BioCycle May 2018
Nairobi, Kenya: Sustainable Business Model For Biogas
Energy poverty in the majority of rural households in Kenya is a threat to economic and social development, making availability of an affordable and reliable domestic energy source essential. Researchers at the Centre for Renewable Energy Systems Technology at Loughborough University in the United Kingdom investigated the potential use of biogas for cooking, suitable anaerobic digesters that could be deployed in rural households, and also the viability of a small community biogas business model. Conservative estimates of the business model parameters and sensitivity analysis revealed that there was adequate biogas potential in central and western Kenya while water scarcity affected other regions’ opportunities. Cattle manure was the predominant feedstock, although crop waste has possibilities to contribute to biogas production.
Economically and technically, the inflatable tubular digester was found to be the most suitable type for biogas production in rural Kenya. Discounted cash flow analysis of the business model proved a profitable business to supply household energy at 0.55€/Kg ($0.31/lb) of biogas, with projected household savings of 249€ ($309) annually. Labor cost was found to have high significance on the feasibility of the business model, which was also sensitive to changes in biogas revenues. Kenya’s rural areas have significant biogas potential to reduce energy poverty, generate income and aid social development. The study appeared in the February issue of Renewable Energy.
Paris, France: Biogas Sector Continues To Grow
A study by the French Ministry of Energy Transition states that the biogas market in France continues to develop at a good pace. France’s biogas industry is one of the most developed in Europe, and is the third European country in terms of number of biogas plants. Around 300 biogas and biomethane projects are underway. France has set ambitious targets and is investing heavily in new technologies and projects. The report states that injection capacity of biomethane into the gas grid in France equals to 37 GWh/year and reaches a cumulative total capacity of 533 GWh/year. The number of installations able to produce and inject biogas has more than doubled compared to the previous year. The Ministry of Energy Transition indicates that, due to biomethane, electricity production also continues to rise, with 519 biogas plants able to produce electricity, representing a total generated power of 405 MW. The Grand Est, Hauts-de-France and Ile-de-France regions are the most active regions with most biogas plants, producing 54 percent of overall injections.
Puyallup, Washington: Nutrient Recovery Primer
A new publication from Washington State University (WSU) Extension, “Approaches to Nutrient Recovery from Dairy Manure,” provides an overview of the major nutrient recovery (NR) approaches now emerging or in use for recovery or removal of phosphorus (P), nitrogen (N), potassium (K), and other salts from dairy manure, particularly after anaerobic digestion (AD). The authors — Georgine Yorgey (WSU), Craig Frear (Regenis) and Jingwei Ma (Hunan University) — note that “technologies, markets, and regulatory frameworks are evolving quickly and, as a result, this paper, its technology evaluations, associated performance, and cost estimates must be considered a time-sensitive snapshot of a changing industry.” The focus is on classes of approaches to nutrient recovery, and reference to specific technology providers has been avoided.
For each of the more common technical approaches being used or considered by the dairy industry, the following indicators are summarized: Approximate performance and capital (CAPEX) and operating and maintenance (OPEX) expenses, performance, coproduct form and price, and impacts on manure management. Information in the review is drawn from pilot and commercial demonstrations of NR technologies, with sources including the scientific literature, pilot reports, company literature, project feasibility studies, and interviews. Making the data comparable required numerous assumptions, which are detailed in two sidebars: “Assumptions for Cost and Performance Indicators” and “Baseline Manure Management Scenario for Calculating Avoided Manure Management Costs.” These assumptions should inform interpretation of the results, say the authors.
Brookings, South Dakota: Biofuels Feedstock Study Supports Billion Ton Estimate
Can farmers produce at least 1 billion tons of nonfood biomass per year that can be used as biofuels feedstock? Analysis of up to seven years of production data by researchers gathered through the Regional Feedstock Partnership, established by the U.S. Department Energy (DOE) and the Sun Grant Initiative, supports DOE’s billon ton estimate. That amount could be available annually by 2030. The goal is to replace 30 percent of the petroleum consumed in the United States with biofuels.
