Tag: biogas

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Small to Mid-Sized Dairies: Making Compact Anaerobic Digestion Feasible

Why Consider Small or Medium Digester Projects?

Anaerobic digestion (AD) is an environmentally-friendly manure management process that can generate renewable energy and heat, mitigate odors, and create sustainable by-products such as bedding or fertilizer for dairies and farmers. However, due to economics, a majority of commercially available AD technologies have been implemented on large farming operations. Since the average herd size of dairies across the country is below 200 head of milking cows, there is a need for small-scale AD systems to serve this market.

eucolino allen farmsWhat did we do?

The University of Wisconsin-Oshkosh, in collaboration with BIOFerm™ Energy Systems, installed the EUCOlino—a small-scale, mixed, plug-flow digester—onto on a 136 milking head Wisconsin Dairy. The system is pre-manufactured, containerized and requires very limited on-site construction.   This includes grading, pouring a concrete pad for the containers and electrical services installation.

Start-up and commissioning were performed after the delivery of the 64 kWe combined heat and power (CHP). The input materials consist of bedded-pack dairy manure (corn or bean stover and straw), parlor wash water, and minor additional substrates such as lactose or fats, oils, and grease.

Solid materials are dumped via bucket tractor into a hopper feeder system that uses an auger to feed substrate into the anaerobic digestion tank. Additional parlor water is piped directly into the anaerobic digestion tank and mixed with the solids to make a feedstock of approximately 13% total solids. The solids are fed hourly, which is controlled by the PLC system.

The digester has a ~30-day retention time and the biogas produced is stored in a bag above the fermenters. Biogas produced is conditioned and combusted in a CHP mounted on a separate skid. Effluent from the system is pumped directly to an open pit lagoon for storage and subsequently land applied as fertilizer. The system produces approximately 25 – 33 m3/hour of biogas, with a raw biogas quality of 52-60% CH4 and less than 700 ppm H2S.

concrete pads for installation
installation
input

What have we learned?

This project has been an important step forward in developing future small-scale anaerobic digesters across the U.S.  Notably, our installation has given us insight into balancing system economics with the size of small-scale models; the energy output of the system must exceed pre-processing energy requirements and the digester must still be large enough for the designed residence time. Our experience has shown that, while reducing the size of a digester, these requirements remain essential for an installation to economically make sense.

Additionally, challenges involved in AD at the small-scale are related to pre-processing or feedstock conveyance. Once suitable consistence or size for conveyance, anaerobically digesting the organic fraction can be relatively easy. Inconsistency of incoming feedstocks is very detrimental to the system’s stability. Additionally, exterior feedstock storage and above ground piping can limit processing potential when severe cold weather settles in. While all of these are challenges that are easily overcome with engineering, they come at a cost and that can make or break the economics at this scale.

Future Plans

For the small-scale EUCOlino to be effective in the United States, it is key to establishing a U.S.- based manufacturing location. Pre-processing needs to be well-suited to the incoming feedstock. Post-digestion products need established off-takers, for electricity generation, bedding, fertilizer, etc.

Authors

Steven Sell, Manager Application Engineer, BIOFerm™ Energy Systems beaw@biofermenergy.com

Whitney Beadle, Marketing Communications, BIOFerm™ Energy Systems

Additional information

The following publications offer additional information on the Allen Farms digester:

Readers interested in this topic can also visit our website for more information on the Allen Farms digester and other BIOFerm projects. We can also be found on Facebook, Twitter, and LinkedIn.

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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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The Great Biogas Gusher


Why Pursue Bio-Energy?

The great Texas Oil Boom, also referred to as the Gusher Age, provided for dramatic economic growth in the US in the early 20th century, and ushered in rapid development and industrial growth. Although we typically think of the Middle East when we consider the impacts of oil discoveries on local economies (reference Dubai), at the time of its discovery, the oil finds in Texas were unprecedented; and the US quickly became the world’s top producer of petroleum.

As we all know, the rest of the world came to the party, and the US was soon falling in the ranks of top petroleum producers. Though the US oil reserves are vast, increasing concerns over the environmental impacts of finding, mining, extracting, refining, and consuming fossil fuels has incentivized the development of renewable energy resources, such as solar, wind, hydro, and bioenergy. Of these forms of renewable energy, bioenergy holds the promise for replacement of fossil fuels for transportation use.

a biogas collection systemWhat did we do?

