Online Bioenergy Training for Extension Educators

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Purpose

The online Bioenergy Training Center provides educational training resources for Extension educators focused not only on the technical feasibility of bioenergy generation, but also on approaches and processes that assist communities in understanding the comprehensive implications of bio-based alternative energy. The intended outcome of the courses is to bring viable bioenergy projects into communities by providing Extension educators with tools and knowledge they can use to make this happen.

What Did We Do?

Developed three peer-reviewed, research-based online modular courses. Content was developed by experts from across the North Central Region. Included in one of the modules is a bioenergy and renewable energy community assessment toolkit.

Screen shot of the front page of the Bioenergy Training web site.

What Have We Learned?

The curriculum went live on the web in February 2013. We have not received any feedback on it to date. However, based on the reviews of individuals who used the bioenergy and renewable energy community assessment toolkit in 2012, it does a very good job of helping developers and communities objectively assess renewable energy projects.

Future Plans

Use the curriculum as a foundation for distance learning courses targeting other audiences.

Authors

M. Charles Gould, Extension Educator, Michigan State University, gouldm@msu.edu

Over 50 individuals participated in some aspect of curriculum development.

Additional Information

The Bioenergy Training Center web site is being revamped. It will be posted here at a later date.

Acknowledgements

Curriculum materials and training programs of ‘The Bioenergy Training Center’ were made possible through a grant from the National Water Resources Program, National Institute of Food and Agriculture, U.S. Department of Agriculture. NIFA/USDA Agreement No. WISN-2007-03790. Project Title: “Energy Independence, Bioenergy Generation and Environmental Sustainability: The Role of a 21st Century Engaged University”.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

Feasible Small-Scale Anaerobic Digestion – Case Study of EUCOlino Digestion System.

 

* Presentation slides are available at the bottom of the page.

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Abstract

While large-scale farms have typically been the focus of anaerobic digestion systems in the U.S., an emerging need has been identified to serve smaller farms with between 50 and 500 head of cattle. Implementing such a small, standardized, all-in-one system for these small farm applications has been developed. Small-scale digesters open the playing field for on-farm sustainability and waste management.

Unloading the first biodigester unit.

This presentation on small-scale digestion would discuss the inputs, processing, function, and outputs of BIOFerm™ Energy Systems’ small agitated plug flow digester (EUCOlino). This plug-and-play digester system has the ability to operate on dairy manure, bedding material, food waste, or other organic feedstocks with a combined total solids content of 15-20%. A case study would be presented that describes the site components needed, the feedstock amount and energy production, as well as biogas end use. Additional details would include farm logistics, potential sources of funding, installation, operation, and overall impact of the project.

This type of presentation would fill an information gap BIOFerm™ has discovered among dairy farmers who believe anaerobic digestion isn’t feasible on a smaller scale. It would provide farmers who attend with an understanding of the technology, how it could work on their specific farm and hopefully reveal to them what their “waste is worth”.

Why Study Small-Scale Anaerobic Digestion

To inform and educate attendees about small-scale anaerobic digestion surrounding the installation and feasibility of the containerized, paddle-mixed plug flow EUCOlino system on a small dairy farm <150 head.

Biodigester unit being installed at Allen Farms.

What Did We Do?

Steps taken to assist in financing the digestion system include receiving grants from the State Energy Office and Wisconsin Focus on Energy. Digester installation includes components such as feed hopper, two fermenter containers, motors, combined heat and power unit, electrical services, etc…

What Have We Learned?

Challenges associated with small project implementation regarding coordination, interconnection, and utility arrangements.

Future Plans

Finalize commissioning phases and optimize operation.

Authors

Amber Blythe, Application Engineer, BIOFerm™ Energy Systems blya@biofermenergy.com

Steven Sell, Biologist/Application Engineer, BIOFerm™ Energy Systems

Gabriella Huerta, Marketing Specialist, BIOFerm™ Energy Systems

Additional Information

Readers interested in this topic can visit www.biofermenergy.com and for more information on our plants, services and project updates please visit us on our website at www.biofermenergy.com. You will also see frequent updates from us in industry magazines (BioCycle, REW Magazine, Waste Age). BIOFerm will also be present at every major industry conference or tradeshow including the Waste Expo, Waste-to-Worth and BioCycle– stop by our booth and speak with one of our highly trained engineers for further information.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

Feasibility of Installation of Anaerobic Digesters at Cattle Operations and Demonstration of a Decision Support Tool

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Abstract

An online decision support tool for determining feasibility of anaerobic digestion has been developed (http://www.erams.info/AD_feasibility/). This decision support tool is specifically targeted to cattle operations in the arid west and provides general information on anaerobic digestion (AD), recommendations on the technical and economic feasibility of AD based on producer provided information on management practices, recommendations on appropriate AD technology based on user defined criteria for the system, guidance on technology provider selection, and required maintenance for operation of an AD system. The goal of the tool is to enable and empower producers to make informed decisions about AD based on unbiased information rather than relying on the biased information often provided by technology providers. In this workshop, the drivers for technical and economic feasibility for on farm AD installation will be discussed and the online decision support tool will be demonstrated.

