Published on June 29th, 2014 | by Guest Contributor
Manure from NC Pigs Turned into BioGas
We suck at math, so maybe you guys can figure this out. If 30,000 hogs create enough manure biogas to run a 600-kilowatt generator, how much electricity can 10 million hogs produce?
We’re only asking because the new 600-kW Storms Hog Farm manure biogas-to-electricity plant in North Carolina has just officially passed its proof-of-concept stage, leaving the field wide open to build even bigger hog manure biogas plants in the state. With a hog population of 10 million the last time we checked, that could add up to quite a bit of biogas, possibly contributing to a sustainable fuel cell market in the region, including fuel cells for electric vehicles.
Biggest Hog Manure Biogas Plant In North Carolina
The Storms Hog Farm facility was developed by AgPower Partners LLC. For those of you familiar with the topic there are a few other hog manure-to-biogas ventures up and running in North Carolina, but according to APP Storms Farm is the largest fully operational one in the state.
The Storms facility actually started up last fall, but it held a ribbon-cutting this past Friday to put the official seal on its operation at proof-of-concept level, marking 90 days of sustained operation at peak or nearly peak capacity.
At that rate, the facility sends enough electricity into the grid to offset the consumption of 300 average homes.
The heart of the operation is the proprietary Two-Stage Mixed Plug FlowTM anaerobic digester from a company called DVO, Inc.
For those of you who are new to the topic, manure biogas is emitted from the tiny microorganisms that digest (aka decompose) the organic matter in manure. Anaerobic refers to bacteria that live in oxygen-free environments, hence the anaerobic digester.
The difference between allowing manure to decompose in lagoons or open fields versus enclosing the operation in a digester is striking.
According to DVO, the digesters reduce emissions of methane-rich biogas by about 90 percent compared to disposal on land or in fields.
Once the microorganisms have done their work, the remaining solids can be used as soil enhancer without the baggage that raw manure has. Unlike raw manure the digested solids are nearly free of pathogens (“almost undetectable” according to APP), and there is “virtually no odor.”
DVO’s proprietary process also involves removing extra phosphorus and ammonia nitrogen, which helps to make the case for using the digested solids as a fertilizer while reducing the risk of nutrient overload in local waterways.
Hog Manure Biogas Is Not As Easy As It Sounds
We’ve spilled quite a bit of enthusiastic ink over livestock manure biogas, but although the technology is available, getting it to the point of commercial viability can be a challenge.
In 2008, for example, hog giant Smithfield sold off a hog manure biogas facility in Utah that failed to perform as expected. Apparently the farm’s high-efficiency hog raising strategies, including diet, breeding, and water use, resulted in a decrease in the nutrient content of the manure.
Since less nutrients translate into less biogas, there goes the profitability of your biogas facility.
The breeding angle in particular could pose some interesting challenges for the future. Our sister site Planetsave, for example, has reported on a new “enviropig,” bred specifically to generate manure that is safer for land application. However, a move in that direction doesn’t necessarily translate into manure that is more efficient for biogas generation.
Plenty O’ Reasons For Manure Biogas
On the other hand, direct profitability is just one driver for making manure-to-energy operations a standard feature of the livestock operation of the future.
Another important motivator is the avoidance of fines for unsound manure disposal practices, as Smithfield found out the hard way back in 2010 (for the record, the hog farms involved in that action were owned by Premium Standard Farms, which Smithfield absorbed in 2007).
The electricity produced by biogas can be used onsite or sold to the grid, helping to reduce utility costs, and the opportunity for renewable energy credits can also help to offset the cost of the operation.
For the Storms Hog Farm biogas facility, that’s what makes the operation viable.
The project got off the ground in 2010 with a grant from the North Carolina Department of Energy, as part of a much broader program to tackle the state’s exploding hog waste disposal problem.
Here’s how it works out for Storms Hog Farm, according to APP’s press materials:
North Carolina Electric Membership Corporation purchases all of the electricity under a long-term contract. This revenue, combined with tipping fees for processing the off-site agricultural waste, the sale of the carbon credits andRenewable Energy Certificates, and the sale of other valuable byproducts, support the sustained operation and maintenance of the facility.
As for that fuel cell connection, check out the toilet of the future invented by CalTech students for the Bill and Melinda Gates Foundation “Reinvent the Toilet” challenge last year, which converts human manure to biogas for fuel cells.
Originally posted on Cleantechnica.