Bioenergy may be described as fuels derived from organic materials, such as agricultural wastes, through processes like anaerobic digestion. The US has even more organic resources above the Earth’s surface than are identified in the petroleum and natural gas deposits yet to be exploited, yet the development of agricultural bioenergy systems seems to be progressing at a snail’s pace, as compare to the great Oil Boom. There is enormous potential in producing biogas from agricultural, industrial, municipal solid waste, sewage and animal byproducts which can be used to fuel vehicles. The EPA estimates that 8,200 US dairy and swine operation could support biogas recovery systems, as well as some poultry operations. Biogas can be collected from landfills and used to power natural gas vehicles or to produce energy. Wastewater treatment plants are estimated by the EPA to have the potential of about 1 cubic foot of digester gas per 100 gallons of wastewater, this energy could potentially meet 12% of the US electricity demand. Industrial, commercial and institutional facilities provide another source of biogas, in particular supermarkets, restaurants, and educational facilities with food spoilage.

What have we learned?

This presentation compares and contrasts the historical development of fossil fuel reserves with the potential for development of bioenergy from agricultural sources, such as animal wastes and crop residues. The US energy potential from these sources is grossly quantified, and current development inhibitions are identified and discussed. Opportunities for gathering biogas and bioenergy from multiple regional sources, similar to the processes used in the Texas oil fields, are discussed. The presentation offers insight into overcoming these obstacles, and how the US may once again rise to the top of the energy development rankings through efficient use and stewardship of our organic resources.

Percentage of waste water treatment plants that send solids to anaerobic digestion broken out by state

Future Plans

Biogas and bioenergy resources present an enormous opportunity for renewable energy development, and progression toward energy independence for the U.S. The U.S. currently has more than 2,000 active biogas harvesting sites, but claims more than 11,000 additional sites can be developed in the U.S., with the potential to power more than 3 million American homes if used to fuel electricity generating power plants. The USDA, EPA and DOE recently created a US Biogas Opportunities Roadmap which is off to a good start, which hopefully will initiate biogas programs, and foster investment in biogas systems to improve the market vitality in each state. To move the process forward, policy-makers, investors and the public need to have improved collaboration and communication on the state level. We need to develop a clear plan and strategy for developing these valuable biogas resources to promote environmental sustainability and economic growth of our b ioenergy sector.

Author

Gus Simmons, P.E., Director of Bioenergy, Cavanaugh & Associates, P.A. gus.simmons@cavanaughsolutions.com

Additional Information           

http://www.cavanaughsolutions.com 1-877-557-8924

http://www.epa.gov/climatechange/Downloads/Biogas-Roadmap.pdf

Acknowledgements      

USDA/DOE/EPA US Bioenergy Roadmap

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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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Money to Burn: How to Capitalize on BioCNG at Your Wastewater Plant

Purpose  

Across the globe, units of government are struggling with the balance of deriving clean energy with economics and environmental protection. This struggle has led to the development of many renewable energy innovations and inventions, such as rapid improvement in the cost and efficiencies of photovoltaic solar (PV) systems and the development of large off-shore wind turbine systems. The challenges imposed on energy utilities associated with managing grid variability leads emphasis on the development of ‘baseload’ alternative energy systems, like bioenergy systems. We should recognize, however, that we have a bounty of organic wastes generated by society each day, and systems that are able to recycle these organic resources into energy are capable of more consistent energy generation, as compared to the intermittency of solar and wind. In this regard, such bioenergy systems hold promise for balancing our energy needs.

Waste to worth mtb figure 1.What did we do?  

Bioenergy systems based on the utilization of organic wastes, such as municipal wastes, food wastes, and crop residues provide the additional benefits of supporting improved pollution prevention and waste treatment systems.

Of the organic wastes available for us in bioenergy systems, one may be directly correlated to the increasing energy needs and clean energy desires of the global population – waste organics associated with municipal wastewater treatment. Municipal wastewater treatment strategies vary by geography, climate, and level of development across our globe. However, in all cases, opportunities exist to utilize these waste as feedstocks for the creation of biogas that may be used to fuel electricity generators, farm implements, and the transportation needs of our population.