Why Look at Anaerobic Digestion for Cattle Operations?

Anaerobic digestion is a waste management tool with many advantages, including generation of energy for on-site use. However, careful consideration must be given regarding technical and economic feasibility for installation on cattle operations. A web-based decision tool has been developed to provide technical and economic guidance to producers on feasibility of on-farm anaerobic digestion (http://www.eramsinfo.com/erams_beta/AD_feasibility/).

Home Page of Web-based Decision Support Tool

What Did We Do?

Based on commonalities found from feasibility studies conducted throughout the state of Colorado, a web-based decision tool has been developed to provide technical and economic guidance to producers on feasibility of on-farm anaerobic digestion (http://www.eramsinfo.com/erams_beta/AD_feasibility/)

What Have We Learned?

For use of conventional anaerobic digestion technology at dairy facilities, manure should be collected on concrete by scraping or flushing. Anaerobic digestion of manure collected on dry lots is not feasible with conventional technology.  Economics are favorable when on-site energy use is high and the energy produced by the digester is primarily used on-site.

Future Plans

We will continue to develop and improve the existing web-based tool. We are also working on developing an anaerobic digestion technology suitable for dry lot collected manure.

Authors

Sybil Sharvelle, Assitant Professor, Colorado State University, Department of Civil and Environmental Engineering, sybil.sharvelle@colostate.edu

Jeffrey Lasker, Research Assistant, Colorado State University

Lucas Loetscher, Research Assistant, Colorado Sate University

Additional Information

http://www.eramsinfo.com/erams_beta/AD_feasibility/

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

Next Generation Technology Swine Waste-to-Energy Project

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Abstract

* Presentation slides are available at the bottom of the page.

The Loyd Ray Farms project is the first swine waste project in the State of North Carolina to generate and transfer renewable energy credits (RECs) to a public utility.  Utilizing an anaerobic digester as primary treatment, this waste treatment system is designed to meet the Environmental Performance Standards set forth by NC law for new and expanded swine facilities through the use of nitrification/denitrification and further treatment. The system implemented at this farm utilizes anaerobic digester technology to turn raw animal waste into biogas.  The biogas is used to fuel a microturbine, generating electricity to power the environmental treatment system, and about half of the farm. Related: Manure value & economics

The farm is a finishing swine operation that houses approximately 9,000 pigs near Yadkinville, NC.  The concept for this approach was conceived by the team in 2006, followed by economic and performance modeling, permitting, and construction of the commercial-scale system.  The project was commissioned on May 27, 2011.  Funding for construction was provided by Duke Energy and Duke University, with support from USDA-NRCS and the NC Division of Soil and Water Conservation.  Google provides operational funding support in exchange for a portion of the carbon offsets created.

Loyd Ray Farms is the only innovative Swine waste system in North Carolina that generates Renewable Energy Credits for an electric utility,  which generates enough power for  the treatment system and has enough surplus electricity to power about half of the farm.  Cavanaugh collaborated in this study with Duke University, Duke Energy,  and Google with funding from NC Soil & Water Conservation and USDA/Natural Resources Conservation Service.

Forefront: Tatjana Vujic of Duke University views the meter readings

The project began as a conversation about greenhouse gas emissions, sources for renewable energy, and sustaining the state’s swine industry among Duke Energy, Duke University, Google, and Cavanaugh.  That conversation led to a project that is getting attention around the world, for its successes in combining strategies to address the concerns for generating renewable energy from agricultural sources, sustaining agriculture, and addressing farming’s relationship to climate change.

The system’s goals: generating about 500 megawatt-hours of electricity annually, reducing greenhouse gas emissions equivalent to 5,000 tons of carbon dioxide annually, reducing ammonia and odor emissions from the farm, and improving the quality of treated wastewater on the farm.”

Is Manure to Energy Important?

We will discuss the successes and challenges in partnered efforts by farmers, electric utilities, and other stakeholders in the marrying of renewable energy generation with enhanced environmental treatment and green house gas emissions reduction, including the economics of such effort.

What Did We Do?

Waste generated by the animals is flushed into an anaerobic digester where bacteria consume the waste and respire energy-rich biogas.  The biogas fuels a microturbine that generates electricity, and excess gas is flared.  After digestion, the liquid waste is further treated to achieve the Environmental performance Standards set forth by North Carolina for Innovative Swine Waste Treatment Systems.

