Digestate Standard Q&A

A formal program roll-out of the American Biogas Council (ABC) Digestate Standard Testing & Certification Program is planned for January 2017, beginning with accreditation of testing laboratories and a training webinar for digestate producers. BioCycle will feature this Q&A column each month to provide you an opportunity to get answers to your questions about the Program, by emailing info@americanbiogascouncil.org.
Q. Is the Digestate Standard Testing & Certification program mandatory?
A. No, this is a voluntary program. Biogas plants that participate will be able to more effectively market their digestate by providing credible information about the digester feedstocks, digestion process and final composition of the digestate. Participation in the program will also help biogas plant operators better understand and control their operations by routinely measuring the digesters’ performance.
Q. How does this impact the regulatory requirements for biogas plants?
A. Biogas plants are still obligated to comply with applicable local, state and federal regulatory requirements. The ABC Program addresses a gap in most regulations — digestate is no longer the same as the feedstocks processed in the anaerobic digester; it has been biologically converted to a new product. The Program provides both the rationale and evidence for regulatory differentiation of inputs (e.g. solid waste) from outputs (digestate) and incorporating this into either voluntary compliance standards or compulsory regulations. Industry-accepted protocol for testing, characterization for incorporation into the permitting process and ongoing permit compliance are provided.
Q. Is the digestate testing and certification intended for biogas plants producing and selling compost from their digestate?
A. No. It is for digestate producers who sell or transfer whole digestate, the separated solid or liquid digestate, without further processing. The digestate may go to a third-party composter, who will then complete the aerobic processing phase. The Program provides composters with analytical data to determine the optimal blend for composting —e.g., whether more carbon and structural material is required — and how much they can reduce their operating costs by using a preprocessed input rather than unprocessed source separated organic waste. The Program also enables the composter to remain compliant with the US Composting Council STA® and/or organic certification program by ensuring they have the required information about their feedstocks.

Manteca, California: City To Codigest Food With Biosolids For Fuel

The City of Manteca will spend $6.1 million over the next two years to add capacity to receive and process food waste at its Wastewater Quality Control Facility (WQCF). As reported by the Manteca Bulletin, the WQCF will have capacity to produce 140,000 diesel gallon equivalents (DGE) of renewable compressed natural gas (RCNG) annually. The operation ultimately could yield 256,000 DGE on an annual basis. Manteca plans to use the RCNG it produces to power its solid waste division fleet to meet tightening San Joaquin Valley clean air standards. Manteca currently flares about 107,000 cubic feet of biogas daily at the wastewater treatment plant. At the same time it burns natural gas in boilers to heat treatment plant digesters.
About 3,140 tons/year of restaurant and commercial food waste from Manteca are currently being disposed at the Austin Road landfill.  In addition, 290 tons of fat, oil and grease are exported to a Bay Area disposal firm, according to the bulletin.  Surveys have shown 45.7 percent of Manteca’s residential garbage consists of food waste. If separated, 9,128 tons of food waste can be diverted to the generation of RCNG. The city applied for a $3 million California Energy Commission matching grant to build the RCNG production facility. It also plans to sell excess RCNG to private sector vehicle owners at a planned fueling station at the wastewater treatment plant.

Washington, D.C.: USDA Opens REAP Grant Applications Window

The U.S. Department of Agriculture’s Rural Business-Cooperative Service is accepting applications for the Rural Energy for America Program (REAP), which can help agricultural producers and rural small businesses install renewable energy systems, including anaerobic digestion (AD). Two types of funding assistance are available. The Renewable Energy Systems and Energy Efficiency program provides grants and loan guarantees to agricultural producers and rural small businesses to install renewable energy systems and make energy efficiency improvements. Eligible renewable energy systems include renewable biomass, including anaerobic digesters. The program also offers energy audit and renewable energy development assistance grants.
Applications for energy audit and renewable energy development assistance grants are due Jan. 31, 2017. Applications for renewable energy systems and energy efficiency grants of $20,000 or less are due March 31, 2017 for the second funding cycle. Applications for renewable energy system and energy efficiency grants of greater than $20,000 and all combination grants and guarantees are also due March 31. USDA will set aside 20 percent of the funds for grants of $20,000 or less. Applications for guaranteed loans will be reviewed and processed when received, with periodic completions.