****the above writing doesn’t explain the work that was conducted as requested

What have we learned?  

Many municipal and industrial wastewater treatment plants (WWTP) across the U.S. already utilize anaerobic digestion as a primary treatment process to reduce sludge or reduce organic loading, expressed as Biochemical Oxygen Demand (BOD), to subsequent aerobic treatment processes. However, most of these facilities presently flare the biogas that is produced from the digestion process. Most often, these managers report the following reason for lack of implementation of energy harvesting. WHAT REASON???

We continue to seek clean, renewable energy sources across the globe to reduce our dependency on fossil fuels for improved air quality and economic stability. While solar, wind, and other renewable energy sources play a vital role in a diversified energy strategy, the development of bioenergy systems that continuously operate in ‘base load’ fashion is very important for grid stability. Additionally, unlike solar and wind, bioenergy systems that convert organic wastes into fuels have opportunities to positively impact transportation fuel needs. The development of systems that harvest biogas from anaerobic digesters employed at municipal wastewater plants can serve to fill a portion of this need, and create improved revenues for the wastewater treatment utility. Often, anaerobic digesters serving municipal wastewater treatment plants are operating well under their optimum capacity, creating opportunities for municipalities to engage in partnerships with private sector waste generators, such as food and beverage processors, restaurants, and farmers.

Many commercial fleets are converting to natural gas fuel to realize the cost savings and participate in programs that reward cleaner air quality through reduced emissions. Each commercial waste truck that is converted to natural gas from diesel has a comparable impact to removing 325 cars from the road. Currently the costs of natural gas-fueled vehicles are slightly higher (10-15%) than conventionally-fueled vehicles. However, as the costs of fossil fuels rise, and more CNG vehicles are manufactured, the costs are likely to become very similar.

 

****An explanation of the table below would be useful.. You should use this document to outline how you conducted the study and what you found, most of the information contained is introductory in nature.

Table 1.

Table 2.Future Plans    

Unlike fossil fuels, which are finite in quantity, bioenergy and biogas systems convert the organic wastes that are generated each day into fuel; often in only a few days’ time. In this regard, bioenergy systems offer a truly infinite resource for renewable energy, while providing the added benefit of pollution reduction and additional revenues to support existing wastewater treatment infrastructure systems.

Author

Gus Simmons, Director of Bioenergy, Cavanaugh & Associates, P.A. gus.simmons@cavanaughsolutions.com

Additional information

www.cavanaughsolutions.com

1-877-557-8924

Acknowledgements      

Clean Water Needs Survey, 2008

Loyd Ray Farms, Yadkinville, NC

Duke University Carbon Offsets Initiative

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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

 

 

 

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Farms of the Future: Seeking Agricultural Energy Independence


Why Look to Agriculture and Bioenergy?

As the world population continues to grow at an exponential rate, the ability to nourish this planet’s inhabitants with clean water and safe, healthy food are of paramount importance. This paper describes some of the considerations for and impacts of the demand for the production of food in developed and developing countries on energy resources, and ways in which advancements in on-farm, bioenergy production systems may help farms achieve the incredible production requirements of the next thirty years. Our challenge is to expand agriculture’s output to accommodate the increasing population, without hindering its environmental footprint.

What did we do?  

Today only roughly two percent (2%) of the population produces the food for our plant. This includes all the fruits, vegetables, meats and dairy products that the world’s population of over 7 billion people acquires and eats from markets, grocers, and restaurants. Our global population is projected to exceed nine billion people by the year 2050, all of who will need to be supplied with food derived from the farms of the future. Through technological advances, and improvements in motorized equipment, each farmer is now able to feed roughly 150 people, compared to only 19 people in the 1940’s (Prax, 2010). In the year 2050, a farmer will be required to feed at least 200 people, and based on the rate of reduction in both the number of farms and the amount of land under agricultural production, that number may reach 300 people. But what will these ‘Farms of the Future’ be like? The number of actively producing farms in the developed world has suffered a slow, steady decline over the past two decades, while the global demand for fresh foods, protein and feedstocks have steadily increased. How will we feed a population of more than nine billion with fewer and fewer farms, and how will we feed the livestock needed to feed the increased population?