The process by which the stakeholders came together in a partnership, the technologies and approaches selected, and the successes/challenges that can be gleaned for advancing future projects.  The Loyd Ray Farms project is the first Swine Waste-to-Energy project in the State of North Carolina to place RECs on the North Carolina Utilities Commission REC Tracking System, and is the first swine farm in North Carolina to transfer RECs to Duke Energy.  Coupling techniques to improve the environmental treatment system employed at the farm, the Loyd Ray Farm project is also the first ‘Innovative Swine Waste Treatment System’ permitted that utilizes an anaerobic digester as a primary form of waste treatment.

Presenters

William G. “Gus” Simmons, Jr., P.E. Cavanaugh & Associates, P.A., gus.simmons@cavanaughsolutions.com

Gus Simmons, lead designer, M. Steve Cavanaugh, Jr., and Marvin Cavanaugh, Sr. during the commissioning of the system.  Cavanaugh developed the concept for Duke University in an effort to create a cost-effective solution that converts swine waste into renewable energy while achieveing a superior level of waste treatment and a reduction in the carbon footprint created by the conventional waste management system.

Gus Simmons, P.E., is the Director of Engineering at Cavanaugh & Associates, a consulting firm specializing in stewardship through innovation.  An NC State University graduate with a BS in Biological & Agricultural Engineering, Gus  has worked for a major agricultural producer where he was Director of Environmental Affairs and Engineering Services, managing engineering and construction for facilities in the US and Europe.  Gus has designed, permitted, and managed over 5,000 acres of wastewater irrigation in NC, and thousand of acres of wastewater irrigation in the Western US. He has assisted many municipalities and private entitites with the development and implementation of reclaimed water systems and reuse irrigation systems, and has actively participated in alternative wastewater management strategies for the NC Pork Industry.  His recent sucessess include the engineering design of an anaerobic digester for animal waste to energy project in Yadkinville, NC which has gained world-wide recognition for its successes in generating RECs and greenhouse gas credits.

Additional Information

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

Anaerobic Digester Workforce Training Curriculum Development

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Purpose

The Cornell University PRO-DAIRY Anaerobic Digester Workforce Development Project is a project funded by the New York State Energy Research and Development Authority, aimed at developing and delivering high quality educational programs targeted to a range of workforces within the dairy farm-based anaerobic digestion (AD) sector of the clean energy field.  One of the barriers to growth of the AD industry in New York State, as identified by current AD operators, is the lack of a trained, skilled workforce to service and maintain different aspects related to the AD and biogas systems.  These courses are aimed at developing a workforce to support this need, and to eliminate this barrier to growth.

What Did We Do?

Six technical short-courses were developed, intending to provide educational training to persons who are involved in the planning and implementation of dairy farm-based anaerobic digestion systems and to those currently or who would soon be managing an operating system.  The short-courses developed are:

 

· Introduction to Farm-based Anaerobic Digestion

· Technical Feasibility of On-farm Anaerobic Digestion

· Economic Feasibility of On-farm Anaerobic Digestion and Economic Assessment Model Instruction Guide

· Practical Considerations and Implementation of Anaerobic Digestion System from Planning and Design to Construction

· Technician’s Start-Up and Operation

· Biogas Clean-up and Utilization Systems Selection, Operation and Maintenance

 

What Have We Learned?

We have learned that it is difficult to deliver technical training for jobs and a workforce that do not yet exist.  Training was mostly targeted at dairy farms currently or expecting to operate an AD and biogas system, and those that advise these farms.  The authors feel that although participant numbers were usually lower than expected, continuing to offer these courses will eventually eliminate a technical expertise barrier, helping aid growth in the field.

Future Plans

Although funding for this project has ceased, efforts will continue to serve technical schools that have interested parties that may be suitable candidates to enter the field and participate in the training programs.  As demand exists, courses will be offered to farms and their advisers across the State.

Authors

Jennifer Pronto, Research Assistant, Cornell University, jlp67@cornell.edu

Additional Information

http://www.manuremanagement.cornell.edu/Pages/Funded%20Projects/AD_Workforce_Development_Project.html

Acknowledgements

The New York State Energy Research and Development Authority was the funding organization for this project.

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

Potential Air Quality Impacts of Anaerobic Digestion Of Dairy Manure

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Abstract

Anaerobic digestion (AD) of livestock manure is better known for the economic return derived from biogas for energy rather than for its, inherent, environmental benefits. The effect of AD of dairy manure on the emissions of odor, ammonia (NH3), and greenhouse gases (GHG) including: carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4), during manure storage and also in subsequent land applications will be presented.  Air samples were collected in 10-L Tedlar bags, at pertinent locations within the AD system, and shipped immediately to the lab for odor analyses by a trained odor panel using the “Dynamic Dilution Forced-choice Olfactometer.” Measurements of GHG emissions from both AD and non-AD manure storages were made using a floating chamber and a photoacoustic gas analyzer (INNOVA model 1412).  Emissions of GHG were determined using the standard closed chamber method from field plots applied with AD and non-AD manure. Although odor analyses of collected air samples indicated increased detection threshold (D/T), odor strength (intensity) and unpleasantness (hedonic tone) decreased after AD of manure. Data indicated significantly higher fluxes of GHG from land applied with non-AD manure than from land applied with AD manure. Injection of non-AD manure further increased CH4 flux from applied manure. More than 50% emissions of CO2 and CH4 were observed during the first 3 days after manure was land applied. Emissions of GHG from the anaerobic lagoon holding AD manure, during all four seasons, were significantly lower than from the anaerobic lagoon with non-AD manure. In contrast, the reverse was observed with NH3 emissions suggesting potential increased emissions of NH3 during storage of post AD manure.