“Regional field trials were conducted for the most promising bioenergy feedstocks,” explains Vance Owens, Director of the North Central Regional Sun Grant Center. “Based on these numbers and other research we’ve done, we would still see over a billion tons available per year as the bioeconomy continues to develop.” South Dakota State University was the lead institution for the more than $20 million project, which began in 2007. It was funded by DOE’s Bioenergy Technologies Office, and involved researchers from the U.S. Departments of Energy and Agriculture, 35 land grant universities, Heidelberg University and several industry partners, as well as Idaho National Laboratory, Oak Ridge National Laboratory, and Argonne National Laboratory.
Field trial results and yield projections for herbaceous crops, including switchgrass, energycane, mixed perennial grasses on Conservation Reserve Program (CRP) land, giant miscanthus and sorghum, as well as the woody feedstocks poplar and shrub willow, are available online in the January issue of GCB Bioenergy (link in online edition of Anaerobic Digest). The duration of this study is unique, notes Owens. “Typically these projects last two to three years, but having trials in place for up to seven years is really important in terms of long-term yield potential.” For example, researchers were able to gather data about how potential biofuels crops reacted to the 2012 national drought and how they recovered in subsequent years in some instances. “Though annual crops suffer, perennials can manage through a one-year drought,” he adds. “Being able to see this was a tremendous advantage — and something we wouldn’t likely see with only a two-year study.”
Among the herbaceous energy crops, field-scale trials using traditional agricultural equipment were conducted for switchgrass and mixed perennial grasses suitable for use on CRP land, while smaller individual plots were utilized for energycane and giant miscanthus due to a lack of vegetative planting materials for these species. “Crop potential varies by region,” explains Owens. “There’s not one that makes sense everywhere; it’s more of a localized environment.” The nationwide yield potential maps track which crops are best suited to a particular area. The model used to estimate yield potential, known as PRISM-ELM, included yield-limiting factors, such as water availability, low-winter and high-summer temperature response, soil pH, salinity and drainage. Modelers and agronomists from each species group met periodically to exchange information and review yield potential maps. The model for perennial grasses, for instance, had to be adjusted based on the plants’ ability to develop roots deep in the soil profile.
Stratford, Ontario: Upgrading Treatment Plant For Codigestion
In 2017, the City of Stratford, the Ontario Clean Water Agency and SUEZ Water Technologies & Solutions began planning an operation to codigest 26,400 tons/year of food waste with the plant’s wastewater solids at the city’s Water Pollution Control Plant (WPCP). The biogas will be conditioned and upgraded to produce 83.34 million ft3/year of renewable natural gas (RNG) that will be injected into the natural gas pipeline distribution system. Greenhouse gas emissions reductions are projected to be 49,031 tons CO2e/yr. The anaerobic digestion infrastructure at the WPCP has a total capacity of 113,000 ft3.
To upgrade the plant for codigestion, SUEZ’s Biological Hydrolysis (BH) technology will be added to the treatment of the combined primary solids and secondary activated wastewater solids, reducing residence time in the AD. The kinetic rate of hydrolysis is increased due to the elevated operating temperature of the BH system, and the cascade flow method through the reactors. For the Stratford system, the first three reactors will operate at 108°F, and the last three will operate as a batch hold at 142°F. The batch acts as a pasteurization step so food waste brought in for codigestion will need to be introduced prior to these tanks. A Re:Sep separation system is being installed to remove contaminants and packaging in the food waste, and then slurry it.
Brussels, Belgium: $5.75 Billion For Biomethane And Biofuels In Italy
The European Commission, based in Brussels, approved an Italian program that supports production and distribution of advanced biofuels, including advanced biomethane, for use in the transport sector. The program has a budget of $5.76 billion and will run from 2018 until 2022. The European Union’s Renewable Energy Directive requires all Member States to ensure that at least 10 percent of all energy consumed in transport comes from renewable sources by 2020. Sustainable biofuels are, together with electric vehicles, one of the main low carbon alternatives to fossil fuels used in transport, as they are easily deployable on existing transport infrastructure.
Because advanced biofuels and biomethane have higher production costs than fossil fuels, producers receive a premium under the program to compensate them for these higher costs and compete with fossil fuels in the transport sector. The premium can be increased if producers also make investments to improve the distribution and liquefaction of advanced biomethane. The level of the premium will be updated each year in relation to the production costs to ensure that producers are not overcompensated. The program will be financed by transport fuel retailers who are obliged by law to include a certain percentage of advanced biofuels and biomethane in their fuel blends. Farmers will be incentivized to produce biofuel and biomethane from manure and other residues originating from their farming activities and use them to power their equipment and vehicles.
