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Renewable Natural Gas (RNG)

What is RNG?

According to the page on the US Department of Energy website, “Renewable natural gas (RNG) is a pipeline-quality gas that is fully interchangeable with conventional natural gas and thus can be used in natural gas vehicles.” RNG is often captured during biomass processing (such as compost, landfills, wastewater processing, or anaerobic digesters), and requires little purifying to create a high-methane, efficient fuel.

How is RNG made?

RNG is the naturally-occurring gas from decomposing organic matter. The best way to collect RNG is a closed system that captures the RNG as it is produced.

What is an Anaerobic Digester?

An anaerobic digester (AD) is a biomass processor that facilitates an oxygen-deprived environment for bacteria to break down organic material such as manure, wastewater, and landfills and capture the resulting methane.

Waste Types Used to Make RNG
image credit: https://www.epa.gov/lmop/renewable-natural-gas

How many Anaerobic Digesters are in Indiana?

There are approximately 11 anaerobic digesters in Indiana; some locations host more than one digester at a single site.

Who has ADs in Indiana?

Anaerobic Digesters in Indiana are often on hog, cattle, and dairy farms to reduce the transport distance from the source to the digester. Some digesters co-digest non-livestock waste like restaurant grease, discarded oils and fats, agricultural reside, and food waste.

Indiana AD Statistics
From AgSTAR Livestock Anaerobic Digester Database
Company Name Plant Location Animal Types Co-digestion Electricity Generated Biogas Production # of Employees
Bio Town Ag Reynolds 4500 cattle, 1600 swine Yes 70,364,700 kWh/yr N/A 14 (0)
Bos Dairy Digester Fair Oaks 3600 dairy No      
Green Cow Power Goshen 1500 dairy Yes   907,200 ft3/day  
Herrema Dairy Digester Fair Oaks 3750 dairy No      
Hidden View Digester Rensselaer 3500 dairy No   7,073,700 kWh/yr  
Homestead Dairy Digester Plymouth 2100 dairy Fats, oils, greases 7,446,000 kWh/yr    
Prairie’s Edge Dairy Site 2, Digester 1 Fair Oaks 12000 dairy No 7,818,300 kWh/yr 1,200,000 ft3/day  
Prairie’s Edge Dairy Site 2, Digester 1 Fair Oaks 4300 dairy No      
Waste No Energy Digester Monticello 300 cattle, 8000 swine Agricultural Residues; Fats, Oils, Greases; Food Processing Wastes; Food Wastes 8,370,000 kWh/yr 408,000 ft3/day  
Windy Ridge Dairy Digester Fair Oaks 7000 animals No      

How electric or gas is made for an AD?

Natural gas and electricity are two of the possible end products for ADs. Through further refinement and purification, both RNG and biogas are renewable fuels. Additionally, the solid byproduct of ADs is reusable in feed, fertilizer, and animal bedding. Because of this continuous cycle of use and come from renewable resources like the dairy and hog industries, anaerobic digesters are highly efficient processors with multiple products.

Anaerobic Digestion Products, Biogas Treatment, and End Uses
image credit: https://www.epa.gov/lmop/renewable-natural-gas