Authors

Pius Ndegwa, Washington State University          ndegwa@wsu.edu

H.S. Joo, Biological Systems Engineering, Washington State University, PO Box 646120, Pullman, WA 99164; J.H. Harrison, E. Whitefield, Animal Sciences, Washington State University, 2606 West Pioneer, Puyallup, WA 98371; A.J. Heber, J.Q. Ni, Agricultural & Biological Engineering, Purdue University, 225 South University Street, West Lafayette, IN 47907

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

Operation of Internal Combustion Engines on Digas for Electricity Production

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Presentation Summary

The purpose of this research is to review engine performance and technology issues relating to generating electricity from digester gas in reciprocating internal combustion engines. Research performed at the Colorado State University (CSU) Engines & Energy Conversion Laboratory (EECL) and published material from other organizations is utilized.

Digester gas (digas) can be used effectively in internal combustion engines for electricity production to offset operating costs and/or sell to the electric utility. Stationary industrial engines are generally employed for this purpose. Four application areas where systems have been successfully demonstrated are sewage processing plants, animal waste facilities, landfills, and agricultural waste processing systems. Digas is generated through anaerobic digestion, or biomethanization, for all these cases. There are many common engine technical issues within these areas, although the digas generation systems employed in each case are different. In this presentation issues pertinent to running engines on digas are explored. The focus is on animal waste facilities, but the presentation draws upon the other application areas for technical insight related to engine technology. Specific stationary engine types are discussed. High engine efficiency and power density are important to the economic viability of anaerobic digestion systems. Engine operational and design changes to maintain high efficiency and power density for digas fueling are analyzed. Management of engine maintenance problems is also key to economic viability. Corrosive gases contained in digas, such as hydrogen sulfide (H2S), are evaluated.

Figure 1 Methane number measurement of various gaseous fuels.

The term biogas is a broad term encompassing both digas and producer, or wood, gas. These gases are very different in their combustion properties. Producer gas is generated in a gasifier by oxidizing biomass in an oxygen-starved environment. Producer gas contains high concentrations of hydrogen (H2) and carbon monoxide (CO), a small concentration of methane (CH4), and high diluent concentrations (CO2 and N2). In contrast digas is primarily CH4 (50-80%) and CO2 (20-50%). One of the main property differences between digas and producer gas is the methane number, which is indicative of the tendency of the fuel to knock. Figure 1 shows methane number measurements of various gaseous fuels made at the CSU EECL[1]. Note that producer gas (wood gas on plot) has a methane number from 60-70, while digas gas has a methane number of almost 140. Consequently, digas is much less likely to knock than producer gas and can be operated with higher compression ratios and higher power densities. Digas is also more knock resistant than natural gas.

Figure 2 Guascor SFGLD-240, rated at 330 kWe at 1200 rpm on 500-600 Btu/SCF digas.

There are three different types of stationary engines that can be used to generate electricity from digas, which are (1) compression ignition (diesel) engines, (2) spark ignition stoichiometric engines, and (3) spark ignited lean-burn engines. Diesel engines (1) are employed by fumigating the intake air with digas. The amount of diesel used is reduced as more digas is added, resulting in dual fuel operation. Limitations on diesel displacement and the necessity of storing two different fuels are drawbacks of this approach. Spark ignition stoichiometric engines have similar operating characteristics to most automotive engines in the United States. They utilize NSCR, or 3-way, catalysts for emissions reduction that required precise air/fuel ratio control. Lean-burn natural gas engines are more efficient than stoichiometric engines and can achieve low emissions without exhaust aftertreatment. Thus, option (3) is the most desirable; it is the approach typically implemented for digas utilization in most large installations. Figure 2 shows a Guascor SFGLD-240 installation by Martin Machinery.

