thermal energy, through a CHP (Combine Heat & Power) micro-turbine. Thus, effectively utilizing the AD treatment process to properly manage, reduce and dispose of acuminating on-farm organic waste streams. At the end of the process, a valued co-product is also produced - in the form of mineralized organic fertilizer and liquid-foliar concentrate that can be used to increase crop production and/or sold to local gardeners and farmers, as an organic soil conditioner. Therefore, through this AD process, on-farm organic waste streams are effectively transformed into value-added energy products that provides the power and heat necessary to operate a Jatropha biodiesel facility and an adjacent solar food drying plant. To where, additionally, the remaining effluent or digestate of the process is dried and concentrated into a nutrient-rich organic fertilizer/foliar concentrate that is utilized by the farmer to enhance crop production and/or sold to nearby farmers or gardeners. The overarching goal of the project is to install the final design and assembled system, as an integrated biogas-solar dehydration system, on a cooperative farm in Waianae, to illustrate the proper management, treatment and utilization of low-value biomass residues to produce several value-added product lines that will generate several revenue streams for the farm. This high-solids, multi-stage AD technology is key to efficiently generating sufficient amounts of biogas to effectively operate a 65-kW micro-turbine (CHP) system to produce clean electrical power and recoverable heat that will sustainably operate a small biodiesel production facility and solar dehydration plant. In addition, a power purchasing agreement (PPA) with the local utility, to purchase any and all of the surplus power generated that can be sold through the grid. Lastly, the system's resulting co-product/effluent, referred to as digestate (solids and liquids) is further utilized, on the farm, as a nutrient-rich organic fertilizer or can be bagged and bottled (respectively) for wholesale in the local market. Therefore, all of the organic waste generated, from both the small biodiesel production facility and solar dehydration plant, now becomes the primary feedstock for the AD system, which is also augmented with other organic substrates, which includes the receipt of commercial food-waste, food-processing residuals and MSW organics that proves to be an additional revenue stream - by charging a tipping fee - in receipt of the delivered wastes. The introduction of anaerobic digestion technology, in rural island communities, will help motivate the community's pursuit of sustainability - both economically and environmentally in these remote island regions. The project brings forward a synergistic and holistic approach that serves many of our predictable needs: in that of energy efficiency, waste-to-energy production, decentralized green energy development, job creation, reduced fossil-fuel dependency, watershed protection, regional food production, agricultural nutrient cycling, reduced greenhouse gas production and carbon sequestration. Therefore, the project's outcome has established a more appropriate AD design that pushes forward sustainable values that support the innovation, commercialization and introduction of AD technology, throughout the islands of Hawaii and the greater American Pacific.
Publications
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