Rahway, New Jersey: Sewage Authority Proceeds With Codigestion

The Rahway Valley Sewerage Authority (RVSA) has three anaerobic digesters with about 30 percent unused capacity, as well as an underutilized electricity generation system. It used a public-private partnership (PPP) framework to source and process high strength organics such as food waste. “We wanted a long-term contract that provides consistent feedstock,” noted Jim Meehan of RVSA in a presentation at BioCycle REFOR16 in Orlando. “The Authority issued an RFP, and Waste Management was selected as our feedstock supply partner under a 10-year contract with a 10-year renewal. The goal of the public private partnership is to optimize digester operations, obtain a guaranteed revenue stream, minimize the need to purchase third party natural gas for plant operations, and to increase the Plant’s sustainability and resiliency while decreasing its carbon footprint.”
Adds Rick Sapir, a partner at the law firm of Hawkins, Delafield & Wood who negotiated the PPP: “The partnership provides a steady supply of material without the need for a dedicated marketing effort by the Authority, guarantees a long term supply before committing the funding for a receiving station, and mitigates the risk of losing supply to lower cost competing facilities or of upsetting Plant operations.” Food waste will be received in an existing gravity thickener; the concrete has to be coated because of the feedstock pH, and internal mixing jets will be added. The steel floating covers on the digesters will be replaced with bladder type covers. This will provide increased gas storage capability. Design engineers established acceptable ranges in the feedstocks for key parameters, including COD, total solids, pH and metals.

Duplin County, North Carolina: Farms Join Forces To Sell RNG

In 2007, North Carolina became the first state in the Southeast to adopt a Renewable Energy and Energy Efficiency Portfolio Standard (REPS). Because of its agricultural economy, and abundance of animal waste, North Carolina is required to produce a percentage of energy from agricultural sources, which created set-asides for poultry and swine waste, explained Gus Simmons, Director of Bioenergy at Cavanaugh & Associates in his presentation at BioCycle REFOR16. “In 2012, the REPS had been in place for five years, and there were four on-farm systems operating, but deployment was very slow, and Renewable Energy Credits (RECs) created were very low. Many proposals were being submitted for centralized, larger systems — but no projects were coming out of the ground.”
In 2013, a team from Duke University published a study titled, “A Spatial-Economic Optimization of Swine Waste-Derived Biogas Infrastructure Design in North Carolina.” The study evaluated four scenarios to address the paucity of projects: 1. On-farm electricity production, using on-farm digesters and on-farm generators; 2. On-farm digesters and biogas collection for direct injection; 3. Transport of biogas from individual farms to a centralized location for electricity production; and 4. Transport of biogas from individual farms to a  centralized location for purification, pressurization and injection into the existing natural gas pipeline. “It was determined that based on levelized cost of electricity (LCOE) for each scenario, on-farm electricity production and centralized directed biogas appeared to be the most cost-efficient approaches for satisfying the REPS,” noted Simmons. “And in May 2016, after years of development, the Optima KV Project — which includes five farms in Duplin County — obtained an agreement with Duke Energy to sell renewable natural gas (RNG) generated by 60,000 pigs, yielding about 80,000 MMBtus per year.”
Project characteristics include: Installation of in-ground anaerobic digesters (like on-farm systems) at each of the five farms; installation of raw biogas gathering pipelines to transport dried biogas from individual farms to a centralized location for upgrading to RNG; pressurization, and injection into the existing natural gas pipeline; and RNG purchased by Duke Energy, selected for use at existing combined cycle plants (directed biogas). This RNG will create swine RECs. “This is the first project ever to inject gas into the natural gas pipeline in the state of North Carolina,” said Simmons. “The KV Optima Project has a 15-year RNG offtake agreement with Duke Energy and should be operational by July 2017.”