Lean-burn natural gas engines can be used without modification for digas installations. However, in this case the engines typically are de-rated, require additional maintenance, and suffer from reduced engine life. Some engine manufacturers offer engines specifically designed for digas, which has several advantages. Digas has unique properties that necessitate design changes to natural gas engines to achieve rated power and minimize maintenance costs. To maintain rated power the flow capacity of the fuel system must be increased, since the energy content of digas is approximately 60% that of natural gas. This is due to the high concentration of CO2 diluent[2]. Other operational changes often made are advanced timing due to slower combustion and richer equivalence ratio[3]. To maintain the same NOx level the equivalence ratio is richer because the diluent in the fuel reduces combustion temperatures. Though not typically done, higher compression ratio pistons can be added to take advantage of the higher methane number of digas, which results in improved efficiency. Corrosion resistant materials and improved crankcase ventilation are design changes often made to combat the effects of corrosive contaminants in the fuel.

Digas can contain trace levels of gases other than CH4 and CO2 such as hydrogen, carbon monoxide, nitrogen, oxygen, ammonia (NH3) and H2S. Digas H2S levels from hog and cattle digesters of ~2000-5000 ppm are typical. These levels are above engine manufacturer H2S limits (250-1000 ppm)[4]. H2S must be reduced below the respective engine manufacturer limit if the engine warrantee is to be valid. When sulfur compounds are combined with water, acids are produced in the engine oil. These acids attack the metals in the engine, causing corrosive wear. Scrubbers can be used to reduce H2S in the fuel below manufacturer limits. Two commercially available H2S scrubber technologies are iron oxides and bio-trickling. H2S reacts with the iron oxide to form insoluble iron sulfides. The material can be regenerated with air to produce pure sulfur. Iron sulfides and/or pure sulfur must be disposed of[5]. Bio-trickling involves a filter media that provides an environment for establishment of a bacteria biofilm. The H2S comes in contact with the biofilm, is solubilized, and subsequently oxidized by the microbes. Sulfur and sulfate compounds are formed as by-products and purged with recirculating water. The by-products are collected and disposed of. Bio-trickling requires more expertise to set up, but requires less maintenance long term[6]

 


[1] Malenshek M., Olsen D.B., “Methane number testing of alternative gaseous fuels”, Fuel, Volume 88, pp. 650-656, 2009.

[2] John C.Y. Lee, Peter Lau, and Thomas Teo,, “Sustainable Application of Reciprocating Gas Engines Operating on Alternative Fuels”,

Caterpillar Inc. publication, October 2008.

[3] Reinbold, E. and von der Ehe, James, “Development of the Dresser Waukesha 16V150LTD Engine for Bio-Gas Fuels”, ASME Internal Combustion Engine Division 2009 Spring Technical Conference, ICES2009-76079, May 3-6, 2009.

[4] Guascor Power, “Anaerobic Digestion Gas Fuel Specifications – Landfill and Digester Gas”, Product Information IC-G-D-30-003e, Sept 2011.

[5] Steven McKinsey Zicari, “Removal of Hydrogen Sulfide from Biogas Using Cow-Manure Compost”, MS Thesis, Cornell University, 2003.

[6] Personal Communications, 1-10-2013, Marcus Martin, Martin Machinery LLC.

Authors

Daniel Olsen, Colorado State University daniel.olsen@colostate.edu

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

Demonstration of a Pilot Scale Leach-bed Multistage Digester for Treating Dry-lot Wastes

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Abstract

Dry-lot feedlot wastes have historically been a challenging feed-stock for digestion due to the dry recalcitrant nature of the waste, and the presence of settleable sand. Leach-bed dry digestion systems could theoretically circumnavigate these difficulties but poor hydraulic conductivities are noted in the literature. In addition to the poor hydraulic conductivities there are often serious problems with system stability and operation.  A leach-bed based design which addresses the hydraulic limitations of previous systems and utilizes a multiple process stages to enhance system stability is currently under development. By adding readily available inert shear stabilizers and biodegradable porosity improvers, hydraulic improvements have been demonstrated to be an order of magnitude higher than without the modifications.  By utilizing a multiple stage process the liquid leachategenerated from the leachate beds is treated through two stages, the buffering/storage tank and the high rate methanogenic reactor. The buffering tank is a tank for the leachate to reach chemical equilibrium and to store the leachate before it is precisely metered into the methanogenic tank.  Within the high rate methanogenic reactor compounds with the leachate are converted into methane which is removed and combusted. This system is demonstrated in a 48’ long refrigeration transport trailer which is essentially energy independent under continuously operation. This system will provide support for the validation of the technology with various wastes and will also serve as a research vessel for the continual optimization of this technology.

Front of the Pilot Unit

Is It Possible to Digest Dry or Solid Manure?

This new anaerobic digestion system has been designed from the ground up based on extension work carried out on Colorado dairy and beef facilities. Previous feasibility studies conducted on these sites indicated that conventional anaerobic digestion was not a recommended technology due to a variety of economic and technical parameters.

However, upon further review, it was found that these constraints were tied to specific technologies, not anaerobic digestion in general. Using an iterative design process, a digestion system was created which could effectively address these problems. In its most basic form, it will efficiently process difficult wastes like Colorado’s dry-lot manures as well as other more conventional waste streams.