Figure 1.

What have we learned?  

The growth in our global population also means a growth in the need for clean water, which is a somewhat fixed volume on planet Earth. More importantly, though, the growth in the demand for clean water for drinking purposes also places a greater constraint on the amount of fresh water available for irrigation of crops and to provide for the drinking water required of livestock. The increase in our population means much greater demands for energy – for everything from transportation, lighting, and communications devices to water treatment, agricultural production, and food processing. The culmination of these increasing demands on our planets finite resources has been dubbed by many as the “Food-Water-Energy Nexus.”

Future Plans  

The interdependency of agriculture, water, and energy has become commonly referred to as “the Nexus.” This term does not indicate a crossroads, where a pathway to agricultural production is independent of impacts on water supply and energy availability. Instead, it denotes a relationship of give and take: the decisions we make to utilize, exploit, or economize one of these critical elements of human existence are likely to have broad-reaching impacts on the other two.

Figure 2.The realization of these interdependencies, and more importantly, the fragility of the balance of satisfying these needs must lead us to proactively invest in agricultural innovations, as much as we have with water and energy. The needs for energy innovations have been wildly popularized in society, such as may be seen through promulgation of solar panels the world-over. Similarly, water sustainability innovations, such as reclaiming water from wastes, water conservation devices, and even desalinization. However, the drive for innovations in maximizing the productivity of healthy foods through sustainable agricultural practices seems, by many, silent in comparison.

There is no doubt that the ‘Farms of the Future’ must be able to be self-sustaining; but what does that mean? Will they be able to take the manures from livestock, swine and poultry, convert them to biogas to run the machinery serving their farms, and also provide the nutrient-rich fertilizers for their crops, and bedding for their animals? Will they be able to return nutrients, water, and carbon to the land in which the food is produced in such a manner that none is wasted (meaning the only export from the farms is the food products that are to be consumed, rather than in the form of air emissions, water waste, and exported solid wastes)? What alternate sources of revenue may be developed to sustain small, locally sourced farms?

Demand Placed on Lands

This presentation will discuss how farms of the future can prepare to deal with issues of climate change and greenhouse gas reduction and what is needed in agriculture, water conservation, and stewardship to prepare our world for the additional people inhabiting the Earth in 2050.

Figure 3.

Author         

Gus Simmons, P.E., Director of Bioenergy, Cavanaugh & Associates, P.A. gus.simmons@cavanaughsolutions.com

Additional information  

www.cavanaughsolutions.com

Gus Simmons, P.E. 1-877-557-8924

Acknowledgements      

Sources:

1. Monfreda, C., N. Ramankutty, and J. A. Foley (In Press), Farming the Planet. 2: The Geographic Distribution of Crop Areas, Yields, Physiological Types, and NPP in the Year 2000, Global Biogeochemical Cycles, doi:10.1029/2007GB002947.

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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

 

 

 

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Antibiotic Degradation During Anaerobic Digestion and Effects of Antibiotics on Biogas Production


Purpose 

The purpose of this research was to investigate the degradation of four animal husbandry antibiotics during anaerobic digestion (AD) and study biogas inhibition from the antibiotics. This study was designed to fill information gaps related to AD inhibition by different antibiotic classes in diluted manures received by anaerobic digesters, particularly cattle manure, and the need to more thoroughly investigate antibiotic degradation products from the AD process.

What did we do? 

We conducted AD bench-scale experiments that investigated biogas inhibition and antibiotic degradation. First, cattle manure was added to glass bottles. A known amount of antibiotic standard was added to the manure. A small amount of dilution water was added and the manure-antibiotic slurry was mixed briefly. Then, anaerobic digestion inoculum was added to the bottle. The air in the bottle was purged with nitrogen gas. Finally, the bottles were sealed and placed in an incubator set at 37°C. Biogas measurements and small liquid samples for antibiotic analysis were taken daily. At the end of the 40 day AD study, the solids were extracted to determine the amount of antibiotic adsorbed to the solids.

What have we learned? 

