Loyd Ray Farms

Overview

The project, located at the Loyd Ray Farms in Yadkin County, North Carolina, is an innovative waste-to-energy project that collects methane generated by the decomposition of hog waste and burns it to generate electricity for use on the farm and to support an innovative animal waste management system to provide other environmental benefits. The destruction of the methane-a greenhouse gas 21 times more potent than carbon dioxide-creates carbon offsets, and the renewable energy generated by the system creates renewable energy certificates (RECs) that can be used to comply with North Carolina's Renewable Energy and Energy Efficiency Portfolio Standard. The innovative animal waste management system allows the farm to meet stringent environmental performance requirements.

The project involves the capture of methane generated by the hog waste in an in-ground lined and covered anaerobic digester. The gas collected under a 60-mil high density polyethylene (HDPE) cover and is used to power a 65-kW microturbine, the electricity from which is used to support five of the nine swine barns at the farm and the operation of the innovative animal waste management system. From the digester, the liquid waste flows to an open-air basin where the wastewater is aerated to reduce the concentrations of ammonia and other remaining pollutants so that it can be reused for irrigation.

This infographic from the American Biogas Council provides a brief overview of biogas production.

See this presentation for more information on the science and engineering that went into this innovative project. Additional information can be found in Resources.

The table below reports the performance of the farm operations since May 2011, found in the Annual report.

System performance May 24, 2011 - June 30, 2012
System Uptime 62%
Biogas Production 8.3 million scf
REC Production 367.5 MWh
Monthly Average Production 24.5-29 MWh
Monthly Average during Best Producing Months (December 2011 - February 2012) 44 MWh
Actual Greenhouse Gas Emissions Reductions 2,087 MTCO2e
Greenhouse Gas Emissions Reduction Potential 5,183 MTCO2e
Climate Action Reserve: Climate Reserve Tonnes (CRT) - verified tons 1442 (CRT)

The report recaps the overall performance of the system in the first 15 months of operations. The biogas production from the digester has exceeded expectations, actually producing more biogas than the microturbine has the capacity to destroy. However, despite an ample supply of biogas, issues associated with the gas conditioning system have impeded the ability to produce electricity. The gas conditioning system, which dehumidifies, cools and compresses the gas for combustion in the microturbine. Thus, any problems with the gas conditioning system prevent the microturbine from operating properly, thereby hindering electricity production. The project team is working to rectify the biogas conditioning issues through the replacement of the biogas conditioning unit.

The production of carbon offsets reached 40% of the total potential reductions possible by the system during the first 15 months of operation. Offset production is less affected by the issues with the gas conditioner because carbon offsets can also be generated when biogas is burned in the flare. The initial offset production was lower than expected due to low flows of biogas to the flare until a blower was installed to increase gas flow. The project, which is registered with the Climate Action Reserve (CAR), underwent third-party verification, completed in December 2012; the project received verified carbon offsets in the form of CAR Climate Reserve Tonnes (CRTs) for the destruction of biogas in the period September 2011 through June 2012.

The environmental system, which includes the aeration of effluent from the digester, has worked well during the initial 15 months of operations, and has been successful in reducing the concentration of ammonia, odors, heavy metals, and pathogens from the swine waste.

Electricity Generation

The main components that comprise the electricity generation system include the anaerobic digester, the biogas conditioning unit, and the 65-kW microturbine. A flare is used to burn the biogas in the event that the electricity system is down or gas produced by the digester exceeds the microturbine's capacity. The electricity generated by the microturbine is used on the farm to support five of the farm's nine swine houses and the innovative animal waste management system.

Carbon Offsets

Greenhouse gas destruction is tracked by measuring the flow and methane concentration of biogas flowing to the microturbine and/or the flare. The project has the potential to reduce the emissions of up to 5,183 MTCO2e, which are the baseline emissions from the farm prior to the installation of the system. Comparing the total potential number of achievable carbon offsets to the emissions reductions actually achieved indicates that the system met 40% of total greenhouse gas emission reductions possible during the first 15 months of operations. The carbon offset generated by the project will be shared by Duke University and Google Inc.

Environmental Performance

In addition to generating renewable energy and carbon offsets, the project employs an innovative animal waste management system that meets the state's stringent environmental performance standards required for all farms that receive funding through the Lagoon Conversion Program and which are required for new and expanding farms. The system which relies on the digester and aeration basin to treat the waste reduces the concentrations of ammonia, heavy metals, odors, nitrogen, phosphorus and pathogens and prevents the discharge of waste to surface and groundwater.

The aeration of the wastewater promotes the growth of nitrifying bacteria which transform the ammonia (NH3) into nitrate (NO3) and nitrite (NO2). Denitrifying bacteria transform some of the nitrate and nitrite into inert nitrogen gas (N2).