What Did We Do?

Colorado State University has a pilot system located on the Foothills Campus. The purpose of this pilot unit is to gather data about the performance of the leachate bay reactor in an integrated system and to provide design criteria for scaling this concept. The system is currently in the inoculation stage. Using a consortium of animal manures and bedding waste generated onsite, the reactors are growing the bacteria needed before further testing can commence.

Intrinsic to the design is a three phased process that is tailored to the available substrates. Solid type wastes (Typically >20% total solids) are placed into the leachate bay reactor where liquid (leachate) is passed through, slowly striping away methane forming organic chemicals.

6kW Generator with Heat Exchanger for Heat Reactors with Waste Heat

Slurry wastes (Typically <20% total solids with high suspended solids) can pass into the second stage of the process- the leachate storage tank. This vessel acts as a pre digestion vessel, solids sedimentation basin, and storage tank for the pre-digestion products. Clarified leachate, rich with dissolved organic compounds, is then pumped into the final stage- the high rate reactor. In the high rate reactor process upset is mitigated by providing a very controlled flow rate of the acidic leachate into the reactor. This moderates the pH in the reactor, allowing the methane producing organisms to operate at maximum potential. Quickly degraded waste waters such as: milk processing water, run-off lagoon water, or nearby industrial wastes can be added directly to the high rate reactor.

What Have We Learned?

Solid wastes appropriate for the leachate bay reactor are dry-lot cattle manure, crop residues, equine and poultry manures, among many others. These types of wastes were the important drivers in the breakdown of technical and economic feasibility of conventional digestion systems. Due to the design of the leachate bay reactors though, many of these constraints were avoided and these wastes instead play a powerful role in this systems effectiveness by allowing digestion of often overlooked waste products. Related: Update on this project presented at the 2015 Waste to Worth conference in Seattle.

Manure Loading Dock with LBR

Future Plans

Extensive infrastructure has been built into this pilot unit to facilitate monitoring and logic control of this facility. Ongoing work will be to build out this sensing network. 

Important design parameters will be teased out of the collected data to guide the development of optimization models. With the use of these models, the system can be further modified. Potential technological enhancements include: nutrient recovery from leachate, various flushing procedures to reduce salt loading, and digestion of ligno-cellulotic by-products.

Authors

Sybil Sharvelle, Sybil.Sharvelle@colostate.edu

Lucas Loetscher, Graduate Reseach Assistant, Colorado State University

Sybil Sharvelle, Assistant Professor, Colorado State University

Acknowledgements

  • Colorado Agriculture Experiment Station
  • Colorado NRCS
  • Colorado Bioscience Discovery Grant
  • Colorado Governors Energy Office

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

Money from Something: Carbon Market Developments for Agriculture

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Abstract

* Presentation slides are available at the bottom of the page.

For more than a decade, the potential to earn revenue from climate-saving activities in agriculture has been touted throughout farm-related industries. This presentation will assume a basic knowledge of the concept of carbon markets as a kind of ecosystem service market. The focus will instead be put on current market opportunities and the importance of learning from past mistakes. Included in the discussion will be carbon offset opportunities for methane capture from manure digesters and composting and nitrous oxide reduction from controls on nitrogen fertilization. Participants will learn about voluntary and compliance market opportunities and the value of offsets versus transactions costs in today’s markets. Sources of market information will also be discussed.

Topics:

  • Ecosystem services markets: Carbon credits and more.
  • Types of offsets relevant to livestock and crop producers (e.g., methane and nitrous oxide).
  • Rules of the road: How to read the key parts of project protocols.
  • Once and future markets: Consider the differences between voluntary and compliance markets.
  • Show us the money: Have any producers really made money from carbon markets?

Purpose

During the past decade, the potential to earn revenue from greenhouse gas reductions in agriculture, especially from anaerobic digestion projects, generated some enthusiasm for this emerging ecosystem market. In 2005, dairies in Washington and Minnesota received the first carbon credit payments for their digesters through the Chicago Climate Exchange (CCX), a pilot cap-and-trade market established in 2003. With the failure of the 111th Congress to complete passage of a national cap-and-trade law in the summer of 2010, the CCX closed shop. What has happened since that time? What is the potential today for livestock producers to benefit from carbon markets or carbon pricing? We look at current markets and summarize the opportunities.

What Did We Do?

The Washington State University (WSU) Energy Program monitors technology, policy and market developments about anaerobic digestion as part of its land-grant mission to support industry and agriculture in Washington state. Because of the potential value of digesters to dairy producers, we follow developments in a wide range of existing and potential ecosystem markets, including renewable energy and fuels, carbon/GHGs, nutrients, and water. Preparation for this presentation included surveys of academic and popular literature, interviews with project developers and market insiders, and analysis of the participation in carbon trading by existing livestock digester projects in the U.S.

What Have We Learned?