Results from our research showed that three out of four antibiotics degraded within 5 days of AD. Several degradation products were detected, some of which could be biologically active. The antibiotic that did not degrade was mostly found in the liquid phase of the AD reactor slurry and a small portion was adsorbed to the solids. Our results suggest that when antibiotic contaminated feedstocks are added to AD reactors, persistent antibiotics and transformation products may contaminate the liquid and solid effluents.

Our results showed the one of the antibiotics tested was more toxic to the AD process. Approximately 6.4-36 mg/L florfenicol lowered biogas production by 5-40%. Greater than 91 mg/L of the other antibiotics was needed to lower biogas production. These higher concentrations can be found in urine and feces of treated animals but they are not typical for the AD reactor following the addition of multiple feedstocks, inoculum, and dilution water. Our results suggest that there is little concern for these antibiotics to lower biogas production when cattle manure is used as an AD feedstock because the antibiotic concentration should be below inhibitory concentrations.

Future Plans 

Future research plans are to investigate the microbial population change in anaerobic digesters due to antibiotic contaminated cattle manure.

Authors

Shannon Mitchell, Post-doctoral Research Associate at Washington State University shannon.mitchell@email.wsu.edu

Craig Frear, Assistant Professor at Washington State University

Additional information 

http://www.ncbi.nlm.nih.gov/pubmed/24113548

Acknowledgements

This research was supported by Biomass Research Funds from the WSU Agricultural Research Center; and by the BioAg (Biologically Intensive Agriculture and Organic Farming) Grant Program of the Washington State University Center for Sustaining Agriculture and Natural Resources.

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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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The Dairy Manure Biorefinery


Why Consider Additional Technologies with Anaerobic Digestion?

Some dairy farms have experimented with “add-on” technologies to enhance the value of the products generated from anaerobic digesters to improve economics and address other environmental and management concerns. This effort has intensified in recent years, as prices paid for electricity continue to fall. This trend is making it more difficult to justify the installation of new digesters or maintain active anaerobic digestion (AD) projects based on electricity sales alone. 

What did we do?

Based on ten years of research and extension within the field of dairy digesters, we are proposing that the concept of a dairy manure biorefinery can be useful to focus ongoing research and commercialization efforts (Figure 1). A biorefinery integrates a core biomass conversion process (in this case, AD, converting manure and in many cases other organic substrates) with additional downstream technologies. These combined technologies generate multiple value-added products including fuels, electricity, chemicals, and other products (NREL, 2009). Most add-on technologies relevant to dairy facilities have been modified from technologies used in the wastewater treatment and oil and gas industries. 

What have we learned?

Ongoing research and commercialization efforts by our team and others aim to:

  • Adapt technologies to fit the economic and other constraints of dairy digesters.
  • Increase efficiency and reduce costs by maximizing the complimentary nature of technologies (e.g. waste heat from one process is used in another process).

Specific add-on technologies that are continuing to evolve within the biorefinery context include:

Biogas Upgrading to remove impurities from biogas (primarily carbon dioxide, hydrogen sulfide, and water vapor).

Output: Purified biogas that can be used as a transportation fuel (e.g. liquefied natural gas) or injected directly into natural gas piplelines.

Additional social and economic benefits: Renewable fuel can reduce demand for fossil fuels, and can often receive economic credits (e.g. renewable identification numbers, low carbon fuel standard)

Fiber Upgrading to process the fiber that is removed from AD effluent.

Output: Upgraded fiber can be sold as a higher-value soil amendment in the horticultural industry

Additional social and economic benefits: Fiber can replace use of non-renewable resource (peat moss) by horticultural industry

Nutrient Recovery to strip nitrogen (N) and phosphorus (P) from anaerobic digester effluent.

Outputs: Soil amendment products that can be sold offsite where nutrients are needed

Additional social and economic benefits: Reductions in N and P applied to nearby fields, and reduced effluent hauling distances/costs for land application due to lower nutrient concentration in effluent

Water Recovery to generate “recycled” water using advanced technologies

Output: Water that can be used for animal drinking, or as dilution water for the AD facility

Additional social and economic benefits: Reduces consumption of fresh water, a limited resource, and reduces costs for land-application of AD effluent

Overall Potential Impact. Improving economics and addressing other critical issues for dairy producers (e.g. nutrient issues) has the potential to advance farm-based AD adoption significantly beyond its current 244 farms. It has been estimated that a mature bio-refinery industry based on AD on large U.S. dairy farms could create an estimated bio-economy of nearly $3 billion that complements the production of milk and dairy products (ICUSD, 2013).