Cochranville, Pennsylvania: Dairy Commissions Digester
Installation and construction of an anaerobic digester (AD) are complete at Ar-Joy Farms in Cochranville. Family-owned and operated by Duane and Marilyn Hershey, Ar-Joy Farms has a dairy herd of 700 milking cows and 160 calves. It is utilizing DVO Inc.’s Two-Stage Linear Vortex™ complete mix, plug flow 2-stage digester (AD). The previous manure management system consisted of a flush system, a sand lane for sand recovery and a 2-stage lagoon. The Hersheys began planning an alternative approach to manure management in 2013 and settled on the DVO system. Manure from Ar-Joy’s 700 milking cows is codigested with waste from a potato chip company three times a week. The farm is seeking additional local feedstocks for the digester.
Biogas will be combusted in a 300 kW Guascor combined heat and power gen-set. Ar-Joy has a net-metering program with its local utility, enabling the farm to lower its electrical costs by offsetting the power from its electrical meters. Excess generated power not used by the dairy is sold to the utility at $0.824/kWh. Ar-Joy Farms also will sell renewable energy credits. Digested solids are dewatered with a screw press and used for bedding. Previously, the cows were bedded with sand. The liquid digestate is stored in a lagoon to be applied as fertilizer. Total cost of the project was about $2.5 million; the estimated payback time is about 8 years. Partial funding was provided by the Pennsylvania Commonwealth Financing Authority.
Swansea, Wales: Cultivating Algal Biomass With Digestate
Scientists at Swansea University in Wales are leading a $6.82 million project dubbed ALG-AD. The project is evaluating whether excess waste nutrients produced from anaerobic digestion of food and farm waste can be used to cultivate algal biomass for animal feed and other products of value. ALG-AD is under the auspices of Interreg North-West Europe (NWE), a European Territorial Cooperation Programme funded by the European Commission. Dr. Carole Llewellyn, Associate Professor in Applied Aquatic Bioscience at Swansea University, is the lead researcher. “With expansion of the AD industry across Europe, there is excess nutrient waste,” explains Llewellyn. “European Union legislation and the introduction of nutrient-vulnerable zones across Europe to prevent nutrient runoff causing pollution means that solutions need to be developed. The ALG-AD project will combine algal and anaerobic digestion technologies. Algae require nutrients to grow, so the excess nutrients from AD provide a source of nutrients. The algae can then be processed to produce commodity products. For example, we will be looking to use the cultivated algae biomass in animal feeds.”
ALG-AD has been funded for 3.5 years. Swansea University is leading the project in collaboration with 10 partners comprising university, industry and policymakers across the UK, France, Germany and Belgium. Swansea University is to receive over $1.24 million from the EU, matched with $867,000 from the Welsh Government.
Buffalo, New York: Antibiotic Persistence In Digested Dairy Manure
A new study by the University of Buffalo and Virginia Tech found that antibiotics are not completely degraded in an anaerobic digester. The study, which appears in the May 2018 issue of Environmental Pollution, notes: “This study examines the occurrence and transformation of sulfonamides, tetracyclines, tetracycline degradation products, and related antibiotic-resistant genes (ARGs) throughout a full-scale advanced anaerobic digester (AAD) receiving continuous manure and antibiotic input. Manure samples were collected throughout the AAD system to evaluate baseline antibiotic and ARG input (raw manure), the effect of hygenization (post-pasteurized manure) and anaerobic digestion (post-digestion manure) on antibiotic and ARG levels.”
Antibiotics were analyzed by liquid chromatography-tandem mass spectrometry, and the ARGs were analyzed by quantitative polymerase chain reaction. Significant reductions in the concentrations of chlortetracycline, oxytetracycline, tetracycline and their degradation products were observed in manure liquids following treatment, concomitant to significant increases in manure solids. These results suggest sorption is the major removal route for tetracyclines during AAD. Moreover, ARGs decreased significantly following AAD in the absence of sulfonamide antibiotics, while tetracyclines-resistant genes remained unchanged.