The existing landscape of livestock anaerobic digestion projects illustrates three major types or models of carbon market finance: utility-based programs, voluntary carbon markets and compliance-based cap-and-trade markets.

Utility-Based Opportunities

Vermont is home to at least 15 operational dairy-based digesters. Only two digesters serve farms with more than 2,000 cows. Of the balance, about half are below and half above 1,000 cows. All of the Vermont digesters produce renewable electricity and participate in one or more utility-based incentive programs. One example is the Vermont’s Sustainably Priced Energy Enterprise Development (SPEED) program, which establishes standard offer contracts between utilities and renewable energy project developers. The goal of the SPEED program is to support in-state production of renewable power from hydro, solar PV, wind, biomass, landfill gas and farm methane with an overall portfolio target of 20 percent by 2017.

A key mechanism of the program is the long-term (20-year) Standard Offer contract and default pricing for the different types of renewable power. Default prices were calculated to allow developers to recover their costs with a positive return on investment. The default prices established for the first two rounds of farm methane projects were $0.16/kWh and $0.14/kWh, respectively. This compares to an average retail price of $0.146/kWh for electricity in the state. The default prices do not account for the environmental attributes of the green power for farm methane projects.

Many of the Vermont digesters participate in the Cow Power Program, established by  the former Central Vermont Public Service (CVPS), now a part of Green Mountain Power, in 2004. The Cow Power Program offers customers the opportunity to purchase the environmental attributes (renewable energy and GHG reduction) from participating dairy digester projects at a rate of $0.04/kWh. This value was passed along to the suppliers of the dairy-based green power.

These two Vermont programs continue to operate in tandem and provide maximum benefit to Vermont’s diary digester projects. By one estimate, customers participating through the Cow Power program have provided to dairy digester operators more than $3.5 million in value for the environmental attributes created in the past eight years.

Other examples of this type of type of utility-based standard offer or incentive pricing for farm power can be found in North Carolina and Wisconsin.

Voluntary Carbon Offsets Opportunities

Voluntary carbon markets are built on decisions by utilities, corporations, and other businesses to offset their carbon footprint impacts through the purchase of third-party verified carbon credits. While the voluntary carbon market has suffered ups and downs, especially during the recent economic downturn, corporations continue to respond to pressures such as corporate stewardship policies or carbon disclosure programs that require accounting for environmental and greenhouse gas impacts. 

The voluntary market is inhabited by both nonprofit and for-profit organizations that bring sellers and buyers together. The types and value of offsets are more varied, depending on the appetites and budgets of the buyers.

For example, the voluntary carbon market has been a preferred option for Washington-based Farm Power, which has agreements with The Carbon Trust (Portland, OR) and Native Energy (Burlington, VT) for carbon credits generated from the capture and destruction of methane from its farm digester projects in Washington state. Both The Carbon Trust and Native Energy use designated registries and protocols, such as the Carbon Action Registry (CAR) or Verified Carbon Standard (VCS), as the vehicle through which credits are registered, verified, and eventually retired on behalf of their customers.

The Climate Trust – Retires registered carbon offsets on behalf of at least five Oregon-based utilities that are required by state law to offset the GHG impacts that occur from installing new power plants in the state. The Trust also sources offsets for the Smart Energy program created by NW Natural as an opportunity for customers to support production of “carbon-neutral” natural gas through farm-based biodigesters.

Native Energy – Has a diverse base of individual and business customers. They source carbon offsets for a wide range of large, environmentally conscious businesses, such as eBay, Stonyfield Farm, Brita, and Effect Partners, who provided some funding up front for offsets from Farm Power’s Rainier Biogas project. Offset values vary widely depending on demand, supply, and the “value” of the project’s story. In a few cases, offset values may loosely track the prices for compliance-grade carbon offsets with a discount for funding provided in advance of project implementation.

Compliance Cap-and-Trade Offsets Opportunities

Finally, the compliance market opportunity refers to cap-and-trade programs established by state governments to reduce GHG pollution. These are formal regulatory systems. The government establishes caps on GHGs for targeted sources and issues permits or allowances that are distributed, sold, or auctioned to regulated entities for each ton of emissions they generate. Allowances are typically tradable instruments, so entities can easily manage their allowance needs and accounts. The goal of cap-and-trade systems is to use market-based mechanisms to achieve pollution reductions at the lowest possible cost and with the least disruption to the economy.

Systems might also allow covered entities to use offsets generated voluntarily by non-covered entities to meet some portion of their emission reduction target. Allowed offsets are generated using approved protocols, verified by approved third-party verifiers, and registered/sold through approved registries. 

Two domestic cap-and-trade programs survived the past decade and are in operation today—the Regional Greenhouse Gas Initiative (RGGI), which involves nine Northeastern states, and the California market, established by Assembly Bill 32 (AB 32) and administered by the California Air Resources Board (CARB). Each of these systems operates under its own sets of rules.