Figure 1. Stepwise depiction of the process

Figure 2. Total likely value added by most likely scenario

Authors

Georgine Yorgey (presenting author)a, Craig Frearb, Nick Kennedya, Chad Krugera, Jingwei Mab, and Tara Zimmermana

a Center for Sustaining Agriculture and Natural Resources, Washington State University

b Department of Biological Systems Engineering, Washington State University

Future Plans

An extension document describing this concept and the add-on technologies in additional detail is being prepared. This document is part of a series of extension documents on Dairy AD Systems, being prepared by the authors and other colleagues at Washington State University. In addition, ongoing work and collaborations by our team are seeking to investigate, evaluate, and improve individual technologies and the linkages amongst them.

Additional Information

ICUSD, 2013. National market value for anaerobic digestion products. Report to Innovation Center for US Dairy, August 2013.

Acknowledgements

This research was supported by USDA National Institute of Food and Agriculture, contract #2012-6800219814; and Biomass Research Funds from the Washington State University Agricultural Research Center.

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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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Renewable Natural Gas – Biogas Cleaning and Upgrading 101

With depressed electrical prices for produced biogas, many projects are now moving towards business models predicated on production of renewable natural gas (RNG). In order to produce RNG, projects must first clean and upgrade raw biogas to pipeline and/or transportation fuel quality through the use of various engineering approaches. In this presentation, an overview of available and emerging biogas cleaning and upgrading technologies are discussed, highlighting positives, negatives and costs.  

Who Should Consider Biogas Cleaning?

The aim of this fact sheet is to provide farmers, third party project developers, regulatory agencies, and other stakeholders with a basic understanding of the chemical composition of renewable natural gas, the most appropriate end use options for dairy digesters, and some of the more common techniques used to clean biogas to RNG quality at dairy digesters.

What did we do? 

The authors utilized years of research and industry expertise as well as thorough literature search describe the concept of renewable natural gas and the technologies to clean the biogas. The authors aimed to provide information based on the current literature, but not to favor one technology over another.

What have we learned? 

When CHP is the end-use of biogas, the most common biogas purification approach for dairy digesters in the US is to remove water vapor and hydrogen sulfide. Existing projects use a variety of approaches, ranging from biological processes (both post digestion and via oxygen injection into the digester) to physical-chemical absorption processes such as iron type-sponge or activated carbon.

However, if RNG is the end-use a higher degree of purity is required. Often times a dedicated water vapor removal unit and hydrogen sulfide scrubbing unit is still required for removal of the bulk of the hydrogen sulfide mass. Thereafter, water scrubbing or PSA are often used to remove carbon dioxide from biogas, producing an RNG fuel that can be utilized in a variety of different ways. Other technologies exist, however their application on dairy digesters has been rather limited due to concerns related to maturity, cost, and complexity. The best technique is also situation-specific, and therefore, it is critical to understand the mechanics of each purification process, its limitations, and its economics before making a decision.

As electrical rates continue to drop throughout the PNW and US, current and new AD project developers are strongly considering a shift from CHP towards higher value end-uses for biogas, particularly RNG. Interest is increasing due to a growing CNG industry in the US, the decoupling of CNG and diesel prices, and the potential for competitive pricing and high revenues in comparison to fossil-CNG, given existing government incentives. Projects are presently limited and business models must still be proven before wide-scale adoption of biogas upgrading technologies within a dairy digester platform. In addition, concerns historically plaguing CHP projects, related to power purchase agreement pricing, interconnection fees, and scaling are still potentially present within a pipeline fuel model. Nonetheless, the potential exists for a new business model approach to AD projects on US farms.

Future Plans 

No future plans.