The table below highlights features of these two market approaches.

Regional Greenhouse Gas Initiative (RGGI)

AB 32 – California Market

Nine states: Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New York, Rhode Island, and Vermont

California only (may establish a market connection with Ontario, Canada)

Covers the electricity sector: 200 power plants

Covers power and industrial entities that generate more than 25,000 metric tons of CO2e annually; will expand to include the transportation fuel sector in 2015

Allowances based on U.S. short tons of CO2

Allowances based on metric  tons of CO2

Allowances are auctioned

Allowances are auctioned, with a minimum floor price of $10/MtCO2e

Offsets are very limited – few types, very strict rules, only 3% of compliance allowed

Offsets are allowed in four categories: livestock methane, forestry, urban forestry, and ozone-depleting substances; entities may use offsets for up to 8% of their compliance obligation

Current auction prices: ~ $2.00

Current auction prices: ~$13.50; offset values are estimated to lag allowance prices by about 25%

 

Among farm digester project developers, interest in the California market is guarded. Agricultural methane capture and destruction is one of just four approved offset categories. The demand for these offsets could become strong, and the rules allow projects from any state to participate. On the other hand, the costs for monitoring equipment can be significant, $15,000 or more for start up, with similar sums every year for verification and registration.  These monitoring and transaction costs will tend to favor projects with larger livestock numbers (1,500+ dairy animal units, or AUs). To date, 60 existing digester projects have listed with the Climate Action Registry—a first step to participation in the California market. Of these projects, 36 have registered more than 800,000 verified carbon credits.

Conclusions:

Values for carbon (i.e., GHG reductions) can be observed in the marketplace and measured in terms of market goodwill or as prices for environmental attributes or carbon credits from voluntary and compliance markets.

Developers of smaller farm digester projects (<1,500 AUs) may find their best value through utility-based incentive programs or through participation in voluntary carbon markets.

Developers of larger farm digester projects (>1,500 AUs) should explore the potential costs and benefits of registering to participate as an offset project in the California carbon market.

Future Plans

The WSU Energy Program will continue to monitor market developments related to this topic and encourage livestock producers to consider methane capture and anaerobic digestion as means to control odors, manage nutrients, and produce valuable biogas resources.

Authors

Jim Jensen, Sr. Bioenergy and Alternative Fuel Specialist, Washington State University Energy Program jensenj@energy.wsu.edu

Additional Information

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

Valuing Feedstocks for Anaerobic Digestion – Balancing Energy Potential and Nutrient Content

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Why Study the Interaction Between Energy and Nutrients for Digestion?

To improve the energy production and revenue generation, many farm digester operators are including off-farm feedstocks in the blend.  Off-farm feedstocks are raw materials with high carbon concentrations that can be degraded anaerobically.  Common off-farm feedstocks include food service or retail waste, food processing byproducts, residuals from biofuels production and FOG (fat, oil & grease) resulting from food preparation.  Typically, off-farm feedstocks have a higher energy potential when compared to manure.  Manures generally have biogas potential in the range of 280 to 500 L of biogas/kg of VS, compared to off-farm feedstocks which can range from 300 to 1,300 L of biogas/kg of VS [1].  In addition to the increased biogas production, revenue can also be generated from tipping fees collected for feedstock brought onto a farm.  The tipping fee is typically comparable to the cost of disposing of the material at a landfill or wastewater treatment plant. 

The purpose of this ongoing project is to evaluate the biogas potential and impact on nutrient management of off-farm feedstocks for anaerobic digestion.  

What Did We Do?

The Anaerobic Digestion Research and Education Center (ADREC) has carried out hundreds of biogas methane potential tests (BMP’s) over the past 5 years.  The purpose of the BMP is to evaluate if a feedstock is anaerobically degradable and predict the biogas production under ideal conditions.  As part of the biogas testing, many feedstocks were also characterized for their nutrient composition.

What Have We Learned?

While off-farm feedstocks do offer opportunities to improve the profitability of anaerobic digestion systems, operators must also consider the costs associated with bring material onto the farm.  Water contained in off-farm feedstock contributes to the manure volume and adds cost during land application.  Nutrients contained in feedstocks need to be measured and considered in the context of nutrient management planning.  In addition, the regulatory and record keeping requirements associated with off-farm feedstock should also be factored into any cost-benefit analysis.

Future Plans

ADREC is planning to continue the BMP evaluations as part its normal fee for service activities.

Authors

Dana Kirk, Specialist, Michigan State University, kirkdana@anr.msu.edu

Louis Faivor, Technician, Michigan State Univeristy

Additional Information

http://researchgroups.msu.edu/adrec/about

 


[1] KTBL.  2012.  Biogas Profitability Calculator.  http://daten.ktbl.de/biogas/showSubstrate.do?zustandReq=3#anwendung

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.