Authors

Craig Frear, Assistant Professor, Washington State University cfrear@wsu.edu

Nick Kennedy, Associate in Research WSU; Georgine Yorgey, Associate in Research WSU; Dan Evans, President Promus Energy; Jim Jensen, Associate in Research, WSU Energy; Chad Kruger, DIrector WSU CSANR

Additional information 

For those seeking additional detail, or information about other technologies, more comprehensive reports and reviews are available (Jensen, 2011; Krich et al., 2005; Ryckebosch et al., 2011). This publication is part of the Anaerobic Digestion Systems Series, which aims to provide information that improves decision-making for anaerobic digestion systems.

Acknowledgements

This research was supported by funding from USDA National Institute of Food and Agriculture, Contract #2012-6800219814; National Resources Conservation Service, Conservation Innovation Grants #69-3A75-10-152; Biomass Research Funds from the WSU Agricultural Research Center; and the Washington State Department of Ecology, Waste 2 Resources Program.

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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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Lifecycle greenhouse gas (GHG) analysis of an Anaerobic Co-digestion Facility Processing Dairy Manure and Industrial Food Waste in NY State

While the theoretical benefits of anaerobic digestion have been documented, few studies have utilized data from commercial-scale digesters to quantify impacts.  Previous studies have analyzed a range of empirical studies to constuct emission factors for a generic European AD plant processing source separated municipal solid waste.  However, most U.S. studies have applied reporting protocols and have been based upon theoretical assumptions.  Furthermore, GHG analyses of U.S. co-digestion facilities are limited to one scenario in protocol based analysis of community digester options. 

Purpose          

We are not aware of any peer-reviewed studies of US anaerobic co-digestion. Several case studies have presented calculations of impacts using GHG reporting protocols, however significant portions of the lifecycle have been neglected such as the feedstock reference case emissions, digestate storage emissions and fertilizer displacement impacts. Furthermore, they have often been modeled using general theoretical assumptions such as number of cows rather than empirical data on feedstock volume and characteristics and digester operation.

What did we do? 

A lifecycle GHG analysis was performed based upon data reported on a farm-based anaerobic co-digestion system in New York State, resulting in an 71% reduction in GHG impact relative to conventional treatment of manure and food waste.

The objective of this study was to provide a comprehensive analysis of GHG emissions based upon a NYS digester that co-digests manure and industrial-sourced food waste. Empirical data on feedstock (t-km transport, avoided disposal, TS, VS, TKN), digester operation (m3CH4, KWh, exhaust emissions) and effluent properties (TS,VS,TKN) were combined with regional parameters (i.e., climate, soil type and management practices) to represent a state-of-the-art, anaerobic co-digestion facility in NYS. This data was combined with information collected through interviews in order to model a reference case, representing the business-as-usual food waste disposal and manure management practices en lieu of the anaerobic co-digestion system.

What have we learned? 

Displacement of grid electricity provided the largest benefit followed by avoidance of food waste landfill emissions and reduced impacts associated with storage of digestate vs. undigested manure. Nominal land application N2O emissions were offset by inorganic fertilizer displacement and carbon sequestration in both cases. The higher volume of digestate increased net land application emissions as did increased transportation distance to the fields and lower carbon sequestration. Digestate is a by-product of the co-digestion process and its treatment must be considered in an LCA. Modeling of land application impacts are highly uncertain and can be significant.

The largest source of direct emissions was CH4 emissions. N2O emissions were larger in the land application phase than during storage. Direct fossil fuel emissions had a minor impact. Emissions were offset by displacement of grid electricity and fossil based fertilizers along with carbon sequestration.

Future Plans    

More empirical research is needed to measure emissions and to provide emission factors that incorporate key variables and characteristics affecting emissions. A whole system, dynamic approach is necessary to incorporate complex interdependencies between stages of farm and manure management.

Authors

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

Ebner, Jackie      jhe5003@rit.edu              Rochester Institute of Technology

Rodrigo A. Labatut, Matthew J. Rankin, Curt A. Gooch, Anahita A. Williamson, Thomas A. Trabold

Additional information               

www.manuremanagement.cornell.edu

Figure 1: Contributional analysis of GHG impacts for the reference and anaerobic co-digestion cases.

Figure 1: Contributional analysis of GHG impacts for the reference and anaerobic co-digestion cases.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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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.

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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.

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